Case Studies case studies pdf
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
NRC 2012 Models for
Estimating Nutrient
Requirements of Pigs
Case studies
1
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Contents
1
INTRODUCTION AND GENERAL OVERVIEW ...............................................................6
2
GESTATING SOWS ..............................................................................................................6
Effects of Stage of Gestation and Feeding Regimen on Nutrient Requirements....................6
Effects of parity and anticipated litter size on nutrient requirements .....................................9
Effects of housing and environmental conditions on nutrient requirements ........................10
Matching observed with predicted performance ..................................................................12
3
LACTATING SOWS............................................................................................................14
Effects of parity and litter growth rate on nutrient requirements .........................................14
Effects of sow body weight and litter growth rate on nutrient requirements .......................16
Effect of environmental temperature on feed intake and sow performance .........................18
Effect of feed intake on sow performance and nutrient requirements ..................................19
4
GROWING-FINISHING PIGS ............................................................................................21
Effect of body weight on nutrient requirements ...................................................................21
Effects of gender, immunization against GnRH and feeding Ractopamine on nutrient
requirements of finishing pigs ...........................................................................................23
2
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Interactive effect of pig genotype and feeding level on nutrient requirements during the
early finisher phase ............................................................................................................24
Matching observed with predicted performance – based on mean intakes, days to slaughter,
and probe back fat thickness ..............................................................................................26
Matching observed with predicted performance – based on observed feed intake and
growth curves (FOR ADVANCED USERS ONLY) ........................................................28
5
DIET FORMULATION AND FEEDING PROGRAMS.....................................................31
Use of the Feeding Program & Diet Formulation module....................................................31
Evaluate the environmental impact of alternative feeding programs ...................................35
Evaluate the effect of using high-fiber coproducts on threonine requirements and energy
utilization in finishing pigs ................................................................................................37
3
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
1
Introduction and General Overview
These case studies have been prepared to help users understand the use and application of
the NRC (2012) models to estimate nutrient requirements of swine.
A detailed description of the models is provided in Chapter 8 of the 11th revised edition
of Nutrient Requirements of Swine published by the U.S. National Research Council (NRC,
2012). Appendix 1 of that publication also contains a User Guide. A slightly updated version of
the User Guide can be downloaded with the models.
The four models (one for starting pigs, one for growing-finishing pigs, one for gestating
sows, and one for lactating sows) are combined into a Microsoft Excel workbook and stored in
the file NRC swine 2012 v1. The program also includes a database with nutrient profiles of
ingredients and a means to formulate diets and generate feeding programs. The nutrient database
and formulation module allow the amounts of nutrients supplied in specified feeding programs to
be compared with estimated requirements. The program also enables nitrogen, phosphorus, and
carbon losses into the environment to be estimated.
Before operating the model, it is recommended that the original program is saved and a
copy is used. Doing this will protect the settings in the original version of the program. To
operate the models, start Excel and open the file NRC swine 2012 v1.
The program contains macros. Depending on the security settings on your computer you
may have to enable macros as outlined in the User Guide.
4
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
When the program opens, the user is asked to agree with the warning about the program’s
use. The user is then directed automatically to the Main Menu, which allows access to the
models and the module Review Feeding Programs. The ingredient database and the feed
formulation system are accessed via the Review Feeding Programs button.
The program allows alternative systems for energy (DE, ME, and DE), amino acids
(standardized ileal digestible [SID], apparent ileal digestible [AID], and total content [applicable
to corn and soybean meal-based diets only]), and phosphorus (standardized total tract digestible
[STTD], apparent total tract digestible [ATTD], and total content [applicable to corn and
soybean meal-based diets only]. Energy and nutrient systems are specified on the Main Menu.
In the models, determinants of nutrient requirements can be entered, and current levels of
performance can be specified. After changing the model inputs and before exploring nutrient
requirements, calculations must be executed by clicking the Calculate button at the top of the
screen. During these calculations nutrient utilization parameters and estimates of nutrient
requirements are generated and stored for individual days.
Once model calculations are executed, estimates of animal performance, key aspects of
nutrient utilization, and nutrient requirements can be explored simply by entering the body
weight range (starting and growing-finishing pigs) or time period (for gestating and lactating
sows) .
Results are presented in graphs and summarized in printable reports.
Notes:
Changes that are made to model inputs, diet compositions, and feeding programs are used
for the current session only. To store changes to inputs for use in future sessions, simply save the
entire file, using a new name.
When using the models to estimate nutrient requirements, there is no need to evaluate
feeding programs. When first using the program it is recommended that No is selected following
Do you wish to evaluate a feeding program? on the Main Menu.
5
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
2
Gestating Sows
EFFECTS OF STAGE OF GESTATION AND FEEDING REGIMEN ON NUTRIENT
REQUIREMENTS
First, ensure that the appropriate nutrient systems are chosen. To do this, navigate to the
Main Menu and under Step I use the three pull-down menus to select ME for energy, SID for
amino acids, and STTD for phosphorus. Under Step II, select No following Do you wish to
evaluate a feeding program?
Under Step III select Gestating Sows. A new window will appear with navigation and
action buttons at the top of the screen. To ensure that the default values are entered for model
inputs, click Enter Default Inputs. The following information should be displayed under
INPUTS:
Diet characteristics that affect nutrient requirements
3300
9.0
Metabolizable energy (ME) content, kcal/kg
Fermentable fiber content, %
Sow performance:
165
2
114
13.5
1.4
Sow body weight at breeding, kg
Parity
Gestation length, day
Anticipated litter size
Anticipated birth weight, kg/pig
Feed intake
0.95
Feed intake / (feed intake + feed wastage)
Start day
1
6
Copyright © National Academy of Sciences. All rights reserved.
30
60
90
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
2.210
Feed intake + feed wastage, kg/day
Consider housing conditions & environmental
temperature?
Match observed with predicted performance?
2.210
2.210
2.610
No
No
Now, all necessary information has been entered to generate estimates of nutrient
requirements for the default scenario. To do this, click Calculate at the top of the screen. The
screen has now automatically moved to the results and you may scroll down or to the right of the
screen to display results more fully. Results can be explored for various time periods during
gestation.
Under the headings RESULTS and Range in days for estimating nutrient requirements
first enter 1 for Initial day and 114 for Final day to explore the mean performance and nutrient
requirements for the entire gestation period. Results for this range of days will be calculated
automatically. To return to data-entry fields click Home at the top of the screen.
Enter key result and nutrient requirements in the first column in the table below for
Scenario 1 (default) and day 1 to 114. To explore performance and nutrient requirements during
early (day 1 to 89) and late gestation (day 90 to 114), enter these two combinations of Initial
day, and Final day and record the results in the 2nd and 3rd column under Scenario 1 in the
Table below.
Scenario
Results
Initial day
Final day
Average feed intake + feed wastage, kg/day
Average total body weight gain, g/day
Average maternal body weight gain, g/day
Avg. maternal body protein deposition, g/day
Average protein deposition in conceptus, g/day
Average maternal body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
Average STTD phosphorus requirement, %
Average STTD phosphorus requirement, g/day
1 (default)
2 (constant daily intake)
1
114
1
89
90
114
1
114
1
89
90
114
526
539
481
524
572
354
96
98
90
94
115
19
7
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
How can the large changes in performance and daily Lys and phosphorus requirements
during gestation be explained?
In the model, default feed intake is increased starting on day 90 of gestation. Does this
seem appropriate? What are the potential consequences of low or negative energy and protein
balances in the (maternal) sow’s body?
(In answering these questions you may view the graphs, click Graph at the top of the
screen and scroll across the graphs, if needed. To return to results you can click Home at the top
of the screen.)
The default increase in feed intake starting on day 90 of gestation is a deviation from
using a constant level of feed intake throughout gestation. To evaluate the effect of maintaining a
constant feeding level go to the Feed intake area under INPUTS, and change all four values for
Feed intake + feed wastage to 2.298. Then redo the calculations, click Calculate, and record the
results for the three different combinations of Initial day and Final day in the table above and
under Scenario 2 (constant daily intake).
These two scenarios result in very similar average feed intake + feed wastage over the
entire gestation period (day 1 and 114).
What scenario is likely to better supports sow performance? Explain why?
Is it appropriate to use the same diet for feeding sows during early and late gestation?
Why or why not?
8
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
EFFECTS OF PARITY AND ANTICIPATED LITTER SIZE ON NUTRIENT
REQUIREMENTS
Click Enter Default Inputs and ensure that the information in the INPUT area is not
changed from that used for section Effect of Stage of Gestation and Feeding Regimen on Nutrient
Requirements. Again, housing conditions will not be considered and observed and predicted
performance will not be matched.
For each scenario listed in the table below, enter the inputs in the model in areas with the
heading Sow performance and Feed intake. Always use a gestation length of 114 days and an
anticipated birth weight of 1.4 kg/pig. For feed intake, always use two feeding levels; they are
increased automatically by 0.4 kg/day at day 90. After inputs are entered for each scenario, click
Calculate and then record results in the table below. Note that the Enter Default Inputs relates
to parity 2.
