Improving Nutritional Quality of Meat Animals
Floyd K. McKeith
Lean tissue quantity and quality are the major factors in determining the value of meat animals. A continuing goal of the livestock industry is to increase the quantity of high-quality lean tissue; and scientists have used technologies based on genetics, nutrition, and physiology to achieve this goal. Increased consumer demand for lean meat has stimulated the need for technologies to reduce fat and increase lean in meat animals.
Repartitioning agents (beta-adrenergic agonists and somatotropins) are compounds that increase lean content and reduce fat content of meat animals, while improving the rate and efficiency of growth. Although studies on cattle and sheep have also been conducted, the bulk of information available about repartitioning agents involves pigs. Current studies at the University of Illinois and elsewhere are evaluating the potential of these products for the beef industry.
Somatotropins. Somatotropin is a protein normally found in all animals. By augmenting existing somatotropin levels with exogenous somatotropin, swine producers can alter the composition of the meat animal. Studies conducted at the University of Illinois indicate that the fat content of meat animals may be reduced by 25 percent using only 3 milligrams of somatotropin per day. Fat reduction improves nutritional quality of meat animals by reducing fat between muscles, thus improving the yield of consumable lean, and thereby enhancing how consumers view meat products. Results from our studies indicate use of somatotropin causes only small changes in pork's tenderness, juiciness, and flavor. Improvements in meat animal composition were accompanied by increased average daily gain (10 to 20 percent) and increased feed efficiency (10 to 15 percent). Increased availability of somatotropin for research and Food and Drug Administration (FDA) evaluation is due to recent advances in biotechnology.
Beta-adrenergic agonists. These feed additive products result in improvements in meat animal composition and the rate and efficiency of growth. Several different compounds have been developed and evaluated. After evaluating cimaterol and ractopamine in our laboratories, we found that these two beta-adrenergic agonists reduced meat animal fat by 10 to 15 percent, while improving average daily gain and feed efficiency by 10 to 15 percent. No consistent differences in color, firmness, or marbling were observed in the quality of the lean meat produced from these animals.
Although somatotropins and beta-adrenergic agonists are unavailable on the marketplace today, the FDA is evaluating their safety and efficacy for future use in the livestock industry.
Floyd K. McKeith, associate professor of animal sciences
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Effects of porcine somatropin (pst) on American and Chinese pigs at the same age.
