DNA polymorphism of DRB 3.2 locus and its association with serum lysozyme in Rathi cattle (Bos indicus)

Genetic polymorphism study of DRB 3.2 alleles was conducted in Rathi cattle to find out its association with serum lysozyme using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The digestion of 284 bp fragment with HaeIII resolved three restriction sites, resulting into three restriction patterns with major fragment of sizes as 135, 104, 45; 142 and 142, 180 and 104 bp with frequencies of 0.79, 0.15 and 0.07, respectively. The genotype HaeIII-aa had the highest frequency (0.57) followed by HaeIII-ab (0.29) and HaeIII-ac (0.14). Serum lysozyme level ranged from 0.33 to 6.62 mu g/ml with young and adult age groups showing higher levels. Mean serum lysozyme levels in the animals belonged to the HaeIII-aa, HaeIII-ab and HaeIII-ac genotypes were 3.21, 3.92 and 4.91 mu g/ml, respectively. The mean serum lysozyme level was also found comparatively higher in the animals belonging to heterozygote genotypes (HaeIII-ab and HaeIII-ac) as compared to the homozygote genotype (HaeIII-aa).