PHOTO: KABIR DHANJI
HEAL ▶▶▶TH
Heat setting off alarm bells in East Africa
East Africa has the largest population of livestock in sub-Saharan Africa. Climate change, with its hotter and more humid weather in the region, is putting increasing pressure on the local dairy sector, making exotic dairy production challenging in much of the region.
BY NATALIE BERKHOUT E
Dairy farmer Lwitiko Mwakaliba in Tanzania.
ast Africa has the highest population growth on the continent and is home to approximately 145 million cattle. However, research published in Nature Food warns that the frequency of dangerous heat stress
conditions and the average number of consecutive days with heat stress events will significantly increase. This will detri- mentally impact the thermal comfort of dairy cows across the region, thereby negatively impacting milk productivity. It is also worth noting that beef cattle production is reported to be less sensitive to heat stress than dairy cattle production. The maximum temperature in East Africa increased by 1.16°C across the period 1953–2013, and by the middle of the 21st century, temperatures are predicted to increase by 2–3°C in the middle and northern parts of East Africa. Such climate
changes will alter the frequency of heatwave events. Further- more, climate data going back to 1981 shows that livestock have already been progressively subjected to heat stress con- ditions, and projections by the team of researchers show that the situation is set to worsen significantly.
Heat stress in dairy The frequency of Severe/Danger heat stress events (events that result in significant decreases in productive and repro- ductive performance) for dairy cows between 1981 and 2010 ranged from less than 2.5% in some areas in the eastern and northern parts of East Africa to more than 50% in the central parts of South Sudan, eastern parts of Kenya and southern parts of Somalia and Eritrea. Furthermore, the frequency of Severe/Danger heat stress for livestock increased in 26% of the study area for dairy cows (Figure 1).
Heat stress projections In terms of future heat stress projections for dairy cows, the average frequency of days with Severe/Danger heat stress is projected to increase by around 12% by the period 2071– 2100 compared to the historical period and to occur on more than 50% of the days of the year. The researchers’ projections show that under future climate conditions, both the number of days with heat stress and the length of heat stress periods will increase in East Africa. For dairy, the average length of heat stress periods categorised as Severe/Danger went from around three days in the historical period to 20 days in the 2071–2100 period. It is interesting to note that, currently, ~11–15% (~2,924,000–~3,987,000 tonnes of milk) of total milk produc- tion occurs in areas where the frequency of Moderate and Se- vere/Danger heat stress is expected to increase significantly by 2071–2100. In the period 2021–2050, 8–15% of milk pro- duction is likely to be affected. These elevated levels of heat stress could make much of East Africa unsuitable for dairy production unless direct and immediate action is taken.
Urgent planning and investment Co-author of the study, Klaus Butterbach-Bahl at the Interna- tional Livestock Research Institute and the Karlsruhe Institute of Technology, which analysed the climate data, said: “This paper is an alarm bell for policymakers and anyone involved
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