132 I
. Bruckental et al. Livestock Production Science 63 2000 131 –140
obvious in the Israeli herd Ron et al., 1984 as well number, milk yield during the previous lactation and
as in other countries Lamming, 1998. Butler and body weight BW. The cows were maintained in the
Smith 1989 found a negative correlation between trial for at least three months. Cows were milked
milk yield and conception rate. Ostergaard et al. three times daily, at 06:00, 14:00 and, 20:00 h. Milk
1990 have suggested that the genetic breeding yield and BW were recorded at each milking by the
program of a dairy herd is focused on high milk Afimilk system S.A.E. AFIKIM, Kibbutz Afikim,
yields only, without a parallel concern for increased Israel. Body condition was scored once a week.
feed consumption. As a result, the partitioning of Milk samples from three consecutive milkings were
absorbed metabolites was directed primarily toward collected every 10 days and analyzed for fat, protein
milk yield, and deficiency, mainly of energy, was and lactose by the infrared procedure at the Israel
developed in other essential metabolic pathways Cattle Association Laboratories Bitan Aharon, Is-
Nebel and McGillard, 1993. rael. Sixty days after the beginning of the experi-
Dairy cows ovulate even if they are in a negative ment, ruminal fluid and jugular blood samples were
energy balance. However, ovarian activity is appar- taken from all cows. Rumen samples were taken
ent earlier in cows with an improved energy status with a stomach tube. Sampling was done before the
Staples et al., 1990. Sklan et al. 1991 improved first morning meal and 4 and 8 h later. Ruminal fluid
the fertility of high-yielding cows by offering diets samples were kept in tubes containing 0.2 ml mer-
supplemented with calcium soaps of fatty acids. cury chloride.
Similar diets in other studies Carroll et al., 1990; Spicer et al., 1993 failed to improve fertility. The
2.2. Diets examination of dietary ingredients such as protein
source and concentration would appear to be desir- Diets were formulated to contain 30 forage on a
able if the aim is ultimately to improve feed intake DM basis and differed mainly in dietary CP and
Dhiman and Satter, 1993. The effect of dietary UDCP contents Table 1. Diet 1 the control diet,
protein on feed intake is explained partially by the contained 167 g kg CP, of which 320 g kg was
effect of protein on microbial fermentation and UDCP. Diet 2 contained 167 g kg CP, of which 380
digestion and by the effect of the amino acid profile g kg was UDCP. Diet 3 contained 180 g kg CP, of
on whole animal metabolism and yield Garnsworthy which 350 g kg was UDCP. The UDCP content of
and Cole, 1990. However, there is still a lack of diet 3 was the same as that of diet 2, and the rumen
information regarding composition and amount of degradable CP RDCP content was the same as in
supplementary crude protein CP. the control diet. Corn gluten meal was added to diets
According to the NRC 1989, undegradable UD 2 and 3 in order to increase undegradability. Ruminal
CP levels in lactating cow diets ranges between 54 degradabilities of organic matter OM and CP
and 63 g kg DM. The present work was designed to contents of the dietary ingredients, as assessed by the
determine the effect of improved protein availability, dacron bag technique Ørskov and McDonald,
via the higher UDCP concentrations, on dry matter 1979, are presented in Table 2. When ingredient
intake DMI, milk yield, energy balance and fertili- additivity of ruminal degradation is assumed, the
ty of high-yielding dairy cows during the first three resultant ratios of ruminally degradable OM to
months postpartum. RDCP in diets 1, 2 and 3 were 4.5, 5.1 and 4.5,
respectively. Cows were group fed. The diets were fed as a
2. Materials and methods TMR at 10:00 h for ad libitum intake. The feed was
moved close to the cows three times a day. Daily 2.1. Animals
DM offered of each group and feed refused were recorded. Diets were sampled once weekly and orts
Forty-five Israeli Holstein cows parity 2 were were sampled daily; a representative sample of orts
assigned to three dietary treatments at 2 d post- was analyzed for DM, CP and neutral-detergent fiber
partum, according to expected calving date, parity NDF.
I . Bruckental et al. Livestock Production Science 63 2000 131 –140
133 Table 1
2.3. Reproductive management
Ingredients of experimental diets
d
Ingredients g kg DM Diet
The cows were examined by a veterinarian during the first week after calving. Following this examina-
1 2
3
tion, cows that were diagnosed to have a retained
a
Corn gluten meal 18.0
43.0 41.0
b
placenta, metritis, or other health problems were
NPN mix 6.9
2.2 7.4
given appropriate medical treatment. Blood for pro-
Milo grain 12.0
. . . . . .
Barley grain 222.0
222.0 222.0
gesterone analysis was sampled three times weekly,
Wheat grain 68.0
62.0 67.0
starting 3 d postpartum and continuing until first
Corn grain 30.0
36.0 36.0
insemination. First postpartum ovulation was defined
Wheat bran 133.0
133.0 133.0
as the first day after calving when plasma progester-
Soybean meal 27.0
22.0 27.0
one concentration reached at least 1 ng ml. Estrus
Rapeseed meal 44.0
44.0 44.0
Whole cottonseeds 46.0
46.0 46.0
detection was performed by an automated pedometer
Citrus pulp 76.0
76.0 76.0
system S.A.E. AFIKIM and by visual observation
Wheat silage 97.0
97.0 97.0
during two 30-min periods daily, at 09:00 and 15:00
Corn silage 117.0
117.0 117.0
h. Insemination was commenced 60 d after calving.
