1993, R. E. Larsen, S. C. Denham, J. F. Boucher, E. L. Adams, Chapter 13: Breeding Season Length Versus Calving Percentage in Beef Cattle Herds, Michael J. Fields, Robert S. Sand (editors), Factors Affecting Calf Crop, CRC Press, page 191, Duration of postpartum anestrus is the period from calving to the first estrus. This anestrus period is recognized as being a major factor in controlling the proportion of cows conceiving each breeding season (Wiltbank et al., 1961).
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