Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol81.Issue3-4.Oct1999:
Animal Feed Science and Technology
81 (1999) 265±277
Effects of grass clover-pellets and whole
plant maize-pellets on the feed intake
and performance of dairy cows
W. Knausa,*, K. Lugerb, W. Zollitscha, H. Guflerc,
L. Gruberd, C. Murauera, F. Lettnera
a
Department of Animal Science, University of Agricultural Sciences, Gregor Mendel-Str. 33,
A-1180 Vienna, Austria
b
Federal Research Institute for Agriculture, Rottenhauser Str. 32, A-3250 Wieselburg, Austria
c
University of Veterinary Medicine, VeterinaÈrplatz 1, A-1210 Vienna, Austria
d
Federal Research Institute for Alpine Agriculture Gumpenstein , A-8952 Irdning, Austria
Received 14 July 1998; received in revised form 5 May 1999; accepted 15 June 1999
Abstract
Twenty dual-purpose Simmental dairy cows were used in a 2 2 cross-over design to evaluate
the effects of feeding, both pelleted vs. ensiled grass clover and whole plant maize on feed intake,
milk production and composition, as well as on blood metabolites and some parameters of rumen
fermentation. In addition to the pelleted/ensiled forages, all animals were offered grass hay, and,
based on the individual milk performance prior to the beginning of the experiment, 1 kg of
concentrate for every 2.35 kg energy-corrected milk (ECM) exceeding a daily production of 15 kg
ECM. In both groups, the forage was offered so that grass hay, grass clover silage or pellets and
whole plant maize silage or pellets would contribute 100, 450 and 450 g kgÿ1 to total forage dry
matter intake (DMI), respectively. Both the treatment periods lasted for seven weeks. Average daily
forage DMI was increased from 12.8 up to 18.6 kg when grass clover and whole plant maize were
fed in the pelleted form. ECM production was elevated from 18.3 up to 20.3 kg (p < 0.001). Also, a
significant increase was observed for milk protein and lactose level, while content of milk fat and
concentration of milk urea were reduced. Rumen pH-values were significantly lower in the pelletfed cows than in the silage-fed cows. The acetate to propionate ratio was narrowed down from
3.80 : 1 to 3.54 : 1. Concentration of blood serum urea was significantly reduced (0.8 mmol lÿ1)
when pellets were fed. Except for glutamate dehydrogenase (GlDH), all the liver specific enzymes
were within normal ranges. The analysis of glucose, protein and ketone bodies in the urine was
*
Corresponding author. Tel.: +43-1-47654/3285; fax: +43-1-47654/3254
E-mail address: knaus@edv1.boku.ac.at (W. Knaus)
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 9 0 - 5
266
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
negative for both the dietary treatments. Pelleted grass clover and whole plant maize proved to be
superior to their ensiled counterparts in regard to DMI and milk performance, without having a
negative impact on the health status of the animals, but extra milk output in relation to the
additional feed intake was very low. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Pellets; Feed conservation; Feed intake; Dairy cows; Performance
1. Introduction
The use of pelleted forages in cattle nutrition has never played an important role in
Austrian agricultural production. There are several reasons for this: capital investment
needed for the dehydration and pelleting facilities far exceeds the costs of other forage
preservation methods and, in addition, harvesting with the original water content,
artificially drying and, finally, pelleting the forage is highly energy intensive.
Nevertheless, pelleted forages are advantageous feedstuffs from a nutritionist's point of
view. It is well established that dry matter intake (DMI) is the cornerstone upon which
productive dairy rations are built. One possible way of achieving a high intake of forage
dry matter (DM) is the alteration of the physical form of the feedstuffs. Pelleting is one of
the most drastic physical changes to which forages can be subjected in commercial
practice. The artificial drying of the freshly cut forage and the reduction of the forage
bulk through the mechanical treatment of pelleting causes a radical reduction in particle
size, promoting a higher voluntary intake and increasing animal efficiency while
decreasing the effective fibre content (Van Soest, 1994). The greatest improvement in
intake after pelleting is observed in bulky forages of good digestibility (Van Soest, 1994).
According to the definition by Moore (1964), pellets usually consist of finely ground
forage compressed into small cylinders 0.6±1.9 cm in diameter and 0.6±3.8 cm in length.
