Early Postpartum Breeding in Dairy Cattle

Abstract

An experiment was conducted to determine if there were detrimental effects · from breeding Holstein dairy cows as soon as possible following calving. The study included 168 cows completing 375 calving intervals. At the time of first calving, cows were assigned at random to one of two breeding groups: 1) bred at first estrus following calving (early breeding), and 2) bred at first estrus 75 or more days following calving (late breeding). Heifers were placed on experiment at first calving and the maximum time that they remained on the experiment was until the 217th day of gestation with their fourth calf. Cows were observed for estrus twice daily and all animals were bred by artificial insemination using frozen semen from "proven" sires. Reproductive tracts during the postpartum interval were examined by rectal palpation at seven-day intervals and ovarian structures were recorded. Pregnancy was determined 39 to 45 days after insemination. Cows were allowed a maximum of 300 open days following calving before being removed from the experiment as non-breeders. Treatment of reproductive problems was limited to three conditions occurring at the time of calving: 1) dystocia, 2) acute metritis, and 3) retained placenta.