The efficacy of the boar effect when conducted in a modified detection-mating area (DMA)

Abstract

Fifty-six Large White/Landrace crossbred gilts from 14 litters were allocated to four treatments by litter and liveweight in a 2x2 factorial experiment. The two factors tested were boar contact v. no boar contact and exposure to a modified Detection-Mating Area (DMA) v. no DMA exposure. All treatments began at a mean gilt age of 160 days and continued on a daily basis for 60 days. Daily boar exposure significantly reduced mean gilt age at puberty (196.2�3.88 v. 216.6�3.26 days respectively, P < 0.01) and increased the proportion of gilts attaining puberty within 60 days of commencement of treatment (0.79 v. 0.30 respectively, P < 0.01), compared with gilts receiving no boar exposure. In contrast, daily exposure to a modified DMA failed to significantly reduce mean gilt age at puberty (202.8�4.63 v. 209.7� 3.35 days respectively) or to increase the proportion of gilts attaining puberty within 60 days of commencement of treatment (0.50 v. 0.59 respectively) compared with gilts receiving no DMA exposure. However, daily exposure to a modified DMA did significantly increase the proportion of gilts pubertal over a 2-day period (days 27-28 of treatment) relative to gilts not exposed to a DMA. It is concluded that (1) daily boar exposure is a potent stimulus for early puberty attainment in gilts, (2) full physical contact with the boar must occur in order to achieve the boar effect, and (3) the current recommendation that gilt puberty stimulation can be adequately achieved by exposing them to a DMA on a daily basis should be re-examined.