Sequence polymorphism at the growth hormone GH1/GH2-N and GH2-Z gene copies and their relationship with dairy traits in domestic sheep (Ovis aries)

"The purpose was to analyze the growth hormone. GH1/GH2-N and GH2-Z gene copies and to assess. their possible association with milk traits in Sarda sheep.. Two hundred multiparous lactating ewes were monitored.. The two gene copies were amplified separately and each. was used as template for a nested PCR, to investigate. single strand conformation polymorphism (SSCP) of the. 50. UTR, exon-1, exon-5 and 30. UTR DNA regions. SSCP. analysis revealed marked differences in the number of. polymorphic patterns between the two genes. Sequencing. revealed five nucleotide changes at the GH1/GH2-N gene.. Five nucleotide changes occurred at the GH2-Z gene: one. was located in exon-5 (c.556G[A) and resulted in a. putative amino acid substitution G186S. All the nucleotide. changes were copy-specific, except c.*30delT, which was. common to both GH1/GH2-N and GH2-Z. Variability in. the promoter regions of each gene might have consequences. on the expression level, due to the involvement in. potential transcription factor binding sites. Both gene. copies influenced milk yield. A correlation with milk. protein and casein content was also evidenced. These. results may have implications that make them useful for. future breeding strategies in dairy sheep breeding"