PSXIV-4 - Body condition and production status impacts on estrus indicators in beef cattle on a producer farm

Abstract: The use of artificial insemination (AI) in cattle can increase farm profitability by increasing the genetic merit of offspring, but animal body condition (fatness) and stage of production can influence breeding efficacy. Therefore, during an on-farm artificial insemination session, the effect of body condition score and production status (nursing offspring or not) on indicators of estrus (readiness for breeding) was examined. Thirty-six cows 3 to 12 years of age and having previously had at least one calf were used. Cows were estrus synchronized by the owners using the Co-Synch with CIDR fixed time AI protocol (GnRH and CIDR® on day 0 followed by CIDR® removal and prostaglandin on day 7 with AI and GnRH on day 10). At AI using cryopreserved semen from a commercial source (Premier Select Sires), body condition score was assessed (1-9, 1=emaciated, 9=obese), and indicators of estrus (presence of mucous, pink color of vulva, turgid and open cervix and easy insemination) were noted. On this farm, body condition scores for the animals the producer chose to estrus synchronize ranged from 3 to 5. Animals were nursing calves 3 to 5 months of age (n=15) or were not nursing calves (n=21). Statistical analysis (with SAS®) indicated that nursing negatively impacted body condition as well as number of estrus indicators noted at AI and that body condition tended to be positively related to the number of estrus indicators noted.