Genetic parameters for fecal eggs count and reproductive/maternal efficiency of does raised in humid subtropical climate

Abstract

The profitability of the animal meat production industry is related to the greater quantity and quality of animals for slaughter. This is related to the reproductive and maternal efficiency of the dams. In the case of goats, this efficiency can be greatly compromised by the sensitivity that this species has to worm infestations. Thus, it is important to select animals that are genetically resistant to these parasites. Fecal eggs count (FEC) has been used as a selection criterion for this purpose. Our hypothesis is that the knowledge about the genetic parameters for FEC, estimated at the times of mating (FECm), kidding (FECk) and weaning of the offspring of a female goat (FECw), together with the estimation of the genetic parameters for the number of offspring born (NOB) and the number of offspring weaned per doe (NOW), will contribute to the establishment of selection strategies to improve reproductive efficiency and animal resistance to parasitism in goat breeding programs. Data came from Tennessee State University (TSU) multibreed goats’ herd. We analyzed FEC data as distinct traits according to the stage of measurement. The NOB and NOW were considered in two ways, as linear or threshold traits. Thus, two multivariate analyzes were performed, the first with the five traits as linear and the second with NOB and NOW as threshold traits. The heritabilities obtained for FEC varied, being lower at mating (0.06 ± 0.01), followed at weaning (0.13 ± 0.04) and higher at kidding (0.39 ± 0.05). Better estimates were obtained when considering NOB and NOW as threshold. The genetic correlations of these traits with FEC where null, when FEC was measured at mating and weaning of offsprings. The estimated heritabilities indicate the possibility of obtaining genetic gains by direct selection in the studied traits. A practical advice for selection for FEC is to do it corresponding to the time of highest worm-challenge in a herd, which usually happens at kidding.