A Comparative Study on Productive and Reproductive Performance of Cross-Bred and Local Breeds of Goats

Abstract

In recent years new breeds of goats have been introduced to the Sudan. These foreign breeds have been located at first in and around Khartoum, but lately have spread throughout the country. Now it is rather difficult to differentiate between the local breeds and their crosses In this study, 12 Nubian female goats divided into two groups (LA and LB) and 10 cross-bred Toggenburg-Nubian goats also divided into two (CA and CB) were alloted to two types of rations. Groups LB and CB were fed on gasap (Sorghum bicolor), berseem (Medicago sativa) ad libitum and concentrates at a rate of 0.5 kg per animal per day. Groups LA and CA were fed only on berseem and gasap ad libitum. The concentrate mixture was composed of 40% dura (Sorghum grains), 24% sesame cake, 15% molasses, 20% wheat bran and 1% table salt. The work described in this thesis was conducted to study the reproductive and productive performance of Nubian goats and their crosses with Toggenburg breed with or without concentrate supplementation. In the absence of the buck, oestrus signs observed on all groups was low (33%) and feeble. The standing heat duration in Nubian goats ranged between 12-48 hours and in the cross-bred goats between 12-38 hours. The oestrus cycle length was found to be short (4-11 days) or normal (19-24 days) in the local breed. Similarly the oestrus cycle length was found to be either short or normal (21-24 days) in the cross-bred goats. The gestation length was longer in the cross-bred does in all in all types of birth (3-5 days) except for single female births. The gestation length ranged between 141.45 - 154 days in all breeds. Generally males were carried about 2 days less than singles. The postpartum oestrus was not regular in all groups. The results also showed that the birth weight of male kids was significantly higher (P<0.05) than female kids of the male in all types of births (single, twins, triplets and quadruplets) except in the single births of female kids in the Nubian does fed on berseem and gasap only. In these births the birth weight of females was insignificantly higher than males. The daily weight gain was significantly higher in kids born to crossbreds than those born to the local breed. In this study the kid mortality was recorded only among kids born to the crossbred group fed on berseem, gasap and concentrates. However, mortality was mainly among quadruplet births in crossbreds. Two female kids died in this group (16.6%) in two different quadruplet births. The second part of this thesis was conducted to study the milk yield and composition. The milk yield of the crossbred goats was found to be significantly higher (P< 0.05) than that of the local breed of goats. It was concluded that crossing led to the improvement of performance of local goats and that improvement was enhanced by concentrate feeding.