Injectable or transdermal flunixin meglumine improves pregnancy rates in embryo transfer recipient beef cows without altering returns to estrus.

OBJECTIVES: were to determine effects of 1) injectable or transdermal flunixin meglumine (FM) at embryo transfer (ET) compared to an untreated control group on pregnancy per ET (P/ET; ∼35 d after ET); 2) embryo and recipient factors on P/ET; 3) FM on hormone concentrations; and 4) FM on returns to estrus. Angus-cross beef cows (n = 1145) at five locations were scored for body condition (BCS; 1-9) and temperament (0 or 1) and given Select-Synch + CIDR. Recipient cows with a corpus luteum (CL) ≥1.5 cm received a frozen-thawed embryo 7 d after estrus and were concurrently given 1.1 mg/kg injectable FM im (INJFM; n = 384), 3.3 mg/kg transdermal FM pour on (TDFM; n = 388), or nothing (CON group; n = 373). Blood samples were collected at ET and 7 d later (60 cows). Accounting for temperament (P < 0.05), ET difficulty score (1-3, easy to difficult; P < 0.01), treatment by temperament (P < 0.001) and treatment by embryo quality (P < 0.05), FM treatments affected P/ET (P < 0.05). The P/ET for cows given INJFM [62.8% (241/384)] or TDFM [58.7% (228/388)] were not different (P = 0.26), but they were greater (P = 0.01 and P = 0.04, respectively) than P/ET for controls [51.2% (191/373)]. The P/ET was greater for calm versus excitable cows, 60.2 (463/769) and 52.4% (197/376), respectively (P < 0.01) and was lower for difficulty score 3 [49.2% (156/317)] compared to score 1 [62.7% (254/405; P < 0.001) or score 2 [59.1% (250/423; P < 0.01)]. There was no effect (P > 0.1) of cow age, BCS, or stage of embryo development on P/ET. Pregnancy rates for embryo quality grade 1 (excellent/good) and grade 2 (fair) were 60.4% (314/520) and 55.4% (346/625), respectively (P > 0.05). Percentages of non-pregnant recipient cows in estrus from Days 18-26 did not differ among treatment groups (P > 0.1). Control cows had lower progesterone concentrations and greater substance-P, PGFM and 8-isoprostane PGF2α concentrations at 7 d after ET compared to FM-treated cows (P < 0.05). In conclusion, injectable or transdermal FM improved pregnancy rates in ET recipients, without affecting nonpregnant cows return to estrus.