POLYMORPHISM OF CANDIDATE GENES CONTROLLING TEMPERAMENT TRAITS AND THEIR ASSOCIATION ON REPRODUCTION TRAITS IN VECHUR CATTLE
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Date
2018-09-30
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Kerala Veterinary and Animal Sciences Mannuthy, Thrissur
Abstract
Temperament in cattle plays an important role in animal safety, production and
reproduction performance. Bos indicus species are known for their aggressive behaviour than
Bos taurus. The present study was conducted to identify the polymorphism of candidate
genes controlling temperament traits and their effects on reproductive performance of Vechur
cattle. The study comprised of 68 Vechur cattle that were divided into four temperament
groups based on their subjective temperament score, social separation test, docile test and
handler’s/milker’s score test. Available reproductive performance data of animals were
collected from Vechur cattle conservation project to study the following traits - age at first
service, age at first calving, service period, conception rate and number of services per
conception. Six candidate genes - Tyrosinase (TYR), Dopamine receptor D4 (DRD4),
Monoamine Oxidase A (MAO A), Cannabinoid receptor 1 (CNR1), Regulator of G-protein
signaling 2 (RGS2) and Plexin A2 (PLXA2) - for temperament were selected. Three selected
SNPs from each gene were screened using PCR-RFLP/ PCR-SSCP and further confirmed by
sequencing. Out of these 18 SNPs, 9 were present in the Vechur herd. The genes MAOA,
TYR, CNR1 and PLXA2 contain two, two, three and two SNPs, respectively. Except TYR
6416322 SNP remaining eight SNPs, coat colour (p=0.003) and sex (p=0.001) were
significantly associated with handler’s/milker’s temperament score of handler three (H3).
MAOA 105380513 SNP C to T transition was fixed in Vechur population. The average
service period of four temperament classes (docile, restless, nervous and aggressive) were
251.02 ± 24.04, 168.57 ± 19.28, 230.59 ± 21.75 and 243.05 ± 32.26 days, respectively.
Second restless group had significantly (p=0.039) lower average service period in
comparison to all other groups. However, age at first service, age at first calving, conception
rate and number of services per conception were not significantly associated with
temperament score in the present study. There were significant correlations among different
reproductive traits. Results of this study revealed that the selected genes were having
significant effect on temperament and reproduction traits, which may be confirmed by further
research using larger population and more accurate temperament score. This would enable us
to incorporate temperament as an important trait in the selection programmes for genetic
improvement of Vechur cattle.
Description
Submitted in partial fulfillment of the requirement for the degree of
Master of Veterinary Science of Animal Genetics and Breeding