Dose Response to Recombinant Bovine Somatotropin from Weeks 15 to 44 Postpartum in Lactating Dairy COWS 1,2 RICHARD A. ERDMAN,2 BAL K. SHARMA,2 RANDY D. SHAVER,3,4 and RALPH M. CLEALE3 Animal Science Department University of Maryland, College Park 20742 and American Cyanamid Company Princeton, NJ 08540 ABSTRACT
fects and effects on reproduction could not be determined from the relatively few cows used in this study. (Key words: postpartum dairy cows, somatotropin, dose response)
Forty Holstein cows were used in an experiment to determine the response of cows to daily subcutaneous injections of 0, to.3, 20.6, and 30.9 mg of recombinant bST. Injections began between 98 and 104 d postpartum and continued for 29 wk, up to 70 d prepartum, or a maximum of 400 d postpartum. Increasing recombinant bST increased milk yield and 3.5% FCM yield in a linear fashion and by 5.2 and 5.7 kg/d, respectively. Milk composition was not changed, and DM intake as a percentage of BW increased from 3.39 to 3.80% with increasing (30.9 mg/d) bST. Feed efficiency (3.5% FCMlDM intake) was increased from 1.35 to 1.64 with increasing dose, suggesting improved efficiency of use of DM intake, primarily by dilution of maintenance. Increasing bST reduced BW gain linearly from .46 kg/d for the control to .22 kg/d for the 30.9 mg/d treatments. Days open tended to be greatest and number of services tended to be higher for cows treated with 30.9 mg/d bST. Calf birth weight, weight of cows at calving, and incidence of metabolic diseases during subsequent calving were not affected by bST. Somatotropin treatment resulted in somewhat smaller increases in milk yield than that reported in previous studies. Long-term health ef-
INTRODUCTION
Received November 13, 1989. Accepted May 14, 1990. IScientific Article A-4998, Contribution Number 8045 of the Maryland Agricultural Experiment Station. Supported by a grant from American Cyanamid Company. 2Animal Sciences Department. 3American Cyanamid Company. 'Tresent address: Dairy Sciences Department, University of Wisconsin, Madison. 1990 1 Dairy Sci 73:2907-2915
Bovine somatotropin hormone has been known to be a galactopoietic agent for more than 50 yr.. Early studies by Asimov and Krouze (2), using crude pituitary extracts that contained bST, demonstrated the potential efficacy of bST in stimulating milk yield in dairy cows. However, practical application of bST was not possible until methods for producing bST by recombinant DNA procedures were discovered. Only a few reports involving the use of recombinant bST (rbST) in long-term studies have been published (3, 4, 7, 15). Knowledge of long-term effects on health of cows treated with rbST is limited. Bauman et al. (3) and Eppard et al. (8) reported no adverse health and reproductive effects in cows treated with bST or rbST beginning at 84 ± 10 d postpartum (PP) for 188 d. However, Chalupa et al. (5) reported negative effects on reproductive performance by cows receiving 50 mg rbST/d in a summary of four trials with 136 cows receiving rbST beginning at 28 to 35 d PP. This suggests that high doses of rbST treatment in early lactation may negatively affect reproductive performance, and treatment in late lactation, where energy balance of cows may be more positive, may be more appropriate. The objective of this experiment was to determine milk production and health responses of lactating cows from increasing doses of rbST administration beginning at d 98 to 105 PP. MATERIALS AND METHODS
Forty Holstein cows (12 primiparous and 28 multiparous) were used. Selection of cows was
2907
2908
ERDMAN ET AL.
TABLE 1. Ingredient and nutrient composition of com silage, concentrate, and total mixed rations. Total ration (% forage)
Feed Item Ingredient, % DM Com silage Ground shelled com Ground barley Soybean meal, 48% CP Trace-mineralized salt! Dicalcium phosphate Limestone Vitamin A, D:f & E supplemen~ K-Mg suHate Composition DM, % Estimated NEIo Mca1/kg DM CP, % Ether extract (%) ADF, % NDF, % Ca, % P, % K, % Mg, % Na, % Zn, ppm Fe, ppm Cu, ppm N, ppm Mo, ppm
Silage
SD
Concentrate SD
100 40.03 20.85 33.56 1.00 1.79 2.00 .11 .66 38.1 1.68 8.6 1.7 23.1 48.1 .26 .26 1.14 .18 .006 21 136 5 38 .9
4.1 .03 .7 .4 4.3 5.4 .03 .02 .14 .02 .005 2 100 1
5 .3
91.8 1.83 27.1 3.0 3.6 20.9 1.31 .68 1.35 .29 .35 48 139 12 47 2.4
1.5 .01 1.7 .6 1.1 2.3 .31 .11 .13 .04 .06 12 25 6 8 l.l
40
52
64
40.00 24.01 12.56 20.13 .60 1.70 1.20 .07 .40
52.00 19.21 10.01 16.11 .48 .86 .96 .05 .32
64.00 14.41 7.51 12.08 .36 .64 .72 .04 .24
70.3 1.77 19.7 2.5 11.4 31.7 .89 .51 1.27 .25 .21 37 138 9 43 1.8
63.9 1.75 17.5 2.3 12.2 35.0 .76 .46 1.24 .23 .17 34 137 8 42 1.6
57.4 1.73 15.3 2.2 16.1 38.3 .64 .41 1.22 .22 .13 31 137 8 41 1.4
"Contains Fe, .23%; MIl. .23%; Zn, .20%; Mg, .10%; S, .04%; Cu, .023%; Co, .007%; and L .007%. 2Contains 6.6 x 106 USP/kg vitamin A, 1.4 x 106 USP/kg vitamin D, and 500 IU/kg vitamin E. 3Contains Mg, 11.7%; S, 22.3%; and K, 10.0%.
