GENETIC VARIABILITY OF TOLL LIKE RECEPTOR 4 AND BETA DEFENSIN 4 GENES AND ITS ASSOCIATION WITH SOMATIC CELL SCORE IN CROSSBRED CATTLE OF KERALA

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2021-10-21, 2021-10-21
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR
Abstract
The main objectives of present study were to identify the single nucleotide variations in exon 3 of TLR4 and exon 1 and 2 of DEFB4 associated with somatic cell score (SCS) and 305 Days Milk Yield (305DMY) and to estimate breeding value in crossbred cattle of Kerala. To assess the genetic variability, PCR-SSCP analysis was done. Blood samples of 200 lactating crossbred cattle were collected from different farms of Kerala Veterinary and Animal Sciences University and field centres of ICAR- FPT scheme, KVASU. Representative samples of each SSCP patterns were sequenced to ascertain the genotypes. The 231 bp fragment of TLR4 (exon 3) was found to polymorphic and two genotypes viz. CC and CD were obtained with frequency 77% and 23% respectively. The frequency of C and D allele in crossbred were found to be 0.88 and 0.12. On sequencing, it revealed that C to T transition had led to one non-synonymous change at 2021th position of ORF. Cattle with CC genotype were more related (p≤0.05) to lower SCS and higher 305 DMY compared to CD genotypes. Monomorphic band patterns were obtained for 192 bp fragment of exon 1 of DEFB4. The 229 bp fragment of exon 2 of DEFB4 was found to be polymorphic and three genotypes viz. PP, QQ and PR were obtained with frequency 54%, 34% and 12%, respectively. The frequency of P, Q and R alleles were found to be 0.60, 0.34 and 0.06, respectively. On sequencing, four non-synonymous SNP (c.121T>A, c.131G>C, c.134T>G and c.188G>C) and one stop-lost SNP (c.191A>G) was obtained. Cattle with PP and QQ genotype were more related (p≤0.05) to lower SCS compared to PR genotypes. Exon 2 of DEFB4 was not significantly associated with 305 DMY. Overall least square mean of SCS and 305 DMY were 4.85 and 2409.35 kg, respectively. The heritability estimates for SCS and 305 DMY were 0.003±0.340 and 0.359±0.076.The average breeding value of 200 crossbred cattle sired by 78 bulls for SCS was 4.16 and for 305DMY was 2743.60 kg. TLR4 and DEFB4 can be used as potential candidate genes for mastitis resistance and SCS would be included in the selection criteria of crossbred cattle of Kerala.
The main objectives of present study were to identify the single nucleotide variations in exon 3 of TLR4 and exon 1 and 2 of DEFB4 associated with somatic cell score (SCS) and 305 Days Milk Yield (305DMY) and to estimate breeding value in crossbred cattle of Kerala. To assess the genetic variability, PCR-SSCP analysis was done. Blood samples of 200 lactating crossbred cattle were collected from different farms of Kerala Veterinary and Animal Sciences University and field centres of ICAR- FPT scheme, KVASU. Representative samples of each SSCP patterns were sequenced to ascertain the genotypes. The 231 bp fragment of TLR4 (exon 3) was found to polymorphic and two genotypes viz. CC and CD were obtained with frequency 77% and 23% respectively. The frequency of C and D allele in crossbred were found to be 0.88 and 0.12. On sequencing, it revealed that C to T transition had led to one non-synonymous change at 2021th position of ORF. Cattle with CC genotype were more related (p≤0.05) to lower SCS and higher 305 DMY compared to CD genotypes. Monomorphic band patterns were obtained for 192 bp fragment of exon 1 of DEFB4. The 229 bp fragment of exon 2 of DEFB4 was found to be polymorphic and three genotypes viz. PP, QQ and PR were obtained with frequency 54%, 34% and 12%, respectively. The frequency of P, Q and R alleles were found to be 0.60, 0.34 and 0.06, respectively. On sequencing, four non-synonymous SNP (c.121T>A, c.131G>C, c.134T>G and c.188G>C) and one stop-lost SNP (c.191A>G) was obtained. Cattle with PP and QQ genotype were more related (p≤0.05) to lower SCS compared to PR genotypes. Exon 2 of DEFB4 was not significantly associated with 305 DMY. Overall least square mean of SCS and 305 DMY were 4.85 and 2409.35 kg, respectively. The heritability estimates for SCS and 305 DMY were 0.003±0.340 and 0.359±0.076.The average breeding value of 200 crossbred cattle sired by 78 bulls for SCS was 4.16 and for 305DMY was 2743.60 kg. TLR4 and DEFB4 can be used as potential candidate genes for mastitis resistance and SCS would be included in the selection criteria of crossbred cattle of Kerala.
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Thesis Submitted in the partial fulfillment of the requirement for the degree of Master of Veterinary Science in Animal Genetics and Breeding
Thesis Submitted in the partial fulfillment of the requirement for the degree of Master of Veterinary Science in Animal Genetics and Breeding
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