EFFECT OF INSEMINATION AT FIRST OESTRUS OR THE USE OF GONADOTROPINS AND INSEMINATION AT SECOND ESTROUS ON LITTER SIZE OF PRIMIPAROUS SOWS

Abstract

The effect of insemination at first estrous post-weaning or the application of gonadotropins and insemination at the second estrous on litter size of first parity sows was evaluated. Productive data of 2003 to 2005 and 2006 to 2007 from a commercial farm in Yucatan, Mexico were analyzed. The data of the sows farrowing from 2003 up to 2005 corresponded to the sows inseminated at the first estrous post-weaning and the data of the sows farrowed from 2006 to 2007 corresponded to sows that received at weaning an injection of PG-600 (400 IU of eCG and 200 IU of hCG); the estrous was skipped and the sows were inseminated until the second estrous. In both groups, and scheme of three inseminations each 12 hours was used. The data collected consisted of litter size at first and second parity for each group, number of piglets born alive and the interval weaning to first service. Data were analyzed using t tests for independent groups. Significant differences were found in litter size between groups. The application of gonadotropins and insemination at second estrous improved the litter size of the second farrowing.