Africa / East Africa / Genetics / ILRI / Indigenous Breeds / Interview / Kenya / LiveGene / Research

Study evidences continual waning of cattle genetic diversity in Western Kenya: Interview with Mary Ndila

For the last four years, Mary Ndila has been studying the population structure of indigenous cattle for her PhD project titled, ‘Genomics diversity of East African Shorthorn Zebu cattle of Western Kenya’, a joint program between ILRI and the University of Nottingham and funded by Wellcome Trust. In this article we find out whether breed improvement programs really improve African breeds and whether African farmers are trading long term ecologically important traits with short term economic traits among other aspects of her study.

Mary Ndila

What attracted you to the genomics diversity of East African Shorthorn Zebu cattle of western Kenya research?
After my masters in molecular entomology at the University of Ghana, I joined ILRI as a research technician. Due to my great passion to carry out result-oriented research for the benefit of the grassroot farmers, I applied for a PhD opportunity that aimed at understanding the current genetic architecture of an indigenous African cattle breed with one of its primary objectives being to identify good cow/bad cow genotypes that could be used in future breeding programmmes. This research was to be carried out under the Infectious Diseases of East African Livestock (IDEAL) project. My application was successful and I joined the IDEAL team in September 2008.

How is the current state of breeding programs in Africa?
Many farmers are keen on improving the productivity of their livestock due to the rapidly changing socio-economic trends. Most improved breeds come in the form of exotic genotypes that are introduced into the indigenous gene pool through artificial insemination services or crossbreeds. A majority of these projects have not been sustainable in the long term largely because of poor adaptability of the new stock to disease, disease vectors and climate as well as lack of long-term breeding strategies resulting to a loss of long-term adaptive traits. The lack of knowledge on the effects of these rampant breed improvement programmes and crossbreeding activities were a great impetus of this study.

How did you carry out your research and what kind of information did you collect?
The IDEAL study area covered 20 sub locations that transverse 4 agro-ecological zones in Western Kenya. A total of 548 recruited calves were exposed to natural disease and vector challenges without any medical intervention apart from euthanasia of critical cases and followed up over a 1-year duration. Detailed reports on clinical episodes, pathogens present in tissue and feacal samples, vector identification and postmortem analyses represented the non-phenotypic data whereas 10 different phenotypic characteristics (coat colour, coat pattern, dewlap presence, horn shape and size etc) were recorded too. The genotypic data was generated from a large–scale genotyping tool BovineSNP50. My research interrogated the genotypic data to establish the genetic structure and define good cow/bad cow genotypes.

What did you observe from the data collected?
It was evident that there was widespread introduction of exotic genotypes into the indigenous zebu gene pool. The effect of crossbreeding activities on the genome integrity of the indigenous zebu breed was evidenced by the skewed distribution of the European taurine introgressed animals across the study region, notable in the northern and southern areas.
The study also evidenced the continual waning of the genetic diversity of the study population through low genetic differentiation estimates suggestive of inbreeding and revealed the persistent shrinkage of the effective population size post rinderpest epidemics. The main cause of this phenomenon was the traditional management practices that involve the sharing of a selected bull within the villages, the encroachment of grazing land resulting to drastic shrinkage of land and subsequent unsupervised mating.

What are the implications of your observation on the distribution of exotic and indigenous genes in the study region?
Whereas breed improvement programs are in all parts of western Kenya, the observed skewed distribution of the exotic genotypes across the study regions draws a lot of attention. The genetic cline observed where higher European taurine genotypes were found in the Northern sub-locations as opposed to the southern ones may be indicative of possible purging out of the European genotypes that are deemed unfit by the tropical environment. The constant disease and vector pressures may be selecting out these exotic genotypes with time. The differences in the climatic conditions in the north and south as well as prevalence of disease and vectors may have significantly contributed to this phenomenon. The inability of these exotic animals to survive long enough to pass on their genes or have surviving offspring in these environments may indicate failed introductions of breed improvement programs. These findings call us to pose pertinent question as to whether the introduction of the exotic genotypes is really beneficial to the average small-scale farmers within certain regions.

What were some of the sources of these exotic animals and how can they be efficiently introduced?
The main sources were bull schemes, artificial insemination and heifer donations by the breed improvement programmes as well as animal markets in Bumala and Amukura sub-locations. With the evidence of possible purging out of exotic genotypes, the introduction of exotic animals in a new environment needs to be systematic and well researched for these programs to be successful. Different animals are suited to different areas and while an animal may be seen to perform better in the short term the case might not be so in the long term.

Is it a worthwhile for international organizations and the government to invest in this venture?
My findings paint a typical “one man’s meat is another man’s poison” scenario where short term results of relatively high-milk production favourable from a socio-economic point of view tip the balance to long term losses of cattle populations to infectious disease due to the loss of adaptive traits that is undesirable from a genetic diversity view point. However, if emphasis by these bodies is put into research to match genotypes to environments we may have favourable results.

What do the findings say about farmers’ knowledge on the introduction of exotic genotypes?
It is obvious that farmers are not aware of the repercussions of introducing exotic genotypes into their indigenous breeds and have thus continued to participate in these activities. There is a pressing need to educate farmers on these effects and to empower them with adequate knowledge on the importance of conserving and managing their indigenous breeds.

What do you recommend based on these findings?
While the productivity of indigenous cattle could be low as compared to the exotic genotypes, these animals possess some very good ecologically important traits like disease/vector resistance and heat tolerance that we cannot afford to lose in this continent. Neither can we afford to trade off adaptability for short term economic gains and expect to bring about lasting solutions to the African farmer. There is a need to work towards a more sustainable goal through tapping into indigenous cattle breeds and improving their productivity and resilience within the confines of Africa. Success need to be confounded to continuity. More studies and a greater understanding of our indigenous cattle need to be done.
The observed drastic reduction in the indigenous zebu stock calls for immediate conservation and management strategies to prevent further loss and possible genetic uniformity that would have unfavorable implications on the populations’ fitness.

Did you face any challenges while carrying out your project?
Both my supervisors (Prof. Olivier Hanotte and Dr. Miika Tapio) left ILRI just as I began my studies but their dedication and commitment towards me attaining the ultimate goal throughout the four years is something that I will forever be grateful for and indebted to them. Last but not the least, redefining the role of an African woman in the present day world was a leap of faith for me. Playing the role of mother, wife, and student were the hardest glass balls to juggle but I got it right at the end.

What are your future prospects after this study?
I’m keen on applying the knowledge I gained to carry out in-depth studies to identify the best suited candidate genotypes that survive best in particular environments. I would like to be involved in projects that are aimed at not only providing economic solutions, but sustainable solutions that will bring lasting change for the African smallholder farmers who have continued to remain lost in the background as we forge ahead in our pursuit in science. The cart has to come after the donkey and that calls too for the African farmer and agricultural research. It’s time to make the African livestock genome work to the benefit of the average farmers, It is time to utilize exhaustively upcoming new bio-technologies to inform the knowledge gap in African animal genetics and oil the rusty cog of the African agricultural wheel churning towards eradication of poverty and targeted breed improvement strategies.

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