Erb R E, Chew B P, Malven P V, Stewart T S, D'Amico M F
J Anim Sci. 1982 Feb;54(2):302-8. doi: 10.2527/jas1982.542302x.
Least-squares associations of month, average daily temperature, photoperiod (h daylight/24 h) and other factors with plasma concentrations of hormones during the prepartum period were examined in 172 Holstein cows and heifers. The data were summarized and expressed as values for prepartum d 7, 4 and 1, which represented the means for d 8 to 6, 5 to 3, and 2 to 0. respectively. All animals calved during a period of 19 consecutive months. Across days, least-squares means for plasma hormones were 4.0 ng/ml for progesterone (P4), 232 pg/ml for estradiol-17 beta (E beta), 478 pg/ml for estradiol-17 alpha (E alpha), 1,970 pg/ml for estrone (E1) and 2,680 pg/ml for total estrogen (TE; sum of E beta, E alpha and E1). Variations in plasma concentrations of certain steroids were associated (P less than .05 to P less than .01) with diet group (E beta), calf sex (TE), prepartum day (all hormones), month (E beta, E alpha) and linear covariates of cow weight (E beta, E alpha) calf birth weight (E beta, E alpha, E 1, TE), temperature (P4, E beta) and photoperiod (P4, E beta). The independent linear regressions for temperature and for photoperiod in prediction equations for each plasma hormone were always inversely related. The combined use of these regressions only partially accounted for fluctuations in the least-squares monthly means for hormones. Changes in least-squares monthly means for P4, E beta and E alpha tended to be only partially paralleled during the year. Nonparallel trends among hormones were most apparent during May to July (decreasing P4 but increasing E beta and E alpha), September to November (decreasing P4 and E beta but increasing E alpha) and January and February (only E alpha elevated). We hypothesize that seasonal differences in parturient traits reported for cows may be explained in part by the seasonally associated nonparallel changes in plasma concentrations of P4, E beta and E alpha.
在172头荷斯坦奶牛和小母牛中，研究了产前期间月份、日平均温度、光照周期（日照小时数/24小时）及其他因素与血浆激素浓度的最小二乘关联。数据进行了汇总，并表示为产前第7天、第4天和第1天的值，分别代表第8至6天、第5至3天和第2至0天的平均值。所有动物在连续19个月的期间内产犊。在不同日期，血浆激素的最小二乘均值分别为：孕酮（P4）4.0 ng/ml、雌二醇-17β（Eβ）232 pg/ml、雌二醇-17α（Eα）478 pg/ml、雌酮（E1）1970 pg/ml、总雌激素（TE；Eβ、Eα和E1之和）2680 pg/ml。某些类固醇血浆浓度的变化与日粮组（Eβ）、犊牛性别（TE）、产前天数（所有激素）、月份（Eβ、Eα）以及母牛体重（Eβ、Eα）、犊牛出生体重（Eβ、Eα、E1、TE）、温度（P4、Eβ）和光照周期（P4、Eβ）的线性协变量相关（P小于0.05至P小于0.01）。每种血浆激素预测方程中温度和光照周期的独立线性回归始终呈负相关。这些回归的联合使用仅部分解释了激素最小二乘月度均值的波动。P4、Eβ和Eα的最小二乘月度均值变化在一年中往往只是部分平行。激素之间的非平行趋势在5月至7月（P4下降但Eβ和Eα升高）、9月至11月（P4和Eβ下降但Eα升高）以及1月和2月（仅Eα升高）最为明显。我们假设，母牛分娩性状的季节性差异可能部分由P4、Eβ和Eα血浆浓度的季节性相关非平行变化来解释。
