Schwalm J W, Tucker H A
J Dairy Sci. 1978 May;61(5):550-60. doi: 10.3168/jds.s0022-0302(78)94409-0.
Concentrations of glucocorticoids were measured in milk and blood serum during the estrous cycle, prepartum, parturition, postpartum, and early and late lactation. Glucocorticoids in milk did not change during the estrous cycle, averaging .35 ng/ml whereas they averaged .50 ng/ml prepartum, 3.08 ng/ml at parturition, and .50 ng/ml 1 wk postpartum. Glucocorticoids in milk declined from .59 ng/ml to .25 ng/ml as lactation advanced from 1 to 10 mo. Concentrations of glucocorticoids in blood serum were approximately 8 to 10 ng/ml during all reproductive states. There was no positive relationship between percentage of milk fat and concentrations of glucocorticoids in milk. Cortisol was the predominant glucocorticoid in serum; in milk corticosterone concentrations exceeded those of cortisol. Glucocorticoids, being more polar, had higher affinity for the nonlipid portion of milk; in contrast, progesterone, estradiol 17beta, and estrone were located predominantly in the lipid fraction of milk.
在发情周期、产前、分娩时、产后以及泌乳早期和晚期，对牛奶和血清中的糖皮质激素浓度进行了测量。发情周期期间牛奶中的糖皮质激素没有变化，平均为0.35纳克/毫升，而产前平均为0.50纳克/毫升，分娩时为3.08纳克/毫升，产后1周为0.50纳克/毫升。随着泌乳从1个月推进到10个月，牛奶中的糖皮质激素从0.59纳克/毫升降至0.25纳克/毫升。在所有生殖状态下，血清中的糖皮质激素浓度约为8至10纳克/毫升。牛奶脂肪百分比与牛奶中糖皮质激素浓度之间没有正相关关系。皮质醇是血清中主要的糖皮质激素；在牛奶中，皮质酮的浓度超过了皮质醇。糖皮质激素极性更强，对牛奶的非脂质部分具有更高的亲和力；相比之下，孕酮、17β-雌二醇和雌酮主要存在于牛奶的脂质部分。
