Effects of flunixin meglumine on reproductive parameters in beef cattle

ABSTRACT

Flunixin meglumine (FM) has been used as an attempt to inhibit luteolysis in ruminants. The effects of FM on seric concentration of progesterone, pregnancy rate and ovarian status of cows were assessed in this study. Fifty-seven cows were divided into Control Group (CG; n = 30) and Treated Group (TG; n = 27) on an estrus synchronization program involving intramuscular(IM) estradiol benzoate (EB) and intravaginal progesterone-releasing insert. After seven days the intravaginal insert was removed, prostaglandin-F2alpha (PGF2α) IM was given, and then EB was administered 24 h later. Fixed-time artificial insemination (FTAI) was conducted 30 h after EB administration. Animals from the TG received 1.1 mg/kg of FM IM daily between the days 11 and 16 of the estrous cycle (day 0 = FTAI), whereas the animals from the CG received physiological solution. Blood from all animals wascollected on days 0, 6, 9, 11 through 18, and 21. Thirty animals from the Nellore breed were selected for the measurement of serum concentrations of progesterone by radioimmunoassay. Animals which returned to estrus were inseminated again (artificial insemination; AI) and allocated back to their groups. Pregnancy diagnosis was conducted by transrectal ultrasound in either FTAI or AI cows after30 days. The ovarian condition of the nin-pregnant animals was reevalunted 4 days later. Progesterone concentration among the animals from the experimental groups was similar until the day 18 of the estrous cycle (P > 0.05). On day 21, pregnant animals presented higher progesterone concentrations (P 0.05). However, non-pregnant animals from the TG presented higher (P > 0.05) follicular persistence than that observed for the animals in the CG, 78.6% (11/14) vs. 33.3% (5/15), respectively (P = 0.025). Results indicate that FM administered during the luteolysis period of beef cattle does not influence progesterone concentration and pregnancy rate, although it influences the occurrence of follicular persistence.