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Effects of recombinant bovine somatotropin (rbST) on rumen ammonia and milk protein content and composition
198
Data were processed by ANOVA. Over the entire period of treatment, rbST increased (P<0.01) milk yield (C: 28.8; Ca-LCFA: 28.8; rbST: 30.3; CaLCFA + rbST: 30.6 kg/day) without affecting milk protein percentages. In cows fed the control diet and the Ca-LCFA diet, rbST significantly reduced plasma levels of a-amino N, uric acid and albumin, and increased total protein. In animals not injected with rbST, the Ca-LCFA diet significantly increased plasma levels of urea and creatinine, rbST administration significantly lowered plasma urea by 9% in animals fed the control diet and by 22% in animals fed the Ca-LCFA diet, but increased plasma creatinine in animals fed the control diet and reduced it in animals fed the Ca-LCFA diet. It is possible that decreases in urea, a-amino nitrogen and uric acid reflect decreased amino acid oxidation, increased milk protein biosynthesis and/or increased N recycling (salvage). The increase in total milk protein yield may be responsible for the decrease in plasma albumin. 35. Effects of recombinant bovine somatotropin (rbST) on rumen ammonia and milk protein content and composition. E. Salimei, G. Savoini, V. Bontempo, L. Degano, P. Polidori and V. Dell'Otto. Ist. Alimentazione Animale, Facolt/l di Medicina Veterinaria, Milano, Italy. The aim of this paper was to study the effects of slow release rbST on rumen ammonia concentration, protein content and composition, and coagulation aptitude of milk. Four dairy cows fitted with rumen cannulae were used. Two animals were alternatively given rbST (640 mg/cow) in one treatment cycle (28 day) and no rbST in the consecutive one (change over design). Ruminal ammonia concentration was not significantly affected by somatotropin administration. Somatotropin administration increased (P < 0.05 ) both milk yield (18.33 kg/cow/day-rbST and 15.36 kg/cow/day-control; SE: 0.986) and dairy milk protein, fat and dry matter yields (650 g, 720 g, 2385 g-rbST and 550 g, 600 g, 1992 g-control; SE: 37, 35 and 213). The results regarding milk protein composition are in the table. Somatotropin did not influence milk freezing point and coagulation aptitude parameters (T, K10, A30) of milk. Somatotropin increased milk yield
Parameters
Protein, % NCN, % NCN/N Casein, % Casein/protein NCN = Non-casein nitrogen.
Treatment Control
rbST
3.62 0.13 24.05 2.75 0.76
3.60 0.13 23.07 2.77 0.76
SEM
P value
0.035 0.011 1.145 0.030 0.029
0.75 0.44 0.40 0.43 0.40
199
without affecting rumen ammonia and milk protein content and composition. Since in Italy the greatest part of milk is processed for cheese-making, it is particularly interesting to note that rbST administration did not affect milk casein content, either as an absolute level and as a fraction of total protein.
36. Effects of heat-treated carbohydrates on milk composition in high-yielding dairy cows. W. VeUe, T. Framstad and S. Tollersrud. Norwegian College of Veterinary Medicine, Oslo, Norway. Norwegian dairies no longer put a premium on high-fat milk, but on highprotein milk. The aim of the study was to produce low-fat milk. All animals were fed grass silage ad lib. and 2 kg hay per day. The control animals (n = 15 ) also received a commercial concentrate mixture, and the experimental animals (n = 9) chopped surplus bread from a bakery, according to yield in both groups. Samples of morning and afternoon milk were collected twice a week for 8 weeks, starting between days 5 and 11 post partum, and analyzed for fat and protein. In the experimental group, milk fat yield was reduced and milk protein yield increased. Yield of milk and milk components (means ± SD) during 8 weeks post partum in dairy cows. Milking intervals: 9 and 15 hr
Milk, kg Fat, % Protein, % Milk, kg/day Fat, g/day Protein, g/day
Control group (n = 15 )
Experimental group ( n = 9 )
Morning
Afternoon
Morning
Afternoon
14.6±2.67 3.87 ± 0.58 3.05 ± 0.35
9.6 _+ 1.60 4.97 +_0.98 3.20 ± 0.34
14.6±2.12 3.39 ± 0.71 *** 3.30 _+0.35***
9.4 ± 1.52 5.01 ± 0.76 3.42 ± 0.37***
24.2 ±4.0 1034± 201 750± 127
24.0± 3.4 968 ± 200* 802± 131"*
Different from controls: *P< 0.05; **P< 0.01 ; ***P< 0.001.
Thus, considering the market situation, substituting some or all of the commercial concentrate allowance with heat-treated carbohydrates might be profitable.