based on absence of physical abnonnalities as diagnosed by an attending veterinarian and minimum milk production of 25.0 and 31.8 kg! d prior to d 98 to 105 PP for primiparous and multiparous cows, respectively. Beginning 98 to 105 d PP, animals began receiving daily subcutaneous injections of 0 (excipient), 10.3, 20.6, and 30.9 mg of rbST monomer. Cows were blocked by parity (primiparous vs. multiparous) and date of calving and were randomly assigned to treatment within each block. Treatments were continued 1) up to 70 d before the expected calving date to allow for a 6O-d dry period, or 2) until daily milk yield was less than 13.6 kg/d, or 3) until animals reached 400 d PP. The experiment was designed such that cows started and finished on the same day each week. Diets fed during the study contained 40, 52, or 64% com silage from (OM basis) (Table 1). Beginning 3 wk prior to the treatment, all Journal of Dairy Science Vol. 73,
No. 10, 1990
cows were fed a total mixed ration containing 40% com silage and 60% concentrate. After treatment began, diet offered was determined by milk production during the previous 2 wk of treatment. Multiparous cows were fed diets containing 40% com silage when milk yield was greater than 31.8 kg/d, 52% com silage when milk yield was 27.2 to 31.8 kg/d, and 64% com silage when milk yield was less than 27.3 kg/d. Primiparous cows were adjusted to respective forage percentages at milk yields of ~8.2, 23.6 to 28.6 and
fects and effects on reproduction could not be determined from the relatively few cows used in this study. (Key words: postpartum dairy cows, somatotropin, dose response)
Forty Holstein cows were used in an experiment to determine the response of cows to daily subcutaneous injections of 0, to.3, 20.6, and 30.9 mg of recombinant bST. Injections began between 98 and 104 d postpartum and continued for 29 wk, up to 70 d prepartum, or a maximum of 400 d postpartum. Increasing recombinant bST increased milk yield and 3.5% FCM yield in a linear fashion and by 5.2 and 5.7 kg/d, respectively. Milk composition was not changed, and DM intake as a percentage of BW increased from 3.39 to 3.80% with increasing (30.9 mg/d) bST. Feed efficiency (3.5% FCMlDM intake) was increased from 1.35 to 1.64 with increasing dose, suggesting improved efficiency of use of DM intake, primarily by dilution of maintenance. Increasing bST reduced BW gain linearly from .46 kg/d for the control to .22 kg/d for the 30.9 mg/d treatments. Days open tended to be greatest and number of services tended to be higher for cows treated with 30.9 mg/d bST. Calf birth weight, weight of cows at calving, and incidence of metabolic diseases during subsequent calving were not affected by bST. Somatotropin treatment resulted in somewhat smaller increases in milk yield than that reported in previous studies. Long-term health ef-
INTRODUCTION
Received November 13, 1989. Accepted May 14, 1990. IScientific Article A-4998, Contribution Number 8045 of the Maryland Agricultural Experiment Station. Supported by a grant from American Cyanamid Company. 2Animal Sciences Department. 3American Cyanamid Company. 'Tresent address: Dairy Sciences Department, University of Wisconsin, Madison. 1990 1 Dairy Sci 73:2907-2915
Bovine somatotropin hormone has been known to be a galactopoietic agent for more than 50 yr.. Early studies by Asimov and Krouze (2), using crude pituitary extracts that contained bST, demonstrated the potential efficacy of bST in stimulating milk yield in dairy cows. However, practical application of bST was not possible until methods for producing bST by recombinant DNA procedures were discovered. Only a few reports involving the use of recombinant bST (rbST) in long-term studies have been published (3, 4, 7, 15). Knowledge of long-term effects on health of cows treated with rbST is limited. Bauman et al. (3) and Eppard et al. (8) reported no adverse health and reproductive effects in cows treated with bST or rbST beginning at 84 ± 10 d postpartum (PP) for 188 d. However, Chalupa et al. (5) reported negative effects on reproductive performance by cows receiving 50 mg rbST/d in a summary of four trials with 136 cows receiving rbST beginning at 28 to 35 d PP. This suggests that high doses of rbST treatment in early lactation may negatively affect reproductive performance, and treatment in late lactation, where energy balance of cows may be more positive, may be more appropriate. The objective of this experiment was to determine milk production and health responses of lactating cows from increasing doses of rbST administration beginning at d 98 to 105 PP. MATERIALS AND METHODS
Forty Holstein cows (12 primiparous and 28 multiparous) were used. Selection of cows was
2907
2908
ERDMAN ET AL.
