Analyses of Birthdate and Growth in Beef Heifers Categorized by Puberty and Pregnancy Status

Heifer records were retrospectively evaluated to see if Julian birthdate, cycling status prior to breeding, and body weight collected from weaning through final pregnancy diagnosis differed when heifers were categorized by 5 different approaches: 1) pubertal status prior to estrous synchronization, 2) whether or not detected in estrus at AI, 3) heifers impregnated by AI vs all other heifers, 4) final pregnancy status, and 5) a 5-way classification accounting for AI and pregnancy status (AI pregnant, heifers subjected to AI that subsequently conceived to bull, heifers not AI that were impregnated by bull, heifers subjected to AI that were not pregnant, heifers not AI and not pregnant). Collectively, results support the concept that earlier birth in the calving season and greater preweaning growth are associated with desirable reproductive response in replacement beef heifers