INFLUENCE OF DIETARY ORNITHINE AND METHIONINE ON GROWTH, CARCASS COMPOSITION, AND POLYAMINE METABOLISM IN THE CHICK
Experiments were conducted to determine the effects of factorial combinations of dietary ornithine and methionine on chick growth, carcass composition, and the regulatory enzymes of polyamine synthesis. Week-old leghorn cockerel chicks were fed 12 soy protein-based semipurified diets containing 0.00, 0.50, 0.85 or 1.25% ornithine plus 0.55, 0.75 or 1.00% methionine for 2 wk. Weight gains were depressed as dietary methionine increased but only when ornithine was fed at less than 0.85%. Ornithine supplements depressed growth regardless of methionine levels. Carcass protein decreased with supplemental ornithine when methionine was fed at 0.55% but not at higher levels. Methionine supplements decreased carcass protein only in the absence of ornithine. Feeding 0.85% ornithine plus 0.55% methionine resulted in increased activity of S-adenosylmethionine decarboxylase in heart, pancreas, and muscle when compared to the control diet containing 0.00% ornithine plus 0.55% methionine. Dietary ornithine supplements lowered ornithine decarboxylase activities in heart, pancreas, and liver regardless of methionine level. It can be concluded that there is a nutritional interrelationship between ornithine and methionine as indicated by their cumulative effects on growth, carcass composition, and S-adenosylmethionine decarboxylase activity.