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Thesis (M.S.)—University of Nebraska—Lincoln, 1957. Department of Dairy Husbandry.


Copyright 1957, the author. Used by permission.


The realization of the importance of the problem of infertility in dairy cattle has been accentuated by the rapid growth of artificial insemination. About 50 per cent of all artificial inseminations are infertile, which signifies the magnitude of this economic problem. Breeding failures are due to a number of reasons. Some of these are embryonic mortality, imbalance of physiological functions, inadequate nutrition and genital infections and abnormalities.

The reason for early embryonic mortality may be that the corpus luteum is not retained for sufficient long time to maintain the hormone environment necessary to keep the young embryo alive. The luteinizing hormone secreted by the anterior pituitary causes the ovulation to take place and is the cause of the formation and retention of the corpus luteum. Chorionic gonadotropin, which is isolated from the urine of pregnant women, contains a principle similar in action to the luteinizing hormone of the anterior pituitary.

The purpose of this investigation was to ascertain whether doses of chorionic gonadotropin injected at the beginning of the estrus period has any effect on (I) the duration of the estrus cycle, (II) ovulation time, (III) conception rate, (IV) sizes of ovaries and corpus luteum and (V) pH of the vaginal secretions.

Advisor: A. B. Schultze