|Dozier Iii, William|
Submitted to: British Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2005
Publication Date: 4/20/2006
Citation: Thornton, S.A., Corzo, A., Pharr, G.T., Dozier III, W.A., Miles, D.M., Kidd, M.T. 2006. Valine needs for immune and growth responses in broilers from 3 to 6 weeks of age. British Poultry Science. 47:190-199. Interpretive Summary: Feed cost represents 65% of the total live production cost for broiler chickens that supports an industry that produces 8 billion birds annually. Large percentage of the cost of the diet is protein/amino acid contributing ingredients. Valine is typically recognized as the fifth limiting amino acid in broiler diets. Due to the lack of research evaluating valine needs during the 3 to 6 week period, four experiments were conducted to assess valine needs for growth, carcass, and immune responses in commercial broilers reared in floor pen environments. Results indicated that dietary dose responses of valine resulted in male, but not female, birds fed 7.3 g Val/kg of diet having improved BW gain and feed conversion versus birds fed 6.4 g Val/kg of diet.
Technical Abstract: Four experiments were conducted to evaluate Valine (Val) needs in Ross x Ross 508 broilers from 3 to 6 weeks of age. Common diets were fed to broilers until 3 weeks of age. Growth and carcase measurements were taken in all experiments. Immune responsiveness measurements were taken in Experiments 1 and 2. Birds fed 7.2 g Val/kg of diet in Experiment 1 had reduced spleen weight and more abdominal fat than birds fed 8.2 g Val/kg of diet, but differences in growth or other carcase measurements did not occur. Because growth performance was not reduced in birds fed 7.2 g Val/kg of diet, Val was reduced to 6.4 g Val/kg of diet in Experiments 2 and 3. Increasing Val from 6.4 to 8.7 g Val/kg of diet resulted in linear increased for BW gain and feed conversion (P ' 0.05) in male birds, and breast meat yield (P = 0.07) in female birds. Quadratic responses to increasing dietary Val were not observed in any experiment. Further quantification of immunity did not substantiate Val effects on the spleen. A nonessential amino acid mixture containing the N content of L-Val additions in Experiment 4 was implemented and tends to support that the Val responses were based on its limitation, rather than N per se. Dietary dose responses of Val resulted in male, but not female, birds fed 7.3 g Val/kg of diet having improved (P ' 0.05) BW gain and feed conversion versus birds fed 6.4 g Val/kg of diet.