Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol82.Issue1-2.Nov1999:
Animal Feed Science and Technology
82 (1999) 131±142
A comparison of total and digestible amino acids
in diets for broilers and layers
D.J. Farrella,b,*, P.F. Manniona, R.A. Perez-Maldonadoa
a
The Queensland Poultry Research and Development Centre, PO Box 327,
Cleveland, Qld. 4163, Australia
b
School of Land and Food, The University of Queensland, St. Lucia, Qld 4072, Australia
Received 14 October 1998; received in revised form 17 March 1999; accepted 9 June 1999
Abstract
Eleven samples of food ingredients were analysed for their total and true digestible amino acid
content, apparent metabolisable energy and other components. Large batches of these ingredients
were retained for a broiler and a layer experiment. Four layer diets were formulated at 0.97 and 0.90
of total and digestible amino acid requirements for egg production using the analysed ingredients.
Eight broiler diets were also formulated from 1.0 to 0.91 of total and digestible amino acid
requirements in starter and finisher diets. Proximate and amino acid analyses and AME values were
within the normal range for the 11 foodstuffs. Digestibility of amino acids was high with very few
exceptions, e.g. cottonseed meal, meat and bone meal. Diets formulated on a total or digestible
amino acid basis gave no differences in egg production parameters or broiler production parameters
with no effect of level of inclusion. However, the main effects showed that diets formulated on a
total compared to a digestible amino acid basis gave better growth rate and feed conversion
efficiency in broilers. It was concluded that nutrient specifications for layers and broilers are not
sufficiently precise to be able to differentiate between 1.97 and 0.90 of requirement for egg
production or 1.0 and 0.91 for broiler growth. The use of digestible amino acids may be justified in
diet formulations only when unusual protein concentrates with low amino acid digestibility values
are used in large amounts. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Ingredient amino acid digestibility; AME values
*
Corresponding author. Tel.:61-7-3824-3081; fax.: 61-7-3824-4316
E-mail address: [email protected] (D.J. Farrell)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 8 0 - 2
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D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
1. Introduction
It is well known that not all of the amino acids in a feedingstuff are digested by the bird
and become available for protein synthesis. It is also known that there is considerable
variation between, and often within, protein sources in the digestibility of amino acids.
Furthermore, the digestibility coefficients of individual amino acids within a feedstuff
may differ considerably.
The methods used to measure amino acid digestibility vary greatly and these have been
reviewed on numerous occasions (Sibbald, 1987; Johnson, 1992; McNab, 1995; Raharjo
and Farrell, 1984a). Site of sampling material for analysis is important and the
indigestible marker used to calculate amino acid digestibility may also differ between
laboratories.
There has been some criticism of the use of excreta in order to determine amino acid
digestibility because of changes in amino acid profile due to microbial fermentation
(Terpstra, 1997; Low, 1977) even in caecectomized birds (Raharjo and Farrell, 1984b).
However, there are few tables that provide information on the digestibility of amino acids
of a wide range of feedstuffs using the same method and from the one laboratory. There
are, however, notable exceptions (Anonymous, 1989; Ravindran et al., 1998).
There have been a number of papers demonstrating the advantages of using digestible
rather than total amino acids to formulate broiler diets. These have generally used poor
quality ingredients in large amounts, such as cottonseed meal (Fernandez et al., 1995), or
over-processed meals (Fernandez and Parsons, 1996) to demonstrate an advantage. There
are very few published papers that have demonstrated a significant improvement in
practical diets for layers and for broilers formulated on the basis of digestible amino acids
when several conventional dietary ingredients have been combined.
The purpose of the two experiments reported here was to test the hypothesis that the
use of amino acid digestibility values of feedstuffs gives a significant improvement in
biological response and/or economic response compared to ingredients using total amino
acids to formulate practical layer and broiler diets using a range of foodstuffs.
2. Materials and methods
2.1. Bioassays and chemical analyses
Substantial quantities of 11 food ingredients were held in silos or bags prior to use in
poultry experiments. Samples (10 kg) were transported to Rhone-Poulenc Animal
Nutrition, Commentry, France for amino acid bioassay using adult birds (Sibbald, 1987)
with modifications (Anonymous, 1989) to determine true amino acid digestibility.
Isabrown cockerels were caecetomized and five birds per treatment were used in a Latin
square design (Green and Kiener, 1989).
The apparent metabolisable energy (AME) of the ingredients was determined with
individual laying hens using the classical, total collection method over four days. Birds
were on the experimental diets for a three-day adjustment period. There were three hens
at each level of inclusion per dietary treatment and six hens on the all-grain diets. The two
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
133
grains were included at 980 g/kg of the diet; the protein sources replaced sorghum at two
different levels; these levels depended on the ingredient. A premix, which contained
minerals and vitamins, was included at 20 g/kg of the diet. AME was calculated by
regression analysis and then extrapolating the line to the rate of inclusion of the test
ingredient of 1000 g/kg diet. Chemical analyses of the raw ingredients followed the
methods of the AOAC, 1984. Gross energy was determined in an adiabatic bomb
calorimeter.
2.2. Layer experiment
A least-cost formulation package (Feedmania) was used to construct diets using the
determined amino acid and AME values for the feedstuffs.
In the layer experiment, diets were formulated to 97% and 90% of total and of
digestible amino acid requirements (SCA, 1987; Anonymous, 1989). The composition of
the least-cost formulated diets is given in Table 1. Each diet was fed for 20 weeks to 50
individually-caged Isabrown birds housed in a saw-tooth shed with open sides and
adjustable side curtains.
Table 1
Ingredient and calculated chemical composition (g/kg as fed basis) of diets formulated on a total (T) and
digestible (D) amino acid basis at 0.97 and 0.90 of amino acid recommendations (Layer experiment)
T-97
T-90
D-97
D-90
Sorghum
Wheat
Cottonseed meal
Faba beans
Meat and bone meal B
Rapeseed meal
Soybean meal
Soybean oil
Limestone
Dical P
Sodium chloride
DL-methionine
Vitamin premixa
280
280
70
94
67
87
±
38.5
79
±
1.9
0.6
2.3
303
303
70
67
50
81
±
36.7
82
1.3
2.1
0.6
2.3
269
269
70
97
67
85
22
38
79
±
1.9
0.7
2.3
291
291
70
72
67
89
±
37
79
±
1.8
0.5
2.3
Chemical composition
Crude protein
AME (MJ/kg)
Lysine
Methionine
Methonine cyst
Tryptophan
Threonine
177
11.9
7.3
3.2
6.1
2.1
5.7
164
11.9
6.4
3.0
5.7
2.1
5.2
158
11.9
6.3
2.9
5.1
1.9
4.8
150
11.9
5.6
2.7
4.8
1.8
4.5
a
The vitamin and mineral premix added per kg of diet: 2.5 mg retionol, 75 mg cholecalciferol, 5 mg atocopherol acetate, 2 mg menadione sodium bisulfite, 1 mg thiamine, 4 mg riboflavin, 2 mg pyridoxine, 10 mg
cyanocobalamin, 1 mg folic acid, 10 mg niacin, 10 mg Ca pantothenate, 30 mg biotin, 150 mg choline, 50 mg
Mn, 50 mg Zn, 50 mg Fe, 600 mg Mo, 500 mg Co, 600 mg I, 4 mg Cu, 70 mg Se, 80 mg Banox (BHA BHT).
134
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Diets were fed ad libitum in mash form. A mineral and vitamin layer premix and a yolk
pigmentor were added to all diets at the recommended levels. Egg production was
recorded on five days each week, eggs were weighed weekly, food intake recorded
monthly and egg specific gravity measured monthly. Hens were weighed at the start and
end of the experiment.
2.3. Broiler experiment
Diets were formulated to total and digestible amino acids at 1.0, 0.97, 0.94 and 0.91 of
nutrient requirements for starter and finisher broilers (SCA, 1987), taking into account the
total and digestible amino acid requirements reported by Baker et al. (1993) and Han and
Baker (1994), and the ideal ratios of amino acids (Baker and Han, 1994; Baker et al.,
1993) for starter and finisher broilers. The starter diets were fed to 21 days and the
finisher diets from 22 to 41 days of age. The diets are shown in Tables 2 and 3.
