Polymorphisms of Pit-1 gene and its association with growth traits in chicken.

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.