Ljøkjel K, Klemetsdal G, Prestløkken E, Ropstad E
Department of Animal Science, Agricultural University of Norway, Oslo.
Acta Vet Scand. 1995;36(4):533-42. doi: 10.1186/BF03547667.
The study involved 34 primiparous cows fed ad libitum grass silage and fixed amounts of concentrate per cow and stage of lactation. It revealed that number of days from calving to maximum progesterone concentration in first luteal phase was negatively related to (p < 0.05) energy balance summarized over weeks 3-12 post-partum. One standard deviation improvement of the summarized energy balance relative to the mean reduced the length of the anovulatory period by 12 days. Similarly, an improved energy balance enhanced progesterone secretion during the oestrus cycle and early pregnancy, as measured by 3 variables; 1) maximum progesterone concentration in first luteal phase, 2) cumulative progesterone secretion bounded by the maximum concentrations in first and in third luteal phase and 3) cumulative progesterone secretion in the first month of pregnancy. All results were supported by the estimated regression coefficients of the 4 ovarian activity variables on summarized non-estrified fatty acids and acetoacetate variables.
该研究涉及34头初产奶牛，每头奶牛根据泌乳阶段自由采食青贮草并给予固定量的精饲料。研究表明，从产犊到第一个黄体期孕酮浓度达到最高值的天数与产后第3至12周的能量平衡呈负相关（p < 0.05）。相对于平均值，总结能量平衡提高一个标准差可使无排卵期缩短12天。同样，通过三个变量衡量，改善能量平衡可增强发情周期和妊娠早期的孕酮分泌；1）第一个黄体期的最高孕酮浓度，2）以第一个和第三个黄体期的最高浓度为界的累积孕酮分泌量，3）妊娠第一个月的累积孕酮分泌量。所有结果均得到4个卵巢活动变量对总结的非酯化脂肪酸和乙酰乙酸变量的估计回归系数的支持。
