47 - Network research: Future developments

J. C.M. TRAIL

To help in visualizing the overall research area, Figure 1 shows the problem tree, as viewed up to the present. The octagonal boxes indicate researchable areas, not necessarily all possible in Network situations of course.

Figure 1. Problem tree.

What we have been and are tackling within the ATLN is laid out in the matrix in Figure 2, with four broad themes. Each is divided into three or four so-called projects with aspects of these being handled in different sites.

Figure 2. THEME X PROJECT X SITE MATRIX IN THE AFRICAN TRYPANOTOLERANT LIVESTOCK NETWORK

Finally there are a set of basically one-page protocols indicating in a few sentences the justification, objectives and activities involved in each case, (Figure 3).

Figure 3. Sample protocol.

A.02 Research Theme	Trypanotolerance
A.06 Project number	2.3
A.07 Short project title	Criteria of trypanotolerance
A.08 Full project title	Criteria of trypanotolerance and their linkage with animal performance.
D.01 Justification
	The increased utilization of trypanotolerant livestock is a promising method for developing livestock production in tsetse affected areas. Improved performance may be possible by selection for trypanotolerance. In order to define effective management and genetic selection programmes, criteria for trypanotolerance must be defined and their relationships with production traits evaluated.
D.02 Objectives
	- Definition of criteria for trypanotolerance
	- Evaluation of the relationships between the criteria for trypanotolerance and the production traits.
D.03 Activities/experiments
	At all sites
	- monthly collection of data in selected herds and/or flocks on livestock health (trypanosome infection, species and parasitaemia score, PCV and intercurrent disease), viability and production (reproductive performance, growth, milk production and draught work as appropriate).
	At appropriate sites
	- evaluation of the effect of number and species of trypanosome infection and their parasitaemia score on traits based on PCV and on the production traits.
	Site details
	2.3.1 Kolo	- N'Dama cattle under ranch management at zero to low and medium trypanosomiasis risk.
	2.3.2 Mushie	- N'Dama cattle under the same ranch management as at Kolo but medium to high trypanosomiasis risk.
	2.3.3 Idiofa	- N'Dama cattle under village management at low and medium trypanosomiasis risk.

Our overall research aims have been summarized in a number of ways over the years; the summary that appears in current ILCA planning documents is as shown in Figure 4.

Figure 4. Overall Research Aims.

ILCA'S STRATEGY AND LONG-TERM PLAN AFRICAN TRYPANOTOLERANT LIVESTOCK NETWORK
1.	Collection and analysis of data on the productivity of trypanotolerant breeds under varying levels of trypanosomiasis risk.
2.	Identification of more reliable indicators of trypanosomiasis risks
3.	Definition of a selection criterion for trypanotolerance, in order to devise optimum breeding programmes.
4.	Evaluation of the costs and benefits of selected tsetse-control measures, and their interaction with prophylactic drugs,
5.	Testing of nutritional interventions to improve livestock productivity in tsetse-infested areas.
6.	Study of the effects of trypanocidal drugs in order to determine appropriate interventions in areas of medium to high trypanosomiasis risk.

It is first of all important to try and put a time perspective on the first broad aim. Everything measured has to be linked to the resultant livestock productivity. If cattle are used as the example, the trait requiring the longest evaluation period is reproductive performance, as measured by calving interval. A major target area is smallholder production systems and Jeannin et al. (article 19) have shown us that typical calving intervals in these systems are two years. A minimum of two calving intervals are required for any meaningful productivity estimation and an average of four years for two calving intervals requires, in practice, five years of data collection.

However, a herd is dynamic with an average turnover of about 20% per year. So in practice, if we record in a herd for five years, only about 50% of our animals will have this complete information for two calving intervals. So a further two years of work are required on at least a proportion of the herd to obtain the optimal amount of information required.

The data that have been reported in the Meeting actually covered January 1984-December 1986, so by the end of 1987 there will be four years data available; a further three years will therefore be required. In our December 1986 report, we indicated that from 1987 onwards we would as often as possible introduce two aspects into the ongoing programme of collecting matching data.

The first aspect was the fitting of properly designed interventions into a site programme so that their effects could be simultaneously evaluated. Examples would be nutritional interventions as reported by Agyemang et al. in The Gambia (article 23); a partial prophylactic regime as reported by Ordner et al. in Gabon (article 31); and a complete prophylactic regime as reported by Maloo et al. in Kenya (article 29) and Hendy in Tanzania (article 30).

The second aspect was the strategic manipulation of key animal groups within geographical situations and seasons of the year. Examples would be such as the temporary movement of young-stock at Ogaprov in Gabon (article 41) and Mushie in Zaire (article 43) where this was done in order to take advantage of the highest possible natural challenge conditions. So these are the operational approaches we have started to use, in order to tackle the other research aims that are summarized in points 2-6 of Figure 4.

