Effects of supplemental oxytocin or prostaglandin F2α analogue in extended boar semen on piglet productivity of gilts and sows artificially inseminated in summer

We determined the effects of oxytocin (OT) and prostaglandin F2α analogue (PG) added to extended boar semen on the duration of artificial insemination (AI) and reproductive performance of pigs bred in July and August (temperate climate of Central Europe). Eighty gilts and second parity sows (G+SP) and sixty-four multiparous sows (M) were divided into three groups. Group OT (11 G+SP and 37 M) and group PG (20 G+SP and 28 M) were artificially inseminated twice (at the onset of estrus and 22–24 h later) using extended semen supplemented with 20 IU of OT or 5 mg of PG, respectively. Thirty-three G+SP and 15 M served as controls (C) inseminated with non-supplemented semen. The mean duration of the first AI was shorter (P<0.05) in M compared with G+SP females inseminated with PG-supplemented semen (80±22 s vs. 191±26 s, respectively), whereas the second AI was shorter (P<0.05) in M than in G+SP artificially inseminated with OT-supplemented semen (93±15 s vs. 192±28 s). The mean pregnancy rate was lower (P<0.05) in C G+SP (26/33; 85%) compared with OT G+SP females (11/11; 100%). The OT M females had more (P<0.05) stillborn piglets per litter compared with their G+SP counterparts (0.8±0.1 vs. 0.1±0.3). In summary, the addition of PG was associated with shorter first AI times in multiparous sows compared with G+SP, but with lower farrowing rates in younger animals. Oxytocin supplementation was associated with a shorter second AI and higher pregnancy rates in young females, but more stillborn piglets per litter in older sows.