This mature boar is penned next to the estrus females to encourage them to stand for AI. (The containers along the top of the image are individual feed bins.)
Puberty is attained more gradually in boars than in gilts. By 5 months of age, most boars can ejaculate sufficient numbers of sperm for fertile mating. By 8 months of age, adequate sperm numbers are produced for use in a breeding program. Mature adult sperm numbers are achieved by 18 months of age.
Boars raised in groups attain puberty earlier, and have more aggressive libidos. Exposure of prepuberal boars to sows or gilts improves postpuberal sexual behavior. Boar libido is probably heritable.
The mating behavior of boars consists of grunting, nuzzling, and chomping behaviors with copious salivation when in contact with the sow. Contact means either nasonasal or nasogenital and frequent "mock fighting" is seen. This will cause initiation of the lordosis reflex in the sow. Multiple false mounts may occur before copulation. During copulation, the penis locks into the cervix and ejaculation occurs over a 4 to 6 minute period.
Frequency of boar use should not exceed once daily or four days per week. Young boars should be used less. Typical ratio is 20 sows per boar in a hand- or pen-mating system. Boar power refers to the efficiency with which the boars are used. It depends first on how many females are in heat. The next consideration is the type of breeding management system used. For example, in artificial insemination systems, boar power is maximized because one boar can service 100 to 200 sows. Because of less control over boar power, pen-mating systems require about one boar for every 10 sows.
The spermatogenic cycle in the boar is 35 days, with 10 days for epididymal transport. Thus 45 days are required from the start of production to ejaculation of sperm. Semen parameters have been set for normal, mature boars.
Copyright ©1997 by the University of Pennsylvania School of Veterinary Medicine
Faculty: Dr. Paul Pitcher
Student: Sandra Springer,'99