Modern forage harvesters allow the forage to be chopped into material of 2±3 cm in
length and make sure that every kernel is opened when maize plants are chopped. This
substrate is fine enough to be formed into a firm pellet without grinding after the process
of dehydration.
Beardsley (1964) compiled data in a review of the effects of pelleting on intake, live
weight gains and feed efficiency for several different forages fed to calves or yearlings
and showed that, calculated on an individual comparison basis and averaged, pelleting a
long hay increased the daily feed intake by 25%, increased daily gain by 98% and
decreased feed required per unit of gain by 36%. Vandersall and Douglass (1974) found
that DMI increased when a combination of whole plant maize-pellets and whole plant
maize silage was fed to Holstein cows, but observed no effect on milk production. As a
consequence of altering particle size distribution of forage by grinding and pelleting,
Thomson and Beever (1979) noted a depression in overall apparent digestibility of
organic matter, which was generally greater for grasses (up to 15 percentage units) than
legumes (3±6 percentage units).
The purpose of this work was to elucidate the effects of feeding pelleted grass clover
and whole plant maize roughages as compared to ensiled on DMI, milk production and
composition, as well as on blood metabolites and some parameters of fermentation in the
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
267
rumen of dual purpose Simmental dairy cows. Based on the available literature and on
practical experience gathered at federal research institutes in Austria, it was hypothesized
that dairy cows' voluntary feed consumption would increase when forages were preserved
and fed as pellets rather than as silages, which would result in an elevated milk yield and
body condition due to an improved level of nutrient supply to the animals. It was also
assumed that feeding some long hay in addition to the pelleted forages would help
counteract possible detrimental effects on ruminal digestion, therefore allowing for a
greater total nutrient uptake from the digestive tract, improving the animals' overall
performance.
2. Materials and methods
2.1. Experimental design and diet formulation
Twenty dual-purpose Simmental dairy cows were selected out of a herd of 70
according to their body weight (BW), days in milk (DIM), number of lactations and
current milk performance, and assigned to treatments of 10 animals each, arranged
factorially in a 2 2 Latin square design.
At the beginning of the experiment, cows ranged from 39 to 134 days postpartum, and
in each group they were balanced as nearly as possible with respect to BW, DIM, number
of lactations and milk production, averaging 615 kg, 75, 1.7 and 25.3 kg energy-corrected
milk (ECM), respectively. The animals were kept on rubber mats in a tie stall using
sawdust as a bedding material.
The ingredients of the diet for the control group were whole plant maize silage, grass
clover silage, grass hay and concentrate. Animals from the experimental group were
offered feedstuffs of the same origin which were harvested at the same stage of maturity,
but the whole plant maize and grass clover were artificially dehydrated and pelleted
instead of ensiled.
Grass clover containing about 50% alfalfa was cut, and swaths were either wilted on
the field for a few hours and then ensiled as bales, or chopped to lengths of approximately
25 mm using a forage harvester and dehydrated with hot air in a rotary drum drier.
Optimal DM content in the silage bales was not obtained because of inclement weather
while hauling the grass clover from the field. Maize plants were chopped the same way
and either dehydrated in the same drier or ensiled. The chopped and artificially dried
whole plant maize and grass clover were compressed without the addition of steam or
water into pellets with a matrix press (KAHL, Mod. 34-600). The diameter of the pellets
was 15 mm and their length varied between 20 and 45 mm. The bulk density of the grass
clover-pellets and the whole plant maize-pellets was 420 and 700 kg mÿ3, respectively.
The concentrate consisted of 250 g kgÿ1 maize, 192 g kgÿ1 barley, 188 g kgÿ1 wheat,
125 g kgÿ1 faba bean, 125 g kgÿ1 oats, 62 g kgÿ1 peas, 50 g kgÿ1 soybean meal, 3 g kgÿ1
sodium chloride and 5 g kgÿ1 vitamin premix. An extra 100 g of mineral mixture was
given each cow daily. In both groups the forage was offered in such a manner that grass
hay, grass clover silage/pellets and whole plant maize silage/pellets would contribute 10,
45 and 45% to total forage DMI, respectively.
