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Animal Molecular Breeding 2014, Vol. 4, No. 1, 1-5
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3
DGAT1
genes have been associated with marbling
or intramuscular fat in pigs (Li et al. 2010) and
cattle (Cho et al. 2008). Some variations in these
genes are associated with milk fat content in sheep
(Calvo et al. 2004; Scata et al. 2009). Xu et al.
(2009) have reported association of an SNP in exon
17 with marbling score in Chinese sheep. The
non-synonymous SNP identified in exon 1 of
DGAT1
gene (g.355G > T), in this study, may influence the
gene expression. However, this needs to be
substantiated by further studies.
The average expected heterozygosity at these loci was
0.328. The results of this study suggest that sufficient
level of heterozygosity exists in these sheep breeds at
the investigated gene loci. The gene diversity
observed at these loci was slightly less as compared to
that reported previously for wool keratin intermediate
filament (0.420, Arora et al. 2008) and
β -
lactoglobulin (0.422, Arora et al. 2010) gene loci in
Indian sheep.
Identification of SNPs associated with mutton traits
may not only help in improvement of the production
but also provide economic gains to the rearers. Two
SNPs in the
GDF8
gene known to be associated with
mutton quality and carcass traits in Texel (Kijas et al.
2007) and New Zealand Romney sheep (Hickford et al.
2010) have also been identified in Indian sheep (Arora
et al. 2013). Although the sample size is small the
information generated provides preliminary indication
of functional diversity present in Indian sheep.
The diversity available in Indian sheep breeds at
candidate genes for mutton quality, revealed from this
study, presents the opportunity to exploit the use of
either allele/genotype, once the association is
validated in the Indian sheep population. In order to
substantiate these observations future studies will
need to establish the effect of reported SNPs in the
Indian sheep populations.
3 Material and methods
3.1 Samples
A panel of eleven Indian sheep breeds/populations
representing wide phenotypic and geographic
diversity was used for identification of SNPs. Ten
unrelated genomic DNA samples from each sheep
population namely Bandur (also known as Mandya
and Bannur), Chokla, Deccani, Ganjam, Garole,
Madgyal, Magra, Malpura, Muzaffarnagri, Nali and
Nellore were included in the panel. These breeds are
distributed in three agroecological zones and are
phenotypically diverse. The utility, distribution,
6-month body weight and dressing percentage of the
breeds/populations are presented in Table 1. Chokla,
Magra, Nali, Malpura and Muzzafarnagri belong to
North-western arid and semi arid region. Deccani,
Madgyal, Nellore and Bandur are from the Southern
Peninsular region and Ganjam and Garole are from the
Eastern region of the country. As per utility patterns these
breeds have been classified as carpet wool (Chokla,
Magra, Nali), mutton carpet-wool (Ganjam, Malpura and
Muzaffarnagri) and mutton (Bandur, Deccani, Garole,
Madgyal, Nellore) breeds (Acharya et al. 1982) (Table 3).
Table 3 Distribution zone, utility, 6-month body weight and dressing percentage of breeds/populations investigated
Utility
Breed
Distribution
6-month
Weight (kg)
Dressing
(%)
Ref.
Region
State
Meat
Bandur/Mandya SP
Karnataka
17.28
54.5
Singh et al. 2005
Deccani
SP
Maharashtra, Andhra Pradesh,
Karnataka
19.26
52.65
Singh et al. 2005
Garole
E
West Bengal
8.97
55.87
Singh et al. 2005
Banerjee et al. 2010
Madgyal
SP
Maharashtra
25-30
NA
Anonymous
Nellore
SP
Andhra Pradesh
17.81
58.22
Singh et al. 2005
Carpet Wool
Chokla
NWASA Rajasthan
13.46
NA
Acharya 1982
Magra
NWASA Rajasthan
20.14
44.75
Acharya 1982
Nali
NWASA Rajasthan
13.30
48.25
Acharya 1982
Meat, CarpetWool Ganjam
E
Orissa
12.92
NA
Pattanayak et al. 2003
Malpura
NWASA Rajasthan
24.58
59.13
Singh et al. 2005
Muzaffarnagri NWASA Uttar Pradesh, Uttarakhand
21.17
57.26
Singh et al. 2005
Note: SP-Southern Peninsular; NWASA-Northwestern Arid and Semi Arid; E-Eastern; NA-Not Available