Effects of bovine leptin gene variation on milk traits in New Zealand Holstein-Friesian × Jersey-cross dairy cows

Abstract

ABSTRACT Leptin is a protein hormone secreted by white adipose tissue, and variation in leptin gene (LEP) has been described to affect milk production traits in different cattle breeds. The purpose of this study was to investigate whether nucleotide sequence variations identified in exon 3 of LEP were the same as those reported previously, and ascertain whether the variations detected affected milk traits in New Zealand (NZ) Holstein-Friesian × Jersey-cross (HF×J-cross) cows. Polymerase Chain Reaction – Single Strand Conformation Polymorphism (PCR-SSCP) analysis coupled with nucleotide sequencing, enabled 443 HF×J-cross dairy cows to be studied. The PCR-SSCP and nucleotide sequencing revealed three variant sequences (A, B and C), with a total of five single-nucleotide substitutions. There were no associations revealed between LEP genotypes and milk yield and fat percentage. However, cows carrying the AB genotype had a decreased percentage of protein in their milk. This is the first time such findings in NZ HF×J-cross cows have been reported, and they suggest that variation in exon 3 of LEP may be useful for selecting cows for improvement in key milk traits.