TABLE 1. Ingredient and nutrient composition of com silage, concentrate, and total mixed rations. Total ration (% forage)
Feed Item Ingredient, % DM Com silage Ground shelled com Ground barley Soybean meal, 48% CP Trace-mineralized salt! Dicalcium phosphate Limestone Vitamin A, D:f & E supplemen~ K-Mg suHate Composition DM, % Estimated NEIo Mca1/kg DM CP, % Ether extract (%) ADF, % NDF, % Ca, % P, % K, % Mg, % Na, % Zn, ppm Fe, ppm Cu, ppm N, ppm Mo, ppm
Silage
SD
Concentrate SD
100 40.03 20.85 33.56 1.00 1.79 2.00 .11 .66 38.1 1.68 8.6 1.7 23.1 48.1 .26 .26 1.14 .18 .006 21 136 5 38 .9
4.1 .03 .7 .4 4.3 5.4 .03 .02 .14 .02 .005 2 100 1
5 .3
91.8 1.83 27.1 3.0 3.6 20.9 1.31 .68 1.35 .29 .35 48 139 12 47 2.4
1.5 .01 1.7 .6 1.1 2.3 .31 .11 .13 .04 .06 12 25 6 8 l.l
40
52
64
40.00 24.01 12.56 20.13 .60 1.70 1.20 .07 .40
52.00 19.21 10.01 16.11 .48 .86 .96 .05 .32
64.00 14.41 7.51 12.08 .36 .64 .72 .04 .24
70.3 1.77 19.7 2.5 11.4 31.7 .89 .51 1.27 .25 .21 37 138 9 43 1.8
63.9 1.75 17.5 2.3 12.2 35.0 .76 .46 1.24 .23 .17 34 137 8 42 1.6
57.4 1.73 15.3 2.2 16.1 38.3 .64 .41 1.22 .22 .13 31 137 8 41 1.4
"Contains Fe, .23%; MIl. .23%; Zn, .20%; Mg, .10%; S, .04%; Cu, .023%; Co, .007%; and L .007%. 2Contains 6.6 x 106 USP/kg vitamin A, 1.4 x 106 USP/kg vitamin D, and 500 IU/kg vitamin E. 3Contains Mg, 11.7%; S, 22.3%; and K, 10.0%.
based on absence of physical abnonnalities as diagnosed by an attending veterinarian and minimum milk production of 25.0 and 31.8 kg! d prior to d 98 to 105 PP for primiparous and multiparous cows, respectively. Beginning 98 to 105 d PP, animals began receiving daily subcutaneous injections of 0 (excipient), 10.3, 20.6, and 30.9 mg of rbST monomer. Cows were blocked by parity (primiparous vs. multiparous) and date of calving and were randomly assigned to treatment within each block. Treatments were continued 1) up to 70 d before the expected calving date to allow for a 6O-d dry period, or 2) until daily milk yield was less than 13.6 kg/d, or 3) until animals reached 400 d PP. The experiment was designed such that cows started and finished on the same day each week. Diets fed during the study contained 40, 52, or 64% com silage from (OM basis) (Table 1). Beginning 3 wk prior to the treatment, all Journal of Dairy Science Vol. 73,
No. 10, 1990
cows were fed a total mixed ration containing 40% com silage and 60% concentrate. After treatment began, diet offered was determined by milk production during the previous 2 wk of treatment. Multiparous cows were fed diets containing 40% com silage when milk yield was greater than 31.8 kg/d, 52% com silage when milk yield was 27.2 to 31.8 kg/d, and 64% com silage when milk yield was less than 27.3 kg/d. Primiparous cows were adjusted to respective forage percentages at milk yields of ~8.2, 23.6 to 28.6 and
