Two experiments were conducted to examine further the attainment of puberty in gilts provided daily boar exposure. Of particular interest was an investigation of the proposed habituation effect of gilts to the influence of mature boar presence. Thirty (Experiment 1) and 24 (Experiment 2) peripubertal Duroc gilts (88 kg, 164 days of age) were fed either ad libitum (F) or 1.81 kg (L) of a complete diet daily from allotment to estrus. Gilts and mature active boars were housed in the same breeding facility, and gilts were observed for estrus twice daily through 245 days of age. In both experiments, there was no difference due to the level of feed intake for any reproductive trait measured. Cumulative proportions of subject gilts exhibiting estrus following relocation, mixing with unfamiliar pen mates and initiation of boar exposure were similar for both experiments, with approximately 50% of subject gilts attaining puberty within 42 days of the start of each experiment. Furthermore, cumulative proportions of subject gilts attaining puberty tended to plateau following Day 42 in both experiments. In Experiment 2, 36 novel prepubertal purebred gilts (Yorkshire and Duroc, 80 kg, 159 days of age) were introduced into the breeding facility on Day 73 following initiation of boar exposure. These novel prepubertal gilts were not co-mingled with the original subject gilts and a significant proportion (29%) of the subject gilts was observed to be in estrus within 10 days. Thus the introduction of novel prepubertal gilts into the breeding facility appeared to increase the incidence of estrus observed in peripubertal gilts, regardless of nutritional status. This finding could be attributable to increased levels of activity in mature boars, thereby increasing the efficiency of estrus detection and/ or by enhancing the male pheromonal induction of estrus, both of which require further investigation.
All Science Journal Classification (ASJC) codes
- Food Animals
- Animal Science and Zoology