Evaluation of the benefits of the timing of pregnancy testing by transrectal palpation in dairy cattle

Abstract

Objective - To determine the benefits that were associated with pregnancy testing by use of transrectal palpation during the period 30 to 65 days after unsuccessful insemination of dairy cows. Design - Nonconcurrent, cohort study. Animals - Cows in 15 dairy herds in the United States and Canada. Procedure - Reproductive records of cows (n = 713) that did not calve within 294 days of first-service insemination and that had been evaluated for pregnancy 30 to 65 days after first-service insemination were examined. Records were analyzed to determine the day of parturition or date of culling and to determine if the probability of a cow being culled or the interval to parturition was related to the number of days after insemination that pregnancy testing was performed. Results - For cows that calved more than 294 days after first-service insemination, the interval from first-service insemination until parturition was associated significantly with herd, season, and treatment on the day of pregnancy testing with prostaglandin F(2α) or one of its analogues. Cows treated with prostaglandin F(2α) on the day of pregnancy testing were less likely to be culled than nontreated cows. For cows pregnancy tested 30 to 65 days after insemination, each additional day after day 30 before pregnancy testing was performed resulted in an increase of 1.09 days in the interval until parturition. Clinical implications - Pregnancy testing by means of transrectal palpation as soon as possible after day 30 after insemination can result in shorter calving intervals.