KAP GENE POLYMORPHISM AND ITS ASSOCIATION WITH WOOL TRAITS IN RAMBOUILLET SHEEP

The major proteins that make up the wool fibre are the keratin-associated protein (KAPs) and keratin intermediate-filament proteins (KRTs); KRTs form the skeletal structure of the wool fibre (microfibrils) and are embedded in a matrix of KAPs. KAPs play important role in the stability and the mechanical properties of wool. Present study was conducted on KAP genes polymorphism and its association with wool traits in Rambouillet sheep. Molecular studies comprised of 100 blood samples of Rambouillet sheep maintained at Sheep Breeding and Research Farm, Reasi, Jammu, along with their wool records. Genomic DNA was extracted from the venous blood by HiPurATM SPP blood DNA Kit (Himedia). The amplified PCR product obtained for KAP 1.3 3.2, 7 and 8 genes were 598 bp, 393 bp, 388 bp and 194 bp size respectively. The 598 bp PCR product of KAP 1.3 gene was digested with restriction enzyme Bsr I at 37°C for 6 hrs revealed three types of genotypes AA (350 bp, 225 bp and 23 bp), AB (350 bp, 307 bp, 225 bp, 43 bp and 23 bp and BB (307 bp 225 bp, 43 bp and 23 bp) by the PCR-RFLP. For exploring the genetic polymorphism at KAP 3.2, 7 and 8 genes; amplified PCR products were subjected to polyacrylamide gel at 10%, 10% and 12% respectively for electrophoresis. SSCP variants were found AA, AB and BB for all the genes under study. The genotypic frequency in Rambouillet sheep for KAP 1.3, 3.2, 7 and 8 genes were found to be 0.41, 0.0. 46, 0.34 and 0.14 for AA genotype; 0.47, 0.40, 0.27 and 0.44 for AB genotype and 0.12, 0.14, 0.39 and 0.42 for BB genotype whereas, the gene frequencies were found to be 0.65, 0.66, 0.48 and 0.36 for A alleles and 0.36, 0.34, 0.53 and 0.64 for B allele. Superior FD was recorded for AA genotype (21.74±0.20 u) followed by BB genotype (21.98±0.13 u) and higher by AB genotypes (22.29±0.12 u). High GFW was recorded for AB genotype (2.12±0.07 kg) followed by AA genotype (1.97±0.13 kg) and least by BB genotypes (1.55±0.09 kg) in Rambouillet sheep. Further, the investigation was carried out to evaluate the performance of Rambouillet sheep for wool traits and its relationship with non-genetic factors like sex and period along with phenotypic correlation of wool traits. The data was obtained from the records of 6162 Rambouillet sheep maintained at Government Sheep Breeding and Research Farm, Reasi, Jammu, India. The data of wool traits i.e., GFW, SL and FD was included in the present study over a period from 1998 to 2012. The overall mean for GFW, SL and FD were found to be 1.40±0.01 kg, 5.39±0.02 cm and 21.49±0.01u respectively. The overall least square analysis of variance showed highly significant (P<0.01) effect of year on GFW, SL and FD. The effect of sex on SL was found to be highly significant (P<0.01) and nonsignificant effect were obtained for GFW and FD in Rambouillet sheep. The phenotypic correlation were found to be highly significant (P<0.01) among the wool traits. A positive phenotypic correlation of GFW was found with SL as (0.140) and low negative phenotypic correlation was found with FD (-0.068). SL was found to have low negative phenotypic correlation with FD (-0.075). It was concluded that in the present study BB and AB genotype of KAP 1.3 and KAP 3.2 gene respectively could be regarded as marker for GFW; AA and BB genotype of KAP 7 gene for SL and GFW respectively; AA and AB genotype of KAP 8 gene for superior FD and GFW respectively also could be regarded as marker for early breeding selection of the Rambouillet sheep. The values of analysis of wool parameters also suggested that there was an improvement in wool traits in the Rambouillet sheep due to selection programme being applied in the farm.