Scenario
1
2
3
4
140
1
12.5
2.13
2.53
165
2
13.5
2.21
2.61
205
4
13.5
2.20
2.60
205
4
15.5
2.08
2.48
Inputs
Sow body weight at breeding, kg
Parity
Anticipated litter size
Feed intake + feed wastage, kg/day – start day 1
Feed intake + feed wastage, kg/day – start day 90
Results
Scenario
1
Initial day
1
Final day
89
Change in body weight during gestation, kg
Average total body weight gain, g/day
578
Average maternal body weight gain, g/day
Avg. maternal body protein deposition, g/day
Average protein deposition in conceptus, g/day
Average maternal body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
10.6
Avg. SID Thr requirements, ratio to SID Lys x 100
2
90
114
65
543
16.7
1
89
3
539
90
114
60
481
9.2
15.1
1
89
4
410
90
114
45
340
1
89
416
90
114
45
313
6.7
11.5
6.6
11.9
What contributes to the differences in g/day and % of diet requirements for SID lysine
and STTD phosphorus across parity?
9
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Why does the required SID Thr to SID Lys ratio change across parity?
Is it appropriate to use the same diets to feed sows of different parity? Why or why not?
Discuss the importance of anticipated litter size when establishing optimum feeding
levels and dietary nutrient levels?
EFFECTS OF HOUSING AND ENVIRONMENTAL CONDITIONS ON NUTRIENT
REQUIREMENTS
Click Enter Default Inputs. You can double check the accuracy of the inputs by running
the model after these are entered (click Calculate) to obtain the results presented for Scenario 2
in the table in section Effect of parity and anticipated litter size on nutrient requirements.
To explore the effect of environmental conditions select Yes following Consider housing
conditions & environmental temperature? New data-entry fields will appear; enter or select the
following inputs:
240
Individual
Sow standing, min/day
Housing
o
20
Effective environmental temperature, C
Now run the program (click Calculate), under RESULTS and Range in days for
estimating nutrient requirements enter 1 for Initial day and 114 for Final day, and enter the
10
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
results in the table below under Scenario 1. Then, alter some of the environmental conditions to
generate alternative scenarios; run the program for each scenario and record the results.
Scenario
1
Inputs
2.21
2
3
Feed intake+wastage on start day 1,
2.21
2.21
kg/day
360
240
Sow standing, min/day
240
Housing system
Indiv.
Indiv.
Indiv.
Floor type
o
10
Effective environmental temperature, C
20
20
Results (Initial day: 1; Final day: 114)
Avg. total body weight gain, g/day
526
490
284
Average maternal body weight gain, g/day
Avg. maternal body protein deposition,
g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
10.4
10.4
7.4
4
5
6
2.21
2.21
2.21
360
Group
Other
20
360
Group
Other
10
360
Group
Straw
10
490
409
463
10.4
9.4
10.1
What is the effect of increasing the amount of time sows spend standing (Scenario 2 vs.
1) and decreasing environmental temperature (Scenario 3 vs. 1) on sow body weight gain and
lysine requirements in % of diet and g/day? Why do these changes occur?
In a similar manner discuss how and why group housing (Scenario 4 vs. 1),
environmental temperature for group-housed sows (Scenario 5 vs. 1), and floor type (Scenario 6
vs. 5) affect sow body weight gain and lysine requirements in % of diet and g/day. Why is the
response to changes in environmental temperature different for group- vs. individually housed
sows?
Obviously, group-housed sows require more energy to support increased activity, and
when sows are kept on concrete floors in a cool environment extra energy is needed to maintain
body temperature. Now, by trial-and-error, find out how much more feed is required for group11
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
housed sows that are kept on concrete flooring and at an environmental temperature of 10oC. To
do this, enter the appropriate inputs and increase Feed intake + wastage, run the program, and
monitor in the Average total sow body weight gain until it is within 5 g/day of Scenario 1.
New Feed intake + feed wastage on start day 1:
Revised SID Lys requirements:
0.45
2.55
kg/day
% of diet, and
11.2
g/day
Based on these considerations, discuss how and why environmental conditions should be
considered when establishing optimum feeding levels and target dietary nutrient levels.
MATCHING OBSERVED WITH PREDICTED PERFORMANCE
When observed sow performance is similar to model-generated predicted performance,
confidence in estimated nutrient requirements is increased. To explore this, make sure to return
to the starting scenario (Section Effect of Stage of Gestation and Feeding Regimen on Nutrient
Requirements; click Enter Default Inputs and ensure No is selected following Consider
housing conditions and environmental temperature?).
Now select Yes following Match observed with predicted performance? New data fields
will appear; ensure that the following values are entered:
Body weight at farrowing, kg
P2 back fat at breeding, mm
P2 back fat at farrowing, mm
Observed
230
18
20.5
Adjustment to maintenance energy requirements, %
a
Absolute adjustment to maternal body N gain ,
g/extraMcal ME intake
Model Predicted
0.0
0.00
a
This parameter affects the composition of maternal body weight change (ratio between body protein and body
lipid deposition). A higher value reflects a leaner sow genotype and means that sows will preferentially deposit
more body protein (or lean body mass) and less body lipid. In the model, the default value is determined by
parity only and differences between sow genotypes are not considered.
Now change the two adjustment parameters for the scenarios that are listed in the table
below and record the results. Remember to run the model (click Calculate) after inputs have
changed for each of the scenarios.
12
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Scenario
1
Inputs
Adjustment to maintenance energy requirements, %
0.0
Abs. adjustm. to maternal body N gain,
g/extra Mcal ME intake
0.00
Results (Initial day: 1; Final day: 114)
Model-predicted body weight at farrowing, kg
225
Model-predicted P2 back fat at farrowing
Avg. total body protein deposition, incl. conceptus, g/day
Average maternal body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
10.4
2
3
4
-5.0
-5.0
-5.0
0.00
0.25
0.50
227.4
228.9
230.4
10.4
11.0
11.5
Which of these scenarios most accurately predicts sow body weight and back fat
changes?
How do these adjustments to maintenance energy requirements and to maternal body N
gain per unit of extra energy intake affect SID lysine requirements in % of diet and g/day?
Within this context, discuss the importance of accurately predicting sow performance for
estimating nutrient requirements of gestating sows.
13
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
3
Lactating sows
EFFECTS OF PARITY AND LITTER GROWTH RATE ON NUTRIENT
REQUIREMENTS
Make sure that the appropriate nutrient systems are chosen. To do this, navigate to the
Main Menu and under Step I use the three pull down menus to select ME for energy, SID for
amino acids, and STTD for phosphorus. Under Step II, select No following Do you wish to
evaluate a feeding program?
Under Step III select Lactating Sows. A new window will appear with navigation and
action buttons at the top of the screen. To ensure that the default values are entered for model
inputs, click Enter Default Inputs. The following information should be displayed under the
heading INPUTS:
Diet characteristics that affect nutrient requirements
3300
11.0
Metabolizable energy (ME) content, kcal/kg
Fermentable fiber content, %
Sow performance:
Sow body weight after farrowing, kg
Lactation length, days
Average number of pigs nursed
Daily piglet weight gain, g; mean over entire lactationa
210
21
11.5
230
Feed intake:
0.95
Yes
2 and higher
Feed intake / (feed intake + feed wastage)
Use model predicted feed intakes
Parity number
14
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
No
No
Consider environmental temperature?
Match observed with predicted performance?:
a
The user may choose to use mean piglet weight at weaning as an alternative means to estimate milk
production.
Now all relevant information has been entered to generate estimates of nutrient
requirements for the default scenario. To do this, click Calculate. The screen has now
automatically moved to the results. Results can be explored for various time periods during
lactation. To return to data-entry fields click Home at the top of the screen.
Under the headings RESULTS and Range in days for estimating nutrient requirements
enter 1 for Initial day and 21 for Final day to explore average daily performance and average
nutrient requirements during the entire lactation period. Enter key result and nutrient
requirements in the first column in the table below (Scenario 1; Parity 2 and higher).
To explore nutrient requirements of Parity 1 lactating sows enter the values shown in the
table above and for Scenario 2 (Parity 1) in the appropriate fields under INPUTS and either
Sow performance or Feed intake, run the model (click Calculate) and enter the results in the
table below.
15
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Scenario
1 (Parity 2+)
Inputs
Sow body weight at farrowing, kg
210
Lactation length, days
21
Average number of pigs nursed
11.5
Daily piglet weight gain, g; mean over entire lactation
230
Parity number
2 and higher
Results (Initial day: 1; Final day: 21)
Average feed intake + feed wastage, kg/day
Average sow body weight gain, g/day
-276
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
Average STTD phosphorus requirement, %
Average STTD phosphorus requirement, g/day
48.9
2 (Parity 1)
175
21
11
230
1
-368
45.7
What contributes to the difference in dietary SID Lys requirements (% of diet) between
Parity 1 and Parity 2+ sows? (There is no need to rerun the model to explore the effects of each
input individually; these differences will be explored in more detail in subsequent sections.)
EFFECTS OF SOW BODY WEIGHT AND LITTER GROWTH RATE ON NUTRIENT
REQUIREMENTS
Increase either sow body weight at farrowing or the number of pigs nursed and daily
piglet weight gain in similar proportions and assess the effects of these changes on Lys and
phosphorus requirements.
Return to the default input parameters (click Enter Default Inputs). The results for
Scenario 1 should be identical to those presented for Scenario 1 in section Effects of parity and
litter growth rate on nutrient requirements. Then change inputs as specified in the table below
and record the results, after you have run the model (click Calculate).
