Expression profiles of growth hormone axis genes in lines of native breed chickens

الملخص EN

The aim of this study was to figure out the response of the GH axis to selection criteria in broiler chickens.

Plasma profiles of GH, IGF-I along with gene expression of muscle GH, GHR and IGF-1were examined during pre-hatching and post-hatching period in experimental lines of broiler chickens.

There was increase in plasma GH level and IGF-1 in all stains chickens in 1 month post hatching and gradually decreased in the 2 months after hatching followed by marked decrease in the 3rd months after hatching with significantly increased of GH concentration in Dokki strains than other strains which not noticed in the IGF-1 concentrations, it was noticed that high body weight strains have high plasma IGF-` concentration than low body weight one as shown in Inshas,Salam ,Mandara and Dokki strains respectively.

This pattern of concentration may support the concept that plasma IGF-I does not appear to be GH-dependent.

The result of the present study showed that the GH,GHR and IGF- `expression in muscle showed significant increased at days 16 and 18 pre hatching and decreased in day 20 pre hatching and begin to increase at 1st month post hatching then gradually decrease at the 2nd months after hatching with markedly decrease at the 3rdmonths after hatching .The GH expression in muscle showed no significant difference between different strains, but, the IGF-1 showed increased expression in highly body weight strains than lower one as shown in Inshas, Salam, Mandara and Dokki respectively, which inversely found in GHR expression.

It was markedly noticed that the serum level of GOT was significantly increased and directly proportionally related to the age with significantly decreased level in Mandara strain than those found in the other 3 strains (P≤ 0.05).

There is no significant difference in serum ALP with age in different stains but it was significantly increased in El-salam and Inshas strains than Dokki and Mandara strains.

Implying the importance of other factors besides GH in the regulation of IGF-I in chickens.

This may be a causal mechanism for the different growth curve pattern in highly weight strains than low one.

Assuming that the metabolic basis for these differences is better understood it may be possible to device other procedures for improving meat quality in poultry industry.