268
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
Table 1
Chemical composition of feedsa
Component
ÿ1
Crude protein (g kg )
NEL (MJ kgÿ1)
NDF (g kgÿ1)
ADF (g kgÿ1)
Ether extract (g kgÿ1)
Crude ash (g kgÿ1)
Calcium (g kgÿ1)
Phosphorus (g kgÿ1)
Magnesium (g kgÿ1)
Sodium (g kgÿ1)
a
Whole plant maize
Grass clover
Silage
Pellets
Silage
Pellets
74
5.76
478
247
35
42
4.16
2.87
1.96
0.01
72
5.89
518
239
25
40
2.87
2.46
1.84
0.03
197
4.65
419
339
39
111
20.37
3.30
3.04
0.97
199
4.85
458
318
32
113
20.50
2.75
3.00
0.42
Grass hay
Concentrate
mixture
69
4.32
651
378
23
69
6.52
3.17
1.69
0.24
159
8.66
283
81
25
33
1.96
4.40
1.39
1.15
DM basis.
The average nutrient content of the feedstuffs is shown in Table 1. Chemical
composition of feeds and orts was determined as described by Naumann and Bassler
(1976). In addition, silages were analyzed for lactic, acetic and butyric acids by gas
chromatography (80/120 Carbopack B-DA/4% CARBOWAX1 20 M, Supelco Bellefonte, PA), and potentiometric determination was carried out for ammonia concentration
(type 15 230 3000 ammonia electrode, Mettler-Toledo AG, Greifensee, Switzerland) and
pH-value. The DM content and pH-value of the whole plant maize silage and the grass
clover silage were 305 g kgÿ1, 4.1 and 257 g kgÿ1, 5.2, respectively. In both silages the
proportion of ammonia nitrogen in total nitrogen content was less than 100 g kgÿ1. Based
on DM, concentrations of lactic, acetic and butyric acids in the whole plant maize silage
and in the grass clover silage were 18.3, 3.5, 0.1 g kgÿ1 and 19.3, 9.0, 0.6 g kgÿ1,
respectively. The energy content of the ingredients was estimated based on the gas test
(Menke and Steingass, 1987). The grass clover and the grass hay were harvested quite
late due to the weather conditions in spring/summer 1995, which led to the high fibre
contents.
The first 7 days of each treatment period were used for partial adjustment to the diet by
feeding equal amounts of ensiled and pelleted grass clover and whole plant maize, based
on DM content, and data collection was done from d 8 to d 49.
All cows were weighed at the onset of the experiment and once a week thereafter.
Water was freely available throughout the study except for 3 h prior to weighing. Animals
were milked in their stanchions at 0515 and again at 1600 h.
2.2. Data collection
2.2.1. Dry matter intake
Animals were fed individually between 0500 and 0930 and between 1530 and 1845 h
during the experiment. Feedstuffs were offered twice a day in the following order: whole
plant maize silage/pellets, grass hay, concentrate and grass clover silage/pellets. Daily
concentrate amounts of more than 5 kg were split in thirds and fed additionally before
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
269
grass hay in the morning. Each forage component was offered for about an hour, except
for the grass clover silage/pellets, which remained in the feeding trough until the next
feeding time. Forage amounts were gauged to ensure about 5% feed refusal of the total
DM offered. The amount of forage components offered was based on the intake during
the adjustment period. When there were little or no weigh-backs, forage was offered in
increased amounts in accordance with the forage ratios given above. Based on the
individual milk performance measured 4 days prior to the beginning of the experiment,
1 kg of concentrate was offered throughout the experiment for every 2.35 kg ECM
exceeding a daily production of 15 kg ECM. All feeds offered were weighed individually
for each animal, as were weigh-backs at each feeding. Samples of all ingredients, as well
as individual refusals, were taken twice a week and composited for 2.5-week periods.
2.2.2. Milk performance and composition
Milk yield from each cow was recorded daily using LactoCorder (FOSS Deutschland,
Hamburg, Germany), and samples taken weekly from the morning and evening milkings
were analyzed for protein, fat, lactose and urea by an instrumental method employing
mid-infrared specific absorption spectroscopy according to System 4000 (FOSS
ELECTRIC, Hillerd, Denmark). The counting of somatic cells was performed using
the Fluoro-Opto-Electronic-Cell-Counting principle as also described by System 4000.