16
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Scenario
1
2
Inputs
246
Sow body weight at farrowing, kg
210
Lactation length, days
21
21
Average number of pigs nursed
11.5
11.5
Daily piglet weight gain, g; mean over entire lactation
230
230
Parity
2+
2+
Results (Initial day: 1; Final day: 21)
Average feed intake + feed wastage, kg/day
Average sow body weight gain, g/day
-276
-379
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
Average SID Lys requirement, %
Average STTD phosphorus requirement, %
0.78
0.76
3
4
5
210
21
13.5
230
2+
210
21
11.5
270
2+
210
21
13.5
270
2+
-717
-755
-1280
0.85
0.84
0.92
Which of these factors has the smallest and largest effect on nutrient requirements:
increases in sow body weight, the number of pigs nursed, or daily piglet weight gain? Explain
why.
Obviously sows under Scenario 5 loose a considerable amount of body weight during
lactation. Discuss the potential effect of these body weight losses on subsequent reproductive
losses.
What management tools are available to reduce these sow body weight losses?
17
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
EFFECT OF ENVIRONMENTAL TEMPERATURE ON FEED INTAKE AND SOW
PERFORMANCE
Feed intake in nursing sows is known to vary between sow units and influenced by
various factors associated with the sow genotype and the environment. For example, in section
Effects of parity and litter growth rate on nutrient requirements parity was shown to affect feed
intake. When the model is used to predict feed intake, it is assumed that feed intake is lower in
Parity 1 lactating sows than in Parity 2+ lactating sows.
To explore the effect of environmental temperature with the lactating sow model, click
Enter Default Inputs and in the section with the heading Feed intake, select Yes for Consider
environmental temperature? Then, vary environmental temperature using the values presented
in the table below and record its effect on feed intake, sow body weight gain, and milk
production after running the model (click Calculate after inputs have changed).
Scenario
1
Sow body weight at farrowing, kg
210
Lactation length, day
21
Average number of pigs nursed
11.5
Daily piglet weight gain, g; mean over entire lactation
230
Parity
2+
o
18
Environmental temperature, C
Results (Initial day: 1; Final day: 21)
Average feed intake + feed wastage, kg/day
6.613
Average sow body weight gain, g/day
-276
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
2
3
210
21
11.5
230
2+
22
210
21
11.5
230
2+
26
6.190
-473
5.629
-733
What is the effect of environmental temperature on sow feed intake, milk production and
sow body weight losses?
Does it seem reasonable to assume that environmental temperature does not affect milk
production and litter performance? Why or why not? (The rational for the approach used to
18
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
represent relationships between environmental temperature, feed intake, and milk production is
described on pages 142 to 144 in Nutrient Requirements of Swine.)
EFFECT OF FEED INTAKE ON SOW PERFORMANCE AND NUTRIENT
REQUIREMENTS
To explore the effect of feed intake on nutrient requirements, first enter the default values
(click Enter Default Inputs) and in the section with the heading Feed intake select No for Use
model predicted feed intakes? New data-entry fields will appear; ensure that the following
information is entered:
Intake specification
Mean daily feed intake + feed wastage, kg/day
Mean diet ME content, kcal/kg
Mean
5.000
3300
Then vary Mean daily feed intake + feed wastage using the values presented in the table
below and record its effect on sow body weight gain and nutrient requirements, after you have
run the model (click Calculate).
Scenario
1
2
3
4
210
21
11.5
230
2+
6.00
210
21
11.5
230
2+
7.00
210
21
11.5
230
2+
8.00
-561
-103
325
Inputs
Sow body weight at farrowing, kg
210
Lactation length, day
21
Average number of pigs nursed
11.5
Daily piglet weight gain, g; mean over entire lactation
230
Parity
2+
5.00
Mean daily feed intake + wastage, kg/day
Results (Initial day: 1; Final day: 21)
Average sow body weight gain, g/day
-1026
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
Average SID Lys requirement, %
19
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Average SID Lys requirement, g/day
41.8
46.2
50.6
55.2
How does feed intake relate to milk production, sow body weight changes, and average
sow whole body protein and lipid deposition?
How does mean daily feed intake+ feed wastage affect nutrient requirements, expressed
as % of diet and g/day? Explain.
20
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
4
Growing-Finishing Pigs
EFFECT OF BODY WEIGHT ON NUTRIENT REQUIREMENTS
Make sure that the appropriate nutrient systems are chosen. To do this, navigate to the
Main Menu and under Step I use the three pull down menus to select ME for energy, SID for
amino acids, and STTD for phosphorus. Under Step II, select No following Do you wish to
evaluate a feeding program?
Under Step III select Growing-finishing pigs. A new window will appear with navigation
and action buttons at the top of the screen. To ensure that the default values are entered for
model inputs, click Enter Default Inputs. The following information should be displayed under
the heading INPUTS:
Diet characteristics that affect nutrient requirements
3300
10.5
Metabolizable energy (ME) content, kcal/kg
Fermentable fiber content, %
Gender
Gilts & Barrows
Feed intake
0.95
Feed intake / (feed intake + feed wastage)
Options
Use predicted intake as model input
Gilts & barrows
No
No
Gender
Consider environmental temperature?
Consider pig space?
21
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Immunized against GnRH?
No
Feed Ractopamine?
No
Whole body protein deposition (Pd) pattern
Options
Gender
Use default Pd pattern for each gender
Gilts & barrows
Match observed with predicted performance?
No
Present observed growth performance?
Options
Do not consider
Now all relevant information has been entered to generate estimates of nutrient
requirements. To do this, click Calculate at the top of the screen. The screen has now
automatically moved to the results and you may scroll to the right of the screen to more fully
display results. Results can be explored for various body weight ranges, that are defined under
RESULTS and Range in body weight for estimating nutrient requirements. Results for this
range in body weight will be calculated automatically. To return to data-entry fields click Home
at the top of the screen.
Body weight range
1
2
3
4
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight, kg
25
50
75
100
Final body weight, kg
50
75
100
135
Results
Average feed intake + wastage , kg/day
1.583
2.230
2.637
2.933
Average body weight gain, g/day
Avg. whole body protein deposition, g/day
Average whole body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
14.8
17.9
18.3
16.9
Avg. SID Thr requirement, Ratio to Lys × 100
How do feed intake, whole body protein deposition, and nutrient requirements expressed
as % and g/day and Thr as a ratio to Lys change with increasing body weight? Discuss the
implications for developing phase-feeding programs.
22
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
EFFECTS OF GENDER, IMMUNIZATION AGAINST GNRH, AND FEEDING
RACTOPAMINE ON NUTRIENT REQUIREMENTS OF FINISHING PIGS
Click Enter Default Inputs to return to initial values.
To explore the effect of gender (selected following Gender under INPUTS), feeding
Ractopamine (select Yes following Feed Ractopamine? under INPUTS), or immunizing entire
male pigs against GnRH to control boar taint (select Entire males following Gender and Yes
following Immunized against GnRH? under INPUTS) on nutrient requirements, run the
scenarios described in the table below. Simply enter the inputs that are specified below and in the
footnotes.
In the section RESULTS and Range in body weight for estimating nutrient
requirements, enter 100 for Initial body weight, kg and 130 for Final body weight, kg.
For each scenario, run the model (click Calculate) and record the results.
Viewing the graphs (click Graphs and then on Home to return to inputs and results) may
help in the interpretation of the results and answering the following questions.
Scenario
Gender
Gilts
Barrows
Inputs
Gilts
Barrows
Barrows
fed
Ractoa
pamine
Entire
males
Immunized males
Barrows
Entire
Entire
males
males
b
Yes
Immunized against GnRH?
No
No
No
No
Feed Ractopamine?
No
No
Yes*
No
No
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 100 kg; Final body weight: 130kg
Results
Probe back fat at slaughter body weight, mm
Average feed intake + wastage, kg/day
2.822
3.013
2.991
2.733
3.076
Average body weight gain, g/day
Avg. whole body protein deposition, g/day
Average whole body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
17.4
16.8
19.4
19.3
18.9
Avg. SID Thr requirem., Ratio to Lys × 100
a
When selecting Yes for Feed Ractopamine? new data-entry fields will appear. For Initial body weight (i.e.,
when Ractopamine is first fed) enter 115; for Number of levels (in step-up program) enter 1; for Diet level 1
enter 5.
b
When selecting Yes for Immunized against GnRH?, a new data-entry field will appear. For Body weight at
2nd injection enter 105.
23
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
How do nutrient requirements differ among gilts, barrows, and entire males? How is this
related to feed intake and whole-body protein deposition? Based on nutrient requirements,
discuss the value of split-gender feeding.
How does feeding Ractopamine to barrows influence growth performance, feed intake,
and nutrient requirements?
How does immunizing entire male pigs against GnRH influence growth performance,
feed intake, and nutrient requirements?
INTERACTIVE EFFECT OF PIG GENOTYPE AND FEEDING LEVEL ON NUTRIENT
REQUIREMENTS DURING THE EARLY FINISHER PHASE
Restore the original inputs (click Enter Default Inputs) and run the scenarios described
in the table below. Simply enter the inputs that are specified below, run the model (click
Calculate) and record the results.
To enter values for Actual mean feed intake + waste, under INPUTS, in the section Feed
intake and following Options select Use observed intake as model input. New data-entry fields
will appear. For Actual mean intake or intake curve select Mean, for Actual mean feed intake
+ wastage enter the value specified in the table (e.g. 2.300 for Scenario 1). For Mean diet ME
content, Initial body weight, and Final body weight the following values should be displayed:
3300, 25, and 125.
24
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
To enter values for User defined mean Pd, under INPUTS, in the section Whole body
protein deposition (Pd) pattern and following Options select Specify mean Pd and Gender. For
gender, Gilts & barrows will then be displayed, as specified in the section Gender. For User
defined mean Pd potential enter the value specified in the table (e.g., 120 for Scenario 1).
