Age at Puberty and Ovulation rate in Gilts in Confinement as Influenced by Exposure to a Boar

Abstract

One-hundred-nineteen crossbred gilts were used to determine the influence of exposure to a boar on age at puberty and ovulation rate in confinement. Four trials consisting of 18, 35, 33 and 33 gilts each were conducted. Gilts were divided into two treatment groups on the basis of litters at approximately 6.5 months of age. Gilts in one group were exposed to a boar continuously during a 30-day period in confinement while their littermates were separated from boar influence during the same period. Gilts in both groups were moved from confinement to an outside breeding facility following the 30-day treatment period. A greater proportion of gilts in groups exposed to a boar (P<.01) were detected in estrus in confinement (19 of 58) when compared to gilts not exposed to the boar in confinement (three of 61). The number of gilts in estrus in all time periods was greater (P< .06) in those gilts which were exposed to a boar during the confinement period. Average age at first estrus of gilts exposed to a boar was younger (P<.05) than in gilts not exposed to a boar in confinement (225 days vs 235 days). A significant difference between trials was noted on age at first estrus probably due to seasonal and genetic differences. Ovulation rate was similar for gilts in both treatment groups. Ovulation rate was not influenced by age at first estrus.