Submitted to: Animal Feed Science And Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2007
Publication Date: 4/20/2008
Citation: Dozier III, W.A., Kidd, M.T., Corzo, A., Owens, P.R., Branton, S.L. 2008. Live performance and environmental impact of broilers fed diets varying in amino acids and phytase. Animal Feed Science And Technology. 141:92-103. Interpretive Summary: Market weights of broiler chickens have increased to meet the demand for breast fillets and value-added products. Breast meat is relatively high in lysine (7%) compared with other amino acids. Amino acids/crude protein has a pronounced impact on diet cost; diet cost represents approximately 65% of the cost for live production. This research determined the lysine need of heavy broilers as 0.93% of the diet based on growth responses of meat yield. A 1% improvement in breast meat yield occurred among the treatments translating to approximately 5 million dollar increase in revenue for a broiler company producing 1 million broilers weekly grown to heavy weights. On a national basis, this represents about 168 million dollars annually.
Technical Abstract: Two experiments (Exp) were conducted to examine potential interactive effects of dietary amino acid density (AAD) and phytase. In Exp 1, diets were formulated to high (H) or moderate (M) AAD during each growth phase from 1 to 35 d. Growth phases were from 1 to 7, 8 to 19, and 20 to 35 d of age, respectively, for the pre-starter, starter, and grower period resulting in the following dietary treatments: HHH, HHM, HMM, and MMM. Increasing amino acid density to the HHH feeding regimen improved (P ' 0.05) growth rate and feed conversion from 1 to 35 d of age, but increased (P ' 0.05) nitrogen excretion by 180 g/kg. In Exp 2, three diets were fed varying in AAD (H, M, and low (L)) from 36 to 49 d supplemented with or without phytase. Broilers fed a diet formulated to L AAD had high feed conversion. Increasing AAD increased nitrogen excretion by 0.56 and 0.80 g per bird compared with M and L AAD, respectively. Dietary phytase and AAD did not interact to reduce nitrogen excretion. These results indicate that nitrogen excretion could be reduced without affecting feed conversion from 36 to 49 d of age.