Table 2
Broiler diets formulated to total (T) and digestible (D) amino acid requirements that range from 1.0 to 0.91 of
requirement
Starter formulations (g/kg)
T-100
T-97
T-94
T-91
D-100
D-97
D-94
D-91
270
272
50
30
35
33
40
216
35
7.3
1.4
6.7
1.9
1.5
280
281
50
30
39
30
40
198
34
7.3
1.4
6.7
1.8
1.5
290
289
50
30
30
38
40
181
33
7.2
1.4
6.7
1.7
1.5
300
298
50
30
39
30
40
162
32
7.3
1.4
6.7
1.6
1.5
280
274
50
30
30
37
40
205
35
7.2
1.4
6.7
1.8
1.5
290
282
50
30
30
37
40
188
33
7.2
1.4
6.7
1.7
1.5
290
299
50
30
30
38
40
172
32
7.2
1.4
6.7
1.6
1.5
300
307
50
30
30
38
40
155
31
7.3
1.4
6.7
1.5
1.5
Chemical composition (g/kg)
Crude protein
244
AME (MJ/kg)
12.7
Lysine
12.7
Methionine
5.6
Meth cyst
9.3
Tryptophan
3.0
Threonine
8.3
239
12.7
12.3
5.4
9.0
2.9
8.1
234
12.7
11.9
5.2
8.7
2.8
7.9
228
12.7
11.6
5.0
8.5
2.7
7.7
214
12.7
10.8
5.0
7.8
2.5
7.2
209
12.7
10.5
4.8
7.5
2.4
7.0
205
12.7
10.2
4.6
7.3
2.4
6.8
200
12.7
9.8
4.5
7.1
2.3
6.6
Ingredients
Wheat
Sorghum
Cottonseed meal
Fish meal
Meat and bone meal A
Meat and bone meal B
Sweet lupins
Soybean meal
Sunflower oil
Limestone
Sodium chloride
Vit min premixa
DL-methionine
L-lysine HCl
a
The vitamin and mineral premix added per kg of diet: 3.75 mg retinol, 112 mg D3, 30 mg a-tocopherol
acetate, 3 mg menadione sodium bisulfite, 1.5 mg thiamine, 6 mg riboflavin, 3 mg pyridoxine, 15 mg B12,
1.5 mg folic acid, 55 mg niacin, 15 mg Ca pantothanate, 180 mg biotin, 600 mg choline, 75 mg Mn, 75 mg Zn,
75 mg Fe, 900 mg Mo, 750 mg Co, 900 mg I, 6 mg Cu, 105 mg Se, 120 mg Banox.
135
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 3
Broiler diets formulated to total (T) and digestible (D) amino acid requirements that range from 1.0 to 0.91 of
requirements
Ingredients
Finisher formulations (g/kg)
T-100
T-97
T-94
T-91
D-100
D-97
D-94
D-91
300
327
65
30
54
160
±
40
8.3
2.3
1.7
6.7
2.2
1.7
300
338
68
30
53
147
±
40
8.0
2.6
2.0
6.7
2.0
1.6
300
349
72
30
51
133
±
40
9.0
2.9
2.0
6.7
2.0
1.67
300
361
75
30
50
120
±
40
8.8
3.2
1.7
6.7
1.7
1.5
300
308
±
30
54
180
66
41
7.7
2.3
1.7
6.7
1.9
1.0
300
326
±
30
54
163
65
39
7.7
2.4
1.7
6.7
1.8
1.1
300
345
±
30
54
147
65
38
7.8
2.5
1.7
6.7
1.8
1.2
300
363
±
30
54
130
64
36
7.8
2.5
1.7
6.7
1.7
1.3
Chemical composition (g/kg)
AME (MJ/kg)
13
crude protein
221
Lysine
11.1
Methionine
5.5
Meth cyst
8.8
Tryptophan
2.6
Threonine
8.2
13
217
10.8
5.0
9.0
3.0
8.0
13
212
10.4
5.0
8.0
2.0
8.0
13
208
10.1
4.9
8.0
2.4
7.4
13
199
9.4
5.0
7.7
2.3
7.0
13
194
9.1
4.9
7.5
2.2
6.8
13
189
8.9
4.7
7.2
2.2
6.6
13
184
8.6
4.6
7.0
2.1
6.4
Wheat
Sorghum
Cottonseed meal
Fish meal
Meat and bone meal (B)
Soybean meal
Sunflower meal
Sunflower oil
Limestone
Dicalcium phosphate
Sodium chloride
Vit Min premixa
DL-methionine
L-lysine HCl
a
The vitamin and mineral premix added per kg of diet: 3.75 mg retinol, 112 mg D3, 30 mg a-tocopherol
acetate, 3 mg menadione sodium bisulfite, 1.5 mg thiamine, 6 mg riboflavin, 3 mg pyridoxine, 15 mg B12,
1.5 mg folic acid, 55 mg niacin, 15 mg Ca pantothanate, 180 mg biotin, 600 mg choline, 75 mg Mn, 75 mg Zn,
75 mg Fe, 900 mg Mo, 750 mg Co, 900 mg I, 6 mg Cu, 105 mg Se, 120 mg Banox.
Chicks of a commercial strain (Cobb) were grown from one-day-old. There were four
groups each of 40 males and four groups each of 40 females per dietary treatment. Birds
were grown in floor pens with wood shavings as litter. Treatments were assigned
randomly in blocks of eight pens. Birds and food were weighed at 1, 21 and 41 days of
age. Lighting was adjusted according to commercial practice (Farrell et al., 1999).
Mortality was recorded daily.
Data were analysed using a randomised block analysis of variance model (SAS/STAT
6.04, 1987: SAS Institute Inc., Cary, North Carolina). For broiler treatments therefore all
factorial combinations of two types of amino acids and four levels of formulation; for
layer treatments, there were two types of amino acids and two levels of formulation. Main
effect means and interaction means were compared using the protected LSD test
operating at the 0.05 level of significance. Regression analysis was also undertaken (Steel
and Torrie, 1960).
The experiments were approved by the Animal Research Institute's Animal Ethics
Review Committee.
136
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
3. Results
The proximate analysis of the 11 ingredients used is given in Table 4, and their amino
acid profiles in Table 5. The two meat and bone meals contained 535 g crude protein (A),
and 596 g crude protein (B)/kg on an 'as is' basis. The true digestibility of the amino
acids for each ingredient is given in Table 6.
The two meat meals showed considerable differences in amino acid digestibility
coefficients. Digestible lysine and threonine coefficients were 0.83 and 0.86; and .75 and
0.78 for meat meals A and B, respectively. Cottonseed meal had the lowest lysine
digestibility of 0.60, followed by meat meal B of 0.78.
The apparent metabolisable energy of nine of the 11 ingredients is given in Table 7. All
compare favourably with those reported in the literature. AME values for sweet lupins
and faba beans were taken from a previous study (Perez-Maldonado et al., 1998).
3.1. Layer experiment
The overall results of the layer experiment showed no significant treatment effect on
any parameter (Table 8). There was some indication that the diet formulated to 0.90 of
total amino acid requirements gave a lower egg mass by 2 g/day compared to other
treatments.
3.2. Broiler experiment
The results are shown in Table 9. Since there was no diet sex interaction, data were
combined for the two sexes. Growth rate and FCR to 41 days were about the same as
industry standards. The only difference between dietary treatments was in FCR during the
starter phase. Mean liveweight gain at 21 days of age was significantly higher (p < 0.05)
Table 4
Proximate analysis of feed ingredients on an `as fed' basis (g/kg)
Cotton seed meal
Soybean meala
Sorghum
Lupins
Faba beans
Sunflower meal
Rapeseed
Wheat
Meat and bone meal Ab
Meat and bone meal Bc
Fish meald
a
Crude
protein
Dry
matter
Ash
Fat
Crude
fibre
392
423
108
255
237
337
285
162
535
596
657
895
890
856
904
879
915
917
898
950
950
915
63
57
16
30
33
57
35
16
233
263
152
17
27
33
57
15
16
306
14
147
87
66
121
87
26
157
91
210
82
28
nd
nd
nd
Urease activity: 0.11 mg N (from ammonia)/(g*min).
