Schrick F N, Spitzer J C, Jenkins T C, Henricks D M, Althen T G
Dept. of Anim. Sci., Clemson University, SC 29634-0361.
J Anim Sci. 1990 Oct;68(10):3313-21. doi: 10.2527/1990.68103313x.
A replicated trial was conducted with suckled Angus and Polled Hereford cows (110 d postcalving) to determine metabolic and endocrine responses to an energy-restricted diet after cows had re-established postpartum estrous cyclicity. Cows were individually fed 26.5 Mcal ME (H) or 15.2 Mcal ME (L) for a 30-d preliminary period and fitted with an indwelling jugular cannula at synchronized estrus. Average daily weight change during the estrous cycle was .60 +/- .25 and -1.37 +/- .30 kg/d for H and L, respectively (P less than .05). Blood concentrations of cortisol, progesterone and LH during the estrous cycle were not affected by diet, nor did diet affect frequency or amplitude of LH pulses (P greater than .05). No dietary differences were observed for daily concentrations of total protein, glucose, nonesterified fatty acids or acetate. Mean blood concentrations of propionate and butyrate were not different between diets; however, L cows had lower concentrations of propionate and butyrate on d 11 of the cycle (P less than .05). Cows fed L had higher concentrations of blood urea nitrogen (P less than .05), but they had lower concentrations of cholesterol (P less than .05) on d 4, 11, 18 and subsequent estrus (E). Insulin was not different on d 4 and 11; however, cows fed L had lower insulin concentrations on d 18 and d E (P less than .05). Dietary energy restriction in these cyclic cows caused no change in endocrine responses. Of metabolic responses measured, only blood urea nitrogen, cholesterol and insulin showed consistent changes.
对哺乳的安格斯牛和无角海福特牛（产后110天）进行了一项重复试验，以确定母牛重新建立产后发情周期后，对能量限制日粮的代谢和内分泌反应。在30天的预饲期内，给母牛分别饲喂26.5兆卡代谢能（高能量组，H）或15.2兆卡代谢能（低能量组，L），并在同步发情时植入颈静脉插管。发情周期期间，高能量组和低能量组的平均日体重变化分别为0.60±0.25千克/天和-1.37±0.30千克/天（P<0.05）。发情周期期间，日粮对皮质醇、孕酮和促黄体生成素的血液浓度没有影响，日粮也不影响促黄体生成素脉冲的频率或幅度（P>0.05）。日粮对总蛋白、葡萄糖、非酯化脂肪酸或乙酸的日浓度没有差异。日粮之间丙酸和丁酸的平均血液浓度没有差异；然而，低能量组母牛在周期第11天的丙酸和丁酸浓度较低（P<0.05）。饲喂低能量日粮的母牛血液尿素氮浓度较高（P<0.05），但在第4天、第11天、第18天及随后的发情期，它们的胆固醇浓度较低（P<0.05）。第4天和第11天胰岛素水平没有差异；然而，饲喂低能量日粮的母牛在第18天和发情期的胰岛素浓度较低（P<0.05）。这些处于发情周期的母牛日粮能量限制并未引起内分泌反应的变化。在所测量的代谢反应中，只有血液尿素氮、胆固醇和胰岛素表现出一致的变化。
