Pre-Weaning Growth Performances and Survival Rate of Lambs’ in the highlands of Ethiopia

Abstract

Data collected on 1388 Awassi x Menz 25-50% [1](AM 25-50%), 80 Awassi x Menz 75% (AM[2] 75%) cross breed and 3482 Menz (M[3]) lambs collected  from 1993 through 2004 were analyzed for survival and growth from birth to weaning (90 days) at Sheno Agricultural Research Center. AM 25-50% and AM cross breed lambs were significantly (p<0.0001) heavier at birth and weaning: they also grew faster than the local M lambs. Birth weight increased with increasing blood level of Awassi; AM 75% being the heaviest. Indigenous M breed lambs were 19 and 33% lighter at birth compared to the AM 25-50% and AM 75% lambs. Year and season of Birth had significant (p<0.0001) on lamb weight at birth and weaning and pre-weaning weaning weight. Ewe lambing in the main rainy season produced the heaviest birth weight while lambing of short rainy season hand both the highest weaning weight and pre-weaning weight gain (p<0.0001). Birth weight was lowest for parity one, and subsequently increased at parity two through five. Twin born lambs were significantly (p<0.0001) lighter than single born lambs at birth and weaning; 30 and 24% at birth and weaning, respectively. Lambs born from supplemented ewes were significantly (p<0.0001) heavier at birth and weaning and also a gain advantage of 36% was recorded. Lambs born from heavier (>=46 kg) ewes were significantly (p<0.0001) heaver at birth and weaning than lamb born from lighter ewes (<=25.50 kg). The overall mortality rate was 17.49%. However, a significantly higher proportion of lambs died within three days; 46.26% Vs 11.39% at 60-90 days of age. Lambs that were born under 2.5 kg had greater risk of dying (33%) while lambs that were born above 3.5 kg died only 6.63%. Almost similar proportion (17% for M, 19% for AM 25-50% and 14% for AM 75%) lambs died, respectively. Pre-weaning survival rate of lambs were 78, 84, 80 and 86% for main rain, cold dry, dry and short rainy seasons, respectively. Improving birth weight of lambs, cross breeding of Menz local sheep with improved Awassi breed and adjusting lambing in the short rainy season could enable to produce better lambs in terms of birth weight, pre-weaning growth and pre-weaning survival of lambs in the highlands of Ethiopia.

Keywords: Sheep; Crossbreeding; Supplementation; Birth weight; Lamb mortality.

[1] AM 25-50%= Awassi x Menz 25-50%

[2] AM 75%= Awassi x Menz 75%

[3] Menz = An indigenous Ethiopian sheep categorized under Short fat tailed breed (Gizaw, 2007)