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+) a nd of conditioning the uterus (C+) or not (C-) with an intrauterine infusio n of dead semen on embryonic survival and prostaglandin E2 (PGE(2)) concent rations in the allantoic fluid on day 30 of gestation were studied. Sixty-f our F-1 crossbred gilts (Yorkshire x Landrace) were used in a 2 x 2 factori al design. The initiation of folate supplementation and the intrauterine in fusion 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 es trus cycle (folic acid x period interaction, P less than or equal to 0.007) . Conditioning increased ovulation rate in F- gilts while it tended to decr ease it in F+ gilts (interaction folic acid x conditioning, P less than or equal to 0.03). A similar interaction (P less than or equal to 0.02) was ob served 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 greater than or equal to 0.44), but the frequency of sows having elevate d allantoic PGE(2) (> 4 ng mL(-1)) tended to be higher (P less than or equa l to 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 fol ic acid supplements and conditioning of the uterus with dead semen on the r eproductive 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.