Temporal variation in body measurements in three Taurine cattle populations of Burkina Faso supports introgression of Zebu genes into West African Taurine cattle

Abstract

A total of 769 adult females belonging to 3 taurine and one zebu cattle populations sampled in 3 provinces of Burkina Faso were assessed for 19 body measurements during two different years (2014 and 2018). The aim of this research was to identify temporal morphological variation in cattle bred in the humid southern zones to obtain empirical evidence supporting a possible introgression of zebu cattle genes into Gourounsi and Lobi taurine cattle breeds. Zebu cattle samples were used as out-group for both 2014 and 2018 subsets. Least square means of body measurements allowed to classify Burkina Faso taurine cattle into three subgroups according to body size (Gourounsi–Sanguié –GourS-, Gourounsi-Nahouri –GourN- and Lobi from the tallest to the smallest respectively). Principal Component Analysis suggested that in 2014, taurine populations were structured. Dispersion map constructed using the two first factors informed that the GourS population was well separated from both the Lobi and the GourN, which, in turn, overlapped. However, in 2018 a strong signal of homogenization was identified, with GourN partially overlapping the other two populations. Linear Discriminant Analysis suggested that about 20% of both GourS and GourN individuals were reciprocally misclassified. Clues for such increase have been pointed out by MANOVA analysis. Although on 2014, Lobi cattle was clearly smaller than Gourounsi and both GourS and GourN populations showed clear differences on body traits, on 2018 it could be assessed an increase in size in Lobi cattle and a strong homogenization signal within Gourounsi cattle. Zebu cattle gene flow southwards in Burkina Faso is likely to have caused these changes, suggesting a fast erosion of taurine cattle genetic background. 
 Keywords: Body traits, quantitative traits, Gourounsi cattle, Lobi, Burkina Faso.