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 was
collected 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 after 30 days. The ovarian condition of the nonpregnant
animals was reevaluated 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)
than non-pregnant animals from the TG and TN.
Pregnancy rate was similar among the groups (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.
