The Effect of two Levels of Energy Intake on Reproductive Phenomena in Duroc Jersey Gilts

Abstract

One hundred and two Duroc Jersey gilts were used to determine the effects of two levels of energy intake on attainment of puberty, ovulation rates and embryonic mortality. One-half of the gilts were limited to 50% of the energy intake of a full-fed group. All gilts were bred at second heat. One-third of each ration group was sacrificed at 3 days after breeding, another third 25 days postbreeding and the remainder allowed to farrow. Data were collected during the same season of two consecutive years. The gilts on the limited-energy intake averaged 217 days of age and 160 lb. at puberty. Full-fed gilts averaged 195 days of age and 196 lb. at puberty. Differences between years in age and weight at puberty were extremely small. Limited-fed gilts ovulated an average of 9.9 ova at first heat, compared to 12.8 ova by full-fed gilts. These same gilts had mean ovulation rates of 10.8 and 13.8 in the second heat. The fertilization rate of all ova recovered was 96.5%. The mean ovulation rate at second heat for gilts sacrificed at 25 days of gestation was 11.1 and 12.7 ova for limited and full-fed gilts, respectively. There was a mean of 9.9 normal embryos for limited-fed gilts, and 10.1 for full-fed gilts at this state of pregnancy. Limited-fed gilts farrowed an average of 8.7 live pigs, compared to 9.0 live pigs for full-fed gilts. Differences between years of birth were not significant. Prenatal mortality for the first 25 days of gestation was 11.6% for limited-fed gilts and 22.1% for full-fed gilts. Mortality during the entire gestation period was 20.1% for limited-fed gilts and 31.8% for full-fed gilts. The results of this study indicate that restricting the energy intake delayed puberty, depressed ovulation rate and decreased embryonic mortality. Therefore, it appears that gilts should be full-fed for high ovulation rates, but limited-fed to attain higher embryonic survival rates. Copyright © . .