Ca 73.3, Phos 36.8.
c
Ca 86.6, Phos 42.1.
d
Ca 33.7, Phos 22.4.
b
137
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 5
Amino acid content of feed ingredients on an `as fed' basis (g/kg)
Asp
Thr
Ser
Glu
Pro
Gly
Ala
Cys
Val
Met
Ile
Leu
Tyr
Phe
Lys
His
Arg
Try
CSMa
SBMb
Sorgc
Lupd
Fabe
SFf
Rapg
Whh
MBAi
MBBj
FMk
32.6
11.5
14.3
76.3
13.5
14.6
13.5
6.3
16.9
6.1
11.9
21.2
10.5
19.1
15.4
9.7
41.3
5.8
45.8
16.1
19.7
78.4
20.7
17.0
16.9
7.2
20.3
6.3
19.2
31.3
15.6
20.3
25.1
10.0
29.5
6.4
6.9
3.3
44.3
23.2
8.6
3.0
9.2
1.7
5.3
1.6
4.3
14.1
4.2
5.4
2.1
2.1
3.8
1.2
23.3
8.7
11.5
51.8
9.1
9.6
7.8
2.5
9.8
1.7
10.0
15.9
9.5
9.1
11.1
6.2
25.7
2.5
24.6
8.2
10.5
39.5
9.5
9.4
9.1
2.8
11.0
1.9
9.8
16.9
8.1
9.7
14.8
5.5
22.0
2.1
30.2
12.3
13.7
72
14.2
17.8
13.5
5.7
17.3
7.1
14.5
21.2
9.6
15.4
11.1
7.8
27.9
5.0
18.8
11.7
11.2
54.4
17.3
13.0
11.6
7.1
14.4
6.1
11.5
19.4
8.3
11.0
16.0
7.4
17.8
4.7
7.3
4.4
6.9
52.4
16.5
6.0
5.0
3.2
6.9
2.5
5.5
10.3
5.2
7.3
3.7
3.3
7.0
2.0
37.8
17.9
20.3
65.9
40.2
64.2
34.9
5.4
23.1
9.8
16.9
32.2
13.0
16.8
27.9
8.6
34.9
4.2
40.3
18.2
22.8
71.3
52.3
83.4
42.8
5.6
24.0
8.9
16.2
33.1
13.1
17.7
27.1
8.3
41.6
3.2
57.9
28.1
24.4
86.1
24.0
35.9
38.2
5.1
32.0
17.2
28.1
46.6
21.5
25.2
48.9
20.6
35.3
8.5
a
Cottonseed meal.
Soybean meal.
Grain sorghum.
d
Sweet lupins.
e
Faba beans.
f
Sunflower meal.
g
Rapeseed meal.
h
Wheat.
i
Meat and bone meal A.
j
Meat and bone meal B.
k
Fish meal.
b
c
on the diets formulated to total (723 g) compared to digestible (709 g) amino acid
specifications. This same trend (p < 0.01) was seen at 41 days (2189 g vs. 2152 g) of age.
FCR was also worse (p 0.05) when data were combined for digestible (1.43) compared
to total (1.40) amino acids at 21 days. A similar trend (p 0.06) was observed for FCR at
41 days of age. When data at 21 days were combined, there was a significant (p < 0.05)
decline in FCR as formulations increased from 0.91 to 1.0 of amino acid specifications.
4. Discussion
There are few published experiments in which detailed chemical analysis and amino
acid profiles have been constructed for as wide a range of ingredients as those used here.
Although there was several months delay between the time the ingredients were
dispatched to France and results received, most of the individual ingredients had not
deteriorated visibly during this time. However, the two grains were later replaced with
grains of similar protein content for the broiler trial because of deterioration.
138
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 6
True digestibility coefficients of protein and amino acids in 11 feed ingredients measured using adult
caecetomised cockerels
Protein
Asp
Thr
Ser
Glu
Pro
Gly
Ala
Val
Ile
Leu
Tyr
Phe
Lys
His
Arg
Cys
Met
Try
CSMa
SBMb
Sorgc
Lupd
Fabe
SFf
Rapg
Whh
MBAi
MBBj
FMk
0.791
0.785
0.729
0.764
0.873
0.791
0.718
0.710
0.766
0.737
0.760
0.834
0.846
0.601
0.822
0.892
0.731
0.776
0.796
0.887
0.865
0.842
0.868
0.901
0.872
0.802
0.826
0.852
0.874
0.867
0.902
0.882
0.888
0.891
0.930
0.807
0.902
0.875
0.913
0.919
0.906
0.933
0.958
0.934
0.905
0.955
0.923
0.939
0.959
0.952
0.950
0.860
0.912
0.937
0.864
0.917
0.927
0.934
0.917
0.918
0.918
0.955
0.919
0.904
0.863
0.905
0.927
0.936
0.961
0.934
0.884
0.930
0.927
0.855
0.877
0.914
0.835
0.875
0.842
0.853
0.934
0.851
0.804
0.862
0.857
0.871
0.892
0.865
0.886
0.888
0.865
0.921
0.669
0.797
0.806
0.904
0.884
0.885
0.866
0.950
0.903
0.784
0.863
0.907
0.919
0.917
0.932
0.932
0.873
0.908
0.956
0.772
0.942
0.884
0.881
0.873
0.845
0.859
0.927
0.863
0.845
0.878
0.860
0.878
0.897
0.886
0.901
0.870
0.920
0.932
0.763
0.925
0.887
0.918
0.844
0.877
0.919
0.968
0.966
0.869
0.852
0.904
0.922
0.930
0.941
0.938
0.828
0.914
0.896
0.896
0.921
0.902
0.857
0.662
0.833
0.801
0.834
0.790
0.787
0.782
0.833
0.855
0.862
0.877
0.856
0.856
0.849
0.861
0.612
0.888
0.822
0.824
0.589
0.750
0.732
0.761
0.778
0.769
0.745
0.696
0.785
0.702
0.796
0.826
0.778
0.793
0.820
0.370
0.823
0.688
0.918
0.856
0.914
0.897
0.911
0.862
0.839
0.849
0.876
0.914
0.925
0.921
0.905
0.913
0.908
0.921
0.743
0.923
0.897
a
Cottonseed meal.
Soybean meal.
Grain sorghum.
d
Sweet lupins.
e
Faba beans.
f
Sunflower meal.
g
Rapeseed meal.
h
Wheat.
i
Meat and bone meal A.
j
Meat and bone meal B.
k
Fish meal.
b
c
Table 7
The apparent metabolisable energy (MJ/kg DM) of nine ingredients
Cottonseed meal
Fish meal
Meat and bone meal A
Meat and bone meal B
Rapeseed (full fat)
Sunflower meal
Soybean meal
Sorghum
Wheat
7.21
12.11
11.01
12.28
14.27
7.18
11.35
14.67
12.91
139
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 8
Performance of birds on diets formulated to 0.97 and 0.90 of amino acid requirements on a total and digestible
basis over 20 weeks
Total
Egg production (%)
Food intake (g/day)
Egg weight (g)
Egg mass (g/day)
Food conversion ratio (g/g)
Specific gravity
Body weight change (kg)
a
0.97
90.9
106.8
61.4
55.8
1.92
1.087
0.204
Digestible
0.90
87.3
105.9
61.3
53.5
2.00
1.088
0.187
0.97
89.8
108.5
61.7
55.4
1.98
1.088
0.186
0.90
89.0
107.6
61.5
55.8
1.99
1.087
0.152
SEM
Pa
1.81
1.80
0.69
1.23
0.043
0.0009
0.0346
0.28
0.99
0.91
0.33
0.24
0.24
0.504
Probability.
