Downer J V, Patterson D L, Rock D W, Chalupa W V, Cleale R M, Firkins J L, Lynch G L, Clark J H, Brodie B O, Jenny B F
American Cyanamid Company, Princeton, NJ 08543-0400.
J Dairy Sci. 1993 Apr;76(4):1125-36. doi: 10.3168/jds.s0022-0302(93)77441-x.
Lactating dairy cows (n = 264) were used in seven dose titration experiments at four geographic locations in the United States. A sustained-release formulation of recombinant bST was evaluated for a 30-wk treatment period that began 14 wk postpartum. The first series of four experiments evaluated doses of 0, 140, 350, or 700 mg of bST/14 d (series A); the second series evaluated doses of 0, 56, 140, or 350 mg of bST/14 d (series B). Milk yield, DMI, milk composition, body condition, health, and reproductive parameters were measured. Multiparous cows in series A that were administered 700 mg of bST/14 d yielded 3.0 kg/d more milk and 3.5% FCM than control cows. When all seven experiments were combined, multiparous cows that were administered 350 mg of bST/14 d yielded 2.7 and 2.6 kg/d more milk and 3.5% FCM than control cows. Dry matter intake was not significantly affected by bST administration. In series A, an increase in milk yield with no increase in DMI resulted in lower adequacy of dietary NEL and CP to meet maintenance and yield requirements among multiparous cows administered 700 mg of bST/14 d. Primiparous cows that were administered bST in series A and both parity groups in the combined seven experiments were not different from control cows in the adequacy of dietary NEL or CP to meet maintenance and yield requirements. No adverse effects of bST on health parameters were significant, and doses of 350 mg of bST/14 d or less caused no changes in reproductive parameters. Conception rate was decreased by administration of 700 mg of bST/14 d. These data suggest that 350 mg of bST/14 d increased yields of milk and FCM with no adverse effects on DMI, health, or reproduction in dairy cows.
在美国四个地理位置进行的七次剂量滴定实验中使用了泌乳奶牛（n = 264）。对重组牛生长激素（bST）的缓释制剂进行了评估，治疗期为30周，从产后14周开始。前四次实验系列评估了每14天0、140、350或700毫克bST的剂量（A系列）；第二个系列评估了每14天0、56、140或350毫克bST的剂量（B系列）。测量了产奶量、干物质采食量（DMI）、牛奶成分、体况、健康和繁殖参数。A系列中每14天接受700毫克bST的经产奶牛比对照奶牛每天多产奶3.0千克，多产3.5%的乳脂校正乳（FCM）。当所有七次实验合并时，每14天接受350毫克bST的经产奶牛比对照奶牛每天多产奶2.7千克和2.6千克，多产3.5%的FCM。bST给药对干物质采食量没有显著影响。在A系列中，产奶量增加而DMI没有增加，导致每14天接受700毫克bST的经产奶牛中，满足维持和产奶需求的日粮净能（NEL）和粗蛋白（CP）充足率较低。A系列中接受bST的初产奶牛以及合并的七次实验中的两个胎次组在满足维持和产奶需求的日粮NEL或CP充足率方面与对照奶牛没有差异。bST对健康参数没有显著的不良影响，每14天350毫克或更低剂量的bST对繁殖参数没有影响。每14天给予700毫克bST会降低受胎率。这些数据表明，每14天350毫克bST可提高奶牛的产奶量和FCM产量，且对DMI、健康或繁殖没有不良影响。
