Gyawu P, Pope G S
J Steroid Biochem. 1983 Jul;19(1C):877-82. doi: 10.1016/0022-4731(83)90027-4.
The steroid oestrogens oestradiol-17 beta, oestrone and oestradiol-17 alpha have all been adequately identified in various body fluids and tissues of cattle. There is also good evidence for the presence of oestrone sulphate. Oestriol (or similar triols) may also be present. The oestrogens found in the systemic plasma of cattle are present in milk in similar concentrations; whether their passage into milk involves metabolism by the mammary gland is uncertain. Oestrone sulphate, at least at relatively high levels of secretion, is believed to be found only in pregnant cattle and measurement of its concentration in milk is in use as a practical test for pregnancy. A close correlation has been found between the concentrations of oestradiol-17 beta in systemic plasma and milk of non-pregnant cows and levels of this oestrogen in milk may, together with those of progesterone, now be used in studies of post-partum ovarian function.
类固醇雌激素17β-雌二醇、雌酮和17α-雌二醇已在牛的各种体液和组织中得到充分鉴定。也有充分证据表明存在硫酸雌酮。雌三醇（或类似的三醇）也可能存在。在牛的全身血浆中发现的雌激素以相似浓度存在于牛奶中；它们进入牛奶是否涉及乳腺的代谢尚不确定。硫酸雌酮至少在相对较高的分泌水平时，据信仅在怀孕母牛中发现，并且测量其在牛奶中的浓度已被用作妊娠的实际检测方法。已发现非怀孕母牛的全身血浆和牛奶中17β-雌二醇的浓度之间存在密切相关性，并且现在牛奶中这种雌激素的水平可能与孕酮的水平一起用于产后卵巢功能的研究。
