The male contribution to broiler breeder heat-induced infertility as determined by sperm-egg penetration and sperm storage within the hen's oviduct.

The purpose of the present study was to define the role of the male broiler breeder in heat-induced infertility. Seventy-two Arbor Acres roosters were individually caged at 21 wk of age and divided equally among three heated (H) and three control (C) temperature chambers. Control temperature chambers were held at 21 C. After an 8-wk pretreatment period (20 C), an 8-wk treatment period was conducted in which the temperature in all three of the H chambers was varied from week to week according to the following schedule: Week 1, 27 C; Week 2 through Week 4, 32 C; and Week 5 through Week 8, 21 C. On a weekly basis, semen was pooled by room and inseminated into 12 groups of 10 hens each (2 groups per room). During the 1st wk when males were maintained at 27 C for 12 h, in vivo sperm-egg penetration was reduced by 48% as compared to data obtained when males were maintained at 21 C. Fertility, in vivo sperm-egg penetration, and uterovaginal sperm storage were decreased when semen from males exposed to 32 C was used to inseminate hens as compared to insemination with semen from C males. However, during this same period, the ability of sperm to bind and penetrate the egg, as determined by in vitro sperm-egg penetration, was similar between sperm from C and H males. After lowering the temperature in the H chambers back to 21 C, in vivo sperm-egg penetration as a result to insemination with semen from H males was analogous to results obtained when C males were used for insemination. Immediately after decreasing the temperature in the H chambers, fertilization of eggs by sperm from H males increased to a level similar to that obtained when eggs were fertilized by sperm from C males but then declined again during the later weeks.