Abstract: Background: The exploration of milk production traits and prolactin gene polymorphisms in Sahiwal cattle has illuminated the genetic basis for their exceptional milk production process. These findings contribute to tailored breeding approaches aimed at augmenting milk yield, fat and protein content and reproductive efficiency of Sahiwal cattle. Amid evolving agricultural landscapes, this research plays a pivotal role in sustainable livestock production, boostering food security, and supporting rural economies, particularly in challenging climate regions. The selection of genetically superior animals at an early stage of life, the molecular markers are used along with traditional selection. The study was carried out to identify the genetic polymorphism in the exon3 region of the Prolactin and enumerate its effect on milk production performance in Sahiwal cattle.
Methods: The study was conducted on various production traits and association of prolactin gene with the various traits under study on the herd of Sahiwal cattle maintained at the Sahiwal cattle farm, Livestock Farm Complex, College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati-22. Information from a total of 65 lactation records were utilized for the present study for Milk Production traits mainly Average daily milk yield, Lactation milk yield, Peak yield, Number of days to attain peak yield, Persistency of milk yield. A total of 382 milk samples were utilized to study the milk constituent traits. Milk samples were analysed using “Milk Quality Analyser Laktan 1-4” which includes Fat %, SNF (Solid Not Fat) %, Protein % and Density (kg/m3). Genomic DNA were extracted from the collected whole blood samples by using Nucleo-pore (Genetix Brand, India)Genomic DNA Purification Kit #DNASure®Blood Mini Kit (NP-61105) 50 preps.
Results: The least-squares means with standard errors for milk production traits viz; average daily milk yield, lactation milk yield, peak yield, number of days to attain peak yield and persistency of milk yield were found to be 5.93±0.08 kg, 1609.36±31.21 kg, 13.20±0.16 kg, 47.39±0.88 days and 92.88±0.43 days, whereas, the Least Square means with standard errors for milk constituent traits viz; fat%, SNF%, Protein%, Density were found to be 4.34±0.04%, 8.41±0.03%, 3.34±0.07% and 29.28±0.12, respectively. PCR-RFLP was carried out using RsaI restriction endonuclease and revealed three genotypes AA, AB and BB, were 0.5, 0.312 and 0.188, the frequency of A and B allele of prolactin gene (exon 3) were 0.752 and 0.248, respectively. The result shows that cows with AA genotypes yielded most milk as compared to cows with genotype AB and BB.
