Genetic parameters for gastrointestinal parasitosis resistance traits in Junín sheep

Abstract

ABSTRACT The Junín sheep contribute to livestock production in the Peruvian Andes, but face problems related to gastrointestinal parasitism. In this study, we estimated the heritability and repeatability of traits associated with resistance to gastrointestinal parasitism in the genetic nucleus of Junín sheep raised at altitudes above 3600 m. For this purpose, fecal and blood samples were collected from 101 female lambs and 88 male lambs (4-6 months old) during the rainy and dry seasons. The data on live weight (LW), the FAMACHA score (FS), blood hematocrit (HCT), and the fecal egg count (FEC) were analyzed using a repeated multiple-trait animal model; the variance components and genetic parameters were estimated using a Bayesian inferential approach. The results showed that heritability estimates ranged from 0.09 (FS) to 0.27 (LW), with 95% high posterior density intervals (HPD95%) between [0.02-0.19] and [0.12-0.43], respectively. The repeatability ranged from 0.15 (FS) [HPD95%: 0.04-0.27] to 0.74 (LW) [HPD95%: 0.67-0.81]. The genetic correlations were moderate to low, with HPD95% intervals including zero. This indicated that, at least based on the data collected, no clear relationships occurred between traits that were selected for application in a breeding program. However, focusing the breeding program on the FEC, with a heritability of 0.16 [HPD95%: 0.05-0.28], could be a viable strategy to increase resistance to parasitism. Additional data on other traits are also needed to achieve more precise estimates for this population.

Keywords

• Fecal egg count
• FAMACHA score
• hematocrit
• heritability
• repeatability