Table 9
Bodyweight and feed conversion ratio (FCR) of broilers (sexes combined) given diets formulated on a total (T)
or digestible (D) amino acid basis and to 0.91ÿ1.0 of requirements
Diet
1
2
3
4
5
6
7
8
Probability
SEM
Amino acid
formulation
T
T
T
T
D
D
D
D
Amino acid
specification
of requirement
1.0
0.97
0.94
0.91
1.0
0.97
0.94
0.91
Liveweight
gain (g/bird)
FCR
Liveweight
gain (g/bird)
FCR
(21 days)
(21 days)
(41 days)
(41 days)
726
728
726
714
717
706
711
701
0.44
14.3
1.39bc
1.39c
1.41abc
1.43a
1.41abc
1.43ab
1.42abc
1.45a
0.045
0.018
2192
2192
2205
2167
2163
2165
2142
2134
0.15
27.4
1.78
1.79
1.81
1.81
1.80
1.81
1.81
1.87
0.18
0.015
The chemical composition and AME values were typical of each ingredient and agreed
well with published data. Amino acid content and their true digestibility coefficients were
also generally high and similar to those reported for these ingredients. The two exceptions
were meat and bone meal B and cottonseed meal where true lysine digestibility was 0.78
and 0.60, respectively. Surprisingly, meat and bone meal B had a high crude protein
content of 600 g/kg (Table 4). Composition of the starting material and heat treatment can
affect amino acid digestibility of meat and bone meals. Except for wheat, cottonseed meal
and meat and bone meal B, digestibility coefficients for lysine varied from 0.86 to 0.91,
and for threonine from 0.84 to 0.92 for the remaining ingredients. Thus, these ingredients
when combined into practical least-cost formulations would produce diets with generally
high and similar true amino acid digestibility values, and only about 10±15% less than
total, but consistently so. It would be difficult therefore to show differences between
dietary treatments particularly as the amino acid requirements used are normally over-
140
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
generous. Also, where requirements for total amino acids have been determined using a
diet dilution technique (i.e. not dosing with synthetic amino acids), the results take
account of the indigestibility of the amino acids in the experimental diets. Thus, it is not
surprising that we were unable to demonstrate a significant difference in performance
when formulating on a total vs. digestible amino acid basis particularly as ingredients of
very low digestibility were not used in significant amounts. As pointed out in SCA
(1987), estimates of amino acid allowances for poultry have already taken their
digestibility into account.
A recent paper by Rostango et al. (1995) showed that there was economic benefit in
formulating diets on a digestible rather than a total amino acid basis. But the benefit was
not seen on the diet with highly digestible amino acids. Only when diets contained
feedstuffs of low digestibility was there a benefit in formulating diets on a digestible
amino acid basis.
Wang and Parsons (1998) were unable to show a consistent advantage in using
digestible amino acids in diets containing high and low quality meat and bone meals
when fed to broilers. They conceded that the method of measurement used to determine
true amino acid digestibility may overestimate amino acid bioavailability.
The results of the experiment with laying hens suggest that their amino acid
requirements are over-generous. Excellent production was observed when amino acids
were included at only 0.90 of requirements. There was also no clear indication that
formulating diets to a digestible amino acid requirement gave improved performance over
that when formulated on a total basis. Feed conversion ratio which might show some
response to a marginal amino acid insufficiency was not different between diets.
Recently, Schutte and Swink (1998) found that the total lysine requirement of a laying
hen consuming 110 g/day of a diet with a calculated AME content of 11.8 MJ/kg was
7.3 g/kg for maximum egg mass but higher for optimum food efficiency. For apparent
faecal digestible lysine the figure was 5.37 g/kg. These are similar to those values used
here (Table 1) for diets with 0.97 of requirements and higher than our 0.90 formulation.
The faecal digestibility method for measuring amino acids will likely give raised values
for the reasons discussed previously.
It is interesting that although broilers showed no significant difference in growth rate
that related to total or digestible amino acids levels on any of the diets, there was an
indication that growth rate tended to be inferior on the digestible amino acid
formulations. Compared to the total, FCR also tended to be worse on these latter diets.
The reason for this may be that the digestible amino acid requirements of broilers are not
known precisely. It is however clear that diets formulated to 1.0 of digestible amino acid
specifications are over-specified by at least 10%.
Han and Baker (1994) found that optimum food efficiency was seen for digestible
lysine at 8.9 g/kg for males and 8.5 g/kg for females between three and six weeks of age.
These values are slightly lower than the 9.4 g/kg used in the 1.0 digestible lysine
formulation (Table 3) for both sexes.
The requirement for total lysine (Table 2) was only marginally higher than that
recommended by NRC (1994) for starter birds (12.2 g/kg) but is in line with that
predicted by a computer simulation model (Gous, 1998). It is the same as that
recommended by the NRC (1994) for birds 3±6 weeks of age.
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
141
Alternatively, the method used to determine the true digestibility of amino acids, using
caecectomised cockerels force-fed individual ingredients, may not be appropriate.
The use of digestible amino acids in diet formulation does not appear to be justified
unless ingredients are being used that are known either to vary greatly in amino acid
composition or to have low digestible amino acid coefficients, e.g. cottonseed meal,
canola meal, some meat and bone meals.
In conclusion, considerable savings can be made for both layers and broilers in finetuning specifications for some essential amino acids. From these studies, requirements for
egg production may be over 10% too high, while those for broilers may be from 5% to
10% too high. Although it is recognised that feed formulators must err on the generous
side in determining amino acid specifications there is opportunity to optimise diets in
order to give maximum economic returns.
5. Acknowledgements
We thank the RIRDC (Chicken Meat and Egg Programs) for financial support and the
staff at QPRDC for skilled technical assistance.
References
Anonymous, 1989. Nutrition Guide. Feed Formulation with Digestible Amino Acids 1st ed., pp. 35. Rhone
Poulenc Animal Nutrition, Commentry.
Association of Official Analytical Chemists, 1984. Official Methods of Analysis, 14th ed. Association of
Official Analytical Chemists, Washington, DC.
Baker, D.H., Han, Y., 1994. Ideal amino acid profile for chickens during the first three weeks of growth. Poult.
Sci. 73, 1441±1447.
Baker, D.H., Parsons, C.N. Fernandez, S.A., Aoygai, S., Han. Y., 1993. Digestible amino acid requirements of
broiler chickens based upon ideal protein considerations. Proc. Arkansas Nut. Conf. University of Arkansas,
Fayetteville, A.R., pp. 22-24.
Farrell, D.J., Perez-Maldonado, R.A., Mannion, P.F., 1999. The optimum inclusion of field peas, faba beans,
chick peas and sweet lupins in poultry diets. II Broiler experiments. Br. Poult. Sci. (in press).
Fernandez, S.R., Parsons, C.M., 1996. Bioavailability of digestible lysine in heat-damaged soybean meal for
chick growth. Poult. Sci. 75, 224±231.
Fernandez, S.R., Zhang, Y., Parsons, C.M., 1995. Dietary formulation with cottonseed meal on a total amino
acid versus a digestible amino acid basis. Poult. Sci. 74, 1168±1179.
Gous, R.M., 1998. Making progress in the nutrition of broilers. Poult. Sci. 77, 111±117.
Green, S., Kiener, T., 1989. Digestibilities of nitrogen and amino acids in soybean, sunflower, meat and rapeseed
meals measured with pigs and poultry. Anim. Prod. 48, 157±179.
Han, J., Baker, D.H., 1994. Digestible lysine requirements of male and female broiler chicks during the period
three to six weeks posthatching. Poult. Sci. 13, 1739±1745.
Johnson, R.J., 1992. Principles. problems and application of amino acid digestibility in poultry. Wld's Poult. Sci.
J. 48, 232±246.
Low, A.G., 1977. Digestibility at several sites in pigs. Proc. Nut. Soc. 36, 189±194.
McNab, J.M., 1995. Amino acid digestibilities : determination and application. In: Rowe, J.B., Nolan, J.V.
