Magotra, AnkitDeepak2024-02-222024-02-222023-06https://krishikosh.egranth.ac.in/handle/1/5810207021The present study aimed to investigate the association of polymorphisms in the β-LG and κ- CN genes with milk and udder conformation traits in Harnali and Munjal sheep breeds. A total of 105 Harnali and 34 Munjal sheep were included in the study, and blood samples were collected for DNA isolation and genetic profiling.For the β-LG gene, genotype frequencies in Harnali were 54% (AA), 34% (AB), and 12% (BB), with corresponding allele frequencies of 71% (A) and 29% (B). In Munjal, genotype frequencies were 35% (AA), 24% (AB), and 41% (BB), with allele frequencies of 47% (A) and 53% (B). Combined analysis of both breeds showed genotype frequencies of 51% (AA), 32% (AB), and 16% (BB), with allele frequencies of 67% (A allele) and 33% (B allele).For the κ-CN gene, genotype frequencies in Harnali were 74% (AA), 5% (AB), and 20% (BB), with allele frequencies of 0.77 (A) and 0.23 (B). In Munjal, targeted loci revealed a monomorphic banding pattern, indicating limited genetic variability.The study found that the AA genotype of the β-LG gene was associated with a decline in milk yields over the four-month period, while the AB genotype showed consistent milk yields, and the BB genotype exhibited an increasing trend. The AA genotype had the lowest milk yields, while the AB genotype had the highest total milk yield (p < 0.05). The AA genotype also showed a gradual increase in fat percentage over the four-month period, while the AB and BB genotypes had relatively consistent fat percentages. Protein percentages showed an increasing trend in the AA genotype, while the AB and BB genotypes had similar protein percentages (p < 0.05). The SNF content varied among genotypes, with the AA genotype showing fluctuations. Density values and lactose percentages showed slight variations among genotypes (p < 0.05).Regarding udder conformation traits, the genotype of the β-LG gene had a significant effect, but the significance varied across different months. The κ-CN gene genotype showed a significant influence on both monthly milk yield and total milk yield, as well as a significant association with fat percentage for the AA and BB genotypes. The AA genotype exhibited increasing fat percentages over the four-month period, while the BB genotype had higher fat percentages overall. The genotypes of the κ-CN gene were significantly associated with udder circumference (UC), udder width (UW), and teat length left (TLL), with variations observed across different months (p < 0.05). Age at lambing and weight at lambing showed significant associations with milk traits (p < 0.05) and litter weight (p < 0.01). Breed also had significant impacts on certain traits, such as first-month protein percentage, udder width and udder height (p < 0.05).The study employed different prediction methods, including Artificial Neural Network (ANN), Bayesian (BT), and Multiple Regression (MR), to assess the accuracy of predicting milk yield. The ANN method exhibited the highest correlation coefficient (r value) of 0.84, indicating the strongest predictive accuracy for milk yield. The BT method achieved a correlation coefficient of 0.77, while the MR method had a correlation coefficient of 0.64. Overall, these findings enhance our understanding of the genetic factors influencing milk composition traits in Harnali and Munjal sheep. The study highlights the potential implications for selective breeding and management practices in the sheep industry, aiming to improve milk yield and composition through genetic selection. Student Major Advisor HeadEnglishThesis