Abstract:
In Ethiopia, there are 32.85 million sheep, more than 99% of which are indigenous.
However, the productivity of local sheep under traditional production system is low
with high mortality of lambs. Between sheep breed differences in performance do
exist and have begun to attract some research attention in recent years. Yet, little
selection has been undergone for improved meat production and true breed potentials
are not known and not all breeds have been sufficiently well characterized. There is a
need to better acknowledge the unique features of these breeds, their products, their
socio-cultural and religious uses, and their production systems. Multiple-visit,
multiple-subject survey was conducted to characterize sheep production system,
growth and reproductive performance, phenotypic features and genetic diversity study
and generate information’ to design sheep breeding schemes. Purposive sampling
method was employed to select study areas or districts and households engaged in
sheep production. Pre-teested semi-structure questionnaire was administered for data
collection. Data collection was carried out for two years from September, 2017 to
October, 2019 G.C. Households under investigation have a small patch of land. Mean
±SD values of land holding per household of Burie, Mandura and Quara were
1.03±0.89 ha, 2.66±1.61 ha and 11.46±5.76 ha, respectively, resulting in insufficient
pasture and feed shortages. Feed shortage, disease and parasites and lack of input
were prioritized as major challenges of sheep production. The growth and
reproductive performances traits of Washera and Gumuz sheep were comparable to
other Ethiopian and African sheep. Breed type affected live weight significantly
(P<0.001). Average age at first lambing and lambing interval were also affected by
breed significantly. Body weight recorded for Washera, Gumuz and Rutana Sheep
were 27.5, 26.89 and 38.71 kg, respectively. Chest girth and body length were best
body weight predictors for Gumuz female sheep at p<0.001 level of significance. Tail
length, ear length and body length were best body weight predictors for Gumuz male
sheep at p<0.001 level of significance. For Washera female sheep, tail length, chest
girth, height at withers and body length were best body weight predictors at p<0.001
level of significance. Tail length, chest girth and head length were best body weight
predictors for Washera male sheep at p<0.001 level of significance. Higher mean
values of morph metric traits were recorded canonical bone length. The variations in
phenotypic features need to be supplemented by molecular diversity study. Clustering
analysis using principal component (PC1) differentiates Rutana from Gumuz and
Washera sheep supporting this variation. Polymorphic information content was 0.89,
0.90 and 0.88 for Gumuz, Rutana and Washera sheep, respectively. These values
could be recognized as reasonably (moderately) informative to carry out genetic
diversity study. Expected heterozygosity was found to be higher than observed
heterozygosity attributed to the discrepancy to forces such as inbreeding. Observed
heterozygosity ranged from 0.33 in Gumuz to 0.34 in Rutana and Washera sheep.
Expected heterozygosity ranged from 0.37 in Rutana to 0.38 in Gumuz and Washera
sheep. Higher inbreeding coefficient (0.12) was recorded for Gumuz sheep compared
to 0.09 of Rutana and Washera sheep. Our whole-genome SNP analysis revealed high
variation within populations. These within-breed variabilities were used as input for
designing a selective breeding program. Phenotypically, two highly rated selection
criteria (body size and litter size) were preferred for Gumuz and Washera ewe.
Improving 25 kg sale weight (at yearling age) and the number of lambs qualifying for
the market and home consumption were the proposed breeding objectives or goals.
Genetic gain predicted for six- month weight of Gumuz and Washera sheep were 0.46
and 0.60 kg of live weight, respectively. Genetic gain predicted for yearling weight of
Gumuz and Washera sheep were 0.58 and 0.66 kg of live weight, respectively. A
sheep breeding program with 10% selection proportion and one year ram use for
breeding was recommended giving special emphasis to yearling weight.