Lambing Interval in Zero-Weaned West African Dwarf (WAD) Ewes Reared Intensively with Rams in a Humid Tropical Environment

Abstract

This experiment was performed to determine lambing interval in a flock of West African Dwarf ewes run continuously with rams in complete confinement, in order to take advantage of “ram effect”, but without weaning (zero weaning) their lambs. Twenty-four (24) mature West African Dwarf ewes aged 18 to 24 months were run continuously with three (3) mature rams of the same breed and age range for two years, and managed in complete confinement. They were fed fresh, cut forages (Panicum maximum, Gliricidia sepium and Leucaena leucocephala) supplemented with a concentrate diet of Brewers’ Dried Grains (BDG), rice bran, palm kernel cake (PKC) and a vitamin/mineral premix. All 24 ewes (100%) lambed during the experimental period, and produced a total of 72 lambs in 63 lambing, giving a lambing rate of 114.30%. Average litter size (or prolificacy) was 1.14 lambs. Single births made up about 84% of all births, while twin births were about 16%. There were no triplets. The number of lambs born per ewe per year (fecundity) was approximately 1.50. Mean lambing interval was 242.93 ± 10.04 days (range, 174 to 291 days), and was slightly longer in male lambs (248.75 ± 11.72 days) compared with female lambs (236.29 ± 17.52 days), and in twin lambs (254.33 ± 17.39 days) than in single lambs (235.33 ± 12.25 days), although the differences were not significant (P>0.05). Mean postpartum interval to conception ranged from 27 days (once in only one ewe) to 144 days, and averaged 95.93 ± 10.03 days while the average re-breeding interval was 95.93 ± 10.03 days. Mean lamb birthweight was 1.90 ± 0.10kg. Mean live-weight gain to lambing was 4.88 ± 0.39kg, and higher, though non-significantly (P>0.05), in male lambs and twin births than in female and single lambs respectively. It was concluded that zero-weaned WAD ewes kept in complete confinement, and run continuously with rams are more likely to achieve three lamb crops in two years.

Keywords: West African Dwarf ewes, lambing interval, lambs, rams, zero-weaning