Breeding in Swine
Breeding begins at weaning of the previous litter in mature sows and begins at a targeted age/weight in gilts.
Production goals for Breeding:
- Average wean to 1st service interval 6 days
- First service conception rate 90%
- Average matings per service 2-3
Optimum fertility occurs 18 to 42 hours after the onset of standing heat and requires live sperm present in the reproductive tract during ovulation. Breeding more than 10 hours after ovulation yields low pregnancy rates because aging ova and/or spermatozoa significantly results in lowered fertility through genetic losses of embryos. In healthy sows bred to fertile boars, 90 to 100% of ova are fertilized and 80 to 90% of sows will farrow. However, if fewer than 5 ova are fertilized, pregnancy will not be maintained. Farrowing rates increase when different boars are used during different services of the same mating. However, so-called "heterospermic mating" can preclude or delay the discovery of subfertile boars.
Breeding management practices include pen-mating, hand-mating, or AI. Many schemes exist for timing of services in hand-mating and AI systems. Sows should be serviced at least once every 24 hours after the onset of estrus until the animal will no longer stand. It is common to include an additional service 12 hours after the observed onset of estrus to better target ovulation. Gilts should be serviced every 12 hours during standing heat because of their shorter estrus period and earlier ovulation. Litter size increases with number of services and well managed herds will average >3 services per mating.
(Note: Fertilized ovum at the 4-cell stage enter the uterus at 2 days after ovulation, on average. This is sooner than in other domestic animals.)
Copyright ©1997 by the University of Pennsylvania School of Veterinary Medicine
Faculty: Dr. Paul Pitcher
Student: Sandra Springer,'99