Growth and Reproductive Performance of the Indigenous Sheep of Nigeria Reared in a Humid Tropical Environment

Abstract

In a study to determine the growth and reproductive performances of sheep from the arid and semi-arid north of Nigeria (the Yankasa (Y), Ouda (U) and Balami (B)) the West African Dwarf (W) sheep as well as YxW and BxW crosses in a hot, humid tropical environment, adult Yankasa (Y) sheep ( 3 rams and 7 ewes), Ouda (U) (2 rams and 1 ewe) and Balami (B) (2 rams and 2 ewes) sheep acquired from various locations in northern Nigeria were introduced into the experimental location at Ile-Ife, southwest Nigeria. The sheep, together with West African Dwarf (W) sheep (2 rams, 5 ewes), 11 YxW and 3 BxW crossbred ewes were kept in complete confinement for 24 months, and stall-fed with fresh forage (Panicum maximum, Gliricidia sepium and Leucaena leucocephala) and a concentrate diet. Data collected included ewe body weights, average daily gains (ADG) (in gd^-1) and all lambing records. Within-season comparisons of the average daily gains (ADG) revealed significant genotype differences, with higher gains occurring in the Balami x West African Dwarf crossbred (B x W) and Ouda (U) ewes than in the other genotypes at the first early and late rainy season (April-September). All genotypes lost weight during the dry season (October – March), with the greatest losses occurring in the BxW, YxW and U ewes. Average number of lambs born per ewe per year depended on genotype, and was higher in the W and BxW (1.50 each) and lowest in the purebred genotypes from the north of Nigeria: Y (0.67), B (0.5) and U (0.5). Lambs from the Y, B and U had significantly higher birth weights (2.39 – 2.95kg) than the W (1.87kg) and the Y x W (1.91kg) lambs. Y, W and YxW ram lambs born as singles were heavier at birth than their ewe-lamb counterparts. Lambs born as twins and triplets generally had lower birthweights than those born as singles. Percent multiple births ranged from 25.00 to 47.83% and was highest in the YxW ewes. Lambing interval ranged from 255.18d in the West African dwarf (W) sheep to 402.67d in the Yankasa. Percent lamb mortality from birth to 180d was higher in the Balami (50.00%), the YxW (56.52%) and BxW (44.44%) than in the other genotypes. Litter size per ewe was lowest in the northern purebred genotypes (Y, B and U) than in the W and its crossbred progenies with the Y and B. It was concluded that although lambs from the B, YxW and BxW ewes were most susceptible to the vagaries of climate, and had higher mortalities than the Y, U and W, the similarity between these sheep and the W ewes in lambing performance suggests that sheep from the drier northern regions of Nigeria can, with better management and feeding, be reared to reproduce successfully in the rainforest zone of Nigeria.

Keywords: Nigerian sheep, reproductive performance, season, lamb, tropics, genotype