PCR-RFLP Analysis of Insulin-Like Growth Factor 2 Gene Polymorphisms in Two Commercial Broiler Chicken Strains (Cobb 500 and Hubbard F-15) and Their Associations with Performance Traits.

The present research aimed to study the polymorphisms of the chicken insulin-like growth factor 2 (IGF2) in two commercial broiler breeds (Cobb 500 and Hubbard F-15). In total, 300 avian blood samples were obtained. The genomic DNA was isolated using a fast salt-extraction technique. Moreover, polymerase chain reaction (PCR) was used to amplify 1146 bp fragments of the gene. The amplified fragments were subjected to restriction enzyme digestion using the HinfI endonuclease enzyme, and the digested products were separated on a 2% agarose gel. The findings indicated that there were two alleles T and C for the target locus, with frequencies of 73.3% and 26.7%, respectively. Three distinct genotype variations, TT, TC, and CC, were found, with genotype frequencies of 59.1%, 28.4%, and 12.5%, respectively. A test based on actual and anticipated frequencies of various genotypic variances of the IGF2 gene revealed that the divergence from Hardy-Weinberg equilibrium was not significant (P≤0.01) in commercial broiler breeds (Cobb 500 and Hubbard F-15) chickens. In addition, it was found that birds with genotype TC had a greater body mass at 8 weeks of age, compared to those with genotypes TT and CC. It was determined that the IGF2 gene exhibited a significant degree of variability and might be regarded as a possible genetic marker in selection and breeding programs for poultry.

Plasma alkaline phosphatase and production traits in laying hens as influenced by dietary protein, strain and age.

1. Plasma alkaline phosphatase (ALP) activity was determined in 4 laying strains (White Leghorn, New Hampshire, Native Brown and Native Barred) at 48 and 54 weeks of age. Birds were fed 1 of 2 isoenergetic diets with calculated crude protein contents of 152 and 181 g/kg. 2. No significant differences in plasma ALP activity were noted between the strains, although significant differences in laying performance between strains were evident. 3. There was no response in plasma ALP activity to the high dietary protein level in any strain. Depressed plasma ALP activity was associated with increasing age of birds. 4. The results failed to confirm the suggestion that ALP activity is related to egg production of the laying hen.