Estimation of ideal ratios of methionine and threonine to lysine in starting broiler chicks using response surface methodology

In a dose-response study, dietary levels of standardized ileal digestible methionine (dMet), lysine (dLys), and threonine (dThr) were optimized by response surface methodology (RSM) using a central composite rotatable design in starting broiler chicks that were feed-deprived 2 d posthatch. In total,...

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Bibliographic Details
Published in:Poultry science 2012-03, Vol.91 (3), p.771-777
Main Authors: Mehri, M, Davarpanah, A. A, Mirzaei, H. R
Format: Article
Language:English
Subjects:
Animals
Body Weight - physiology
broiler chickens
Chickens - growth & development
Chickens - metabolism
diet
feed conversion
ileum
lysine
Lysine - metabolism
Male
methionine
Methionine - metabolism
Regression Analysis
response surface methodology
threonine
Threonine - metabolism
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Summary:In a dose-response study, dietary levels of standardized ileal digestible methionine (dMet), lysine (dLys), and threonine (dThr) were optimized by response surface methodology (RSM) using a central composite rotatable design in starting broiler chicks that were feed-deprived 2 d posthatch. In total, 60 floor pens of 6 birds each were assigned to 15 diets of central composite rotatable design containing 5 levels of dMet (0.42–0.58%), dLys (0.88–1.32%), and dThr (0.53–0.87%) from 3 to 16 d of age. Experimental levels of dMet, dLys, and dThr significantly affected bird performance. The second-order models for BW gain and feed conversion ratio (FCR) were generated. The response surface analysis showed significant quadratic models for BW gain and FCR. The crossproduct of amino acids was significant for FCR but not significant for BW gain. Canonical analyses on BW gain and FCR models showed that the maximum BW gain at the stationary point may be obtained with 0.54, 1.12, and 0.78% of dMet, dLys, and dThr in the diet, respectively, and the minimum FCR at the stationary point may be obtained with 0.53, 1.13, and 0.75% of dMet, dLys, and dThr in diet, respectively. Estimated ideal ratios of dMet and dThr to dLys were 48 and 70% for BW gain and 47 and 66% for FCR. Canonical analysis revealed the most important amino acids in the models of BW gain and FCR were Lys and Thr, respectively.
ISSN:0032-5791
1525-3171
DOI:10.3382/ps.2011-01818