Results from these analyses were weighted by the amount of milk and daily mean values
were used for the statistical analysis.
2.2.3. Physiological investigations
Rumen fluid samples (50 ml) were taken via stomach tube through the esophagus from
all animals four times per treatment, equally spaced throughout the treatment period,
three hours after feeding. At the same time, venous blood samples were drawn from the
jugular vein in vacuum tubes containing Fluoride/EDTA (Fa. Greiner, KremsmuÈnster,
Austria) for determination of plasma glucose concentration, and in vacuum tubes for
serum collection (Fa. Greiner, KremsmuÈnster, Austria) and were centrifuged at 3000 g
for 10 min. The plasma was harvested and used for colorimetric determination (Ektachem
DT 60, Kodak, USA) of glucose while calcium, inorganic phosphate, magnesium, total
protein (TP), albumin, urea, total bilirubin (TBIL), aspartate amino transferase (AST),
glutamate dehydrogenase (GlDH) and gamma glutamyl transferase (GGT) were analyzed
colorimetrically (Ektachem DT 60, Kodak, USA) from the harvested serum within 48 h.
Urine samples were also collected on these occasions and pH, glucose, protein and ketone
bodies were determined (Combur10-Test1UX, Fa. Boehringer Mannheim, Germany).
Rumen fluid pH was measured (glass electrode) before samples were centrifuged at
4000 g for 20 min. Supernatant was diluted with H2O 1 : 10 and analyzed for volatile
fatty acids (VFAs) by gas chromatography (80/120 Carbopack B-DA/4% CARBOWAX1
20 M, Supelco, Bellefonte, PA).
2.3. Statistical analysis
One animal was removed prematurely from the experiment because of a leg condition,
and data from this animal was excluded from analysis. Only data collected from day 15 to
270
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
day 49 of each treatment were included in the statistical analysis. Statistical
analyses were conducted using Model 6 of the LSMLMW computer program (Harvey,
1990). Data were analyzed as a completely randomized 2 2 cross-over design. The
model included animal and treatment effects and their interaction. The statistical model
was:
Yijk Gi Tj G Tij eijk
where: Gi = group, Tj = animal, (GT )ij = interaction between group and animal, and
eijk = error.
All data are presented as least squares means. Statistical differences were considered to
be significant when P < 0.05.
3. Results
Least squares means, pooled standard errors and probabilities from ANOVA
concerning feed intake, milk performance, milk composition and body weight are shown
in Table 2. Average daily forage DMI was increased from 12.8 up to 18.6 kg when grass
clover and whole plant maize were preserved through the process of dehydration and
pelleting instead of ensiling. The same increase was observed in total DMI because the
amount of concentrate offered was not adjusted according to the forage DMI. The energy
intake from forage in the pellet group equaled the total energy intake in the silage group.
The residual NEL intake represents the difference between the total NEL intake and the
Table 2
Effects of feeding ensiled or pelleted grass clover and whole plant maize on dry matter intake, energy and crude
protein supply, milk yield, milk composition and body weight change of dairy cows
Item
Silage
group
Pellet
group
Pooled standard
error
Significance
(P)
Forage DMIb (kg dayÿ1)
Total DMIb (kg dayÿ1)
NELc intake (MJ dayÿ1)
Residual NELc intake (MJ dayÿ1)
CPd intake (g dayÿ1)
CPd balance (g dayÿ1)
Milk (kg dayÿ1)
ECMe (kg dayÿ1)
Milk fat (g kgÿ1)
Milk fat (g dayÿ1)
Milk protein (g kgÿ1)
Milk protein (g dayÿ1)
Lactose (g kgÿ1)
Lactose (g dayÿ1)
Milk somatic cells (counts 103 mlÿ1)
Milk urea (mg 100 mlÿ1)
BWa change (kg dayÿ1)
12.8
16.5
98.3
1.5
2145
255
17.5
18.3
42.1
731
36.2
630
48.5
851
101
25.7
0.12
18.6
22.4
131.0
17.0
2945
819
20.2
20.3
37.9
762
37.5
755
48.9
986
99
18.2
0.59
0.5
0.6
3.8
24.3
220
229
1.0
1.0
1.9
48
0.9
29
0.4
55
36
3.25
0.17
81 (1999) 265±277
Effects of grass clover-pellets and whole
plant maize-pellets on the feed intake
and performance of dairy cows
W. Knausa,*, K. Lugerb, W. Zollitscha, H. Guflerc,
L. Gruberd, C. Murauera, F. Lettnera
a
Department of Animal Science, University of Agricultural Sciences, Gregor Mendel-Str. 33,