In the section RESULTS and Range in body weight for estimating nutrient
requirements, enter 100 for Initial body weight, kg and 125 for Final body weight, kg.
Scenario
1
Actual mean feed intake + wastage, kg/day
User defined mean Pd, g/day
Inputs
2.300
120
2.100
120
2
1.950
120
3
2.300
160
4
2.100
160
5
1.950
160
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 100 kg; Final body weight: 125kg
Results
Probe back fat at slaughter body weight, mm
Avg. whole body protein deposition, g/day
Average whole body lipid deposition, g/day
Average feed intake + wastage , kg/day
Average body weight gain, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
16.3
16.1
15.8
18.8
18.7
17.5
Avg. SID Thr requirem., ratio to Lys × 100
At the highest level of feed intake how and why do lysine requirements differ between
the two pig genotypes?
How do Lys requirements expressed as g/day and % of diet change with reductions in
feed intake for the two genotypes of pigs (e.g., low and high mean Pd)?
How can you explain the differences in response to energy intake for these two types of
pigs? (View the Whole body protein gain graph to help with the interpretation).
25
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
How and why do Thr requirements, expressed as a ratio to Lys × 100, change with
feeding level and type of pig?
MATCHING OBSERVED WITH PREDICTED PERFORMANCE – BASED ON MEAN
INTAKES, DAYS TO SLAUGHTER, AND PROBE BACK FAT THICKNESS
When observed growing-finishing pig performance is similar to model-predicted
performance, confidence in estimated nutrient requirements is increased. To explore this, be sure
to return to the starting scenario (click Enter Default Inputs).
Under the header Feed intake and Options select Use observed intake as model input,
and ensure that Mean is entered following Actual mean intake or intake curve , and that the
values 2.300, 3300, 25.0, and 125.0 are entered in the data-entry fields for Actual mean intake +
wastage, Mean diet ME content, Initial body weight, and Final body weight, respectively.
Under the header Whole body protein deposition (Pd) pattern and Options select Specify
mean Pd and gender, and ensure that Gilts & barrows is displayed following Gender and the
value 120 is entered following User defined mean Pd potential.
Following Match observed with predicted performance? select Yes and ensure that the
values 0 and 1 are entered for Adjustment to maintenance energy requirements and Adjustment
to slope of Pd versus E intake, respectively.
Following Present observed growth performance? and Options select Specify days from
starting to slaughter body weight and ensure that the values 25, 125, 16.5, and 119, are entered
in the data-entry fields for Starting body weight, Slaughter body weight, Probe back fat at
slaughter body weight, and Days from starting to slaughter body weight.
Now vary User defined mean Pd potential and Adjustment to maintenance energy
requirements as indicated under inputs in the table below, and run the model (click Calculate)
and record the results.
26
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
For each of the scenarios, also record Lys requirements, as % and g/day, for pigs between
100 and 125 kg body weight. In the section RESULTS and Range in body weight for estimating
nutrient requirements, enter 100 for Initial body weight, kg and 125 for Final body weight, kg
to evaluate Lys requirements.
Observed
1
Performance
Predicted, scenario
2
3
4
Inputs
User defined mean Pd potential, g/day
Adjustm. to maintenance energy requirem,%
-
120
0
130
0
140
0
RESULTS, section: Overall performance; between starting and slaughter body weight
Starting body weight, kg
25
Slaughter body weight, kg
125
Probe back fat at slaughter body weight, mm
16.5
Average body weight gain, g/day
840
a
Average overall lean tissue gain, g/day
318
278
302
326
140
13
318
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 100 kg; Final body weight: 125kg
RESULTS, section: Average SID AA, calcium and phosphorus requirements
Average SID Lys requirement, %
Average SID Lys requirement, g/day
a
Lean gain is calculated from estimated carcass lean yield that is calculated from probe back fat. The equations that
are used to estimate carcass lean yield from carcass weight and probe back fat thickness vary among packing plants
and can be adjusted. To make adjustments, click the Carcass evaluation under Inputs and section Match observed
with predicted performance?
How are average body weight gain and back fat thickness affected by changes in mean
Pd potential and maintenance energy requirements? How can this be explained?
How and why does overall lean tissue gain change when maintenance energy
requirements are increased? How does this affect digestible Lys requirements between 100 and
27
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
125 kg body weight? (HINT: use the Whole body protein deposition (Pd) graph to better
understand how maintenance energy requirements affect whole body protein deposition at the
various stages of growth; you may also evaluate the effect of maintenance energy requirements
on Whole body protein deposition in RESULTS section Performance and diet characteristics
for 25 to 50 vs. 100 to 125 kg body weight).
MATCHING OBSERVED WITH PREDICTED PERFORMANCE – BASED ON
OBSERVED FEED INTAKE AND GROWTH CURVES (FOR ADVANCED USERS
ONLY)
A limitation of the approach used in section Matching observed with predicted
performance – based on mean intakes, days to slaughter, and probe back fat thickness is that
observed and model-predicted performance is matched based on mean intakes and days to
slaughter and probe back fat. It is thus possible that observed feed intake or growth rates could
be higher at lower body weights and lower at higher body weights, or vice versa, without
affecting mean values. This can have implications for estimated nutrient requirements. It is more
accurate to match performance based on feed intake and growth curves (i.e., to characterize
performance at various stages of growth).
To explore matching performance based on curves, make sure to return to the starting
scenario (click Enter Default Inputs).
Under the header Feed intake and Options select Use observed intake as model input,
and ensure that Curve is selected following Actual mean intake or intake curve, and that
Polynomial is selected following Curve Type. The values 310.4, 173.41, -1.1024, and
0.00002664 should already be entered in the data-entry fields for a, b, c, and d, respectively.
Under the header Whole body protein deposition (Pd) pattern and Options select Specify
PdMax and start PdMax decline, and ensure that the values 135 and 90 are entered following
PdMax Body weight at start PdMax decline, respectively.
28
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Following Match observed with predicted performance? select Yes and ensure that the
values 0 and 1 are entered for Adjustment to maintenance energy requirements and Adjustment
to slope of Pd versus E intake, respectively.
Following Present observed growth performance? and options select Specify growth
curve; Polynomial function and ensure that the values 25.0, 125, and 19.5 are presented in the
data-entry fields for Starting body weight, Slaughter body weight, and Probe back fat at
slaughter, respectively. NOTE that for Probe back fat at slaughter the value 19.5 has to be
entered manually.
For the polynomial growth function the values 24.5, 0.57, 0.0044, and -0.000018 should
already be entered in the data-entry fields for a, b, c, and d, respectively.
Now vary PdMax, Body weight at start PdMax decline, and Adjustment to slope of Pd
versus E intake as indicated under inputs in the table below, run the model (click Calculate) and
record the results for overall performance (RESULTS section Overall performance; between
starting and slaughter body weight) .
In the section RESULTS and Range in body weight for estimating nutrient
requirements, enter 25 for Initial body weight, kg and 50 for Final body weight, kg to evaluate
lysine requirements (RESULTS section Average SID AA, calcium and phosphorus
requirements).
Also, after each change view the Body weight gain graph to monitor how changes to the
model inputs improve the match between observed and model-predicted body weight gains at the
different stages of growth (e.g., at the low, intermediate, and high body weight).
Observed
Performance
Predicted, scenario
1
2
3
4
Inputs
PdMax, g/day
Body weight at start PdMax decline, kg
Adjustm. to slope of Pd versus E intake, fraction
-
135
90
1
145
90
1
145
75
1
RESULTS, section: Overall performance; between starting and slaughter body weight
Starting body weight, kg
24.5
Slaughter body weight, kg
125.2
Probe back fat at slaughter body weight, mm
19.5
Average body weight gain, g/day
839
Average overall lean tissue gain, g/day
300
298
321
313
29
Copyright © National Academy of Sciences. All rights reserved.
145
75
0.9
300
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 25 kg; Final body weight: 50kg
RESULTS, section: Average SID AA, calcium and phosphorus requirements
Average SID Lys requirement, %
0.95
0.98
0.98
Average SID Lys requirement, g/day
-
0.89
Consider how PdMax, Body weight at start PdMax decline and Adjustm. to slope of
Pd versus E intake can be adjusted to more closely match observed and model-predicted body
weight gains at the various stages of growth and nutrient requirements, especially at the lower
body weight.
30
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
5
Diet Formulation and Feeding Programs
USE OF THE FEEDING PROGRAM & DIET FORMULATION MODULE
Feeding programs must be specified in order to compare levels of nutrients that are
supplied with the diets with model-generated estimates of nutrient requirements. Specified
feeding programs are also required to estimate losses of nitrogen, phosphorus, and carbon into
the environment.
Feeding programs provide information on dietary nutrient levels and the order in which
diets are fed. The diet formulation program can be used to calculate dietary nutrient levels from
feed ingredient compositions. Within feeding programs, diet changes are identified by either day
(gestating sows, lactating sows, and growing-finishing pigs) or body weight (growing-finishing
pigs only). Feeding levels are specified elsewhere, as inputs for the different models.
