Genetic parameters for growth and reproductive traits of Morada Nova sheep kept by smallholder in semi-arid Brazil

Abstract

The objective of the present study was to estimate genetic parameters for growth and reproductive traits of Morada Nova sheep reared by smallholder farmers in the semi-arid northeastern region of Brazil. Data from 11 participating flocks, between 2007 and 2011, were used for the estimation of (co)variance components and genetic parameters for birth weight (BW), weight at weaning adjusted for 112 days of age (WW), average daily weight gain from birth to weaning (ADG), days to lambing (DL), lambing interval (LI), total litter weight at birth (LWB), total litter weight at weaning (LWW) and the ratio between total litter weight at birth and weaning and metabolic weight of the dam (LWB/MW and LWW/MW, respectively). The direct heritabilities obtained by one-trait analysis were 0.19, 0.14, 0.11, 0.13, 0.0, 0.44, 0.19, 0.41, 0.15, respectively for BW, WW, ADG, DL, LI, LWB, LWW, LWB/MW and LWW/MW. The direct heritabilities for BW and WW obtained by two-trait analysis were similar to those estimated by one-trait analysis. However, the direct heritabilities for LWB, LWW and LWW/MW obtained by two-trait analysis were higher than those estimated by one-trait analysis. The genetic correlation between BW and WW were 0.75 and between LWB, LWW and LWW/MW were 0.8, 0.9 and 1.0, respectively. In conclusion, except for LI, there is genetic variability that can be explored by direct and indirect selection to obtain genetic gains in the flocks participating in the Nucleus of Participatory Breeding of Morada Nova Sheep.