Signatures of positive selection for local adaptation of African native cattle populations:A review

Cattle are central to the lives and diverse cultures of African people.It has played a crucial role in providing valuable protein for billions of households and sources of income and employment for producers and other actors in the livestock value chains.The long-term natural selection of African cattle typically signals signatures in the genome,contributes to high genetic differentiations across breeds.This has enabled them to develop unique adaptive traits to cope with inadequate feed supply,high temperatures,high internal and external parasites,and diseases.However,these unique cattle genetic resources are threatened by indiscriminate cross-breeding,breed replacements with exotic cosmopolitan breeds,and climate change pressures.Although there are no functional genomics studies,recent advancements in genotyping and sequencing technologies have identified and annotated limited functional genes and causal variants associated with unique adaptive and economical traits of African cattle populations.These genome-wide variants serve as candidates for breed improvement and support conservation efforts for endangered cattle breeds against future climate changes.Therefore,this review plans to collate comprehensive information on the identified selection footprints to support genomic studies in African cattle to confirm the validity of the results and provide a framework for further genetic association and QTL fine mapping studies.

Production Systems, Genetic Diversity and Genes Associated with Prolificacy and Milk Production in Indigenous Goats of Sub-Saharan Africa: A Review

Goats are one of the oldest domesticated animal species widely distributed in the world playing an important role in the food production system in Sub-Saharan African Region (SSAR). Due to their multiple uses (milk production, meat, fiber and hides) and adaptation aptitudes to ecological conditions, goats produce and contribute positively to farmers’ socio-economy status in various production systems. This review aimed at giving a summary overview on the goat’s production systems characteristics, the genetic diversity and the candidate genes affecting reproductive and milk production performances in goat breeds in SSAR. It has been observed that traditional livestock production system with communal grazing system is the most used in goat keeping in SSAR. The geographical locations play an important role in the relationships between goat’s distributions in the region. At the same time, goats might have been differentiated and isolated one to others due to the wide geographic range, the diversify climate and the topography in the region. Among the six worldwide known haplogroups of goat (A, B, C, D, G and F), haplogroup A is the most representative in SSAR. However, haplogroup G and B can be found in some goat populations in some countries in east (Kenya and Ethiopia) and south parts of Africa. This review reveals that little is known on the candidate genes associated with prolificacy and milk production traits in indigenous goat breeds in the region. That observation suggests the importance of assessing candidate genes associated with economic traits in the populations of goat in SSAR.