Abstract. Leptin is a protein hormone secreted from white adipose tissue. It regulates
food/feed intake, body weight, immune function and reproduction. In our
investigation, the polymerase chain reaction (PCR) amplification coupled
with single-strand conformational polymorphism (SSCP) analysis was used to
reveal variation in bovine leptin gene (LEP) in New Zealand (NZ)
Holstein Friesian × Jersey (HF × J) dairy cows.
Subsequent sequence analysis of a 430 bp amplicon spanning the entirety of
exon 3 and part of the intron 2 region revealed three variant sequences
(A3, B3 and C3) containing a total of five nucleotide substitutions,
all of which have been reported previously. Using general linear
mixed-effect model analyses, the presence of variant A3 (the most common
variant) was associated with a decreased level of C15:1, C18:1 trans-11, C18:1
all trans, C18:2 trans-9, cis-12, C22:0 and C24:0 levels but increased levels of C12:1 and
C13:0 iso (p<0.05). Variant B3 was associated with reduced levels
of C6:0, C8:0, C11:0, C13:0 and C20:0 but increased C17:0 iso and C24:0 levels
(p<0.05). Variant C3 was associated with decreased C17:0 iso
levels but increased C20:0 (p<0.05) levels. In a genotype model, the
A3B3 genotype was associated with increased levels of C22:0 and
C24:0 but decreased C8:0, C10:0, C11:0, C13:0, C15:0 and grouped medium-chain fatty acid (MCFA) levels (p<0.05). Genotype
A3C3 was found to be associated with decreased levels of C10:0,
C11:0, C13:0 and grouped MCFA (p<0.05). This is the first report of
findings of this kind in NZ HF × J cows, and they suggest that
variation in exon 3 of bovine leptin gene could be explored as a means of
decreasing the concentration of saturated fatty acids in milk.