Submitted to: Journal of Applied Poultry Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/1/2009
Publication Date: 2/20/2009
Citation: Corzo, A., Kidd, M.T., Dozier, W.A., Kerr, B.J. 2009. Dietary Glycine and Threonine Interactive Effects in Broilers. Journal of Applied Poultry Research. 18(1):79-84. Interpretive Summary: Glycine is important in broilers due to its involvement in eliminating nitrogen from the body of the bird through its function in uric acid production. In addition, the ability of glycine to be synthesized from threonine is important because in certain circumstances glycine is an essential amino acid for optimal bird growth. Lastly, because threonine is considered the third limiting amino acid after methionine and lysine, it is important to maintain adequate levels in broiler diets to maintain optimal growth. Consequently, a study was conducted to define the potential relationship between glycine and threonine in growing broilers. This experiment demonstrated that dietary glycine is an important amino acid for proper growth under certain conditions, such as when feeding all-vegetable diets, and because diets are often formulated to contain lower crude protein values as a way to reduce cost, overcoming marginal levels of dietary glycine may be accomplished by allowing moderate excesses of dietary threonine. This information is important for nutritionists at universities, feed companies, and broiler production facilities showing them the importance of glycine and threonine levels in broiler diet formulations to maintain optimal bird performance.
Technical Abstract: There is little information regarding the interaction of dietary threonine and glycine on potential metabolic sparing effects, live production, or breast meat yield of broilers. To test these potential interactions, 432 one-day-old Ross 308 male broilers were fed a common diet up to 21 days of age and then fed 1 of 6 experimental diets. A factorial arrangement of treatments consisted of 3 dietary levels of standardized digestible threonine (0.57, 0.61 and 0.65%) in combination with 2 levels of total glycine+serine (1.55 and 1.65%). Experimental diets were fed from 21 to 42 days of age with live performance, carcass traits, and free blood plasma levels of glycine, serine, and threonine serving as evaluation criteria. Interactions (P = 0.05) were observed for body weight gain, feed consumption, carcass and breast meat weight, and carcass yield, all showing improvements with increasing dietary threonine in combination with low dietary glycine+serine treatments. Circulating plasma glycine, serine, and threonine were affected by their respective dietary status.