Standardized Ileal Digestible Threonine Requirements and Its Effects on Performance and Gut Morphology of Broiler Chicks Fed Two Levels of Protein

Zaghari, M.; Zaefarian, F.; Shivazad, M.

Standardized Ileal Digestible Threonine Requirements and Its Effects on Performance and Gut Morphology of Broiler Chicks Fed Two Levels of Protein

Authors

M. Zaghari

F. Zaefarian

M. Shivazad

Department of Animal Science, College of Agriculture, University of Tehran, Karaj, Islamic Republic of Iran.

Abstract

The objective of this study was to determine the effects of 8 levels of threonine (0.4, 0.5,
0.6, 0.7, 0.8, 0.9, 1.0 and 1.1%) and 2 levels of protein (17.5 and 20.5%) on growth
performance, gut sizes and morphology as well as to estimate Standardized Ileal
Digestible (SID) Thr requirements in Ross 308 males at 0 to 21 days of age. Chicks were
randomized into 64 battery cages (5 chicks per replicate). FI was lower for broiler given
the high CP diets as compared to those fed on low CP diets. BWG and FCR improved up
to 0.7% Thr in both CP levels. Fitted broken lines indicated break points at 0.62 and
0.66% SID Thr for weight gain at 17.5 and 20.5% crude protein, respectively. Significant
interaction was found between CP and Thr on relative weight and length of duodenum
and jejunum (P< 0.05). Thr supplementation significantly affected villus height, epithelial
thickness, goblet cell number and crypt depth in duodenum, jejunum and ileum (P< 0.01).
Low CP diets adequate in Lys, Total Sulfur Amino Acid (TSAA) supplemented with Thr
may result in optimal BWG and FCR as well as in growth of intestinal length. Such
parameters of gut functionality as microvilli height, crypt depth and epithelial thickness
seemed to be improved with even higher levels of dietary SID Thr levels.

Keywords

Broiler Chicks

Gut Functionality

Standardized Ileal Digestibility (SID)

Threonine