Comparison of palpable corpora lutea with serum progesterone concentrations in cows

Serum progesterone concentrations were used to evaluate rectal palpation of corpora lutea as a method for assignment of postpartum beef cows to prostaglandin treatment and nontreatment groups. On the basis of 124 evaluations, 18% of the cows were assigned incorrectly to the treatment group and 37% of the cows were assigned incorrectly to the nontreatment group. The inability of palpators to accurately select cows with a mature corpus luteum may diminish the success of estrus synchronization regimens that use rectal palpation of corpora lutea for selection of cows for prostaglandin therapy.