Masters Theses

Date of Award

5-1989

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

B.H. Erickson

Committee Members

Jim Godkin, Bill Backus

Abstract

It is commonly recognized that reproductive inefficiency is a major cause of economic loss in the beef industry. Nationally, the average cow-calf program produces only 80 viable calves per 100 cows (Neumann, 1977) and approximately 12 or 60% of the 20 lost calves are accounted for by failure of the beef cow to become pregnant (Bellows et al., 1979), and early embryonic mortality. An extended postpartum anestrus also adds to reproductive inefficiency. In suckled beef cows that conceive during a 100-day breeding period, postpartum anestrus can vary from 40 to 100 days (Casida et al., 1968). Using costs that they considered representative, Gerrits et al. (1979) estimated that a 5% increase in the calf crop on a national basis, would result in a savings to the beef industry of $588 million, and $112 million would be saved in costs of cow maintenance if the average postpartum interval were reduced by 6 d, and $96 million would be gained through an increase in average calf weight at weaning.

Since either delays in conception or infertility can be attributed mainly to deficiencies in the hypothalamic-pituitary-ovarian axis in the absence of disease, studies of the source, magnitude and variability in these deficiencies should do much to help us realize the economic gains listed above.

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