Genetic polymorphism of the osteopontin gene and milk composition traits in Red Kandhari cattle

Abstract

Osteopontin (OPN) is an important multifunctional glycoprotein involved in milk production, bone metabolism, and immune regulation in cattle, making it a potential candidate gene for production trait studies. The present investigation aimed to detect polymorphism in the intron-4 region of the bovine OPN gene and to evaluate its association with milk composition traits in Red Kandhari cattle. A total of 30 lactating Red Kandhari cows were genotyped using the BsrI/PCR-RFLP technique. A 290 bp fragment of the OPN intron-4 region was amplified through touchdown PCR using annealing temperatures ranging from 63 °C to 53 °C, followed by restriction digestion with BsrI enzyme. PCR-RFLP analysis revealed two genotypes, TT (290 bp) and CT (290, 200, and 90 bp), while the CC genotype was absent in the studied population. The observed frequencies of TT and CT genotypes were 0.97 and 0.03, respectively, with corresponding allele frequencies of 0.983 for T and 0.017 for C, indicating predominance of the T allele. Cows carrying the TT genotype exhibited mean fat, SNF, protein, and lactose contents of 4.27 ± 0.05, 8.43 ± 0.04, 3.38 ± 0.03, and 4.40 ± 0.03 per cent, respectively. The single CT genotype cow showed slightly higher values for these traits. Due to limited genotype variability, statistical association between OPN intron-4 polymorphism and milk composition traits could not be established. The study confirms polymorphism at the OPN intron-4 locus in Red Kandhari cattle and highlights the need for large-scale molecular screening to elucidate the functional role of OPN in indigenous cattle.