Whole genome characterization of autochthonous Bos taurus brachyceros and introduced Bos indicus indicus cattle breeds in Cameroon regarding their adaptive phenotypic traits and pathogen resistance
Abstract BackgroundWest African indigenous taurine cattle display unique adaptive traits shaped by husbandry management, regional climate and exposure to endemic pathogens. They are less productive with respect to milk and meat production which has been associated with a number of factors, amongst others small size, traditional beliefs and husbandry practices. This resulted in the severe dwindling of their populations size rendering them vulnerable to extinction. The Namchi (Doayo) taurine cattle breed has documented resistance traits against trypanosome infection and exposure to tick infestation. Nonetheless, the historically later introduced Zebu cattle are the main cattle breeds in Africa today, even though they suffer more from locally prevailing pathogens. By using a reference-based whole genome sequencing approach, we sequenced for the first time the genomes of five cattle breeds from Cameroon: the Namchi (Doayo), an endangered trypanotolerant taurine breed, the Kapsiki, an indigenous trypanosusceptible taurine breed, and three Zebu (Bos indicus indicus) breeds: Ngaoundere Gudali, White Fulani and Red Fulani.ResultsApproximately 167 Giga bases of raw sequencing data were generated and mapped to the cattle reference genome UMD3.1. The coverage was 22 to 30-fold. The single nucleotide polymorphisms (SNPs) were compared with reference genomes of European Bos taurus Holstein and of Asian Bos indicus Brahman and the African trypanotolerant N’Dama breeds.Of a total of 50 million SNPs identified, 3.43 million were breed-specific ranging from 0.37 to 0.47 million SNPs in the domestic Cameroonian breeds and approximately 0.58 million constituted of small insertions and deletions. We identified breed specific-non-synonymous variants as genetic traits that could explain certain cattle-breed specific phenotypes such as increased tolerance against trypanosome parasites in the Namchi (Doayo) breed, heat tolerance in the Kapsiki breed, and growth, metabolism and meat quality in the Gudali breeds. Phylogenetic comparison grouped Namchi (Doayo) to the African Zebu clade indicating a hybrid status of the selected animal with a Zebu breed, albeit it showed the Namchi breed’s phenotype.ConclusionsThe findings provide the first comprehensive set of full genome variant data of the most important Cameroonian cattle breeds. The genomic data shall constitute a foundation for breed amelioration whilst exploiting the heritable traits and support conservation efforts for the endangered local cattle breeds.