Reproductive performance and uterine prostaglandin secretion in gilts conditioned with dead semen and receiving dietary supplements of folic acid

The effects of dietary supplements of folic acid at 0 (F−) or 15 ppm (F+) and of conditioning the uterus (C+) or not (C−) with an intrauterine infusion of dead semen on embryonic survival and prostaglandin E2 (PGE 2 ) concentrations in the allantoic fluid on day 30 of gestation were studied. Sixty-four F 1 crossbred gilts (Yorkshire × Landrace) were used in a 2 × 2 factorial design. The initiation of folate supplementation and the intrauterine infusion of dead semen were done at the estrus preceding the fertile mating. Folate status in serum was lower in F+ gilts than in F− gilts during the estrus cycle (folic acid × period interaction, P ≤ 0.007). Conditioning increased ovulation rate in F− gilts while it tended to decrease it in F+ gilts (interaction folic acid × conditioning, P ≤ 0.03). A similar interaction (P ≤ 0.02) was observed on the number of presumably live embryos at 30 d of gestation. Mean PGE 2 concentration in the allantoic fluid was not affected by treatments (P ≥ 0.44), but the frequency of sows having elevated allantoic PGE 2 (> 4 ng mL −1 ) tended to be higher (P ≤ 0.06) in F+ sows. Overall values of PGE 2 were correlated with total litter weight (R 2  = 0.54). In conclusion, there was no synergism between folic acid supplements and conditioning of the uterus with dead semen on the reproductive performance or on the secretion of allantoic PGE 2 at 30 d of gestation. The secretion of allantoic PGE 2 appears as an important factor involved in the control of litter size and weight. Key words: Folic acid, artificial insemination, semen, gilts, conditioning, embryo mortality