IMPROVING OF BROILER CHICKENS USING MODERN GENETICAL TECHNIQUES

Abstract

This study aimed to evaluate insulin-like growth factor I (IGF-I), growth hormone receptor (GHR) gene, cathepsin L2 (CTSL2), forkhead box O (FOXO), muscle ring finger-1 (MuRF1), muscle atrophy-induced ubiquitin ligases (atrogin-1) in breast muscle. However, the expression of phosphatidylinositol 3-kinase Regulatory 1 (PI3KR1) was elevated in liver. The differences in expression between a broiler strain (Cobb 500) and a native Egyptian breed (Fayoumi) fed different methionine levels were studied. Three weeks old chicks were distributed in 3 treatments and control for each strain (control diet, T1 - 0.09% added methionine, T2 - 0.20% added methionine, T3 - 0.30% added methionine).The increase of dietary methionine levels had significant beneficial effects on most traits studied. The highest level of methionine in the diet of Cobb and Fayoumi chicks, until 6 weeks of age, caused important alteration in the mRNA expression of GHR and IGF-I in their breast muscle. However, it was noticeable that birds fed the lowest level of methionine tended to show a higher expression of atrogin-1 in Cobb 500 strain while the higher expression of the same gene, atrogin-1, was found in the intermediate level of methionine in Fayoumi strain. As for the CTSL2 and FOXO genes, they show the highest gene expression levels in the highest level of DL-methionine in both strains. The lower level of methionine resulted in the highest expression of MURF-1 in Cobb 500 strains, while the highest expression of the same gene was observed in the lowest methionine level (control) of the Fayoumi strain. As for PI3KR1gene expression, the lowest level of methionine in Cobb strain showed the highest expression in liver, while the highest level of methionine showed the highest expression of the same gene in Fayoumi strain. Our results indicated that methionine addition