THE SEXUAL MOTIVATION OF BOARS HOUSED ADJACENT TO OVARIECTOMIZED GILTS DID NOT AFFECT THE EFFICIENCY OF DETECTING HORMONALLY INDUCED ESTRUSUSING THE BACK PRESSURE TEST

This study tested the hypothesis that the efficiency of detecting oest rus in gilts, using the back pressure test (BPT), will be reduced when gilts are housed adjacent to a boar of high sexual motivation compare d to when gilts are housed adjacent to a boar of low sexual motivation . The experiment was a 2 X 2 Latin square design with three replicates . Boars of high and low sexual motivation were selected on the basis o f the total number of copulations and the mean reaction time to first mount during three mating tests. Twelve boars were observed in mating tests and the three highest and lowest ranking boars were assigned to three pairs, each pair containing a boar of high and a boar of low sex ual motivation. One pair was used in each replicate. In each replicate , two groups of six ovariectomised gilts were housed for 14 days, comm encing 7 days prior to hormonally induced oestrus, adjacent to a boar of either high or low sexual motivation. All gilts were checked twice daily for oestrus using the BPT. In the first replicate, the level of preceptive behaviour of the gilts was quantified immediately after che cking for oestrus in a 3-min test in which the amount of time that the gilts spent within 0.5 m of a pen containing a sexually mature boar w as recorded. There were no effects of housing gilts adjacent to boars of high or low sexual motivation on the percentage of gilts detected i n oestrus, the percentage of gilts detected in oestrus for more than 1 day, the duration of oestrus or the level of preceptive behaviour of gilts. These data suggest that the level of sexual motivation of boars does not influence the efficiency of detecting hormonally induced oes trus, using the BPT, in ovariectomised gilts housed adjacent to boars.