A-1180 Vienna, Austria
b
Federal Research Institute for Agriculture, Rottenhauser Str. 32, A-3250 Wieselburg, Austria
c
University of Veterinary Medicine, VeterinaÈrplatz 1, A-1210 Vienna, Austria
d
Federal Research Institute for Alpine Agriculture Gumpenstein , A-8952 Irdning, Austria
Received 14 July 1998; received in revised form 5 May 1999; accepted 15 June 1999
Abstract
Twenty dual-purpose Simmental dairy cows were used in a 2 2 cross-over design to evaluate
the effects of feeding, both pelleted vs. ensiled grass clover and whole plant maize on feed intake,
milk production and composition, as well as on blood metabolites and some parameters of rumen
fermentation. In addition to the pelleted/ensiled forages, all animals were offered grass hay, and,
based on the individual milk performance prior to the beginning of the experiment, 1 kg of
concentrate for every 2.35 kg energy-corrected milk (ECM) exceeding a daily production of 15 kg
ECM. In both groups, the forage was offered so that grass hay, grass clover silage or pellets and
whole plant maize silage or pellets would contribute 100, 450 and 450 g kgÿ1 to total forage dry
matter intake (DMI), respectively. Both the treatment periods lasted for seven weeks. Average daily
forage DMI was increased from 12.8 up to 18.6 kg when grass clover and whole plant maize were
fed in the pelleted form. ECM production was elevated from 18.3 up to 20.3 kg (p < 0.001). Also, a
significant increase was observed for milk protein and lactose level, while content of milk fat and
concentration of milk urea were reduced. Rumen pH-values were significantly lower in the pelletfed cows than in the silage-fed cows. The acetate to propionate ratio was narrowed down from
3.80 : 1 to 3.54 : 1. Concentration of blood serum urea was significantly reduced (0.8 mmol lÿ1)
when pellets were fed. Except for glutamate dehydrogenase (GlDH), all the liver specific enzymes
were within normal ranges. The analysis of glucose, protein and ketone bodies in the urine was
*
Corresponding author. Tel.: +43-1-47654/3285; fax: +43-1-47654/3254
E-mail address: knaus@edv1.boku.ac.at (W. Knaus)
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 9 0 - 5
266
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
negative for both the dietary treatments. Pelleted grass clover and whole plant maize proved to be
superior to their ensiled counterparts in regard to DMI and milk performance, without having a
negative impact on the health status of the animals, but extra milk output in relation to the
additional feed intake was very low. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Pellets; Feed conservation; Feed intake; Dairy cows; Performance
1. Introduction
The use of pelleted forages in cattle nutrition has never played an important role in
Austrian agricultural production. There are several reasons for this: capital investment
needed for the dehydration and pelleting facilities far exceeds the costs of other forage
preservation methods and, in addition, harvesting with the original water content,
artificially drying and, finally, pelleting the forage is highly energy intensive.
Nevertheless, pelleted forages are advantageous feedstuffs from a nutritionist's point of
view. It is well established that dry matter intake (DMI) is the cornerstone upon which
productive dairy rations are built. One possible way of achieving a high intake of forage
dry matter (DM) is the alteration of the physical form of the feedstuffs. Pelleting is one of
the most drastic physical changes to which forages can be subjected in commercial
practice. The artificial drying of the freshly cut forage and the reduction of the forage
bulk through the mechanical treatment of pelleting causes a radical reduction in particle
size, promoting a higher voluntary intake and increasing animal efficiency while
decreasing the effective fibre content (Van Soest, 1994). The greatest improvement in
intake after pelleting is observed in bulky forages of good digestibility (Van Soest, 1994).
According to the definition by Moore (1964), pellets usually consist of finely ground
forage compressed into small cylinders 0.6±1.9 cm in diameter and 0.6±3.8 cm in length.
