PSA-Environment and Management-Enteric Bacteria

The objectives of this study were to evaluate the effects of flunixin meglumine (FM), an inhibitor of PGF2α synthesis, administered at the time of embryo transfer (ET) and insertion of an intravaginal progesteronereleasing device (CIDR) at the time of ET on pregnancy rates (PR) and the resynchronization of estrus. Beef cows (n = 552) and heifers (n = 160) in three locations were assigned randomly within age to one of four treatments: FM = injection of FM (500 mg i.m.; Phoenix Scientific; St. Joseph MO) 2 to 12 min prior to ET; CIDR = insertion of a CIDR (1.38 g progesterone; Pfizer; New York, NY) for 13 d immediately following ET; FM + CIDR or untreated control. Fresh or frozen embryos were randomly assigned to be transferred to recipients on d 6 to 9 of the estrous cycle. At one location, recipients (n = 493) were observed for signs of return to estrus beginning 9 d after ET. Recipients that returned to estrus were bred by AI or received an embryo 7 d after estrus. Pregnancy was diagnosed (d 28 to 60) by ultrasonography or palpation per rectum. PR were analyzed using the LOGISTIC procedure of SAS. Variation in the timing of the return to estrus was determined by an F-test for heterogeneity of variances. PR following the initial ET was not affected by CIDR administration (P > 0.05; 69% with CIDR, 76% without CIDR). There was a significant FM x location interaction on PR (Location 1, 89 vs 57%; Location 2, 70 vs 66%; Location 3, 74 vs 77% for FM vs no FM, respectively). The timing of the return to estrus was less variable (P < 0.01) for recipients fitted with a CIDR, but PR following AI (69 and 64%) or second ET (74 and 82%) did not differ (P > 0.05) in cows receiving or not receiving a CIDR, respectively. Effects of FM on PR varied among locations and CIDR insertion at ET reduced variation in timing of the return to estrus.