Age at puberty and estrous activity of straightbred and reciprocal crossbred gilts

Age at puberty, estrous activity and growth were evaluated in 294 straightbred and reciprocal crossbred gilts maintained in confinement conditions. Trial 1 used straightbred Landrace (L), Yorkshire (Y) and reciprocal crossbred (LY, YL) gilts. Trial 2 used LY and YL gilts, and Trial 3 used L and Duroc (D) reciprocal crossbred gilts (LD, DL). Daily observations for estrous activity with a mature boar were initiated at 150 days of age and continued until gilts reached 255 days of age. Gilts not exhibiting estrus by 255 days of age were examined by laparoscopy to determine reproductive status. In Trial 1, age at puberty was greater for Y gilts compared to L and reciprocal crossbred gilts. Differences between reciprocal crosses for age at puberty were not significant in any trial. In Trial 1, the percentage of gilts exhibiting regular estrous cycles at 195 days of age was lower for Y gilts than for the other three groups of gilts; however, by 225 days of age, this difference was not significant. In all trials, reciprocal crossbred gilts did not differ with respect to percentage exhibiting regular estrous cycles or in percentage prepubertal. In Trial 1, Y gilts had a higher percentage prepubertal at 255 days of age than the reciprocal crossbred gilts. The percentage of gilts exhibiting behavioral anestrus at 255 days of age did not differ among breed groups within any trial. Based on these observations, we concluded the breed maternal effects were small or nonexistent relative to direct additive and nonadditive genetic effects in the breed combinations that were investigated.