To illustrate the use of the diet formulation system and the approach for developing
feeding programs, make sure that the appropriate nutrient systems are chosen. To do this,
navigate to Main Menu and under Step I use the three pull down menus to select ME for energy,
SID for amino acids, and STTD for ph
NRC 2012 Models for
Estimating Nutrient
Requirements of Pigs
Case studies
1
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Contents
1
INTRODUCTION AND GENERAL OVERVIEW ...............................................................6
2
GESTATING SOWS ..............................................................................................................6
Effects of Stage of Gestation and Feeding Regimen on Nutrient Requirements....................6
Effects of parity and anticipated litter size on nutrient requirements .....................................9
Effects of housing and environmental conditions on nutrient requirements ........................10
Matching observed with predicted performance ..................................................................12
3
LACTATING SOWS............................................................................................................14
Effects of parity and litter growth rate on nutrient requirements .........................................14
Effects of sow body weight and litter growth rate on nutrient requirements .......................16
Effect of environmental temperature on feed intake and sow performance .........................18
Effect of feed intake on sow performance and nutrient requirements ..................................19
4
GROWING-FINISHING PIGS ............................................................................................21
Effect of body weight on nutrient requirements ...................................................................21
Effects of gender, immunization against GnRH and feeding Ractopamine on nutrient
requirements of finishing pigs ...........................................................................................23
2
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Interactive effect of pig genotype and feeding level on nutrient requirements during the
early finisher phase ............................................................................................................24
Matching observed with predicted performance – based on mean intakes, days to slaughter,
and probe back fat thickness ..............................................................................................26
Matching observed with predicted performance – based on observed feed intake and
growth curves (FOR ADVANCED USERS ONLY) ........................................................28
5
DIET FORMULATION AND FEEDING PROGRAMS.....................................................31
Use of the Feeding Program & Diet Formulation module....................................................31
Evaluate the environmental impact of alternative feeding programs ...................................35
Evaluate the effect of using high-fiber coproducts on threonine requirements and energy
utilization in finishing pigs ................................................................................................37
3
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
1
Introduction and General Overview
These case studies have been prepared to help users understand the use and application of
the NRC (2012) models to estimate nutrient requirements of swine.
A detailed description of the models is provided in Chapter 8 of the 11th revised edition
of Nutrient Requirements of Swine published by the U.S. National Research Council (NRC,
2012). Appendix 1 of that publication also contains a User Guide. A slightly updated version of
the User Guide can be downloaded with the models.
The four models (one for starting pigs, one for growing-finishing pigs, one for gestating
sows, and one for lactating sows) are combined into a Microsoft Excel workbook and stored in
the file NRC swine 2012 v1. The program also includes a database with nutrient profiles of
ingredients and a means to formulate diets and generate feeding programs. The nutrient database
and formulation module allow the amounts of nutrients supplied in specified feeding programs to
be compared with estimated requirements. The program also enables nitrogen, phosphorus, and
carbon losses into the environment to be estimated.
Before operating the model, it is recommended that the original program is saved and a
copy is used. Doing this will protect the settings in the original version of the program. To
operate the models, start Excel and open the file NRC swine 2012 v1.
The program contains macros. Depending on the security settings on your computer you
may have to enable macros as outlined in the User Guide.
4
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
When the program opens, the user is asked to agree with the warning about the program’s
use. The user is then directed automatically to the Main Menu, which allows access to the
models and the module Review Feeding Programs. The ingredient database and the feed
formulation system are accessed via the Review Feeding Programs button.
The program allows alternative systems for energy (DE, ME, and DE), amino acids
(standardized ileal digestible [SID], apparent ileal digestible [AID], and total content [applicable
to corn and soybean meal-based diets only]), and phosphorus (standardized total tract digestible
[STTD], apparent total tract digestible [ATTD], and total content [applicable to corn and
soybean meal-based diets only]. Energy and nutrient systems are specified on the Main Menu.
In the models, determinants of nutrient requirements can be entered, and current levels of
performance can be specified. After changing the model inputs and before exploring nutrient
requirements, calculations must be executed by clicking the Calculate button at the top of the
screen. During these calculations nutrient utilization parameters and estimates of nutrient
requirements are generated and stored for individual days.
Once model calculations are executed, estimates of animal performance, key aspects of
nutrient utilization, and nutrient requirements can be explored simply by entering the body
weight range (starting and growing-finishing pigs) or time period (for gestating and lactating
sows) .
Results are presented in graphs and summarized in printable reports.
Notes:
Changes that are made to model inputs, diet compositions, and feeding programs are used
for the current session only. To store changes to inputs for use in future sessions, simply save the
entire file, using a new name.
When using the models to estimate nutrient requirements, there is no need to evaluate
feeding programs. When first using the program it is recommended that No is selected following
Do you wish to evaluate a feeding program? on the Main Menu.
5
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
2
Gestating Sows
EFFECTS OF STAGE OF GESTATION AND FEEDING REGIMEN ON NUTRIENT
REQUIREMENTS
First, ensure that the appropriate nutrient systems are chosen. To do this, navigate to the
Main Menu and under Step I use the three pull-down menus to select ME for energy, SID for
amino acids, and STTD for phosphorus. Under Step II, select No following Do you wish to
evaluate a feeding program?
Under Step III select Gestating Sows. A new window will appear with navigation and
action buttons at the top of the screen. To ensure that the default values are entered for model
inputs, click Enter Default Inputs. The following information should be displayed under
INPUTS:
Diet characteristics that affect nutrient requirements
3300
9.0
Metabolizable energy (ME) content, kcal/kg
Fermentable fiber content, %
Sow performance:
165
2
114
13.5
1.4
Sow body weight at breeding, kg
Parity
Gestation length, day
Anticipated litter size
Anticipated birth weight, kg/pig
Feed intake
0.95
Feed intake / (feed intake + feed wastage)
Start day
1
6
Copyright © National Academy of Sciences. All rights reserved.
30
60
90
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
2.210
Feed intake + feed wastage, kg/day
Consider housing conditions & environmental
temperature?
Match observed with predicted performance?
2.210
2.210
2.610
No
No
Now, all necessary information has been entered to generate estimates of nutrient
requirements for the default scenario. To do this, click Calculate at the top of the screen. The
screen has now automatically moved to the results and you may scroll down or to the right of the
screen to display results more fully. Results can be explored for various time periods during
gestation.
Under the headings RESULTS and Range in days for estimating nutrient requirements
first enter 1 for Initial day and 114 for Final day to explore the mean performance and nutrient
requirements for the entire gestation period. Results for this range of days will be calculated
automatically. To return to data-entry fields click Home at the top of the screen.
Enter key result and nutrient requirements in the first column in the table below for
Scenario 1 (default) and day 1 to 114. To explore performance and nutrient requirements during
early (day 1 to 89) and late gestation (day 90 to 114), enter these two combinations of Initial
day, and Final day and record the results in the 2nd and 3rd column under Scenario 1 in the
Table below.
Scenario
Results
Initial day
Final day
Average feed intake + feed wastage, kg/day
Average total body weight gain, g/day
Average maternal body weight gain, g/day
Avg. maternal body protein deposition, g/day
Average protein deposition in conceptus, g/day
Average maternal body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
Average STTD phosphorus requirement, %
Average STTD phosphorus requirement, g/day
1 (default)
2 (constant daily intake)
1
114
1
89
90
114
1
114
1
89
90
114
526
539
481
524
572
354
96
98
90
94
115
19
7
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
How can the large changes in performance and daily Lys and phosphorus requirements
during gestation be explained?
In the model, default feed intake is increased starting on day 90 of gestation. Does this
seem appropriate? What are the potential consequences of low or negative energy and protein
balances in the (maternal) sow’s body?
(In answering these questions you may view the graphs, click Graph at the top of the
screen and scroll across the graphs, if needed. To return to results you can click Home at the top
of the screen.)
The default increase in feed intake starting on day 90 of gestation is a deviation from
using a constant level of feed intake throughout gestation. To evaluate the effect of maintaining a
constant feeding level go to the Feed intake area under INPUTS, and change all four values for
Feed intake + feed wastage to 2.298. Then redo the calculations, click Calculate, and record the
results for the three different combinations of Initial day and Final day in the table above and
under Scenario 2 (constant daily intake).
These two scenarios result in very similar average feed intake + feed wastage over the
entire gestation period (day 1 and 114).
What scenario is likely to better supports sow performance? Explain why?
Is it appropriate to use the same diet for feeding sows during early and late gestation?
Why or why not?
8
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
EFFECTS OF PARITY AND ANTICIPATED LITTER SIZE ON NUTRIENT
REQUIREMENTS
Click Enter Default Inputs and ensure that the information in the INPUT area is not
changed from that used for section Effect of Stage of Gestation and Feeding Regimen on Nutrient
Requirements. Again, housing conditions will not be considered and observed and predicted
performance will not be matched.
For each scenario listed in the table below, enter the inputs in the model in areas with the
heading Sow performance and Feed intake. Always use a gestation length of 114 days and an
anticipated birth weight of 1.4 kg/pig. For feed intake, always use two feeding levels; they are
increased automatically by 0.4 kg/day at day 90. After inputs are entered for each scenario, click
Calculate and then record results in the table below. Note that the Enter Default Inputs relates
to parity 2.
Scenario
1
2
3
4
140
1
12.5
2.13
2.53
165
2
13.5
2.21
2.61
205
4
13.5
2.20
2.60
205
4
15.5
2.08
2.48
Inputs
Sow body weight at breeding, kg
Parity
Anticipated litter size
Feed intake + feed wastage, kg/day – start day 1
Feed intake + feed wastage, kg/day – start day 90
Results
Scenario
1
Initial day
1
Final day
89
Change in body weight during gestation, kg
Average total body weight gain, g/day
578
Average maternal body weight gain, g/day
Avg. maternal body protein deposition, g/day
Average protein deposition in conceptus, g/day
Average maternal body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
10.6
Avg. SID Thr requirements, ratio to SID Lys x 100
2
90
114
65
543
16.7
1
89
3
539
90
114
60
481
9.2
15.1
1
89
4
410
90
114
45
340
1
89
416
90
114
45
313
6.7
11.5
6.6
11.9
What contributes to the differences in g/day and % of diet requirements for SID lysine
and STTD phosphorus across parity?
