Genetic polymorphism of promoter region of lactoferrin gene and its association with mastitis resistance in Jersey crossbred cattle

Lactoferrin, a protein found in variety of body secretions, acts as a defense factor in the mammary gland. Total of 50 samples of blood and milk of Jersey crossbred cattle were collected from the Government Dairy Cattle farm, Belicharana. Genomic DNA was isolated and specific primer was used for the amplification of the promoter region of lactoferrin gene. The PCR product comprised of 115 bp. The PCR product was digested with Taq I restriction enzyme. The amplicon has no restriction site and all the 50 animals revealed only one type of genotype (HH) with respect to Taq I / PCR-RFLP. The same PCR products were subjected to SSCP. Amplicons were initially denatured with denaturing agents and then run on native PAGE which was later silver stained. All the 50 samples revealed one type of banding pattern viz., two bands. Single genotype was present in all animals. Hence promoter region of Lactoferrin gene is monomorphic in crossbred cattle under the present study. Somatic cell count was done by staining milk samples with Newmans stain. A total of 19 milk samples had somatic cell count of less than 1,00000 cells/ml with no history of mastitis were considered as resistant, while other 20 samples having somatic cell count more than 5,00000 cells/ml with mastitis were considered as susceptible. Though variation in response to mastitis resistance was detected, no association was established. The reason being that promoter region of lactoferrin gene was monomorphic with respect to Taq I / PCR-RFLP and PCR-SSCP.