Non-genetic factors affecting the reproduction performance, lamb growth and productivity indices of Djallonke sheep

Two important components that determine sheep production efficiency are reproduction and live bodyweight. An understanding of environmental factors affecting these traits is needed to implement optimal breeding and selection programs in Benin (West Africa). In this study, age at first lambing, length of the lambing interval, prolificacy, dam's post-partum weights, lambs weight at weaning and productivity indices of West African Dwarf sheep (Djallonke sheep) were analysed under research conditions. The non-genetic effects (season of birth, year of birth, parity of the ewes and sex of lambs) were determined. Age at first lambing (622.4 +/- 55.6 days) was significantly (p < 0.001) affected by year and season of birth. Lambing interval (242.6 +/- 20.8 days) was affected (p < 0.001) by the year of lambing, sex of the lamb, type of birth (single, twin), parity of the ewe and type of birth-parity interaction. The number of offspring per birth (1.4 +/- 0.5) was significantly affected (p < 0.001) by the year of lambing. Lamb weaning weights at 90 days of age (10.6 +/- 2.1 kg) and ewe postpartum weights at lambing (27.5 +/- 2.4 kg) were significantly affected (p < 0.001) by all the fixed effects. Ewes with a heavier body weight exhibited shorter lambing intervals (P < 0001) and heavier offspring at 90 day of age (p < 0.01). Productivity expressed as the body weight of a 90 days of old lamb produced per breeding female per year (17.0 +/- 3.1 kg), per kg breeding female per year (0.6 +/- 0.1 kg) and per kg breeding female per year (1.4 +/- 0.2 kg) were affected (p < 0.01) by the year of lambing, the parity of ewes, the sex of lambs, and the parity sex interaction. The number of births per month (95.7 +/- 74.4) was higher during the rainy season than in dry season. Environmental effects estimated in this study are important and will need to be taken into consideration for sheep breeding improvement. (c) 2005 Elsevier B.V. All rights reserved.