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Improving the Swine Industry Through Genetics and Breeding
Livestock Update, December 2002
Mike Ashby and C. M. Wood, Virginia Tech
At the American Society of Animal Science meetings this past July, the Swine Species session "Value-Added Pork Products for the 21st Century Consumers" included a presentation on the role of breeding and genetics in the evolving swine industry (Emsley, 2002). Improvements over the last 40 years include 33% less feed to the same weight and 33% more lean from today's hogs. Using new technolgies, researchers continue to improve their understanding of gene functions and interactions, and more research is underway to provide what the consumer will demand in the future.
If DNA markers can be found for important quantitative traits, greater economic gains can be made. In one simulation (Hayes et al., 2001), a 20-sow nucleus herd was selected for growth and back fat, feed conversion ratio, number born alive, and meat quality using DNA markers. Accuracy for selection of all traits increased and after seven generations of selection, economic returns increased 4 to 5 %.
Current feed prices are up hog prices are down, creating a renewed interest in restricted feeding programs. In an Australian study, grower pigs from lines divergently selected for and against lean growth under a restricted feeding program were assigned to four progeny groups. A group of high-line pigs and a group of low-line pigs were fed a diet ad libitum; another pair of groups was fed the same diet restricted by 20%. The high line groups outperformed the low line groups on both diets, and consumed less feed on the ad libitum diet (Mcphee et al., 2001).
Another exciting advancement in swine genetics involves single-sex litters. Several large companies joined together to finance development of a technique to make single-sex litters. The technique is based on identifying sex-specific proteins on the surface of sperm. Based on preliminary results, researchers believe the practice will be 95% accurate (Dunn, 2000).
In the future, consumers will want low-cost, healthy, safe, and convenient products. Genetic programs will utilize better record keeping and will consider environmental interactions and food processing, requiring breeders with high levels of skill and experience. Knowledge about the swine genome will increase substantially, while costs of DNA testing will decrease greatly, yielding more accurate marker genes that will allow better selection. The consumer will be able to get high quality products at reasonable prices, and hopefully, producers will realize savings in production costs, boosting the swine industry into the future(Emsley, 2002).
Literature Cited
Dunn, N. 2000. One-sex litters in 2003. Pig Progress, Vol. 16 (No. 6):10-13
Emsley, J. A. B. 2002. Breeding and genetics in the evolving swine industry. J. Anim. Sci. 80(Suppl. 1):12-13 (Abstr.).
Hayes, B., P. J. Bowman, and M. E. Goddard. 2001. Genetic gain from marker assisted selection in a commercial pig enterprise. In: Manipulating Pig Production VIII. Adelaide, South Australia. p 44 (Abstr.).
McPhee, C. P., N. H. Nguyen, and L. J. Daniels. 1999. Selection for efficient lean growth under restricted feeding: 2. grower performance. In: Manipulating Pig Production VII. Adelaide, South Australia. p 96 (Abstr.).