9
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Why does the required SID Thr to SID Lys ratio change across parity?
Is it appropriate to use the same diets to feed sows of different parity? Why or why not?
Discuss the importance of anticipated litter size when establishing optimum feeding
levels and dietary nutrient levels?
EFFECTS OF HOUSING AND ENVIRONMENTAL CONDITIONS ON NUTRIENT
REQUIREMENTS
Click Enter Default Inputs. You can double check the accuracy of the inputs by running
the model after these are entered (click Calculate) to obtain the results presented for Scenario 2
in the table in section Effect of parity and anticipated litter size on nutrient requirements.
To explore the effect of environmental conditions select Yes following Consider housing
conditions & environmental temperature? New data-entry fields will appear; enter or select the
following inputs:
240
Individual
Sow standing, min/day
Housing
o
20
Effective environmental temperature, C
Now run the program (click Calculate), under RESULTS and Range in days for
estimating nutrient requirements enter 1 for Initial day and 114 for Final day, and enter the
10
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
results in the table below under Scenario 1. Then, alter some of the environmental conditions to
generate alternative scenarios; run the program for each scenario and record the results.
Scenario
1
Inputs
2.21
2
3
Feed intake+wastage on start day 1,
2.21
2.21
kg/day
360
240
Sow standing, min/day
240
Housing system
Indiv.
Indiv.
Indiv.
Floor type
o
10
Effective environmental temperature, C
20
20
Results (Initial day: 1; Final day: 114)
Avg. total body weight gain, g/day
526
490
284
Average maternal body weight gain, g/day
Avg. maternal body protein deposition,
g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
10.4
10.4
7.4
4
5
6
2.21
2.21
2.21
360
Group
Other
20
360
Group
Other
10
360
Group
Straw
10
490
409
463
10.4
9.4
10.1
What is the effect of increasing the amount of time sows spend standing (Scenario 2 vs.
1) and decreasing environmental temperature (Scenario 3 vs. 1) on sow body weight gain and
lysine requirements in % of diet and g/day? Why do these changes occur?
In a similar manner discuss how and why group housing (Scenario 4 vs. 1),
environmental temperature for group-housed sows (Scenario 5 vs. 1), and floor type (Scenario 6
vs. 5) affect sow body weight gain and lysine requirements in % of diet and g/day. Why is the
response to changes in environmental temperature different for group- vs. individually housed
sows?
Obviously, group-housed sows require more energy to support increased activity, and
when sows are kept on concrete floors in a cool environment extra energy is needed to maintain
body temperature. Now, by trial-and-error, find out how much more feed is required for group11
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
housed sows that are kept on concrete flooring and at an environmental temperature of 10oC. To
do this, enter the appropriate inputs and increase Feed intake + wastage, run the program, and
monitor in the Average total sow body weight gain until it is within 5 g/day of Scenario 1.
New Feed intake + feed wastage on start day 1:
Revised SID Lys requirements:
0.45
2.55
kg/day
% of diet, and
11.2
g/day
Based on these considerations, discuss how and why environmental conditions should be
considered when establishing optimum feeding levels and target dietary nutrient levels.
MATCHING OBSERVED WITH PREDICTED PERFORMANCE
When observed sow performance is similar to model-generated predicted performance,
confidence in estimated nutrient requirements is increased. To explore this, make sure to return
to the starting scenario (Section Effect of Stage of Gestation and Feeding Regimen on Nutrient
Requirements; click Enter Default Inputs and ensure No is selected following Consider
housing conditions and environmental temperature?).
Now select Yes following Match observed with predicted performance? New data fields
will appear; ensure that the following values are entered:
Body weight at farrowing, kg
P2 back fat at breeding, mm
P2 back fat at farrowing, mm
Observed
230
18
20.5
Adjustment to maintenance energy requirements, %
a
Absolute adjustment to maternal body N gain ,
g/extraMcal ME intake
Model Predicted
0.0
0.00
a
This parameter affects the composition of maternal body weight change (ratio between body protein and body
lipid deposition). A higher value reflects a leaner sow genotype and means that sows will preferentially deposit
more body protein (or lean body mass) and less body lipid. In the model, the default value is determined by
parity only and differences between sow genotypes are not considered.
Now change the two adjustment parameters for the scenarios that are listed in the table
below and record the results. Remember to run the model (click Calculate) after inputs have
changed for each of the scenarios.
12
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Scenario
1
Inputs
Adjustment to maintenance energy requirements, %
0.0
Abs. adjustm. to maternal body N gain,
g/extra Mcal ME intake
0.00
Results (Initial day: 1; Final day: 114)
Model-predicted body weight at farrowing, kg
225
Model-predicted P2 back fat at farrowing
Avg. total body protein deposition, incl. conceptus, g/day
Average maternal body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
10.4
2
3
4
-5.0
-5.0
-5.0
0.00
0.25
0.50
227.4
228.9
230.4
10.4
11.0
11.5
Which of these scenarios most accurately predicts sow body weight and back fat
changes?
How do these adjustments to maintenance energy requirements and to maternal body N
gain per unit of extra energy intake affect SID lysine requirements in % of diet and g/day?
Within this context, discuss the importance of accurately predicting sow performance for
estimating nutrient requirements of gestating sows.
13
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
3
Lactating sows
EFFECTS OF PARITY AND LITTER GROWTH RATE ON NUTRIENT
REQUIREMENTS
Make sure that the appropriate nutrient systems are chosen. To do this, navigate to the
Main Menu and under Step I use the three pull down menus to select ME for energy, SID for
amino acids, and STTD for phosphorus. Under Step II, select No following Do you wish to
evaluate a feeding program?
Under Step III select Lactating Sows. A new window will appear with navigation and
action buttons at the top of the screen. To ensure that the default values are entered for model
inputs, click Enter Default Inputs. The following information should be displayed under the
heading INPUTS:
Diet characteristics that affect nutrient requirements
3300
11.0
Metabolizable energy (ME) content, kcal/kg
Fermentable fiber content, %
Sow performance:
Sow body weight after farrowing, kg
Lactation length, days
Average number of pigs nursed
Daily piglet weight gain, g; mean over entire lactationa
210
21
11.5
230
Feed intake:
0.95
Yes
2 and higher
Feed intake / (feed intake + feed wastage)
Use model predicted feed intakes
Parity number
14
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
No
No
Consider environmental temperature?
Match observed with predicted performance?:
a
The user may choose to use mean piglet weight at weaning as an alternative means to estimate milk
production.
Now all relevant information has been entered to generate estimates of nutrient
requirements for the default scenario. To do this, click Calculate. The screen has now
automatically moved to the results. Results can be explored for various time periods during
lactation. To return to data-entry fields click Home at the top of the screen.
Under the headings RESULTS and Range in days for estimating nutrient requirements
enter 1 for Initial day and 21 for Final day to explore average daily performance and average
nutrient requirements during the entire lactation period. Enter key result and nutrient
requirements in the first column in the table below (Scenario 1; Parity 2 and higher).
To explore nutrient requirements of Parity 1 lactating sows enter the values shown in the
table above and for Scenario 2 (Parity 1) in the appropriate fields under INPUTS and either
Sow performance or Feed intake, run the model (click Calculate) and enter the results in the
table below.
15
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Scenario
1 (Parity 2+)
Inputs
Sow body weight at farrowing, kg
210
Lactation length, days
21
Average number of pigs nursed
11.5
Daily piglet weight gain, g; mean over entire lactation
230
Parity number
2 and higher
Results (Initial day: 1; Final day: 21)
Average feed intake + feed wastage, kg/day
Average sow body weight gain, g/day
-276
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
Average STTD phosphorus requirement, %
Average STTD phosphorus requirement, g/day
48.9
2 (Parity 1)
175
21
11
230
1
-368
45.7
What contributes to the difference in dietary SID Lys requirements (% of diet) between
Parity 1 and Parity 2+ sows? (There is no need to rerun the model to explore the effects of each
input individually; these differences will be explored in more detail in subsequent sections.)
EFFECTS OF SOW BODY WEIGHT AND LITTER GROWTH RATE ON NUTRIENT
REQUIREMENTS
Increase either sow body weight at farrowing or the number of pigs nursed and daily
piglet weight gain in similar proportions and assess the effects of these changes on Lys and
phosphorus requirements.
Return to the default input parameters (click Enter Default Inputs). The results for
Scenario 1 should be identical to those presented for Scenario 1 in section Effects of parity and
litter growth rate on nutrient requirements. Then change inputs as specified in the table below
and record the results, after you have run the model (click Calculate).
16
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Scenario
1
2
Inputs
246
Sow body weight at farrowing, kg
210
Lactation length, days
21
21
Average number of pigs nursed
11.5
11.5
Daily piglet weight gain, g; mean over entire lactation
230
230
Parity
2+
2+
Results (Initial day: 1; Final day: 21)
Average feed intake + feed wastage, kg/day
Average sow body weight gain, g/day
-276
-379
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
Average SID Lys requirement, %
Average STTD phosphorus requirement, %
0.78
0.76
3
4
5
210
21
13.5
230
2+
210
21
11.5
270
2+
210
21
13.5
270
2+
-717
-755
-1280
0.85
0.84
0.92
Which of these factors has the smallest and largest effect on nutrient requirements:
increases in sow body weight, the number of pigs nursed, or daily piglet weight gain? Explain
why.
