1961 - Modeling of Threonine Requirement in Fast-Growing Chickens Depending on Age Sex Protein Deposition and Dietary Threonine Efciency Samadi and

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Modeling of Threonine Requirement in Fast-Growing Chickens, Depending on Age, Sex, Protein Deposition, and Dietary Threonine Ef±ciency Samadi and F. Liebert 1 Institute for Animal Physiology and Animal Nutrition, Georg-August-University, D-37077 Goettingen, Germany ABSTRACT In addition to dose-response studies, mod- eling of N utilization, depending on intake of the ±rst limiting amino acid in the diet, is one of the tools for assessing amino acid requirements in growing animals. Based on a veri±ed nonlinear N-utilization model and following the principles of the diet dilution technique, N- balance experiments were conducted to estimate the Thr requirement of fast-growing chickens (genotype Cobb), depending on age, sex, CP deposition. and ef±ciency of dietary Thr utilization. Different predictions were made for the feed intake to conclude the optimal Thr concentra- tion in the feed. The results are based on N-balance experi- ments with a total of 144 male and 144 female growing chickens within 4 age periods (I: 10 to 25 d; II: 30 to 45 d; III: 50 to 65 d; IV: 70 to 85 d), using diets with graded protein supply (6.6, 13, 19.6, 25.1, 31.8, and 37.6% CP in Key words : threonine, ef±ciency of utilization, requirement, modeling, broiler 2006 Poultry Science 85:1961–1968 INTRODUCTION Inadequate formulation of dietary amino acids impairs protein utilization and increases total N excretion. It has been well documented that several factors such as geno- type, age, and sex in²uence the requirement in growing chickens (Hurwitz et al., 1980; Moran and Bilgili, 1990; Zuprizal et al., 1992; Webel et al., 1996). Threonine may be considered as the third limiting amino acid ( LAA ) in chicken diets based on corn, wheat, and soybean meal, following Met and Lys (Han et al., 1992; Fernandez et al., 1994). Kidd (2000) reported that Thr de±- ciency resulted in decreasing utilization of TSAA and Lys. Several studies about Thr requirements in growing chick- ens have been published with varying results, depending on diet composition, age, sex, and breed. In early studies, Krautmann et al. (1958) proposed 0.55 and 0.60% of the diet, or 2.6 and 2.9% of dietary CP, as the optimal Thr concentration using diets with 21% CP. Hewitt and Lewis (1972) proposed 0.48% Thr in diets with 16.2% CP, corres- 2006 Poultry Science Association Inc. Received March 30, 2006. Accepted July 4, 2006. 1 Corresponding author: ²[email protected] 1961 DM) from high-protein soybean meal with a constant amino acid ratio and Thr as the ±rst limiting amino acid (3.87 g of Thr/100 g of CP; dietary Lys:Thr = 1:0.54). The observed optimal Thr concentration (% of feed) was in²uenced by age, sex, level of CP deposition, dietary ef±ciency of Thr utilization, and predicted feed intake. For male chickens, assuming an average CP deposition (60% of the potential) and average ef±ciency of Thr utili- zation, 0.78% (10 to 25 d), 0.73% (30 to 45 d), 0.65% (50 to 65 d), and 0.55% (70 to 85 d) total dietary Thr were observed as optimal total Thr concentration in the diet (corresponding to 60, 135, 160, and 180 g of daily feed intake, respectively). Data are discussed in context with the main factors of in²uence like age, sex, level of daily
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/28/2011 for the course VET 4335 taught by Professor Sakomura during the Spring '11 term at University of South Pacific.

Page1 / 8

1961 - Modeling of Threonine Requirement in Fast-Growing Chickens Depending on Age Sex Protein Deposition and Dietary Threonine Efciency Samadi and

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online