Genomic Characterization of Zambian Indigenous Cattle Breeds
Edward Smith Virginia Polytechnic Institute and State University, Animal and Poultry Sciences, Blacksburg, VA
Breed characterization is a primary step in designing appropriate management and conservation programs of livestock in developing countries. Since cattle represent a major food animal species in Zambia, its conservation is a major goal for both the government and non-governmental organizations. To support the conservation effort, the objective of this thesis research was to assess the phenotypic and molecular characteristics of indigenous Zambian cattle breeds including Angoni, Barotse, Tonga, and Baila based on body measurements and randomly amplified polymorphic DNA (RAPD) markers, respectively. A total of 100 animals, 25 from each of the four breeds associated with different tribes and region of Zambia, were used in the molecular analysis research. Additionally, 10 Holstein x Jersey crossbred animals were used as a reference and to test the extent of cross-breeding, if any, of the indigenous stock with exotic breeds. To further compare the Zambian indigenous breeds, morphometric measurements including body length, heart girth, and height at withers on 50 animals of each breed were measured. Blood was collected from animals at randomly selected farms and DNA isolated by standard protocols in Zambia. A total of 10 primers, of the 20 evaluated for informativeness, were used in the RAPD-PCR analyses. Differences among the four breeds for all the three morphometric measurements were significant with the Barotse significantly higher than the other three (P<0.05). The average number of bands per primer was 7.1 and the percentage of polymorphic bands per primer ranged from 40 to 71.4 with an average of 64.8%. Breed divergence was highest between the Tonga and the Barotse and lowest between the Tonga and Baila breeds. Both the morphometric measurements and RAPD-based distance estimates suggest that the Barotse may be different from the other indigenous breeds while the Tonga and Baila were more closely related. In addition, the genetic distance estimates imply that the Holstein x Jersey crosses are different from the four Zambian indigenous cattle breeds evaluated. This thesis research provides, for the first time, the basic genetic information necessary for conservation of Zambian cattle breeds and the use of these populations for effective crossbreeding. The data suggest that though there is isolated by geographic distance and cultural differences among the tribes, two of the breeds are significantly related.