Obviously sows under Scenario 5 loose a considerable amount of body weight during
lactation. Discuss the potential effect of these body weight losses on subsequent reproductive
losses.
What management tools are available to reduce these sow body weight losses?
17
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
EFFECT OF ENVIRONMENTAL TEMPERATURE ON FEED INTAKE AND SOW
PERFORMANCE
Feed intake in nursing sows is known to vary between sow units and influenced by
various factors associated with the sow genotype and the environment. For example, in section
Effects of parity and litter growth rate on nutrient requirements parity was shown to affect feed
intake. When the model is used to predict feed intake, it is assumed that feed intake is lower in
Parity 1 lactating sows than in Parity 2+ lactating sows.
To explore the effect of environmental temperature with the lactating sow model, click
Enter Default Inputs and in the section with the heading Feed intake, select Yes for Consider
environmental temperature? Then, vary environmental temperature using the values presented
in the table below and record its effect on feed intake, sow body weight gain, and milk
production after running the model (click Calculate after inputs have changed).
Scenario
1
Sow body weight at farrowing, kg
210
Lactation length, day
21
Average number of pigs nursed
11.5
Daily piglet weight gain, g; mean over entire lactation
230
Parity
2+
o
18
Environmental temperature, C
Results (Initial day: 1; Final day: 21)
Average feed intake + feed wastage, kg/day
6.613
Average sow body weight gain, g/day
-276
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
2
3
210
21
11.5
230
2+
22
210
21
11.5
230
2+
26
6.190
-473
5.629
-733
What is the effect of environmental temperature on sow feed intake, milk production and
sow body weight losses?
Does it seem reasonable to assume that environmental temperature does not affect milk
production and litter performance? Why or why not? (The rational for the approach used to
18
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
represent relationships between environmental temperature, feed intake, and milk production is
described on pages 142 to 144 in Nutrient Requirements of Swine.)
EFFECT OF FEED INTAKE ON SOW PERFORMANCE AND NUTRIENT
REQUIREMENTS
To explore the effect of feed intake on nutrient requirements, first enter the default values
(click Enter Default Inputs) and in the section with the heading Feed intake select No for Use
model predicted feed intakes? New data-entry fields will appear; ensure that the following
information is entered:
Intake specification
Mean daily feed intake + feed wastage, kg/day
Mean diet ME content, kcal/kg
Mean
5.000
3300
Then vary Mean daily feed intake + feed wastage using the values presented in the table
below and record its effect on sow body weight gain and nutrient requirements, after you have
run the model (click Calculate).
Scenario
1
2
3
4
210
21
11.5
230
2+
6.00
210
21
11.5
230
2+
7.00
210
21
11.5
230
2+
8.00
-561
-103
325
Inputs
Sow body weight at farrowing, kg
210
Lactation length, day
21
Average number of pigs nursed
11.5
Daily piglet weight gain, g; mean over entire lactation
230
Parity
2+
5.00
Mean daily feed intake + wastage, kg/day
Results (Initial day: 1; Final day: 21)
Average sow body weight gain, g/day
-1026
Average sow whole body protein deposition, g/day
Average sow whole body lipid deposition, g/day
Average milk production, kg/day
Average SID Lys requirement, %
19
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Average SID Lys requirement, g/day
41.8
46.2
50.6
55.2
How does feed intake relate to milk production, sow body weight changes, and average
sow whole body protein and lipid deposition?
How does mean daily feed intake+ feed wastage affect nutrient requirements, expressed
as % of diet and g/day? Explain.
20
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
4
Growing-Finishing Pigs
EFFECT OF BODY WEIGHT ON NUTRIENT REQUIREMENTS
Make sure that the appropriate nutrient systems are chosen. To do this, navigate to the
Main Menu and under Step I use the three pull down menus to select ME for energy, SID for
amino acids, and STTD for phosphorus. Under Step II, select No following Do you wish to
evaluate a feeding program?
Under Step III select Growing-finishing pigs. A new window will appear with navigation
and action buttons at the top of the screen. To ensure that the default values are entered for
model inputs, click Enter Default Inputs. The following information should be displayed under
the heading INPUTS:
Diet characteristics that affect nutrient requirements
3300
10.5
Metabolizable energy (ME) content, kcal/kg
Fermentable fiber content, %
Gender
Gilts & Barrows
Feed intake
0.95
Feed intake / (feed intake + feed wastage)
Options
Use predicted intake as model input
Gilts & barrows
No
No
Gender
Consider environmental temperature?
Consider pig space?
21
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Immunized against GnRH?
No
Feed Ractopamine?
No
Whole body protein deposition (Pd) pattern
Options
Gender
Use default Pd pattern for each gender
Gilts & barrows
Match observed with predicted performance?
No
Present observed growth performance?
Options
Do not consider
Now all relevant information has been entered to generate estimates of nutrient
requirements. To do this, click Calculate at the top of the screen. The screen has now
automatically moved to the results and you may scroll to the right of the screen to more fully
display results. Results can be explored for various body weight ranges, that are defined under
RESULTS and Range in body weight for estimating nutrient requirements. Results for this
range in body weight will be calculated automatically. To return to data-entry fields click Home
at the top of the screen.
Body weight range
1
2
3
4
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight, kg
25
50
75
100
Final body weight, kg
50
75
100
135
Results
Average feed intake + wastage , kg/day
1.583
2.230
2.637
2.933
Average body weight gain, g/day
Avg. whole body protein deposition, g/day
Average whole body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
14.8
17.9
18.3
16.9
Avg. SID Thr requirement, Ratio to Lys × 100
How do feed intake, whole body protein deposition, and nutrient requirements expressed
as % and g/day and Thr as a ratio to Lys change with increasing body weight? Discuss the
implications for developing phase-feeding programs.
22
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
EFFECTS OF GENDER, IMMUNIZATION AGAINST GNRH, AND FEEDING
RACTOPAMINE ON NUTRIENT REQUIREMENTS OF FINISHING PIGS
Click Enter Default Inputs to return to initial values.
To explore the effect of gender (selected following Gender under INPUTS), feeding
Ractopamine (select Yes following Feed Ractopamine? under INPUTS), or immunizing entire
male pigs against GnRH to control boar taint (select Entire males following Gender and Yes
following Immunized against GnRH? under INPUTS) on nutrient requirements, run the
scenarios described in the table below. Simply enter the inputs that are specified below and in the
footnotes.
In the section RESULTS and Range in body weight for estimating nutrient
requirements, enter 100 for Initial body weight, kg and 130 for Final body weight, kg.
For each scenario, run the model (click Calculate) and record the results.
Viewing the graphs (click Graphs and then on Home to return to inputs and results) may
help in the interpretation of the results and answering the following questions.
Scenario
Gender
Gilts
Barrows
Inputs
Gilts
Barrows
Barrows
fed
Ractoa
pamine
Entire
males
Immunized males
Barrows
Entire
Entire
males
males
b
Yes
Immunized against GnRH?
No
No
No
No
Feed Ractopamine?
No
No
Yes*
No
No
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 100 kg; Final body weight: 130kg
Results
Probe back fat at slaughter body weight, mm
Average feed intake + wastage, kg/day
2.822
3.013
2.991
2.733
3.076
Average body weight gain, g/day
Avg. whole body protein deposition, g/day
Average whole body lipid deposition, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
17.4
16.8
19.4
19.3
18.9
Avg. SID Thr requirem., Ratio to Lys × 100
a
When selecting Yes for Feed Ractopamine? new data-entry fields will appear. For Initial body weight (i.e.,
when Ractopamine is first fed) enter 115; for Number of levels (in step-up program) enter 1; for Diet level 1
enter 5.
b
When selecting Yes for Immunized against GnRH?, a new data-entry field will appear. For Body weight at
2nd injection enter 105.
23
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
How do nutrient requirements differ among gilts, barrows, and entire males? How is this
related to feed intake and whole-body protein deposition? Based on nutrient requirements,
discuss the value of split-gender feeding.
How does feeding Ractopamine to barrows influence growth performance, feed intake,
and nutrient requirements?
How does immunizing entire male pigs against GnRH influence growth performance,
feed intake, and nutrient requirements?
INTERACTIVE EFFECT OF PIG GENOTYPE AND FEEDING LEVEL ON NUTRIENT
REQUIREMENTS DURING THE EARLY FINISHER PHASE
Restore the original inputs (click Enter Default Inputs) and run the scenarios described
in the table below. Simply enter the inputs that are specified below, run the model (click
Calculate) and record the results.
To enter values for Actual mean feed intake + waste, under INPUTS, in the section Feed
intake and following Options select Use observed intake as model input. New data-entry fields
will appear. For Actual mean intake or intake curve select Mean, for Actual mean feed intake
+ wastage enter the value specified in the table (e.g. 2.300 for Scenario 1). For Mean diet ME
content, Initial body weight, and Final body weight the following values should be displayed:
3300, 25, and 125.
24
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
To enter values for User defined mean Pd, under INPUTS, in the section Whole body
protein deposition (Pd) pattern and following Options select Specify mean Pd and Gender. For
gender, Gilts & barrows will then be displayed, as specified in the section Gender. For User
defined mean Pd potential enter the value specified in the table (e.g., 120 for Scenario 1).
In the section RESULTS and Range in body weight for estimating nutrient
requirements, enter 100 for Initial body weight, kg and 125 for Final body weight, kg.
