Variation in genetic diversity evaluated under different breeding schemes in Sahiwal herd

The present study conducted on an organised herd of Sahiwal cattle to elucidate the population structure parameter based on seven decades of genealogical information. The genealogical data (N = 4164) spanning 1949 to 2023 maintained at ICAR-National Dairy Research Institute, Karnal, India was considered with the aim to evaluate depth and accuracy of pedigree, population parameter and genetic diversity in different breeding schemes for whole population and pertinent reference cohort. The animal born from 1979 to 2009 grouped as reference 1 and from 2010 to 2023 as reference 2 cohort. The comprehensiveness of the whole population, reference 1 and reference 2 was over 50% up to the fourth, third and sixth generations respectively. The average relatedness and inbreeding coefficient were 5.92% and 2.69% for whole population, 5.44% and 1.96% for reference 1 and 6.98% and 3.85% for reference 2 respectively. The effective population size varied from 32.31 to 145.51 in the study. The average generation interval varies from 9.2 years in reference 1 to 8.2 years in whole pedigree and 6.6 years in reference 2 under study. The ratio (f_e/f_a) of effective number of founders (f_e) and ancestors (f_a) were 1.67, 1.59 and 1.90 for the whole, reference 1 and reference 2 respectively. The estimate for f_g/f_a ratio indicated that 54% of ancestral genetic diversity is retained in the current generation. Thus, present study provides critical insights to maintain effective population size, rate and level of inbreeding with contribution of founders in current population for optimum genetic diversity and improving breeding efficiency in planning future breeding programs.