Data were processed by ANOVA. Over the entire period of treatment, rbST increased (P<0.01) milk yield (C: 28.8; Ca-LCFA: 28.8; rbST: 30.3; CaLCFA + rbST: 30.6 kg/day) without affecting milk protein percentages. In cows fed the control diet and the Ca-LCFA diet, rbST significantly reduced plasma levels of a-amino N, uric acid and albumin, and increased total protein. In animals not injected with rbST, the Ca-LCFA diet significantly increased plasma levels of urea and creatinine, rbST administration significantly lowered plasma urea by 9% in animals fed the control diet and by 22% in animals fed the Ca-LCFA diet, but increased plasma creatinine in animals fed the control diet and reduced it in animals fed the Ca-LCFA diet. It is possible that decreases in urea, a-amino nitrogen and uric acid reflect decreased amino acid oxidation, increased milk protein biosynthesis and/or increased N recycling (salvage). The increase in total milk protein yield may be responsible for the decrease in plasma albumin. 35. Effects of recombinant bovine somatotropin (rbST) on rumen ammonia and milk protein content and composition. E. Salimei, G. Savoini, V. Bontempo, L. Degano, P. Polidori and V. Dell'Otto. Ist. Alimentazione Animale, Facolt/l di Medicina Veterinaria, Milano, Italy. The aim of this paper was to study the effects of slow release rbST on rumen ammonia concentration, protein content and composition, and coagulation aptitude of milk. Four dairy cows fitted with rumen cannulae were used. Two animals were alternatively given rbST (640 mg/cow) in one treatment cycle (28 day) and no rbST in the consecutive one (change over design). Ruminal ammonia concentration was not significantly affected by somatotropin administration. Somatotropin administration increased (P < 0.05 ) both milk yield (18.33 kg/cow/day-rbST and 15.36 kg/cow/day-control; SE: 0.986) and dairy milk protein, fat and dry matter yields (650 g, 720 g, 2385 g-rbST and 550 g, 600 g, 1992 g-control; SE: 37, 35 and 213). The results regarding milk protein composition are in the table. Somatotropin did not influence milk freezing point and coagulation aptitude parameters (T, K10, A30) of milk. Somatotropin increased milk yield
Parameters
Protein, % NCN, % NCN/N Casein, % Casein/protein NCN = Non-casein nitrogen.
Treatment Control
rbST
3.62 0.13 24.05 2.75 0.76
3.60 0.13 23.07 2.77 0.76
SEM
P value
0.035 0.011 1.145 0.030 0.029
0.75 0.44 0.40 0.43 0.40
199
without affecting rumen ammonia and milk protein content and composition. Since in Italy the greatest part of milk is processed for cheese-making, it is particularly interesting to note that rbST administration did not affect milk casein content, either as an absolute level and as a fraction of total protein.
36. Effects of heat-treated carbohydrates on milk composition in high-yielding dairy cows. W. VeUe, T. Framstad and S. Tollersrud. Norwegian College of Veterinary Medicine, Oslo, Norway. Norwegian dairies no longer put a premium on high-fat milk, but on highprotein milk. The aim of the study was to produce low-fat milk. All animals were fed grass silage ad lib. and 2 kg hay per day. The control animals (n = 15 ) also received a commercial concentrate mixture, and the experimental animals (n = 9) chopped surplus bread from a bakery, according to yield in both groups. Samples of morning and afternoon milk were collected twice a week for 8 weeks, starting between days 5 and 11 post partum, and analyzed for fat and protein. In the experimental group, milk fat yield was reduced and milk protein yield increased. Yield of milk and milk components (means ± SD) during 8 weeks post partum in dairy cows. Milking intervals: 9 and 15 hr
Milk, kg Fat, % Protein, % Milk, kg/day Fat, g/day Protein, g/day
Control group (n = 15 )
Experimental group ( n = 9 )
Morning
Afternoon
Morning
Afternoon
14.6±2.67 3.87 ± 0.58 3.05 ± 0.35
9.6 _+ 1.60 4.97 +_0.98 3.20 ± 0.34
14.6±2.12 3.39 ± 0.71 *** 3.30 _+0.35***
9.4 ± 1.52 5.01 ± 0.76 3.42 ± 0.37***
24.2 ±4.0 1034± 201 750± 127
24.0± 3.4 968 ± 200* 802± 131"*
Different from controls: *P< 0.05; **P< 0.01 ; ***P< 0.001.
Thus, considering the market situation, substituting some or all of the commercial concentrate allowance with heat-treated carbohydrates might be profitable.