T.W. Schillhorn van Veen
Department of Large Animal Clinical Sciences and Microbiology
Michigan State University
East Lansing MI 48823 USA
Measurement of production losses
New developments in animal husbandry and health
Disease and marketing
Livestock support infrastructure
Recognition of opportunities
Some general aspects of small ruminant health and the effect of health on production are reviewed. Examples are given of the management practices, new technologies and infrastructural changes which may improve the production and marketing of sheep and goats. Health improvement mainly by means of education through extension services and minor use of drugs and vaccines may considerably increase productivity.
Health is still a major constraint to efficient livestock production. Interventions which enhance health are very popular among livestock owners in Africa and elsewhere, and appear to have an attractive short term return. Despite these optimistic observations, there is still a lot to be learned about the improvement of health and production in African livestock. Although we are fairly knowledgeable about the deficiencies and disease problems, the control and prevention effort has been less successful than expected. Various reasons are given, as discussed elsewhere (Eicher, 1984; Schillhorn van Veen, 1984), but poor organization and low priority for livestock services in, and outside, governmental organizations seems to be a major cause.
This paper discusses some of the constraints on production, the economic benefit and difficulties of introducing interventions and the effects of health on international marketing. It also lists some technological developments which may, ultimately, have some impact on livestock production in Africa.
The bias towards discussing mainly West African examples is partly related to the author's personal interest and experiences but also to the lack of published material from other parts of Africa.
Until recently disease in African livestock was only measured in terms of mortality. Production diseases and deficiencies were rarely considered important. In the last decade, however, there has been an increased interest in measurement of production losses, which in some cases shows that the benefit of preventing diseases with a high morbidity but low mortality may be greater than preventing occasionally fatal epidemics (Akerejola, Schillhorn van Veen & Njoku, 1979; Aklaku, 1980; Matthewman, 1980; Sumberg & Mack, 1985).
The methodology of measuring production losses is unfortunately still not universally standardized and criteria developed in Europe or the USA are often not applicable to African conditions. The common denominators for production in developed countries, e.g. weight (either body weight, fleece weight or milk production), total production per unit area and mortality, may not be the exact criteria to measure production under conditions in Africa. Firstly, because animals are kept for additional reasons (manure production, skins, ceremonial use). Secondly, because the residual value of old, diseased or dying animals is higher than in developed countries. During a survey in rural slaughterhouses in northern Nigeria in the early 1970s, for example, the value of a diseased animal at the slaughter house was approximately 50 per cent of the price of a normal animal of the same size and 25 per cent if the animal had to be slaughtered in the compound of the owner or in the field.
The measurement of production losses as such is extremely difficult, expecially under field conditions where control animals are still exposed to a variety of diseases, parasites and deficiencies.
Bioscientists have made further efforts to define normal animals by looking at clinical and biochemical parameters (Oduye & Adadevoh, 1976; Saror & Schillhorn van Veen, 1977; Thomas & Chiboka, 1984) or physiological criteria (Schillhorn van Veen & Folaranmi, 1978; Preston & Allonby, 1979; Buvanendran et al, 1981). The latter studies revealed that the small ruminant population in Africa shows considerable variability in genetic make-up which opens up interesting avenues of research on genetically determined disease and production factors. Results of this research should not be expected too soon and, in the meantime, improvement in production can and has to be achieved by improvement of husbandry and management.
Management is often a major factor in the success or failure of a farm enterprise but little effort is made to study management except in a few specialized areas (Schillhorn van Veen, 1983). Table 1 provides an example of a number of production losses and diseases, nearly all of which are influenced by management. There is ample evidence that the traditional African livestock owner is well aware of the role of management in the avoidance and control of animal disease (Croix, 1945; Ba, 1984). There is little evidence in the literature, however, that controlled studies have been done on the effect of certain husbandry practices and their impact at farm and village level. Typically, the discussion about these practices is performed along disciplinary lines: sociologists and economists rarely make an effort to understand the techniques of livestock raising and veterinarians and animal scientists respond in kind. More effort should be made to integrate these different aspects or viewpoints, as tried in an example in Table 2.
On-farm management is strongly influenced by local conditions. Spharim & Seligman (1983) identified 18 different husbandry systems in the relatively small northern Negev in Israel and reviewed these with respect to various inputs. Their model indicated, for example, that highly fertile Finn sheep required a more labour intensive system than the less fertile Awasi sheep: a similar situation is found in arid western USA where high fertility is considered a liability rather than an asset.
