Blood polymorphism in west African breeds of sheep

Analysis of the Genetic Diversity and Population Structure of Four Senegalese Sheep Breeds Using Medium-Density Single-Nucleotide Polymorphisms

Simple Summary

This paper reported genetic parameters of four Senegalese sheep breeds, in relation to inbreeding, diversity and genetic proximity. The results provide informations on genetic conservation and adaptability of the breeds in the Senegalese context.

Abstract

In Senegal, sheep breeds have adapted to their environment and play a key socio-economic role. This study aimed to explore the genetic diversity and structure of four Senegalese sheep breeds (Peul-peul, Djallonke, Touabire, and Ladoum) and their relationships with global sheep breeds. To that end, forty-seven sheep were genotyped using the OvineSNP50 BeadChip, and these genotypic data were analysed with those of 73 sheep breeds representative of worldwide ovine diversity (2729 animals). The average observed heterozygosity (Ho) ranged from 0.293 in Djallonke sheep to 0.339 in Touabire sheep. The estimated Fis values were low, ranging from 0.019 for Ladoum to 0.034 for Peul-peul sheep. The estimated Fst values were low (0.003–0.044) among the trypanosusceptible breeds (Peul-peul, Touabire, and Ladoum) but high between the previous breeds and the trypanotolerant Djallonke breed (0.075–0.116), indicating better genetic conservation of the Djallonke sheep. A principal component analysis revealed clustering of the Senegalese sheep breeds according to their geographic distribution. However, owing to genetic improvement practices, the introgression of Touabire sheep blood seems to have reshaped the genetic landscape of the trypanosusceptible sheep breeds in Senegal. The Senegalese sheep breeds showed lower genetic diversity than their presumed ancestral sheep breeds of the Middle East. They also presented some relatedness with Caribbean sheep breeds, which reveals their contribution to the global genetic diversity and to the development of Caribbean sheep breeds.

Characterization of indigenous fat-tailed and fat-rumped hair sheep in Kenya: diversity in blood proteins

This paper reports the variation in five blood proteins from five populations of sheep found in Kenya. Blood samples were collected from a total of 309 adult sheep of both sexes in Kwale, Makueni and Kakamega districts for the fat-tailed sheep and in Isiolo district for the fat-rumped hair sheep. Fine-wooled Merino sheep were used in this study as the reference population. Transferrin, esterase-A and esterase-C were polymorphic in all the populations investigated, while albumin was monomorphic for the S allele in the fat-tailed sheep and haemoglobin was fixed for the B allele in the Kwale, Makueni and Isiolo populations. Phylogenies derived from the pairwise genetic distance estimates showed a clear separation between the indigenous sheep populations and the exotic Merino. However, the topology of the former showed rather poor consistency with their morphological classification based on the localization of their fat deposits, namely fat-tailed or fat-rumped hair sheep.