(Eds.), Recent Advances in Animal Nutrition in Australia. University of New England, Armidale, NSW, pp.
7±13.
NRC, 1994. Nutrient Requirements of Poultry, 9th ed. Natl. Acad. Sci., Washington, D.C.
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Perez-Maldonado, R.A., Mannion, P.F., Farrell, D.J., 1998. Practical levels of inclusions of four grain legumes in
broiler diets in a large-scale experiment. . Proc. Aust. Poult. Sci. Symp. 10, 144±147.
Raharjo, Y., Farrell, D.J., 1984a. A new biological method for determining amino acid digestibility in poultry
feedstuffs using a simple cannula and the influence of dietary fibre on endogenous amino acid output. Anim.
Feed Sci. Technol. 12, 29±45.
Raharjo, Y.C., Farrell, D.J., 1984b. Effects of caecectomy and dietary antibiotics on the digestibility of amino
acids in poultry feeds determined by excreta analysis. Aust. J. of Exp. Agric. and Anim. Husb. 24, 516±521.
Ravindran, V., Hew, L.I., Bryden, W.L., 1998. Digestible Amino Acids in Poultry Feedstuffs. RIRDC
Publication No. 98/9, Project No. US-67CM PRF Occasional Bulletin No. 4.
Rostango, H.S., Pupa, J.M.R., Pack, M., 1995. Diet formulation for broilers based on total versus digestible
amino acids. J. of Appl. Poult. Res. 4, 293±299.
SCA, 1987. Standing Committee on Agriculture Poultry Sub Committee. Feeding Standards for Australian
Livestock Poultry CSIRO, East Melbourne, Vic.
Schutte, J.B., Swink, W., 1998. Requirement of the laying hen for apparent fecal digestible lysine. Poult. Sci. 77,
697±701.
Sibbald, I.R., 1987. Estimation of bioavailable amino acids in feedingstuffs for poultry and pigs : a review with
emphasis on balanced experiments. Can. J. of Anim. Sci. 67, 221±301.
Steel, R.G.D., Torrie, J.H., 1960. Principles and Procedures of Statistics. McGraw Hill, New York.
Terpstra, K. 1997. Determination of digestibilities of protein and amino acids in poultry feeds. Proc. Vth Int.
Symp. on Amino Acids, Budapest, February 1997 pp. 221±226.
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82 (1999) 131±142
A comparison of total and digestible amino acids
in diets for broilers and layers
D.J. Farrella,b,*, P.F. Manniona, R.A. Perez-Maldonadoa
a
The Queensland Poultry Research and Development Centre, PO Box 327,
Cleveland, Qld. 4163, Australia
b
School of Land and Food, The University of Queensland, St. Lucia, Qld 4072, Australia
Received 14 October 1998; received in revised form 17 March 1999; accepted 9 June 1999
Abstract
Eleven samples of food ingredients were analysed for their total and true digestible amino acid
content, apparent metabolisable energy and other components. Large batches of these ingredients
were retained for a broiler and a layer experiment. Four layer diets were formulated at 0.97 and 0.90
of total and digestible amino acid requirements for egg production using the analysed ingredients.
Eight broiler diets were also formulated from 1.0 to 0.91 of total and digestible amino acid
requirements in starter and finisher diets. Proximate and amino acid analyses and AME values were
within the normal range for the 11 foodstuffs. Digestibility of amino acids was high with very few
exceptions, e.g. cottonseed meal, meat and bone meal. Diets formulated on a total or digestible
amino acid basis gave no differences in egg production parameters or broiler production parameters
with no effect of level of inclusion. However, the main effects showed that diets formulated on a
total compared to a digestible amino acid basis gave better growth rate and feed conversion
efficiency in broilers. It was concluded that nutrient specifications for layers and broilers are not
sufficiently precise to be able to differentiate between 1.97 and 0.90 of requirement for egg
production or 1.0 and 0.91 for broiler growth. The use of digestible amino acids may be justified in
diet formulations only when unusual protein concentrates with low amino acid digestibility values
are used in large amounts. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Ingredient amino acid digestibility; AME values
*
Corresponding author. Tel.:61-7-3824-3081; fax.: 61-7-3824-4316
E-mail address: [email protected] (D.J. Farrell)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 8 0 - 2
132
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
1. Introduction
It is well known that not all of the amino acids in a feedingstuff are digested by the bird
and become available for protein synthesis. It is also known that there is considerable
variation between, and often within, protein sources in the digestibility of amino acids.
Furthermore, the digestibility coefficients of individual amino acids within a feedstuff
may differ considerably.
The methods used to measure amino acid digestibility vary greatly and these have been
reviewed on numerous occasions (Sibbald, 1987; Johnson, 1992; McNab, 1995; Raharjo
and Farrell, 1984a). Site of sampling material for analysis is important and the
indigestible marker used to calculate amino acid digestibility may also differ between
laboratories.
There has been some criticism of the use of excreta in order to determine amino acid
digestibility because of changes in amino acid profile due to microbial fermentation
(Terpstra, 1997; Low, 1977) even in caecectomized birds (Raharjo and Farrell, 1984b).
However, there are few tables that provide information on the digestibility of amino acids
of a wide range of feedstuffs using the same method and from the one laboratory. There
are, however, notable exceptions (Anonymous, 1989; Ravindran et al., 1998).
There have been a number of papers demonstrating the advantages of using digestible
rather than total amino acids to formulate broiler diets. These have generally used poor
quality ingredients in large amounts, such as cottonseed meal (Fernandez et al., 1995), or
over-processed meals (Fernandez and Parsons, 1996) to demonstrate an advantage. There
are very few published papers that have demonstrated a significant improvement in
practical diets for layers and for broilers formulated on the basis of digestible amino acids
when several conventional dietary ingredients have been combined.
The purpose of the two experiments reported here was to test the hypothesis that the
use of amino acid digestibility values of feedstuffs gives a significant improvement in
biological response and/or economic response compared to ingredients using total amino
acids to formulate practical layer and broiler diets using a range of foodstuffs.
2. Materials and methods
2.1. Bioassays and chemical analyses
Substantial quantities of 11 food ingredients were held in silos or bags prior to use in
poultry experiments. Samples (10 kg) were transported to Rhone-Poulenc Animal
Nutrition, Commentry, France for amino acid bioassay using adult birds (Sibbald, 1987)
with modifications (Anonymous, 1989) to determine true amino acid digestibility.
Isabrown cockerels were caecetomized and five birds per treatment were used in a Latin
square design (Green and Kiener, 1989).
The apparent metabolisable energy (AME) of the ingredients was determined with
individual laying hens using the classical, total collection method over four days. Birds
were on the experimental diets for a three-day adjustment period. There were three hens
at each level of inclusion per dietary treatment and six hens on the all-grain diets. The two
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
133
grains were included at 980 g/kg of the diet; the protein sources replaced sorghum at two
different levels; these levels depended on the ingredient. A premix, which contained
minerals and vitamins, was included at 20 g/kg of the diet. AME was calculated by
regression analysis and then extrapolating the line to the rate of inclusion of the test
ingredient of 1000 g/kg diet. Chemical analyses of the raw ingredients followed the
methods of the AOAC, 1984. Gross energy was determined in an adiabatic bomb
calorimeter.
2.2. Layer experiment
A least-cost formulation package (Feedmania) was used to construct diets using the
determined amino acid and AME values for the feedstuffs.
In the layer experiment, diets were formulated to 97% and 90% of total and of
digestible amino acid requirements (SCA, 1987; Anonymous, 1989). The composition of
the least-cost formulated diets is given in Table 1. Each diet was fed for 20 weeks to 50
individually-caged Isabrown birds housed in a saw-tooth shed with open sides and
adjustable side curtains.
