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A three-year longitudinal study was conducted to evaluate effects of strategic anthelmintic treatment regimes on age at first lambing (AFL), weight at first lambing (WFL) and lambing interval (LI) of 356 communally grazed ewes and 675 lambs owned by 10 smallholder farmers in the central highlands of Ethiopia. The ewes were stratified by weight and randomly allocated to three treatment groups as untreated control (TG1), twice-dosed per year (TG2) for both nematodes and trematodes in mid-January and mid-June and four-time-dosed per year (TG3) in June for nematodes, in August–September for nematodes and adult Fasciola, in November–December and January–February for immature flukes. The fixed effect of anthelmintic treatments, parity, season and year of lambing on AFL and LI was evaluated. Mean ± standard error (SE) of lambing interval was 292 ± 3 days. Both anthelmintic treatments (TG2 and TG3) shortened (P 0.05). Birth and lambing seasons of the ewe lamb had significant (P

This review summarizes available information on genetics of adaptation in major livestock species focusing on small ruminants. Adaptation to humans and consequences of domestication on predator aversion, mechanisms of adaptation to available feed and water resources, severe climates and genetic evidence of disease tolerance or resistance have been presented. The latter focuses on gastrointestinal parasites and bacterial diseases. The resource allocation by the animal to production and fitness traits under both optimal and sub-optimal conditions has a genetic background. Such information would help in identifying the most appropriate and adapted genotypes capable of coping with the environmental challenges posed by the production systems or, wherever possible, in adapting the environments to the requirements of the animals.