Livestock sector plays a vital role in the economy of Pakistan. Main contribution of milk comes from buffaloes and cattle. Cattle are the major elements of livestock in the country and possess great importance for economy in the form of milk and meat production. Cholistani, Sahiwal and Dajal are the major cattle breeds of Pakistan.
Conventional classification of breeds was based on phenotypic traits. In some cases, recent genetic studies have found differences in the structure proposed. In cattle ,one has to bear in mind that morphological changes were not the result of adaptation to the environment, but have a social significance thus may not be indicative of the genetic relationship. In recent years Y chromosomal genes have proved to be very useful for the determination of genetic relationship among population. Comparative studies have highlighted the advantages of the SRY and ZFY genes of Y chromosome. These genes have been considered as competent and powerful tool for the purpose of breed characterization and species identification of cattle.
Blood samples from true representative animals of each of the three cattle breeds (Cholistani, Sahiwal and Dajal) were collected from different Government livestock farms and their respective home tracts in Punjab. DNA was extracted by inorganic method and amplification of the SRY and ZFY (exon 5) genes of Y chromosome was done with especially designed primers using Primer3 software in Molecular Biology and Genomics Laboratory at Institute of Biochemistry and Biotechnology, University of Veterinary and Animal Sciences, Lahore. Specific primers are designed for these genes amplification. Then primers were optimized for successful amplification with minimum reagent concentration. PCR was 58
performed for amplification of SRY and ZFY (exon 5) genes on each sample. Sequencing was conducted on amplicons to find out the different single nucleotide polymorphism (SNP) to make haplotypes with the help of bioinformatics software like Blast 2sequence and Neighbor Joining phylogenetic tree was constructed by using MEGA version 5. The results obtained from this study now can contribute to the establishment of routine DNA typing service to the advantages of the cattle in livestock industry.