Vetch hay 30.0
30.0 30.0
Cows were inseminated at 11:00 h. Pregnancy was
Oat hay 52.0
52.0 52.0
Oil 3.6
. . . 1.1
diagnosed 45 d following insemination by rectal
CaCO 16.0
16.0 16.0
3
palpation.
NaCl 4.5
4.5 4.5
c
Vitamins and minerals 0.7
0.7 0.7
2.4. Chemical analyses
a
Contained 60 of CP.
b
Non-protein nitrogen. Contained g kg 500 ground milo
Chemical analyses were performed on dry feed
grain, 333 urea and 167 NH SO . Calculated to supply 1270
4 2 4
samples that had been ground using a 2-mm mill.
g kg of CP.
c 6
6
Contained 16 ? 10 IU of vitamin A, 3.2 ? 10 IU of vitamin D,
Dry matter was assayed after samples were dried at
6
16 ? 10 IU of vitamin E, 48 g of Mo, 48 g of Zn, 48 g of Fe, 19.2
1058C for 12 h; corn silage and citrus pulp were first
g of Cu, 3.4 g of I, 0.32 g of Co and 0.48 g of Se.
dried at 608C for 48 h. OM was determined after
d
No. 1, 16.7 dietary CP, of which 32 was undegradable
ashing at 6008C for 2 h. Crude protein was analysed
control; No. 2, 16.7 CP, of which 38 was undegradable; and
using a Kjeldhal autoanalyser Tecator, Hoganas,
No. 3, 18.0 CP, of which 35 was undegradable.
Sweden. The NDF content was determined accord- ing to the method of Van Soest et al. 1991. In situ
degradabilities of OM and CP in dietary feeds and the kinetics of their degradation in the rumen were
Table 2
determined following the method of Ørskov and
Chemical composition g kg of DM of experimental diets
McDonald 1979 and as described by Arieli et al.
b
Diet
1989. The fractional rate of particulate outflow from the rumen was assumed to be 6.5 h. Volatile
1 2
3
fatty acids VFAs in ruminal fluid that had been
OM 889
903 897
centrifuged were assessed by gas–liquid chromatog-
CP 167
167 180
a
raphy Model 5890; Hewlett-Packard, Avondale, PA,
UDCP 52
63 64
a
RDCP 115
103 116
USA on 0.3 Carbovax 20M with 0.1 phosphoric
a
RDOM 522
522 522
acid Supelco, Bellefonte, PA, USA, and ammonia
NDF 345
345 345
was determined by the phenol procedure Tagari,
Ether extract 75
45 53
1969. Blood was centrifuged, and the plasma was
NE Mcal kg 1.72
1.72 1.72
L
separated and analyzed for urea Tagari, 1969.
RDOM RDCP 4.5
5.1 4.5
a
Glucose was determined by a Beckman Glucose
UDCP 5 Undegradable CP; RDCP 5 rumen degradable CP;
Analyzer 2 Fullerton, CA, USA, and plasma insulin
RDOM 5 rumen degradable OM.
b
See footnote d in Table 1.
and plasma progesterone were determined using
134 I
. Bruckental et al. Livestock Production Science 63 2000 131 –140
radioimmunoassay kits Diagnostic Products, Los 21.4 and 20.4 kg d, respectively. Accordingly, net
Angeles, CA, USA. energy NE intake of the control cows and cows fed
diets 2 and 3 was 40.9, 36.8 and 35.1 Mcal d, 2.5. Calculations and statistical analyses
respectively. Crude protein and UCP intakes of control cows and of cows fed diets 2 and 3 were 4.0
Data were statistically analysed using the GLM and 1.2, 3.6 and 1.4, and 3.7 and 1.3 kg d, respec-
procedure of SAS 1985 to examine the effect of tively. No significant differences among the three
cow, parity number, milk yield during previous diets were found for milk yield and milk fat, protein
lactation, BW and treatment on performance parame- and lactose concentrations or yields Table 3. Milk
ters. Comparison between control and CGM-sup- yield curves are described in Fig. 1a. Data for BW
plemented diets 1 vs. 2 and 3 was tested using and body condition score BCS are presented in
nonorthogonal contrast. Averages of NH N and
Table 4, and changes in BW and BCS of cows
3
VFAs in ruminal fluids and of urea N in plasma for during the trial period are described in Fig. 1b and c,
samples taken before the first morning meal and 4 respectively. The control cows lost 35.0 kg during
and 8 h later, were used for comparing the effect of the first 27.2 d 1.29 kg d postpartum, and then
diet. The repeated measures analysis of variance started gaining weight. By approximately day 70
ANOVA was used for these metabolites. Reproduc- these cows attained their calving weight. Cows fed
tive parameters were compared by t test. Statistical diet 2 lost 54.0 kg of BW during 44.8 d 1.21 kg d
difference was determined at P , 0.10. postpartum, and by the end of the trial the cows still
had not attained their calving weight. Cows fed diet 3 lost 55.0 kg BW during 44.4 d 1.24 kg d; P ,
3. Results 0.164 and, by the end of the trial these cows still
