Is the introgression of Lobi/Baoul cattle by zebuine genes in Burkina Faso Lobi cattle threatened?

Burkina Faso livestock is made up of two main cattle population, namely Zebuine and Taurine. Transhumance and settlement of Zebu cattle breeders in tsetse challenged areas lead to cross-breeding Zebu and Taurine. Introgression of the Zebu cattle may have changed the structure of the trypanotolerant Lobi/Baoule breed. The objective of the present study was to appreciate the introgression of Zebu genes into Baoule population by assessing the structure and the genetic diversity of cattle populations across the tsetse belt in Burkina Faso. Therefore, 450 blood samples were taken for genotyping in 29 villages of 3 main regions where Baoule, Baoule×Zebu and Zebu populations are found. Twenty five loci of 22 autosomes have been genotyped. The mean of observed alleles per locus was 12.44±4.31 while the mean of expected alleles was 4.67±1.48. The heterozygosity ranged from 0.34 to 0.76 and 0.36 to 0.87, respectively for observed and expected heterozygosity across loci. The average heterozygosity across population was 0.73±0.10. The mean estimates of F-statistics were FIS = 0.117±0.019, FIT = 0.158±0.019 and FST = 0.047±0.005. The phylogenetic tree showed the Baoule South-West segregating apart from the other populations, Baoule×Zebu being an intermediate genetic group between Baoule South-West and Zebu North populations. The Baoule West could not be differentiated from crosses. The Baoule breed seems to be impacted by the introgression of Zebu genes to its biotope and pure Baoule seems to be confined to the South-West with very few pure individuals in the West.   Key words: Burkina Faso, Zebu, Baoule×Zebu, Baoule, introgression, microsatellite.