Pregnancy rates relating to plasma progesterone levels in recipient heifers at day of transfer

THERIOGENOLOGY GTEGNANCYRATES RELATING To PLASMA FTKGESTERONELlZV!XS

IN MXXPIEWT HEIFERS AT DAY OF TRANS%X* L.G. Remsen*, J.D. Roussel, and A.K. Karihaloo Departmentof JMry Science Louisiana State University Baton Rouge, LA 70603 and &nation/Genetics Hughson, CA 95326

A group of Holstein heifers (r&23) weighing approximately 454 kg were used in the determinationof pregnancy rates in relation to plasma progesteroneconcentrationsin recipientson the day of embryo transfer. All recipients were in estrus within f. 12 hours of the donor cows. These data showed a cubic trend by regressionanalysis. CM-square test revealed that there was a significant (P5.00 Wml. Corpora lutea were classified as good, poor, or cystic by both manual and visual observation. These observationsrevealed that manual palpation of the corpus luteum was not a valid criterionof the function of the corpus luteum as measured by plamna progesteroneconcentrations. Further observationrevealed no significantrelationshipbetween plasma progesterone and whether the corpus luteum was on the left or right ovary. Hence, pregnancy rate was not significantlyassociatedwith the left or right ovary. Pregnancieswere determined by rectal palpationat 60 days.

JANUARY

1982VOL.17NO.l

105