Effects of artificial boar stimuli on the expression of oestrus in sows

In this study, the effects of artificial boar stimuli on oestrus expression in sows were compared to that of a boar. During consecutive cycles, 12 gilts and 38 sows were subjected to one of the three treatments. A Back-Pressure-Test (BPT) was carried out twice daily in the presence of a robot boar (R) with: (1) olfactory and auditory stimuli (R + O + A), (2) auditory stimuli (R + A) or (3) without additional stimuli (R). As a reference, a BPT was carried out in the presence of a mature boar 30 min after the robot procedure. With the boar, detection rate was higher (100% versus 66% (R + O + A), 81% (R + A), and 75% (R); P <0.01) and the duration of oestrus was longer (56 ± 7 h versus 33 ± 4 h (R + O + A), 54 ± 5 h versus 36 ± 5 h (R + A), and 60 ± 3 h versus 38 ± 3 h (R); P <0.01) than with any combination of artificial boar stimuli. The different combinations of artificial stimuli did not differ in detection rate and duration of oestrus (P > 0.10). Artificial, olfactory and auditory stimuli did not add to the visual stimuli. Furthermore, the presence of a boar results in better oestrus expression than a combination of all artificial stimuli.