Stanisiewski E P, Krabill L F, Lauderdale J W
Agricultural Division, Upjohn Company, Kalamazoo, MI 49001.
J Dairy Sci. 1992 Aug;75(8):2149-64. doi: 10.3168/jds.S0022-0302(92)77975-2.
Cows (n = 210) were assigned to the following treatments: uninjected controls through 130 d postpartum; zero to high, uninjected through 60 d then injected with 14 mg of bST/d from 61 through 130 d postpartum; low, 5 mg of bST/d from 14 through 130 d postpartum; low to high, 5 mg of bST/d from 14 through 60 d then 14 mg of BST/d from 61 through 130 d postpartum; and high, 14 mg of bST/d from 14 through 130 d postpartum. Cows given 5 mg of bST/d (low and low to high treatments) yielded 1.2 kg of FCM/d more and high group cows yielded 1.3 kg of FCM/d more than control cows between 14 and 60 d postpartum. Cows given bST yielded 2.7 to 4.1 kg of FCM/d more than control cows during 61 to 130 d postpartum. Overall, control cows yielded 35.1 kg of FCM/d, and bST-dosed cows yielded 2.2 to 3.2 kg/d more FCM. Low group cows had improved pregnancy rate (80.0%) and conception rate (82.2%) compared with high group cows (57.2 and 60.3%). Neither pregnancy (70.0%) nor conception rates (71.5%) of controls differed from other groups. However, low group cows had first service conception rate of 57.8% compared with 34.3% for high and 38.2% for low to high group cows. First postpartum estrus was observed in high group cows about 13 to 16 d later than in low and low to high group cows, whereas low group cows came into first estrus 9 d sooner than controls. Cows of high group had lower body condition than controls (2.5 vs. 2.9), but other groups did not differ (2.7 to 2.9) from controls. Health was not adversely affected. Early postpartum bST administration at 5 mg/d increases FCM and, perhaps, reproductive performance of dairy cattle compared with herdmates.
210头奶牛被分配到以下处理组：产后130天内未注射的对照组；零剂量至高剂量组，产后60天内未注射，然后从产后61天至130天每天注射14毫克牛生长激素（bST）；低剂量组，从产后14天至130天每天注射5毫克bST；低剂量至高剂量组，从产后14天至60天每天注射5毫克bST，然后从产后61天至130天每天注射14毫克bST；高剂量组，从产后14天至130天每天注射14毫克bST。在产后14天至60天期间，每天注射5毫克bST的奶牛（低剂量组和低剂量至高剂量组）比对照组奶牛每天多产1.2千克乳脂校正乳（FCM），高剂量组奶牛比对照组奶牛每天多产1.3千克FCM。在产后61天至130天期间，注射bST的奶牛比对照组奶牛每天多产2.7至4.1千克FCM。总体而言，对照组奶牛每天产35.1千克FCM，注射bST的奶牛每天多产2.2至3.2千克FCM。与高剂量组奶牛（57.2%和60.3%）相比，低剂量组奶牛的妊娠率（80.0%）和受胎率（82.2%）有所提高。对照组的妊娠率（70.0%）和受胎率（71.5%）与其他组没有差异。然而，低剂量组奶牛的首次输精受胎率为57.8%，而高剂量组为34.3%，低剂量至高剂量组为38.2%。高剂量组奶牛产后首次发情比低剂量组和低剂量至高剂量组奶牛晚约13至16天，而低剂量组奶牛比对照组奶牛早9天进入首次发情期。高剂量组奶牛的体况评分低于对照组（2.5对2.9），但其他组与对照组没有差异（2.7至2.9）。健康状况未受到不利影响。与同群奶牛相比，产后早期每天注射5毫克bST可提高奶牛的FCM产量，或许还能提高其繁殖性能。
