A note on the effects of contact frequency and time of day of boar exposure on the efficacy of the boar effect

Sixty-four Large White/Landrace crossbred gilts were used in this study, 16 gilts being allocated to each of four treatments to compare the effects on puberty attainment of exposure to boar contact either 0, 1 or 2 times dail y. The once-daily exposure occurred in either the morning or the afternoon (AM vs. PM). Treatments were of 20-min duration starting at a mean gilt age of 160 days and continuing for 60 days. Boar exposure significantly increa sed the proportion of gilts attaining puberty within 60 days of the commenc ement of treatments (P < 0.05) compared with gilts not receiving boar conta ct. Gilts receiving boar exposure twice daily attained puberty significantl y earlier than did gilts in the two treatment groups (AM and PM, respective ly) given a single daily boar exposure period (mean gilt ages at puberty 17 6.4 vs. 192.7 and 189.2 days of age, respectively, P < 0.05). It is conclud ed that (a) twice-daily boar contact enhances the efficacy of the boar effe ct in gilts above that seen with a single daily boar exposure period and (b ) this enhanced response of the gilt is due to the frequency of boar contac t and not to the time of day at which the contact occurs. (C) 1999 Elsevier Science B.V. All rights reserved.