Coming back then to the four themes laid out in the matrix of Figure 2, some general points would be as follows. In theme one, Jordan (article 4) brought out the need for evaluating, at a representative group of sites, the development of challenge over a reasonable period, suggesting ten years. An example from Leak et al. (article 5) indicates the importance of this and we have currently planned selected evaluations to run for seven years. Nankodaba (article 6) emphasized the necessity of focussing on herds within situations, to have a better chance of relating tsetse challenge to the trypanosome prevalence situation. Our colleagues in the ODA-funded tsetse operation at the ITC in The Gambia, of which Wacher (article 8) is a members are trying to go much deeper into challenge-estimate aspects than we have personnel or facilities for at any other site. Murray (article 15) among others has emphasized the importance of the diagnosis of trypanosomiasis. We look forward to the field testing of new methods at our sites, when ILRAD and perhaps the International Atomic Energy Agency are ready to undertake this.

In theme two, as far as criteria of trypanotolerance are concerned, we think there are major possibilities in short-term manipulation of animal groups to expose them to the highest possible challenge for relatively short periods and link results with an easily recorded performance trait such as growth (e.g. article 41). With other traits, such as reproductive performance, however, there seems to be little alternative but to build up as much information as possible over much longer periods at the sites that have the highest year-round challenge levels (article 21). Obviously in interactions between trypanosomiasis and other diseases we are concentrating on situations where such possibilities really exist (e.g. article 12). A key problem referred to in the meeting was the lack of high challenge situations within which we are able to work. McIntire (article 34) emphasized how focus should be on studying differentials within sites and exploiting their potential.

In theme three, we have presented the very first indications on possible heritability levels of criteria of trypanotolerance (article 43), which also illustrated the major problems in arranging single sire matings to obtain paternal half-sib groups. The practical possibilities of blood grouping for parentage information, presented by Thorpe (article 42), would seem to offer great opportunities to very rapidly progress in this important area. Teale (article 44) has samples collected at Mushie, Zaire, from N'Dama cattle whose trypanotolerance criteria have been very extensively documented. This should maximize the possibility of detecting associations between the major histo-compatability complex and performance and health aspects.

In theme four, we have had discussions on a considerable range of intervention possibilities. The evaluation of the prophylaxis intervention in the Muhaka village situation in Kenya, where the biological results were presented by Maloo (article 29) and the economic appraisal by Itty (article 35), are very good examples of the capability of the Network operation to carry through assessments to the point where they are of genuine value to development planners in coming to decisions on funding.

Thus, in summary, the outputs expected from the work programme of the ATLN, with significant results achieved by the end of 1989 are:

1. Determination of the contribution that tsetse evaluation can make in planning for increased livestock production resulting from predictions of animal health and performance.

2. Accurate evaluation for field use of diagnostic tests for trypanosomiasis that have been developed by other agencies (using network animals serially recorded over time).

3. Quantification of health and productivity data from trypanotolerant and susceptible livestock under varying conditions.

4. Quantification of breed differences in trypanotolerance and associated performance.

5. Determination of the heritabilities of and the genetic relationships between the three major characteristics of trypanotolerance and animal performance. This will indicate whether it will be possible to increase production through selection programmes based on trypanotolerance criteria.

6. Determination of any association between the major histo-compatibility complex and trypanotolerance that could then be used in practical selection programmes.

7. Determination of the relevance of future field research based on artificial challenge regimes, by measuring the phenotypic and genetic relationships found between the effects of natural and artificial challenge.

8. Identification of network sites with the highest challenge levels. These are where maximal progress will be possible if natural challenge is shown to be a prerequisite for selection on some criteria of trypanotolerance.

9. Scientific understanding of the factors affecting economic performance of trypanotolerant livestock in a wide range of production systems.

10. Development of a cadre of national scientists and technicians capable of increasing livestock productivity under trypanosomiasis risk and of providing further training to their colleagues.

In planning research operations, it is not always realized what an apparently straightforward decision, such as to manipulate animal groups in a site, means to our colleagues who are carrying out the field work. To obtain the highest possible exposure to natural challenge means that animals probably have to be moved to the most isolated, least developed area of the site, at a time of year when rains make travel very difficult. They then have to be very carefully recorded over perhaps a six-month period. It really requires dedication to operate in such circumstances. So our colleagues throughout the Network must be praised for the dedicated work they have put in over the past year. It is to be hoped that they can continue to find such enthusiasm and dedication over the next few years of our joint research programme.

Finally, the results presented at the meeting clearly suggest that further programme focussing and grouping of sites on a regional basis from 1988 onwards will allow optimal progress to be achieved. Thus sites in Gabon and Zaire appear best suited for research in genetic and animal breeding aspects; sites in The Gambia and Senegal for research in nutrition, reproduction and milk extraction; sites in Cote d'Ivoire and Burkina Faso for research involving the West African Shorthorn, interaction between trypanosomiasis and other diseases, and the effect of tsetse reduction on animal health and productivity; and associated sites in Ethiopia and Kenya for research on susceptible livestock and specific cattle groups that have demonstrated a degree of adaptation to a trypanosomiasis affected environment.