Influence of boar contact on attainment of puberty in gilts after removal of the olfactory bulbs.

At 6-7 weeks of age the olfactory bulbs were removed from gilts which were then exposed to vasectomized boars for 30 min/day, starting on Day 160. Mean +/- s.e.m. age at first oestrus was similar in these gilts (230 +/- 15 days) to that in intact gilts not exposed to a boar (234 +/- 8 days) but greater (P < 0.05) than for sham- and un-operated gilts exposed to a boar (204 +/- 3 and 208 +/- 9 days, respectively). There were no differences in growth rate or ovulation rate at first oestrus. It is concluded that the main stimulus involved in the boar effect is olfactory in nature.