EMBRYONIC LOSS FROM 30 TO 60 DAYS POST BREEDING AND THE EFFECT OF PALPATION PER RECTUM ON PREGNANCY

This study was conducted over a 12-mo period to determine the rate of bovine embryo death between 30 and 60 d of gestation. In addition, pal pation per rectum as a means of pregnancy detection was evaluated as a possible cause of embryo death. Estrus was synchronized in Holstein h eifers (n=1358), weighing greater than or equal to 385 kg, with a sing le intramuscular injection of 25 mg prostaglandin F-2 alpha. Estrus wa s primarily detected by the absence of paint marks on the tailhead. Th e heifers were artificially inseminated with semen from 5 Holstein sir es. Blood was collected between 30 and 45 d after breeding, and sera w ere evaluated for the presence of bovine pregnancy specific protein B (bPSPB) by RIA to determine pregnancy. Palpation far fetal membrane sl ip was conducted by an experienced technician in approximately one-hal f of the inseminated heifers. To determine embryonic survival, a secon d blood sample was collected at approximately 60 d from 862 heifers th at were determined to be pregnant at the first blood sampling. Embryon ic loss averaged 5.3% during the interval between the initial detectio n of pregnancy at 30 to 45 d and the subsequent detection of pregnancy at 60 d of gestation. Embryo loss in heifers that were palpated was 6 .5% compared with that of 4.3% in the control heifers (X(2); P=0.145). These findings establish that there was substantial loss of embryos b etween 30 and 60 d post breeding but that embryo loss was not affected by palpation per rectum.