Table 1
Ingredient and calculated chemical composition (g/kg as fed basis) of diets formulated on a total (T) and
digestible (D) amino acid basis at 0.97 and 0.90 of amino acid recommendations (Layer experiment)
T-97
T-90
D-97
D-90
Sorghum
Wheat
Cottonseed meal
Faba beans
Meat and bone meal B
Rapeseed meal
Soybean meal
Soybean oil
Limestone
Dical P
Sodium chloride
DL-methionine
Vitamin premixa
280
280
70
94
67
87
±
38.5
79
±
1.9
0.6
2.3
303
303
70
67
50
81
±
36.7
82
1.3
2.1
0.6
2.3
269
269
70
97
67
85
22
38
79
±
1.9
0.7
2.3
291
291
70
72
67
89
±
37
79
±
1.8
0.5
2.3
Chemical composition
Crude protein
AME (MJ/kg)
Lysine
Methionine
Methonine cyst
Tryptophan
Threonine
177
11.9
7.3
3.2
6.1
2.1
5.7
164
11.9
6.4
3.0
5.7
2.1
5.2
158
11.9
6.3
2.9
5.1
1.9
4.8
150
11.9
5.6
2.7
4.8
1.8
4.5
a
The vitamin and mineral premix added per kg of diet: 2.5 mg retionol, 75 mg cholecalciferol, 5 mg atocopherol acetate, 2 mg menadione sodium bisulfite, 1 mg thiamine, 4 mg riboflavin, 2 mg pyridoxine, 10 mg
cyanocobalamin, 1 mg folic acid, 10 mg niacin, 10 mg Ca pantothenate, 30 mg biotin, 150 mg choline, 50 mg
Mn, 50 mg Zn, 50 mg Fe, 600 mg Mo, 500 mg Co, 600 mg I, 4 mg Cu, 70 mg Se, 80 mg Banox (BHA BHT).
134
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Diets were fed ad libitum in mash form. A mineral and vitamin layer premix and a yolk
pigmentor were added to all diets at the recommended levels. Egg production was
recorded on five days each week, eggs were weighed weekly, food intake recorded
monthly and egg specific gravity measured monthly. Hens were weighed at the start and
end of the experiment.
2.3. Broiler experiment
Diets were formulated to total and digestible amino acids at 1.0, 0.97, 0.94 and 0.91 of
nutrient requirements for starter and finisher broilers (SCA, 1987), taking into account the
total and digestible amino acid requirements reported by Baker et al. (1993) and Han and
Baker (1994), and the ideal ratios of amino acids (Baker and Han, 1994; Baker et al.,
1993) for starter and finisher broilers. The starter diets were fed to 21 days and the
finisher diets from 22 to 41 days of age. The diets are shown in Tables 2 and 3.
Table 2
Broiler diets formulated to total (T) and digestible (D) amino acid requirements that range from 1.0 to 0.91 of
requirement
Starter formulations (g/kg)
T-100
T-97
T-94
T-91
D-100
D-97
D-94
D-91
270
272
50
30
35
33
40
216
35
7.3
1.4
6.7
1.9
1.5
280
281
50
30
39
30
40
198
34
7.3
1.4
6.7
1.8
1.5
290
289
50
30
30
38
40
181
33
7.2
1.4
6.7
1.7
1.5
300
298
50
30
39
30
40
162
32
7.3
1.4
6.7
1.6
1.5
280
274
50
30
30
37
40
205
35
7.2
1.4
6.7
1.8
1.5
290
282
50
30
30
37
40
188
33
7.2
1.4
6.7
1.7
1.5
290
299
50
30
30
38
40
172
32
7.2
1.4
6.7
1.6
1.5
300
307
50
30
30
38
40
155
31
7.3
1.4
6.7
1.5
1.5
Chemical composition (g/kg)
Crude protein
244
AME (MJ/kg)
12.7
Lysine
12.7
Methionine
5.6
Meth cyst
9.3
Tryptophan
3.0
Threonine
8.3
239
12.7
12.3
5.4
9.0
2.9
8.1
234
12.7
11.9
5.2
8.7
2.8
7.9
228
12.7
11.6
5.0
8.5
2.7
7.7
214
12.7
10.8
5.0
7.8
2.5
7.2
209
12.7
10.5
4.8
7.5
2.4
7.0
205
12.7
10.2
4.6
7.3
2.4
6.8
200
12.7
9.8
4.5
7.1
2.3
6.6
Ingredients
Wheat
Sorghum
Cottonseed meal
Fish meal
Meat and bone meal A
Meat and bone meal B
Sweet lupins
Soybean meal
Sunflower oil
Limestone
Sodium chloride
Vit min premixa
DL-methionine
L-lysine HCl
a
The vitamin and mineral premix added per kg of diet: 3.75 mg retinol, 112 mg D3, 30 mg a-tocopherol
acetate, 3 mg menadione sodium bisulfite, 1.5 mg thiamine, 6 mg riboflavin, 3 mg pyridoxine, 15 mg B12,
1.5 mg folic acid, 55 mg niacin, 15 mg Ca pantothanate, 180 mg biotin, 600 mg choline, 75 mg Mn, 75 mg Zn,
75 mg Fe, 900 mg Mo, 750 mg Co, 900 mg I, 6 mg Cu, 105 mg Se, 120 mg Banox.
135
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 3
Broiler diets formulated to total (T) and digestible (D) amino acid requirements that range from 1.0 to 0.91 of
requirements
Ingredients
Finisher formulations (g/kg)
T-100
T-97
T-94
T-91
D-100
D-97
D-94
D-91
300
327
65
30
54
160
±
40
8.3
2.3
1.7
6.7
2.2
1.7
300
338
68
30
53
147
±
40
8.0
2.6
2.0
6.7
2.0
1.6
300
349
72
30
51
133
±
40
9.0
2.9
2.0
6.7
2.0
1.67
300
361
75
30
50
120
±
40
8.8
3.2
1.7
6.7
1.7
1.5
300
308
±
30
54
180
66
41
7.7
2.3
1.7
6.7
1.9
1.0
300
326
±
30
54
163
65
39
7.7
2.4
1.7
6.7
1.8
1.1
300
345
±
30
54
147
65
38
7.8
2.5
1.7
6.7
1.8
1.2
300
363
±
30
54
130
64
36
7.8
2.5
1.7
6.7
1.7
1.3
Chemical composition (g/kg)
AME (MJ/kg)
13
crude protein
221
Lysine
11.1
Methionine
5.5
Meth cyst
8.8
Tryptophan
2.6
Threonine
8.2
13
217
10.8
5.0
9.0
3.0
8.0
13
212
10.4
5.0
8.0
2.0
8.0
13
208
10.1
4.9
8.0
2.4
7.4
13
199
9.4
5.0
7.7
2.3
7.0
13
194
9.1
4.9
7.5
2.2
6.8
13
189
8.9
4.7
7.2
2.2
6.6
13
184
8.6
4.6
7.0
2.1
6.4
Wheat
Sorghum
Cottonseed meal
Fish meal
Meat and bone meal (B)
Soybean meal
Sunflower meal
Sunflower oil
Limestone
Dicalcium phosphate
Sodium chloride
Vit Min premixa
DL-methionine
L-lysine HCl
a
The vitamin and mineral premix added per kg of diet: 3.75 mg retinol, 112 mg D3, 30 mg a-tocopherol
acetate, 3 mg menadione sodium bisulfite, 1.5 mg thiamine, 6 mg riboflavin, 3 mg pyridoxine, 15 mg B12,
1.5 mg folic acid, 55 mg niacin, 15 mg Ca pantothanate, 180 mg biotin, 600 mg choline, 75 mg Mn, 75 mg Zn,
75 mg Fe, 900 mg Mo, 750 mg Co, 900 mg I, 6 mg Cu, 105 mg Se, 120 mg Banox.
Chicks of a commercial strain (Cobb) were grown from one-day-old. There were four
groups each of 40 males and four groups each of 40 females per dietary treatment. Birds
were grown in floor pens with wood shavings as litter. Treatments were assigned
randomly in blocks of eight pens. Birds and food were weighed at 1, 21 and 41 days of
age. Lighting was adjusted according to commercial practice (Farrell et al., 1999).
Mortality was recorded daily.
