Genetic Diversity of Exon 4 of Kappa Casein (k-CSN 3) Gene in Thamankaduwa White Cattle Compared with Jersey Cross and Friesian Breeds
Abstract
White cattle or Thamankaduwa breed is a unique
type of local cattle that has been well adapted
to local environment. Only few studies have
been carried out to characterize White cattle
and thus little information is available on their
genetic diversity, especially considering the
polymorphism of kappa-casein gene (k-CSN3)
that plays an important role in milk chemistry.
The objective of this study was to analyze the
genetic diversity of White cattle by using exon
4 of k-CSN3 and compare the same with Jersey
cross and Friesian animals. Blood samples
from eight White cattle, six Jerseys cross and
seven Friesians were collected. Exon 4 of
k-CSN3 was amplified by PCR mixture with
forward (5’-TTCACTCTGCTTCTGCTGCT-3’)
and reverse (5’-ATTAGCCCATTTCGCCTTCT-3’)
primers. PCR amplicons were sequenced in both
directions, edited and aligned to corresponding
gene sequence of Bos taurus which is available in
GenBank®. Codon code, Phase v2.1 and Arliquin
v3.5.2.2 software programmes were used to
analyze the findings. Genetic analysis indicated
presence of six types of novel haplotypes and six
novel single nucleotide polymorphic sites (SNPs)
in White cattle. Among them all six haplotypes
and one SNP were unique for White cattle. A
significantly high genetic diversity was recorded
in White cattle (0.080±0.07) when compared
with Friesian (0.49±0.15) and Jersey crossbred
(0.68±0.09). In conclusion, White cattle showed
the highest genetic diversity compared with
other two exotic breeds, considering the exon 4 of
k-CSN3. This study gives preliminary evidences
for further studies aimed at further genetic
improvements of indigenous cattle in Sri Lanka.