Explicating the genetic diversity and population structure of Saanen x Beetal goats using pedigree analysis

Abstract

Abstract Pedigree analysis is required to assess the genetic diversity and population structure of a close breeding population in order to effectively manage the breeding program and keep inbreeding under acceptable limits. Saanen x Beetal is a crossbred population of goats, reared at National Dairy Research Institute (NDRI) Karnal for the last five decades. This germplasm has been acclimated to a tropical climate and has a higher milk potential and prolificacy. Objective of this study was to elucidate the genetic diversity, population structure, and inbreeding in the flock of the Saanen x Beetal goats. The data were collected from the Animal Genetics and Breeding Division of ICAR-NDRI, Karnal for 2603 animals from the year 1971–2021. Animals born between 2014–2017 were considered as a reference cohort. Results revealed that the average generation interval was 3.44 years for the complete pedigree. The average inbreeding coefficient and the average relatedness were 4.20% and 6.87%, respectively, for the complete pedigree and 10.78% and 10.80%, for the reference population. Higher inbreeding coefficient and average relatedness in the reference cohort demonstrated impact of enclosed gene pool and demands immediate intervention for managing diversity in the closed nucleus under study. Ancestors contributing 50% of the gene pool were 8 and 3 for the complete pedigree and reference cohort, respectively, which illustrates the fact that very few ancestors were responsible for genetic diversity in the flock, which results in the decline of effective population size. Effective number of founders (fe), ancestors (fa), and founder genome equivalents (fg) were 15, 7, and 3.11, respectively. The (fe/fa) ratio in the reference population was 2.14 indicating the occurrence of the bottleneck effect in the flock. We observed that inbreeding was non-significant for all reproductive traits except for age at first service and age at first kidding. To lessen inbreeding and augment genetic diversity in the flock, the stratified breeding plan needs to be followed, where, mate sele ction would be based on relatedness. Furthermore, introduction of unrelated Saanen and Beetal crosses will help alleviate the inbreeding accumulation.