Scenario
1
Actual mean feed intake + wastage, kg/day
User defined mean Pd, g/day
Inputs
2.300
120
2.100
120
2
1.950
120
3
2.300
160
4
2.100
160
5
1.950
160
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 100 kg; Final body weight: 125kg
Results
Probe back fat at slaughter body weight, mm
Avg. whole body protein deposition, g/day
Average whole body lipid deposition, g/day
Average feed intake + wastage , kg/day
Average body weight gain, g/day
Average SID Lys requirement, %
Average SID Lys requirement, g/day
16.3
16.1
15.8
18.8
18.7
17.5
Avg. SID Thr requirem., ratio to Lys × 100
At the highest level of feed intake how and why do lysine requirements differ between
the two pig genotypes?
How do Lys requirements expressed as g/day and % of diet change with reductions in
feed intake for the two genotypes of pigs (e.g., low and high mean Pd)?
How can you explain the differences in response to energy intake for these two types of
pigs? (View the Whole body protein gain graph to help with the interpretation).
25
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
How and why do Thr requirements, expressed as a ratio to Lys × 100, change with
feeding level and type of pig?
MATCHING OBSERVED WITH PREDICTED PERFORMANCE – BASED ON MEAN
INTAKES, DAYS TO SLAUGHTER, AND PROBE BACK FAT THICKNESS
When observed growing-finishing pig performance is similar to model-predicted
performance, confidence in estimated nutrient requirements is increased. To explore this, be sure
to return to the starting scenario (click Enter Default Inputs).
Under the header Feed intake and Options select Use observed intake as model input,
and ensure that Mean is entered following Actual mean intake or intake curve , and that the
values 2.300, 3300, 25.0, and 125.0 are entered in the data-entry fields for Actual mean intake +
wastage, Mean diet ME content, Initial body weight, and Final body weight, respectively.
Under the header Whole body protein deposition (Pd) pattern and Options select Specify
mean Pd and gender, and ensure that Gilts & barrows is displayed following Gender and the
value 120 is entered following User defined mean Pd potential.
Following Match observed with predicted performance? select Yes and ensure that the
values 0 and 1 are entered for Adjustment to maintenance energy requirements and Adjustment
to slope of Pd versus E intake, respectively.
Following Present observed growth performance? and Options select Specify days from
starting to slaughter body weight and ensure that the values 25, 125, 16.5, and 119, are entered
in the data-entry fields for Starting body weight, Slaughter body weight, Probe back fat at
slaughter body weight, and Days from starting to slaughter body weight.
Now vary User defined mean Pd potential and Adjustment to maintenance energy
requirements as indicated under inputs in the table below, and run the model (click Calculate)
and record the results.
26
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
For each of the scenarios, also record Lys requirements, as % and g/day, for pigs between
100 and 125 kg body weight. In the section RESULTS and Range in body weight for estimating
nutrient requirements, enter 100 for Initial body weight, kg and 125 for Final body weight, kg
to evaluate Lys requirements.
Observed
1
Performance
Predicted, scenario
2
3
4
Inputs
User defined mean Pd potential, g/day
Adjustm. to maintenance energy requirem,%
-
120
0
130
0
140
0
RESULTS, section: Overall performance; between starting and slaughter body weight
Starting body weight, kg
25
Slaughter body weight, kg
125
Probe back fat at slaughter body weight, mm
16.5
Average body weight gain, g/day
840
a
Average overall lean tissue gain, g/day
318
278
302
326
140
13
318
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 100 kg; Final body weight: 125kg
RESULTS, section: Average SID AA, calcium and phosphorus requirements
Average SID Lys requirement, %
Average SID Lys requirement, g/day
a
Lean gain is calculated from estimated carcass lean yield that is calculated from probe back fat. The equations that
are used to estimate carcass lean yield from carcass weight and probe back fat thickness vary among packing plants
and can be adjusted. To make adjustments, click the Carcass evaluation under Inputs and section Match observed
with predicted performance?
How are average body weight gain and back fat thickness affected by changes in mean
Pd potential and maintenance energy requirements? How can this be explained?
How and why does overall lean tissue gain change when maintenance energy
requirements are increased? How does this affect digestible Lys requirements between 100 and
27
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
125 kg body weight? (HINT: use the Whole body protein deposition (Pd) graph to better
understand how maintenance energy requirements affect whole body protein deposition at the
various stages of growth; you may also evaluate the effect of maintenance energy requirements
on Whole body protein deposition in RESULTS section Performance and diet characteristics
for 25 to 50 vs. 100 to 125 kg body weight).
MATCHING OBSERVED WITH PREDICTED PERFORMANCE – BASED ON
OBSERVED FEED INTAKE AND GROWTH CURVES (FOR ADVANCED USERS
ONLY)
A limitation of the approach used in section Matching observed with predicted
performance – based on mean intakes, days to slaughter, and probe back fat thickness is that
observed and model-predicted performance is matched based on mean intakes and days to
slaughter and probe back fat. It is thus possible that observed feed intake or growth rates could
be higher at lower body weights and lower at higher body weights, or vice versa, without
affecting mean values. This can have implications for estimated nutrient requirements. It is more
accurate to match performance based on feed intake and growth curves (i.e., to characterize
performance at various stages of growth).
To explore matching performance based on curves, make sure to return to the starting
scenario (click Enter Default Inputs).
Under the header Feed intake and Options select Use observed intake as model input,
and ensure that Curve is selected following Actual mean intake or intake curve, and that
Polynomial is selected following Curve Type. The values 310.4, 173.41, -1.1024, and
0.00002664 should already be entered in the data-entry fields for a, b, c, and d, respectively.
Under the header Whole body protein deposition (Pd) pattern and Options select Specify
PdMax and start PdMax decline, and ensure that the values 135 and 90 are entered following
PdMax Body weight at start PdMax decline, respectively.
28
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Following Match observed with predicted performance? select Yes and ensure that the
values 0 and 1 are entered for Adjustment to maintenance energy requirements and Adjustment
to slope of Pd versus E intake, respectively.
Following Present observed growth performance? and options select Specify growth
curve; Polynomial function and ensure that the values 25.0, 125, and 19.5 are presented in the
data-entry fields for Starting body weight, Slaughter body weight, and Probe back fat at
slaughter, respectively. NOTE that for Probe back fat at slaughter the value 19.5 has to be
entered manually.
For the polynomial growth function the values 24.5, 0.57, 0.0044, and -0.000018 should
already be entered in the data-entry fields for a, b, c, and d, respectively.
Now vary PdMax, Body weight at start PdMax decline, and Adjustment to slope of Pd
versus E intake as indicated under inputs in the table below, run the model (click Calculate) and
record the results for overall performance (RESULTS section Overall performance; between
starting and slaughter body weight) .
In the section RESULTS and Range in body weight for estimating nutrient
requirements, enter 25 for Initial body weight, kg and 50 for Final body weight, kg to evaluate
lysine requirements (RESULTS section Average SID AA, calcium and phosphorus
requirements).
Also, after each change view the Body weight gain graph to monitor how changes to the
model inputs improve the match between observed and model-predicted body weight gains at the
different stages of growth (e.g., at the low, intermediate, and high body weight).
Observed
Performance
Predicted, scenario
1
2
3
4
Inputs
PdMax, g/day
Body weight at start PdMax decline, kg
Adjustm. to slope of Pd versus E intake, fraction
-
135
90
1
145
90
1
145
75
1
RESULTS, section: Overall performance; between starting and slaughter body weight
Starting body weight, kg
24.5
Slaughter body weight, kg
125.2
Probe back fat at slaughter body weight, mm
19.5
Average body weight gain, g/day
839
Average overall lean tissue gain, g/day
300
298
321
313
29
Copyright © National Academy of Sciences. All rights reserved.
145
75
0.9
300
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
Specified in RESULTS and section Range in body weight for estimating nutrient requirements:
Initial body weight: 25 kg; Final body weight: 50kg
RESULTS, section: Average SID AA, calcium and phosphorus requirements
Average SID Lys requirement, %
0.95
0.98
0.98
Average SID Lys requirement, g/day
-
0.89
Consider how PdMax, Body weight at start PdMax decline and Adjustm. to slope of
Pd versus E intake can be adjusted to more closely match observed and model-predicted body
weight gains at the various stages of growth and nutrient requirements, especially at the lower
body weight.
30
Copyright © National Academy of Sciences. All rights reserved.
Nutrient Requirements of Swine: Eleventh Revised Edition: NRC 2012 Models for Estimating Nutrient Requirements of Pigs Case studies
5
Diet Formulation and Feeding Programs
USE OF THE FEEDING PROGRAM & DIET FORMULATION MODULE
Feeding programs must be specified in order to compare levels of nutrients that are
supplied with the diets with model-generated estimates of nutrient requirements. Specified
feeding programs are also required to estimate losses of nitrogen, phosphorus, and carbon into
the environment.
Feeding programs provide information on dietary nutrient levels and the order in which
diets are fed. The diet formulation program can be used to calculate dietary nutrient levels from
feed ingredient compositions. Within feeding programs, diet changes are identified by either day
(gestating sows, lactating sows, and growing-finishing pigs) or body weight (growing-finishing
pigs only). Feeding levels are specified elsewhere, as inputs for the different models.
To illustrate the use of the diet formulation system and the approach for developing
feeding programs, make sure that the appropriate nutrient systems are chosen. To do this,
navigate to Main Menu and under Step I use the three pull down menus to select ME for energy,
SID for amino acids, and STTD for ph