Dawson F L
J Reprod Fertil. 1977 Sep;51(1):53-6. doi: 10.1530/jrf.0.0510053.
Dairy cattle were served at consecutive heats up to three times each; they were then slaughtered, and the genital tracts were examined. Seventy-four cattle had been discarded from herds because they had not bred; 14 had never calved, and 14 were primiparous. Of these 28 animals, 12 (43%) conceived readily, and had normal pregnancies; normal genital tracts were found at slaughter. Eleven of the 16 animals that did not conceive had normal genitalia. The remaining 46 animals were mature cows, with a mean parity of 4-9; 9 (19-6%) became pregnant and had live embryos at autopsy, while in 7 other cows (15-2%) conception had been followed by embryonic death. Five of the uteri associated with these 16 conceptions showed pathological changes. Thirty of the 46 mature cows (65%) did not conceive; 12 (40%) had normal genitalia, and 18 (60%) showed severe pathological changes in the uterus and/or oviduct. Nine 'control' cows discarded because of poor milk yield were infertile, but 5 cows, discarded for various other reasons, all bred normally.
对奶牛连续进行三次发情配种；之后将它们屠宰，并检查生殖道。有74头牛因未受孕而被牛群淘汰；14头从未产犊，14头为初产牛。在这28头动物中，12头（43%）很容易受孕且怀孕正常；屠宰时发现生殖道正常。16头未受孕的动物中有11头生殖器正常。其余46头是成熟母牛，平均产次为4至9次；9头（19.6%）怀孕且在尸检时有活胚胎，而另外7头母牛（15.2%）受孕后胚胎死亡。与这16次受孕相关的子宫中有5个出现了病理变化。46头成熟母牛中有30头（65%）未受孕；12头（40%）生殖器正常，18头（60%）子宫和/或输卵管出现严重病理变化。9头因产奶量低而被淘汰的“对照”母牛不育，但5头因其他各种原因被淘汰的母牛都正常受孕。
