Variants mining of Kappa casein K-CN and Prolactin PRL genes among four indigenous cattle breeds in Nigeria

The study determined the allele and genotype frequencies of genetic variants in two genes associated with milk production traits in four indigenous cattle breeds (N’dama, White Fulani, Muturu and Keteku) in Nigeria. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) technique was used to detect genetic polymorphisms in two milk genes (kappa casein (K-CN) and Prolactin (PRL)). Three genetic variants (AA, AB and BB) of K-CN gene were detected in White Fulani and Muturu cattle breeds among the four breeds considered in this study. While the PRL gene was found monomorphic in all the sampled animals as they were all genotyped as AA homozygous PRL genotype. The detection of genetic polymorphism in White Fulani and Muturu cattle breeds revealed the following allele frequencies of kappa-casein gene A and B estimated as 0.69, 0.31 for White Fulani; 0.56 and 0.44 for Muturu respectively. The detection of both alleles A and B as observed in these animals established a high degree of genetic variability among the four cattle breeds for K-CN locus. The milk genes are polymorphic in their expression and there were genetic diversities in the cattle population understudy.  Also, a higher frequency of A allele in the animal sample population which has been associated with unfavorable milk production and protein yield revealed the need to breed for increased B allele among the Nigerian indigenous cattle through genomic selection.  Overall, the results of this study showed that breeding to improve milk production among indigenous cattle breeds are feasible through genomic selection.