Research Project 4: The interaction of work and nutrition on the trypanotolerance of N'dama cattle in The Gambia (1993-5)

Purpose
The disease trypanosomiasis restricts the use of cattle in sub-Saharan Africa.  However, some breeds of cattle (e.g. the N'dama) are naturally tolerant to the disease.  Exploitation of this tolerance offers a practical option for increasing livestock productivity in areas where the disease is endemic.  Although trypanotolerant cattle are able to survive in areas of heavy tsetse fly challenge, trypanosomiasis will reduce their productivity, including the performance of any animals used for work.  This study investigated the interactions between work, nutrition and trypanotolerance, using N'dama cattle in The Gambia as an example.

Activities
The immune responses of working and non-working N'dama cattle, when challenged with a Trypanosoma congolense serodeme were studied in bulls on two planes of nutrition in The Gambia.  A 2 x 2 factorial experiment with eight 2-4 year-old bulls in each group was carried out.

In this study trypanosomiasis caused the working speed and power output of trypanotolerant N'dama cattle to decrease.  In contrast, the mean weekly lap times and power output of the control team remained almost constant.  These animals had been challenged with a trypanosome isolate to which they were immunologically naive.  In areas where trypanosomiasis is endemic, the disease may have a less dramatic effect on the work output, where adult cattle have had prior experience of infection.  Plane of nutrition had no effect on performance in any of the three phases (uninfected, prepatent or parasitaemic).  In general, increasing the plane of nutrition did not ameliorate the effects of the disease, nor did it prevent loss of appetite in infected animals.

The experiment showed the strong antagonistic effect between work and disease in trypanotolerant N'dama cattle challenged with a novel serodeme.  The marked decrease in work performance, a fall in trypanotolerance, and a loss in body weight could only be alleviated by stopping work.  These results support the case for prophylactic protection of work animals against trypanosomiasis prior to the start of the working season, even if the animals are regarded as trypanotolerant, since failure to do so could affect crop production.

Collaboration
The project was funded mainly by the ODA (now DFID).  Scientists from CTVM, the International Trypanotolerance Centre (ITC) in The Gambia, and the Natural Resources Institute, Kent, UK collaborated in the research, undertaken in The Gambia.

Outputs
As well as the articles and reports, written by the main collaborators from the different institutions, Richard Clemence and Jamie Bennison, the two main investigators, obtained their PhD degrees for their work, and one MSc was obtained:

PhD

	R.G. Clemence, 1997 (University of Edinburgh), Relationships between disease, work and nutrition in draught cattle and buffalo.
	J.J. Bennison, 1997 (Wye College, University of London), The effects of nutrition and trypanosomosis on the productivity of trypanotolerant N'dama cattle.

MSc

R.J. Alford, 1994 (University of Edinburgh), Working and feeding strategies of draught N'dama oxen in a Gambian village

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