Study On Application Of Exogenous Reproductive Hormones In The Improvement Of Sows' Reproductive Efficiency

The studies were performed on the available protocols for the induction of estrous in the gilts, multiparous sows (the first filial generation of Landrace×Yorkshire) and the purebred Landrace sows to improve the litter size. The gilts, multiparous sows were treated with PMSG and LRH-A3 (experiment 1) and the multiparous purebred Landrace sows with LRH-A3(experiment 2).Experiment 1: 20 anestrus Landrace-Yorkshire gilts and 20 anestrus Landrace-Yorkshire weaned sows were treated with PMSG and LRH-A3 to induce estrus. The results of the experiments indicated: The estrus rate of treated gilts (90.0%) and sows (85.0%) were higher (P<0.01) than that of the controls (15.0% and 10.0% respectively), while there was no significant difference (P>0.05) in the conception rate, litter size and the number of alive piglets per litter between treatments and controls, showing that the 2 hormones were effective to the induction of estrus in the sows.Experiment 2: 20 estrous purebred Landrace sows were treated with LRH-A3 and another 20 sows with no LRH-A3. The average litter size and the number of alive piglets per litter of the treated sows (11.47 and 11.10) were higher (P<0.05) than those of the controls (10.29 and 9.94), showing that LRH-A3 was conducive to the improvement of the sow fertility.