Evaluation of goat breeds in the tropical North-East Brazil. I. A study of birth-related traits of native and exotic goat breeds

Abstract

Most of the North-East Brazil is a hot tropical semi-arid area and most of the Brazil's goat population (approximately 6.1 million out of 6.6) exists in this region. In the present study, five breeds were compared for their pre-natal growth. The birth weight was divided by the duration of pregnancy to obtain values of per day foetal gain, and the latter by the mother-doe's weight at parturition to calculate net per day gain per kg of dam's weight. The breeds were: indigenous -(1) Canindé-Repartida, (2) Moxotó, (3) Marota; exotic - (4) Anglo-Nubian, (5) Bhuj. The results showed that the birth weight was not strictly according to the dam's weight at parturition. Although the adult Bhuj were the heaviest followed by Anglo-Nubian and indigenous breeds, the heaviest kids were produced by Anglo-Nubian and the kids of other four breeds, including Bhuj, were much lighter and identical among themselves. This trend was also reflected in average daily gain but not in net gain. The net gain was identical in Anglo-Nubian and indigenous breeds and much lower in Bhuj. Within breeds, dams with larger size appeared to produce kids with greater birth weight and daily gain. Single born kids had a distinct advantage over kids born in multiple pregnancies in all growth traits, but sex of kid; in general, appeared to have no significant effect though the male kids in Marota and Anglo-Nubian breeds were significantly heavier to females and also had a better average daily gain. Adult body weights and gestation lengths varied between breeds but these traits were not influenced by other sources of variation.