Population structure and inbreeding effects on growth traits of Morada Nova sheep

Abstract

Genealogical records of 6,631 animals were used to describe the population structure, evaluate the genetic variability, and estimate the effect of inbreeding on the growth traits of Morada Nova sheep. The depth of the whole population was shallow (t = 1.25), that the way we used a reference population (t = 2.99), formed by animals with both parents known and born in the last four year, to make the inferences. For this population, birth weight (BW, n = 220), weaning weight (WW, n = 157), and pre-weaning weight gain (WG, n = 155) were available. The effective numbers of founders (fe) and ancestors (fa) were 43 and 34, respectively; 12 ancestors were responsible for 50% of the genetic variability in this reference population. The effective sizes for maximum, complete, and equivalent generations were 113.63, 41.67, and 60.97, respectively. The effective size, average inbreeding (2.88%), average relatedness coefficient (1.24%), the fe⁄fa (1.26), beyond other results, indicate attention with the future of the breed, which is not comfortable in relation to inbreeding and variability. Inbreeding depression was observed only for BW, where for each one percent increase in the average of individual increase inbreeding there is an average decrease of 0.0751kg in birth weight.