ABSTRACT
Twenty-three percent of all dairy cows are culled from the herd because of reproductive problems. Repeat breeders are cows that require three or more services per conception, have a normal interestrus interval, and normal reproductive-tract condition. Two common reproductive problems are cystic ovarian degeneration and repeat-breeder cow syndrome. Cysts can be induced by passive immunization with antiluteinizing hormone antiserum. Repeat-breeder cows are not sterile since they will ultimately conceive after repeated breedings. The repeat-breeder syndrome is one of the most poorly understood subjects in bovine infertility. Management, nutrition, infection, genetics, hormonal imbalances, artificial insemination techniques, and semen quality are some of the factors cited as plausible causative agents for this problem. Repeat breeders had higher levels of antibodies against seminal antigens in their genital secretions, Identification of additional specific factors that contribute to the repeat-breeder syndrome continue to pose a major research challenge to animal scientists.
