Staples C R, Head H H, Darden D E
Dairy Science Department, University of Florida, Gainesville 32611.
J Dairy Sci. 1988 Dec;71(12):3274-82. doi: 10.3168/jds.S0022-0302(88)79932-4.
Our objective was to evaluate response of lactating dairy cows to daily injections of bovine somatotropin during a subtropical summer. Ten Holstein cows, averaging 196 d in lactation, were used in a 30-d study. No treatment was imposed during d 1 to 10 (period 1) and d 21 to 30 (period 3). During d 11 to 20 (period 2), cows were injected daily with either 0 or 59 IU of pituitary-derived bovine somatotropin in 30 ml solution. Dry matter intake and milk yield and composition were measured daily. Jugular blood samples, taken on d 10, 15, 20, and 30, were analyzed for insulin, nonesterified fatty acids, urea nitrogen, and insulin-like growth factor-1. Body temperatures and respiration rates were measured at 1400 h on 4 or 5 d during each 10-d period. Data were analyzed using orthogonal contrasts. Contrast of period 1 plus period 3 vs. period 2 for treatment X days interaction was significant for milk yield, respiration rate, serum nonesterified fatty acids, and insulin-like growth factor-1. Under heat stress, cows injected with bovine somatotropin for 10 d produced 9.3% more milk than control cows with no change in feed intake. This increased production was accompanied by higher respiration rates (6%) and higher concentrations of serum nonesterified fatty acids (150%) and insulin-like growth factor-1 (222%).
我们的目标是评估亚热带夏季泌乳奶牛对每日注射牛生长激素的反应。选用10头平均泌乳196天的荷斯坦奶牛进行为期30天的研究。在第1至10天（阶段1）和第21至30天（阶段3）不进行处理。在第11至20天（阶段2），奶牛每天被注射0或59国际单位垂体来源的牛生长激素，溶于30毫升溶液中。每天测量干物质摄入量、产奶量及成分。在第10、15、20和30天采集颈静脉血样，分析胰岛素、非酯化脂肪酸、尿素氮和胰岛素样生长因子-1。在每个10天周期中的4或5天的14:00测量体温和呼吸频率。数据采用正交对比分析。处理×天数交互作用中，阶段1加阶段3与阶段2的对比在产奶量、呼吸频率、血清非酯化脂肪酸和胰岛素样生长因子-1方面具有显著性。在热应激条件下，注射牛生长激素10天的奶牛产奶量比未注射的对照奶牛高9.3%，而采食量无变化。产奶量增加伴随着更高的呼吸频率（6%）以及更高浓度的血清非酯化脂肪酸（150%）和胰岛素样生长因子-1（222%）。
