Understanding the genetic resources and adaptive traits of locally adapted cattle breeds: the case of Afrikaner and Bonsmara cattle in Namibia

There is rising interest in locally adapted livestock breeds as reservoirs of genetic diversity and adaptive fitness traits. In Namibia locally adapted cattle breeds are mainly reared in commercial farms south of the veterinary cordon fence. This study focused on the Afrikaner and Bonsmara cattle which are locally adapted breeds and have for many years been reared under low management levels in Namibia and subjected to strong environmental pressures and diverse disease challenges. The objective of this study was to explore the adaptation potential of these two breeds by investigating its genetic diversity and resistance to ticks. The genotypic data obtained revealed that Afrikaner cattle exhibit high levels of genetic diversity with an expected heterozygosity (He) of 0.660 and 5.50 mean number of alleles. Bonsmara cattle also exhibited high genetic diversity with an expected heterozygosity (He) of 0.637and 7. 00 mean number of alleles. A clear deficit of heterozygotes was observed as evidenced by the high FIS value of 0.247 suggesting high levels of inbreeding. Contrarily, an excess of heterozygotes was observed in Bonsmara cattle suggesting outbreeding. A low tick burden of 11-30 ticks on average in summer season was observed in both cattle breeds indicating high resistance to ticks. Results suggest that Afrikaner and Bonsmara cattle possess valuable traits such as tick resistance and therefore hold potential for production in harsh and unpredictable Namibian environmental conditions which are exacerbated by climate change. The Afrikaner and Bonsmara breeds like many other indicine-taurus cattle breeds have proved to be productive in harsh environments and selecting and breeding from their high producing phenotypes and ecotypes would go a long way towards concentrating desired genes for production and tolerance to diseases, thus mitigating climate change.