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Exposure Data
To collect reproductive data on potential replacement heifers, a yearling heifer exposure inventory must be produced. This inventory would typically be sent to breed associations in May for spring born heifers and in November for fall born heifers. On the inventory, producers should indicate breeding season start and end dates, individual exposure status, management group, and disposal information. Differences among management groups in post-yearling feeding, management, or mating practices should be recorded.
General recommendations for exposing heifers is 2 to 3 weeks before older cows to allow for enough time to return to estrus after their first calving. This will help first-calf heifers return from the postpartum interval and cycle again in the same time-frame as older cows in the herd (Geary, 2003; Lents et al., 2003). It is also recommended that heifers conceive by approximately 14 months of age so that they calve as a two year old. Age should be balanced with estrus activity, where exposing heifers on their pubertal estrus should be avoided. Instead, it is recommended that heifers be actively cycling 1 to 3 months prior to be exposed to bulls for breeding (Byerley et al., 1987).
References:
Byerley, D.J., R.B. Staigmiller, J.G. Beradinelli, and R.E. Short. 1987. Pregnancy rates of beef heifers bred either on puberal or third estrus. J. Anim. Sci. 65:645-650. [1]
Geary, T.W. 2003. Management of young cows for maximum reproductive performance. Proc. 2003 Beef Improvement Federation Annual Convention. [2]
Lents, C.A., R.K. Peel, G.E. Seidel, Jr., and G.D. Niswender. 2003. Reproduction on the ranch. Proc. Range Beef Cow Symposium XVIII, Mitchell NE. [3]