Modern forage harvesters allow the forage to be chopped into material of 2±3 cm in
length and make sure that every kernel is opened when maize plants are chopped. This
substrate is fine enough to be formed into a firm pellet without grinding after the process
of dehydration.
Beardsley (1964) compiled data in a review of the effects of pelleting on intake, live
weight gains and feed efficiency for several different forages fed to calves or yearlings
and showed that, calculated on an individual comparison basis and averaged, pelleting a
long hay increased the daily feed intake by 25%, increased daily gain by 98% and
decreased feed required per unit of gain by 36%. Vandersall and Douglass (1974) found
that DMI increased when a combination of whole plant maize-pellets and whole plant
maize silage was fed to Holstein cows, but observed no effect on milk production. As a
consequence of altering particle size distribution of forage by grinding and pelleting,
Thomson and Beever (1979) noted a depression in overall apparent digestibility of
organic matter, which was generally greater for grasses (up to 15 percentage units) than
legumes (3±6 percentage units).
The purpose of this work was to elucidate the effects of feeding pelleted grass clover
and whole plant maize roughages as compared to ensiled on DMI, milk production and
composition, as well as on blood metabolites and some parameters of fermentation in the
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
267
rumen of dual purpose Simmental dairy cows. Based on the available literature and on
practical experience gathered at federal research institutes in Austria, it was hypothesized
that dairy cows' voluntary feed consumption would increase when forages were preserved
and fed as pellets rather than as silages, which would result in an elevated milk yield and
body condition due to an improved level of nutrient supply to the animals. It was also
assumed that feeding some long hay in addition to the pelleted forages would help
counteract possible detrimental effects on ruminal digestion, therefore allowing for a
greater total nutrient uptake from the digestive tract, improving the animals' overall
performance.
2. Materials and methods
2.1. Experimental design and diet formulation
Twenty dual-purpose Simmental dairy cows were selected out of a herd of 70
according to their body weight (BW), days in milk (DIM), number of lactations and
current milk performance, and assigned to treatments of 10 animals each, arranged
factorially in a 2 2 Latin square design.
At the beginning of the experiment, cows ranged from 39 to 134 days postpartum, and
in each group they were balanced as nearly as possible with respect to BW, DIM, number
of lactations and milk production, averaging 615 kg, 75, 1.7 and 25.3 kg energy-corrected
milk (ECM), respectively. The animals were kept on rubber mats in a tie stall using
sawdust as a bedding material.
The ingredients of the diet for the control group were whole plant maize silage, grass
clover silage, grass hay and concentrate. Animals from the experimental group were
offered feedstuffs of the same origin which were harvested at the same stage of maturity,
but the whole plant maize and grass clover were artificially dehydrated and pelleted
instead of ensiled.
Grass clover containing about 50% alfalfa was cut, and swaths were either wilted on
the field for a few hours and then ensiled as bales, or chopped to lengths of approximately
25 mm using a forage harvester and dehydrated with hot air in a rotary drum drier.
Optimal DM content in the silage bales was not obtained because of inclement weather
while hauling the grass clover from the field. Maize plants were chopped the same way
and either dehydrated in the same drier or ensiled. The chopped and artificially dried
whole plant maize and grass clover were compressed without the addition of steam or
water into pellets with a matrix press (KAHL, Mod. 34-600). The diameter of the pellets
was 15 mm and their length varied between 20 and 45 mm. The bulk density of the grass
clover-pellets and the whole plant maize-pellets was 420 and 700 kg mÿ3, respectively.
The concentrate consisted of 250 g kgÿ1 maize, 192 g kgÿ1 barley, 188 g kgÿ1 wheat,
125 g kgÿ1 faba bean, 125 g kgÿ1 oats, 62 g kgÿ1 peas, 50 g kgÿ1 soybean meal, 3 g kgÿ1
sodium chloride and 5 g kgÿ1 vitamin premix. An extra 100 g of mineral mixture was
given each cow daily. In both groups the forage was offered in such a manner that grass
hay, grass clover silage/pellets and whole plant maize silage/pellets would contribute 10,
45 and 45% to total forage DMI, respectively.
