Genetic Analysis of Local Pig Populations in Ghana

The Ashanti Dwarf Pig (ADP) of Ghana is an endangered pig breed with hardy and disease resistant traits. Characterisation of animal genetic resources provides relevant data for their conservation and sustainable use for food security and economic development. We investigated the origin and phylogenetic status of the local ADP of Ghana and their crosses with modern commercial breeds based on mtDNA, MC1R and Y-chromosome sequence polymorphisms, and genome-wide SNP genotyping. The study involved 164 local pigs sampled from the three agro-ecological zones of Ghana. Analyses of the mitochondrial D-loop region and Y-chromosome sequences revealed that the ADP of Ghana has both European and Asian genetic signatures. The ADP also displays considerable variation in the MC1R gene. Black coat colour is the most predominant within the breed, with the dominant black alleles of both Asian and European origin contributing to the majority of alleles in the pool. European alleles for spotting are present at a low frequency in the sample set, and may account for the occurrence of spotted piglets in some APD litters. Other colour variants may be due to epistatic interactions with additional coat colour loci, or mutations. The wide variations in coat colour patterns suggest that morphology alone cannot be used to adequately characterise Ghanaian local pigs. PCA analysis of SNP genotyping data revealed a strong location effect on clustering of local Ghanaian pigs. Based on this work, we recommend that further studies be carried out on more local pigs to find out the effect of admixture on important adaptive and economic traits of the ADP and other local Sus breeds in Africa to help develop a sustainable conservation programmes to prevent the decline of this genetic resource. 71 independent samples, with one sample replicated. The samples included DNA from 5 animals imported from Europe (European commercial breed background), 20 local animals with known mixed ancestry, and 46 animals classified as local Ashanti Dwarf Pigs. The animals were sampled from six different agro-ecological zones. Animals were selected from different local farms in each area sampled.