Age and Synchrony of First Estrus in Gilts as Influenced by Type and Duration of Daily Boar Exposure (BE)

University of Nebraska 1996 Swine Day Report. Fence-line boar exposure (FBE) and physical boar exposure (PBE), each with durations of 10 minutes or four hours, were evaluated for their ability to trigger puberty in gilts. Gilts provided PBE attained puberty 11.8 days earlier than gilts provided FBE. Duration of boar contact was without effect. Earlier age at first estrus resulted, in large part, from a more rapid pubertal response after initiation of boar exposure (BE). The mean interval from initiation of BE to pubertal estrus was 13.5 days for PBE gilts and 24.8 days for FBE gilts. Fenceline boar exposure stimulates earlier puberty in gilts (shown in previous studies), but is less effective than PBE for triggering a rapid pubertal response in gilts. Physical boar exposure is required to achieve the maximal pubertal response to boar exposure when applied daily for limited periods (4 hours or less) to gilts nearing onset of puberty.