Luteal Inhibition in the Bovine as a Result of Oxytocin Injections, Uterine Dilatation, and Intrauterine Infusions of Seminal and Preputial Fluids

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Abstract
The effects of 3 treatments on estrous cycle length and development of the corpus luteum in the bovine were studied. The treatments consisted of oxytocin injections, uterine dilatation and intrauterine infusions of raw semen of the sediment obtained by centrifuging seminal and preputial fluids. Daily subcutaneous injections of 100 U.S.P. units of oxytocin during days 3-6 inclusive of the estrous cycle shortened the cycle length in heifers to 8-12 days. Oxytocin injections during the first 6 days of the cycle similarly shortened the cycle length in mature lactating cows, but larger doses were required. Uterine dilatation during the first 7 days of the cycle also caused a large proportion of cows and heifers so treated to have shortened estrous cycles, which were often 8-12 days in length. Intrauterine infusions of relatively large amounts of raw semen or the sediment obtained by centrifuging raw semen and preputial fluids into the uterus of heifers also produced precocious estrus in a large proportion of the treated animals. All 3 treatments caused a marked inhibition in the development of the corpus luteum. In some cases cystic corpora lutea resulted; in others the corpora lutea were simply quite small. Relatively few normal functional luteal cells were present in either case.