Data were analysed using a randomised block analysis of variance model (SAS/STAT
6.04, 1987: SAS Institute Inc., Cary, North Carolina). For broiler treatments therefore all
factorial combinations of two types of amino acids and four levels of formulation; for
layer treatments, there were two types of amino acids and two levels of formulation. Main
effect means and interaction means were compared using the protected LSD test
operating at the 0.05 level of significance. Regression analysis was also undertaken (Steel
and Torrie, 1960).
The experiments were approved by the Animal Research Institute's Animal Ethics
Review Committee.
136
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
3. Results
The proximate analysis of the 11 ingredients used is given in Table 4, and their amino
acid profiles in Table 5. The two meat and bone meals contained 535 g crude protein (A),
and 596 g crude protein (B)/kg on an 'as is' basis. The true digestibility of the amino
acids for each ingredient is given in Table 6.
The two meat meals showed considerable differences in amino acid digestibility
coefficients. Digestible lysine and threonine coefficients were 0.83 and 0.86; and .75 and
0.78 for meat meals A and B, respectively. Cottonseed meal had the lowest lysine
digestibility of 0.60, followed by meat meal B of 0.78.
The apparent metabolisable energy of nine of the 11 ingredients is given in Table 7. All
compare favourably with those reported in the literature. AME values for sweet lupins
and faba beans were taken from a previous study (Perez-Maldonado et al., 1998).
3.1. Layer experiment
The overall results of the layer experiment showed no significant treatment effect on
any parameter (Table 8). There was some indication that the diet formulated to 0.90 of
total amino acid requirements gave a lower egg mass by 2 g/day compared to other
treatments.
3.2. Broiler experiment
The results are shown in Table 9. Since there was no diet sex interaction, data were
combined for the two sexes. Growth rate and FCR to 41 days were about the same as
industry standards. The only difference between dietary treatments was in FCR during the
starter phase. Mean liveweight gain at 21 days of age was significantly higher (p < 0.05)
Table 4
Proximate analysis of feed ingredients on an `as fed' basis (g/kg)
Cotton seed meal
Soybean meala
Sorghum
Lupins
Faba beans
Sunflower meal
Rapeseed
Wheat
Meat and bone meal Ab
Meat and bone meal Bc
Fish meald
a
Crude
protein
Dry
matter
Ash
Fat
Crude
fibre
392
423
108
255
237
337
285
162
535
596
657
895
890
856
904
879
915
917
898
950
950
915
63
57
16
30
33
57
35
16
233
263
152
17
27
33
57
15
16
306
14
147
87
66
121
87
26
157
91
210
82
28
nd
nd
nd
Urease activity: 0.11 mg N (from ammonia)/(g*min).
Ca 73.3, Phos 36.8.
c
Ca 86.6, Phos 42.1.
d
Ca 33.7, Phos 22.4.
b
137
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 5
Amino acid content of feed ingredients on an `as fed' basis (g/kg)
Asp
Thr
Ser
Glu
Pro
Gly
Ala
Cys
Val
Met
Ile
Leu
Tyr
Phe
Lys
His
Arg
Try
CSMa
SBMb
Sorgc
Lupd
Fabe
SFf
Rapg
Whh
MBAi
MBBj
FMk
32.6
11.5
14.3
76.3
13.5
14.6
13.5
6.3
16.9
6.1
11.9
21.2
10.5
19.1
15.4
9.7
41.3
5.8
45.8
16.1
19.7
78.4
20.7
17.0
16.9
7.2
20.3
6.3
19.2
31.3
15.6
20.3
25.1
10.0
29.5
6.4
6.9
3.3
44.3
23.2
8.6
3.0
9.2
1.7
5.3
1.6
4.3
14.1
4.2
5.4
2.1
2.1
3.8
1.2
23.3
8.7
11.5
51.8
9.1
9.6
7.8
2.5
9.8
1.7
10.0
15.9
9.5
9.1
11.1
6.2
25.7
2.5
24.6
8.2
10.5
39.5
9.5
9.4
9.1
2.8
11.0
1.9
9.8
16.9
8.1
9.7
14.8
5.5
22.0
2.1
30.2
12.3
13.7
72
14.2
17.8
13.5
5.7
17.3
7.1
14.5
21.2
9.6
15.4
11.1
7.8
27.9
5.0
18.8
11.7
11.2
54.4
17.3
13.0
11.6
7.1
14.4
6.1
11.5
19.4
8.3
11.0
16.0
7.4
17.8
4.7
7.3
4.4
6.9
52.4
16.5
6.0
5.0
3.2
6.9
2.5
5.5
10.3
5.2
7.3
3.7
3.3
7.0
2.0
37.8
17.9
20.3
65.9
40.2
64.2
34.9
5.4
23.1
9.8
16.9
32.2
13.0
16.8
27.9
8.6
34.9
4.2
40.3
18.2
22.8
71.3
52.3
83.4
42.8
5.6
24.0
8.9
16.2
33.1
13.1
17.7
27.1
8.3
41.6
3.2
57.9
28.1
24.4
86.1
24.0
35.9
38.2
5.1
32.0
17.2
28.1
46.6
21.5
25.2
48.9
20.6
35.3
8.5
a
Cottonseed meal.
Soybean meal.
Grain sorghum.
d
Sweet lupins.
e
Faba beans.
f
Sunflower meal.
g
Rapeseed meal.
h
Wheat.
i
Meat and bone meal A.
j
Meat and bone meal B.
k
Fish meal.
b
c
on the diets formulated to total (723 g) compared to digestible (709 g) amino acid
specifications. This same trend (p < 0.01) was seen at 41 days (2189 g vs. 2152 g) of age.
FCR was also worse (p 0.05) when data were combined for digestible (1.43) compared
to total (1.40) amino acids at 21 days. A similar trend (p 0.06) was observed for FCR at
41 days of age. When data at 21 days were combined, there was a significant (p < 0.05)
decline in FCR as formulations increased from 0.91 to 1.0 of amino acid specifications.
4. Discussion
There are few published experiments in which detailed chemical analysis and amino
acid profiles have been constructed for as wide a range of ingredients as those used here.
Although there was several months delay between the time the ingredients were
dispatched to France and results received, most of the individual ingredients had not
deteriorated visibly during this time. However, the two grains were later replaced with
grains of similar protein content for the broiler trial because of deterioration.
138
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 6
True digestibility coefficients of protein and amino acids in 11 feed ingredients measured using adult
caecetomised cockerels
Protein
Asp
Thr
Ser
Glu
Pro
Gly
Ala
Val
Ile
Leu
Tyr
Phe
Lys
His
Arg
Cys
Met
Try
CSMa
SBMb
Sorgc
Lupd
Fabe
SFf
Rapg
Whh
MBAi
MBBj
FMk
0.791
0.785
0.729
0.764
0.873
0.791
0.718
0.710
0.766
0.737
0.760
0.834
0.846
0.601
0.822
0.892
0.731
0.776
0.796
0.887
0.865
0.842
0.868
0.901
0.872
0.802
0.826
0.852
0.874
0.867
0.902
0.882
0.888
0.891
0.930
0.807
0.902
0.875
0.913
0.919
0.906
0.933
0.958
0.934
0.905
0.955
0.923
0.939
0.959
0.952
0.950
0.860
0.912
0.937
0.864
0.917
0.927
0.934
0.917
0.918
0.918
0.955
0.919
0.904
0.863
0.905
0.927
0.936
0.961
0.934
0.884
0.930
0.927
0.855
0.877
0.914
0.835
0.875
0.842
0.853
0.934
0.851
0.804
0.862
0.857
0.871
0.892
0.865
0.886
0.888
0.865
0.921
0.669
0.797
0.806
0.904
0.884
0.885
0.866
0.950
0.903
0.784
0.863
0.907
0.919
0.917
0.932
0.932
0.873
0.908
0.956
0.772
0.942
0.884
0.881
0.873
0.845
0.859
0.927
0.863
0.845
0.878
0.860
0.878
0.897
0.886
0.901
0.870
0.920
0.932
0.763
0.925
0.887
0.918
0.844
0.877
0.919
0.968
0.966
0.869
0.852
0.904
0.922
0.930
0.941
0.938
0.828
0.914
0.896
0.896
0.921
0.902
0.857
0.662
0.833
0.801
0.834
0.790
0.787
0.782
0.833
0.855
0.862
0.877
0.856
0.856
0.849
0.861
0.612
0.888
0.822
0.824
0.589
0.750
0.732
0.761
0.778
0.769
0.745
0.696
0.785
0.702
0.796
0.826
0.778
0.793
0.820
0.370
0.823
0.688
0.918
0.856
0.914
0.897
0.911
0.862
0.839
0.849
0.876
0.914
0.925
0.921
0.905
0.913
0.908
0.921
0.743
0.923
0.897
a
Cottonseed meal.
