Pedigree Analysis and Estimation of some Population Parameters of Sanjabi Sheep at Mehrgan Station

Genetic diversity determines the capacity of a population to respond to selection and genetic improvement. In order to evaluate the breeding programs carried out on a population and decide to continue it, it is necessary to evaluate the genetic diversity of that population. The purpose of this project was to investigate the genetic diversity and estimate the population parameters of sanjabi sheep based on the analysis of their pedigree information.

The information used in this study included animal number, father number, mother number, sex and date of birth of 2067 purebred sheep that were collected in Mehrgan station during 2009 to 2022. Pedigree analysis was performed on the entire population or a reference population in order to estimate population parameters such as inbreeding coefficients, increase rate of inbreeding, effective population size, generation interval, effective number of founders and effective number of ancestors.

The generation interval and the average relationship were estimated as 2.87 years and 0.43%, respectively. The average inbreeding in the entire population was calculated as 0.48%, which indicated the low level of inbreeding in this population. The trend of inbreeding changes during the studied years was unfavorable. The effective size of the population was estimated to be 260.86 using the increase of individual inbreeding and the method of the maximum number of generations. The effective size of the founder was estimated to be 272.60, which indicated the balanced participation of the base population in reproduction. The effective number of founder individuals (fe) and the effective number of ancestors (fa) were equal to 109 and 100 heads, respectively. The fe/fa ratio was calculated as 1.09, which indicated the low effect of genetic bottlenecks. 50% of the total genetic diversity was created by 38 heads of ancestors, which indicated the balanced participation of ancestors in creating the genetic diversity of the next generation.

The results showed that despite the small and closed population, there is relatively high genetic diversity among the individuals. Since the loss of genetic diversity and increase in homozygosity will lead to a decrease in production performance, it is necessary to prevent the reduction of genetic diversity and its adverse effects in the future by examining genetic diversity and and making decisions to preserve it