Comparison and Estimation of Digestible Threonine Requirements of Broiler Chickens of Ross 308 and Cobb 500

Document Type : Scientific - Research Articles

Authors

• Mehran Mehri ¹
• Hasan Nasirimoghadam ²
• Hasan Kermanshahi ²
• Mohsen Danesh Mesgaran ²

¹ Department of Animal Science, Faculty of Agriculture, University of Zabol, Zabol, Iran

² Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad,Mashhad, Iran

10.22067/ijasr.v4i1.13919

Abstract

Two experiments were conducted to determine threonine (Thr) requirements of two commercial strains, Ross
308 and Cobb 500, based on standardized ileal digestibility from 15 to 28d of age. Basal diet consisted of wheat,
triticale, and corn gluten meal was formulated according to Quick Chick (2006) to be adequate in all nutrients
except for Thr. Incremental levels of supplemental Thr were added to the basal diet generating six experimental
treatments in a range from 0.46 to 0.81% digestible Thr. Birds were randomized across 48 floor pens (4
replicates and 12 birds in each replicate) in a completely randomized design and each pen was fed one of the six
amino acid levels from 15 to 28d of age. Body weight gain, feed intake, feed conversion ratio, and digestible Thr
intake were measured during the experimental period. Performance traits responded quadratically to graded
levels of digestible Thr, and interaction effects between Thr and strain were significant for all performance traits
except for body weight gain. Strain did not affect the feed conversion ratio and feed efficiency was the same in
two strains. Digestible Thr requirements were estimated using broken-line linear and broken-line quadratic
models. In Ross 308, digestible Thr requirements for body weight gain and feed conversion ratio were estimated
at 0.69 and 0.76% of diet, respectively, by broken-line linear model. Digestible Thr need for body weight gain
was optimized at 0.79% of diet using broken-line quadratic model. In Cobb 500, Thr requirements for body
weight gain and feed conversion ratio were estimated at 0.69 and 0.71% of diet, respectively, by broken-line
linear model. Digestible Thr need for body weight gain and feed conversion ratio were optimized at 0.79 and
0.81% of diet using broken-line quadratic model. Regarding response criterion and statistical model to estimate
the requirements, no differences were observed in Thr requirements of two strains during the grower period.

Keywords

• Digestible threonine
• Strain
• Requirement
• Broken-line model

---