268
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
Table 1
Chemical composition of feedsa
Component
ÿ1
Crude protein (g kg )
NEL (MJ kgÿ1)
NDF (g kgÿ1)
ADF (g kgÿ1)
Ether extract (g kgÿ1)
Crude ash (g kgÿ1)
Calcium (g kgÿ1)
Phosphorus (g kgÿ1)
Magnesium (g kgÿ1)
Sodium (g kgÿ1)
a
Whole plant maize
Grass clover
Silage
Pellets
Silage
Pellets
74
5.76
478
247
35
42
4.16
2.87
1.96
0.01
72
5.89
518
239
25
40
2.87
2.46
1.84
0.03
197
4.65
419
339
39
111
20.37
3.30
3.04
0.97
199
4.85
458
318
32
113
20.50
2.75
3.00
0.42
Grass hay
Concentrate
mixture
69
4.32
651
378
23
69
6.52
3.17
1.69
0.24
159
8.66
283
81
25
33
1.96
4.40
1.39
1.15
DM basis.
The average nutrient content of the feedstuffs is shown in Table 1. Chemical
composition of feeds and orts was determined as described by Naumann and Bassler
(1976). In addition, silages were analyzed for lactic, acetic and butyric acids by gas
chromatography (80/120 Carbopack B-DA/4% CARBOWAX1 20 M, Supelco Bellefonte, PA), and potentiometric determination was carried out for ammonia concentration
(type 15 230 3000 ammonia electrode, Mettler-Toledo AG, Greifensee, Switzerland) and
pH-value. The DM content and pH-value of the whole plant maize silage and the grass
clover silage were 305 g kgÿ1, 4.1 and 257 g kgÿ1, 5.2, respectively. In both silages the
proportion of ammonia nitrogen in total nitrogen content was less than 100 g kgÿ1. Based
on DM, concentrations of lactic, acetic and butyric acids in the whole plant maize silage
and in the grass clover silage were 18.3, 3.5, 0.1 g kgÿ1 and 19.3, 9.0, 0.6 g kgÿ1,
respectively. The energy content of the ingredients was estimated based on the gas test
(Menke and Steingass, 1987). The grass clover and the grass hay were harvested quite
late due to the weather conditions in spring/summer 1995, which led to the high fibre
contents.
The first 7 days of each treatment period were used for partial adjustment to the diet by
feeding equal amounts of ensiled and pelleted grass clover and whole plant maize, based
on DM content, and data collection was done from d 8 to d 49.
All cows were weighed at the onset of the experiment and once a week thereafter.
Water was freely available throughout the study except for 3 h prior to weighing. Animals
were milked in their stanchions at 0515 and again at 1600 h.
2.2. Data collection
2.2.1. Dry matter intake
Animals were fed individually between 0500 and 0930 and between 1530 and 1845 h
during the experiment. Feedstuffs were offered twice a day in the following order: whole
plant maize silage/pellets, grass hay, concentrate and grass clover silage/pellets. Daily
concentrate amounts of more than 5 kg were split in thirds and fed additionally before
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
269
grass hay in the morning. Each forage component was offered for about an hour, except
for the grass clover silage/pellets, which remained in the feeding trough until the next
feeding time. Forage amounts were gauged to ensure about 5% feed refusal of the total
DM offered. The amount of forage components offered was based on the intake during
the adjustment period. When there were little or no weigh-backs, forage was offered in
increased amounts in accordance with the forage ratios given above. Based on the
individual milk performance measured 4 days prior to the beginning of the experiment,
1 kg of concentrate was offered throughout the experiment for every 2.35 kg ECM
exceeding a daily production of 15 kg ECM. All feeds offered were weighed individually
for each animal, as were weigh-backs at each feeding. Samples of all ingredients, as well
as individual refusals, were taken twice a week and composited for 2.5-week periods.
2.2.2. Milk performance and composition
Milk yield from each cow was recorded daily using LactoCorder (FOSS Deutschland,
Hamburg, Germany), and samples taken weekly from the morning and evening milkings
were analyzed for protein, fat, lactose and urea by an instrumental method employing
mid-infrared specific absorption spectroscopy according to System 4000 (FOSS
ELECTRIC, Hillerd, Denmark). The counting of somatic cells was performed using
the Fluoro-Opto-Electronic-Cell-Counting principle as also described by System 4000.
Results from these analyses were weighted by the amount of milk and daily mean values
were used for the statistical analysis.