Soybean meal.
Grain sorghum.
d
Sweet lupins.
e
Faba beans.
f
Sunflower meal.
g
Rapeseed meal.
h
Wheat.
i
Meat and bone meal A.
j
Meat and bone meal B.
k
Fish meal.
b
c
Table 7
The apparent metabolisable energy (MJ/kg DM) of nine ingredients
Cottonseed meal
Fish meal
Meat and bone meal A
Meat and bone meal B
Rapeseed (full fat)
Sunflower meal
Soybean meal
Sorghum
Wheat
7.21
12.11
11.01
12.28
14.27
7.18
11.35
14.67
12.91
139
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
Table 8
Performance of birds on diets formulated to 0.97 and 0.90 of amino acid requirements on a total and digestible
basis over 20 weeks
Total
Egg production (%)
Food intake (g/day)
Egg weight (g)
Egg mass (g/day)
Food conversion ratio (g/g)
Specific gravity
Body weight change (kg)
a
0.97
90.9
106.8
61.4
55.8
1.92
1.087
0.204
Digestible
0.90
87.3
105.9
61.3
53.5
2.00
1.088
0.187
0.97
89.8
108.5
61.7
55.4
1.98
1.088
0.186
0.90
89.0
107.6
61.5
55.8
1.99
1.087
0.152
SEM
Pa
1.81
1.80
0.69
1.23
0.043
0.0009
0.0346
0.28
0.99
0.91
0.33
0.24
0.24
0.504
Probability.
Table 9
Bodyweight and feed conversion ratio (FCR) of broilers (sexes combined) given diets formulated on a total (T)
or digestible (D) amino acid basis and to 0.91ÿ1.0 of requirements
Diet
1
2
3
4
5
6
7
8
Probability
SEM
Amino acid
formulation
T
T
T
T
D
D
D
D
Amino acid
specification
of requirement
1.0
0.97
0.94
0.91
1.0
0.97
0.94
0.91
Liveweight
gain (g/bird)
FCR
Liveweight
gain (g/bird)
FCR
(21 days)
(21 days)
(41 days)
(41 days)
726
728
726
714
717
706
711
701
0.44
14.3
1.39bc
1.39c
1.41abc
1.43a
1.41abc
1.43ab
1.42abc
1.45a
0.045
0.018
2192
2192
2205
2167
2163
2165
2142
2134
0.15
27.4
1.78
1.79
1.81
1.81
1.80
1.81
1.81
1.87
0.18
0.015
The chemical composition and AME values were typical of each ingredient and agreed
well with published data. Amino acid content and their true digestibility coefficients were
also generally high and similar to those reported for these ingredients. The two exceptions
were meat and bone meal B and cottonseed meal where true lysine digestibility was 0.78
and 0.60, respectively. Surprisingly, meat and bone meal B had a high crude protein
content of 600 g/kg (Table 4). Composition of the starting material and heat treatment can
affect amino acid digestibility of meat and bone meals. Except for wheat, cottonseed meal
and meat and bone meal B, digestibility coefficients for lysine varied from 0.86 to 0.91,
and for threonine from 0.84 to 0.92 for the remaining ingredients. Thus, these ingredients
when combined into practical least-cost formulations would produce diets with generally
high and similar true amino acid digestibility values, and only about 10±15% less than
total, but consistently so. It would be difficult therefore to show differences between
dietary treatments particularly as the amino acid requirements used are normally over-
140
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
generous. Also, where requirements for total amino acids have been determined using a
diet dilution technique (i.e. not dosing with synthetic amino acids), the results take
account of the indigestibility of the amino acids in the experimental diets. Thus, it is not
surprising that we were unable to demonstrate a significant difference in performance
when formulating on a total vs. digestible amino acid basis particularly as ingredients of
very low digestibility were not used in significant amounts. As pointed out in SCA
(1987), estimates of amino acid allowances for poultry have already taken their
digestibility into account.
A recent paper by Rostango et al. (1995) showed that there was economic benefit in
formulating diets on a digestible rather than a total amino acid basis. But the benefit was
not seen on the diet with highly digestible amino acids. Only when diets contained
feedstuffs of low digestibility was there a benefit in formulating diets on a digestible
amino acid basis.
Wang and Parsons (1998) were unable to show a consistent advantage in using
digestible amino acids in diets containing high and low quality meat and bone meals
when fed to broilers. They conceded that the method of measurement used to determine
true amino acid digestibility may overestimate amino acid bioavailability.
The results of the experiment with laying hens suggest that their amino acid
requirements are over-generous. Excellent production was observed when amino acids
were included at only 0.90 of requirements. There was also no clear indication that
formulating diets to a digestible amino acid requirement gave improved performance over
that when formulated on a total basis. Feed conversion ratio which might show some
response to a marginal amino acid insufficiency was not different between diets.
Recently, Schutte and Swink (1998) found that the total lysine requirement of a laying
hen consuming 110 g/day of a diet with a calculated AME content of 11.8 MJ/kg was
7.3 g/kg for maximum egg mass but higher for optimum food efficiency. For apparent
faecal digestible lysine the figure was 5.37 g/kg. These are similar to those values used
here (Table 1) for diets with 0.97 of requirements and higher than our 0.90 formulation.
The faecal digestibility method for measuring amino acids will likely give raised values
for the reasons discussed previously.
It is interesting that although broilers showed no significant difference in growth rate
that related to total or digestible amino acids levels on any of the diets, there was an
indication that growth rate tended to be inferior on the digestible amino acid
formulations. Compared to the total, FCR also tended to be worse on these latter diets.
The reason for this may be that the digestible amino acid requirements of broilers are not
known precisely. It is however clear that diets formulated to 1.0 of digestible amino acid
specifications are over-specified by at least 10%.
Han and Baker (1994) found that optimum food efficiency was seen for digestible
lysine at 8.9 g/kg for males and 8.5 g/kg for females between three and six weeks of age.
These values are slightly lower than the 9.4 g/kg used in the 1.0 digestible lysine
formulation (Table 3) for both sexes.
The requirement for total lysine (Table 2) was only marginally higher than that
recommended by NRC (1994) for starter birds (12.2 g/kg) but is in line with that
predicted by a computer simulation model (Gous, 1998). It is the same as that
recommended by the NRC (1994) for birds 3±6 weeks of age.
D.J. Farrell et al. / Animal Feed Science and Technology 82 (1999) 131±142
141
Alternatively, the method used to determine the true digestibility of amino acids, using
caecectomised cockerels force-fed individual ingredients, may not be appropriate.
The use of digestible amino acids in diet formulation does not appear to be justified
unless ingredients are being used that are known either to vary greatly in amino acid
composition or to have low digestible amino acid coefficients, e.g. cottonseed meal,
canola meal, some meat and bone meals.
In conclusion, considerable savings can be made for both layers and broilers in finetuning specifications for some essential amino acids. From these studies, requirements for
egg production may be over 10% too high, while those for broilers may be from 5% to
10% too high. Although it is recognised that feed formulators must err on the generous
side in determining amino acid specifications there is opportunity to optimise diets in
order to give maximum economic returns.
5. Acknowledgements
We thank the RIRDC (Chicken Meat and Egg Programs) for financial support and the
staff at QPRDC for skilled technical assistance.
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