The Pit-1 gene is involved in regulation of muscle growth through controlling the expression of growth hormone, prolactin, and transforming growth factor-β genes in chicken. The objectives of the study were to explore polymorphisms of the Pit-1 gene and to estimate the effect of these polymorphisms on growth traits in PB-1 and control (broiler strain) and IWI (layer strain) chickens. Single-stranded conformation polymorphism followed by sequencing was performed to reveal polymorphisms of the gene. In total, 10 haplotypes were found across the lines. The mRNA expression of Pit-1 varied among haplogroups and had a significant effect on BW and growth rates. The haplogroups showed a significant effect on BW in wk 7 in PB-1 chickens. In control chickens there was a significant effect at d 1 and in wk 2 and 7, and in IWI strains, there was a significant effect at d 1 and wk 6 and 7. The significant association of haplogroups and growth rate was found between 0 and 2 wk in control and between 0 and 2 and 6 and 7 wk in IWI strains. It was concluded that the Pit-1 gene is polymorphic and has a significant effect on growth traits in chickens.

A study was designed to explore genetic variability of partial promoter and exon 1 of pit-1 gene and its effect on immune competence traits in White Leghorn chicken. Single stranded conformation polymorphism technique followed by sequencing was employed to detect polymorphism of the gene. Three genotypes (AA, AB and BB) were observed in White Leghorn chicken where two alleles (A and B) were found. AB genotype and A allele were predominant in the population. Different demographic parameters estimated in the White Leghorn chicken lines indicated the presence of genetic divergence among the lines. The pit-1 mRNA expression varied among the genotypes where genotype BB expressed higher than genotype AA and AB. The genotypes as well as alleles showed significant effect (P B 0.05) on sheep RBC titre in White Leghorn chicken.

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