Genetic admixture of local Ethiopian sheep breeds and Awassi from SNP markers for designing crossbreeding schemes

In the extreme highlands of Ethiopia many farmers depend on sheep for their livelihood and income source. The preliminary result of the ongoing exotic Awassi with indigenous crossbreeding project in the highlands of Ethiopia indicated that crossbred sheep performed better than their local contemporaries. However their performance varies by exotic genetic composition level, environment and farmers management. Upgrading of indigenous sheep breed to higher exotic inheritance resulted in reduced performance in some cases due to poor feed situation and management. Crossbreeding schemes for smallholder farmers considering the exotic genetic composition level is crucial. This requires evaluation of crossbreds at different genetic composition level. However pedigree recording is less accurately practiced under smallholder farmer’s situation due to uncontrolled mating. A set of autosomal ancestry informative markers (AIMs) from SNP chip data is used to estimate more accurately the individual and population admixture proportions. Ear tissue samples were collected from the pure Wollo sheep breed and two composite populations (Menz-Awassi and Wollo-Awassi). Genomic DNA was extracted from all samples. Pure Wollo sheep samples were genotyped using OvineSNP50 bead Chip. Additional 50K genotype data were obtained for Menz and Awassi sheep from the previous database. Few ancestry informative markers (AIMs) had selected based on their higher FST value in differentiation Awassi and the two (Menz and Wollo) local sheep breeds. The crossbred sheep (about 800 samples with phenotype) will be genotyped based on selected markers using sequenom multiplex genotyping. The genomic admixture will be estimated for each sheep using STRUCTURE software. Association of the estimated genotype level with performances (growth and reproductive) will be employed to identify optimum admixture level for each area.