Installing solar milk cooling in a trial project in Tunisia.
Photo: © University of Hohenheim/Victor Torres Toledo

Milk cooling with solar power for African smallholders

Researchers at the University of Hohenheim are developing solar-powered milk cooling for smallholders in Africa and strategic feeding for dairy cattle in Tunisia and Kenya. The projects are part of the “One World, No Hunger” initiative run by the German development ministry and are being implemented by GIZ in the context of the project "Sustainable Energy for Food – Powering Agriculture".

Smallholders in Africa often have only small numbers of cows and are not linked to the power grid. Lacking refrigerating, they can only market part of the milk they produce. This predicament is to be remedied by a new cooling system based on solar power as well as a strategic feeding concept both of which have been developed by scientists at the University of Hohenheim in Stuttgart, southern Germany.

The research activities are two of three subprojects at the University of Hohenheim that are integrated in a larger project run by the German Federal Ministry for Economic Cooperation and Development (BMZ).

 “Many small dairy farmers in Africa are far from having fully exploited the potential of their farms. In Tunisia, for example, 85 per cent of the dairy farmers have fewer than ten cows, they are often not linked to the power grid, and access to the markets is frequently restricted,” says Professor Joachim Müller of the university’s Agricultural Engineering in the Tropics and Subtropics department.

Together with Professor Karlheinz Köller of the Process Engineering in Plant Production department, Professor Müller is seeking options to provide special support for the milk value chain in Africa. The researchers say that milk cooling is a crucial aspect.

Cooling enables higher milk production, since the farmers can milk their cows twice a day, the scientists explain. Furthermore, cooling retains milk quality and thus ensures premium prices. This in turn improves access to markets for the farmers and also enables them to supply cheese and other dairy products, as the scientists told participants in a workshop held at the University of Hohenheim early in January.

But cooling can only work with electricity. The scientists came up with the idea that if milk cooling had so far been ruled out by the lack of a power connection, solar power could solve the dilemma. Against this background, they developed a solar cooling plant at the University of Hohenheim that is now being installed and tested at one of the so-called Green Innovation Centres in Tunisia.

Technology transfer – the cooling system put to the test

“In our system, ice is first of all prepared with solar power,” says doctoral student Victor Torres Toledo, explaining the principle. “We fill the ice into an extra vessel in the middle of special, insulated, 30-litre milk churns. This enables the milk to be cooled from inside for up to twelve hours, which prevents the formation of germs.”

Ten prototypes of such a solar cooling plant are currently being test-run in Tunisia. Now trials are being run locally in order to assess the system’s potential in real conditions. The researchers then want to extend the system to Kenya and adapt it to the local conditions there.

Animal nutrition – milk performance determined by feeding

Optimised animal feeding was a further option to support the African dairy farmers, Professor Uta Dickhöfer of the Animal Nutrition and Rangeland Management in the Tropics and Subtropics department maintained at the workshop. “Feeding determines milk performance, the quality and composition of the milk – and therefore its price,” Professor Dickhöfer explained. “And in the tropics and subtropics, this is where we face special challenges. There are considerable seasonal discrepancies in the quality and quantity of feed.”

However, the African smallholders often have very little access to concentrated feed, which is commonly used in Europe. And the scientists in Germany often lack basic data on the energy and nutrient requirements of the local animal breeds and available feed.

Strategic feeding instead of concentrated feed for all

Simply giving all cows more concentrated feed would not be efficient and would require too much capital. “Strategic feeding adapted to the day-to-day requirements of the animals aimed at enhancing the productivity of individual animals as well as the herd as a whole makes more sense,” says Professor Dickhöfer. The farmers only give small amounts of concentrated feed to certain animals. In this manner, much can be achieved with relatively little animal feed, and the herd potential can be better exploited, the expert explains.

However, Professor Dickhöfer notes that a number of open questions remain. At the moment, the scientists in Hohenheim still lack many data on keeping and feeding local breeds in the tropics and subtropics. Professor Dickhöfer and her team first of all intend to conduct experiments in Tunisia and Kenya in order to establish the size and structure of cattle herds as well as their fertility. “If we then integrate data on milk performance of different races depending on feeding, we will be able to assess influences on herd performance,” she says.

(Universität Hohenheim/wi)

More information: University of Hohenheim (in German only)