OBJECTIVES AND STRATEGIES IN PIG IMPROVEMENT - AN APPLIED PERSPECTIVE

Largely because of the influence of Charles Smith, simple performance testing of pigs over the previous 30 yr has been highly successful. Wi th larger production units, current genetic objectives can be divided into two components: 1) to raise genetic potential for production trai ts and 2) to maximize the probability that this potential can be reali zed in practice. Faster improvement through increased accuracy and a m ore flexible nucleus structure are offered by BLUP methodology. Electr onic measures of feed intake permit selection based on feeding behavio r and the shape of the feed intake curve. After the elimination of the halothane gene, the next limiting factor for meat quality could be in tramuscular fat. With more than 1500 mapped genes, the main constraint s on marker-assisted selection are the high costs of DNA testing and t he relatively small effects of this selection on performance. A combin ation of the possible effects of BLUP, the Meishan breed, and the ESR gene could give genetic improvements totaling 4 Liveborn piglets per l itter over the next 10 yr. There appear to be no limits on future impr ovement of lean growth, but risks are adverse changes in reproduction and disease resistance. Existing quantitative methods of improvement a re very cost effective. The greatest challenge for molecular technolog ies may be the genetics of the immune system.