The effects of supplementary olfactory and auditory stimuli on the stimulus value and mating success of the young boar

The aim of this study was to investigate the stimulus value and mating success of young boars in the presence or absence of exogenous boar-originating stimuli. Ten Large White × Landrace boars were exposed to each of the following treatments at 6 – 7 months of age (Period 1) and again at 9 – 10 months of age (Period 2): (1) no added boar stimuli; (2) added auditory stimuli; (3) added olfactory stimuli; (4) added auditory and olfactory stimuli. The efficacy of each treatment was determined by subjecting each boar to 2 × 5-min mating tests during each age-period, and assessing gilt proceptivity and sexual receptivity. Gilts used in these tests had been ovariectomized and were induced into behavioural oestrus using a threshold dose of oestradiol benzoate.The addition of both exogenous boar-originating stimuli (Treatment 4) significantly (P<0.05) increased gilt proceptivity and sexual receptivity in Period 1. This indicates that young post-pubertal boars may be deficient in both the auditory and olfactory stimulation that they provide to the female pig. No significant differences were observed between treatments during Period 2. These results therefore suggest that young boars (6–7 months of age) may have a lower stimulus value than their older counterparts, and that this may adversely affect mating success.