Postpartum anestrus of beef cows: importance and evaluation

Abstract

Duration of anestrus period and infertility in postpartum suckled beef cows impact reproductive performance and efficiency of cow-calf operations. Percent cows calving in first 21 days of calving season is higher for herds with shorter (average 50 days) rather than longer (average 80 days) length of postpartum anestrus. Because primiparous cows may have a prolonged postpartum anestrus compared to similarly managed multiparous cows, breeding replacement heifers before mature cows, sometimes referred to as providing a heifer lead time, may increase likelihood that primiparous cows have resumed fertile estrous cycles and have opportunity to conceive during first 21 days of breeding season subsequent to first parturition. While having a 42 day heifer lead time resulted in greater pregnancy success and average weaning weight compared to no lead time, ~ two-thirds of improvement in outcomes was realized with a heifer lead time of only 21 days. Determining length of postpartum anestrus following first and subsequent pregnancies can assist veterinarians and producers to develop optimal herd management strategies.