2.2.3. Physiological investigations
Rumen fluid samples (50 ml) were taken via stomach tube through the esophagus from
all animals four times per treatment, equally spaced throughout the treatment period,
three hours after feeding. At the same time, venous blood samples were drawn from the
jugular vein in vacuum tubes containing Fluoride/EDTA (Fa. Greiner, KremsmuÈnster,
Austria) for determination of plasma glucose concentration, and in vacuum tubes for
serum collection (Fa. Greiner, KremsmuÈnster, Austria) and were centrifuged at 3000 g
for 10 min. The plasma was harvested and used for colorimetric determination (Ektachem
DT 60, Kodak, USA) of glucose while calcium, inorganic phosphate, magnesium, total
protein (TP), albumin, urea, total bilirubin (TBIL), aspartate amino transferase (AST),
glutamate dehydrogenase (GlDH) and gamma glutamyl transferase (GGT) were analyzed
colorimetrically (Ektachem DT 60, Kodak, USA) from the harvested serum within 48 h.
Urine samples were also collected on these occasions and pH, glucose, protein and ketone
bodies were determined (Combur10-Test1UX, Fa. Boehringer Mannheim, Germany).
Rumen fluid pH was measured (glass electrode) before samples were centrifuged at
4000 g for 20 min. Supernatant was diluted with H2O 1 : 10 and analyzed for volatile
fatty acids (VFAs) by gas chromatography (80/120 Carbopack B-DA/4% CARBOWAX1
20 M, Supelco, Bellefonte, PA).
2.3. Statistical analysis
One animal was removed prematurely from the experiment because of a leg condition,
and data from this animal was excluded from analysis. Only data collected from day 15 to
270
W. Knaus et al. / Animal Feed Science and Technology 81 (1999) 265±277
day 49 of each treatment were included in the statistical analysis. Statistical
analyses were conducted using Model 6 of the LSMLMW computer program (Harvey,
1990). Data were analyzed as a completely randomized 2 2 cross-over design. The
model included animal and treatment effects and their interaction. The statistical model
was:
Yijk Gi Tj G Tij eijk
where: Gi = group, Tj = animal, (GT )ij = interaction between group and animal, and
eijk = error.
All data are presented as least squares means. Statistical differences were considered to
be significant when P < 0.05.
3. Results
Least squares means, pooled standard errors and probabilities from ANOVA
concerning feed intake, milk performance, milk composition and body weight are shown
in Table 2. Average daily forage DMI was increased from 12.8 up to 18.6 kg when grass
clover and whole plant maize were preserved through the process of dehydration and
pelleting instead of ensiling. The same increase was observed in total DMI because the
amount of concentrate offered was not adjusted according to the forage DMI. The energy
intake from forage in the pellet group equaled the total energy intake in the silage group.
The residual NEL intake represents the difference between the total NEL intake and the
Table 2
Effects of feeding ensiled or pelleted grass clover and whole plant maize on dry matter intake, energy and crude
protein supply, milk yield, milk composition and body weight change of dairy cows
Item
Silage
group
Pellet
group
Pooled standard
error
Significance
(P)
Forage DMIb (kg dayÿ1)
Total DMIb (kg dayÿ1)
NELc intake (MJ dayÿ1)
Residual NELc intake (MJ dayÿ1)
CPd intake (g dayÿ1)
CPd balance (g dayÿ1)
Milk (kg dayÿ1)
ECMe (kg dayÿ1)
Milk fat (g kgÿ1)
Milk fat (g dayÿ1)
Milk protein (g kgÿ1)
Milk protein (g dayÿ1)
Lactose (g kgÿ1)
Lactose (g dayÿ1)
Milk somatic cells (counts 103 mlÿ1)
Milk urea (mg 100 mlÿ1)
BWa change (kg dayÿ1)
12.8
16.5
98.3
1.5
2145
255
17.5
18.3
42.1
731
36.2
630
48.5
851
101
25.7
0.12
18.6
22.4
131.0
17.0
2945
819
20.2
20.3
37.9
762
37.5
755
48.9
986
99
18.2
0.59
0.5
0.6
3.8
24.3
220
229
1.0
1.0
1.9
48
0.9
29
0.4
55
36
3.25
0.17