Table 1. Major causes of production losses and constraints which are the underlying causes
|Disease (epidemic, PPR, etc.)||*||*||*|
** major role: *? indirect role - mainly related to availability of vaccine, medicine and supplement: * minor role
Table 2. Impact of certain changes in management and disease control
|Enclose animals at night||*||*||*||*|
* impact at farm level: ** impact at village or district level: *** impact at farm and village or district level
Management capabilities are difficult to measure, especially under varying field conditions but simple management improvements that are widely promoted are not widely accepted. These include: feeding from feed troughs rather than from the ground; provision of trace mineral supplements; controlled breeding; adequate feeding of pregnant ewes or does; ensuring intake of colostrum in day-old lambs and kids; and foot care.
Introduction of such management practices requires an adequate extension network and a continuous effort, which should be combined with other health related activities (Bouncy, 1981; Hindson, 1982).
Among the many developments in animal science and biomedicine are some which may be of benefit to the African livestock industry in the foreseeable future.
HERD HEALTH APPROACH
The herd health systems presently developed in Europe and the USA may have some benefit for Africa. Ideally the method provides for sound data collection, either by farmers themselves or through enumerators. Dedicated record keeping over a period of a year or more does indeed provide valuable data (Wilson, 1980; Mack, 1983). Ten years ago the method was used in Nigeria to obtain data on production constraints and on seasonal changes in disease incidence as measured by emergency slaughter in small villages (Figure 1). Sound data on a given system are crucial for the introduction of interventions and are a minimal requirement for any development project.
Seasonal or general undernourishment is a major problem in African livestock. Livestock management interventions such as planned breeding, fodder preservation, early slaughter, mineral supplementation, and treatment of chronic disease are of value to prevent serious losses but they are rarely implemented.
Figure 1. Seasonal distribution of reasons for slaughter of sheep at a rural abattoir in northern Nigeria
On the other hand, bioscientists are better able to understand the physiology of undernourishment. Examples are the effect of hormones such as cholecystokinin which influence feed intake (Symons, 1978) and the purification of cachectin, a macrophage factor which suppresses the activity of the enzyme lipoprotein lipase, leading in experimental models to a chronic wasting disease (Beutler et al, 1985). A better understanding of the role of such hormones may help to solve disease problems in African livestock such as chronic parasitism and trypanosomiasis.
BIOENGINEERED VACCINES AND DIAGNOSTICS
During the early 1980s a number of technological innovations in biochemistry and immunology led to an explosion of new ideas and approaches to health problems in man and animals. So far, however, the substantial and mainly commercially sponsored research has not led to major applications in animal health.
It is doubtful whether these developments may in the next decade indeed produce innovations which will be both applicable and affordable in Africa. The bioengineered foot-and-mouth disease and malaria vaccines produced in the USA are still in the development stage and other vaccines lag behind. Improvement in the diagnosis of disease with the help of monoclonal antibodies still has considerable drawbacks but has successfully been used to identify East Coast Fever strains in cattle in Kenya.
NEW DRUG DELIVERY SYSTEMS
There exists an increasing interest in drug delivery in veterinary medicine. This has led to drugs and feed additives being incorporated in feedblocks, to intra-ruminal slow-release devices and to subcutaneous implants. At present, technology is being developed for pulse release mechanisms, removable implants and local release devices. These methods may have benefits in the control of many livestock diseases which currently require frequent single treatments and the use of long-acting drugs. The unwelcome consequences of long-acting drugs are residues in meat and milk which are a potential hazard to the consumer and, at the national level, restrict export markets. A more delicate use of drugs and feed additives with the help of these newer devices would not only improve the image of the livestock industry but could also in the long run lead to economic benefits as the volume of drugs used is reduced. Most are still in the developmental stage and may well be too expensive for routine use.
UTILIZATION OF DISEASE RESISTANT BREEDS
The utilization of resistance has attracted increasing attention during the last decade, especially with respect to trypanotolerance (ILCA, 1979). In cattle this appears to be an incomplete dominant trait. Biochemists try to determine the genetic base at the molecular level for resistance factors and are now considering inserting genetic material into the nuclei of embryos to improve their genetic make-up.
The two diseases in which applied research on resistance has been carried out are trypanosomiasis (Griffin & Allonby, 1979; Toure et al, 1983; Murray, Trail & Grootenhuis, 1984) and haemonchosis (Preston & Allonby, 1979). In addition, efforts are being made to improve tick and ectoparasite resistance. The results of these research efforts are promising but many problems need to be solved before wider application can be expected (Albers, Burgess & Adams, 1984). Whitelaw et al (1985) were unable to demonstrate resistance against T. congolense in a selected number of breeds and crossbreeds and suggested that "resistance" was probably related to the fact that goats are less attractive to tsetse flies.
Most African breeds are naturally selected for their particular environment. Movement out of that environment or cross-breeding may lead to a decline in adaptation as demonstrated by numerous experiments over the last 50 years. The view that a certain disease or deficiency is the major or only constraint is biased, and other factors (drought resistance for instance) may be more important in the natural selection process (Schillhorn van Veen & Folaranmi, 1978). Moreover, with an intensification of production, the disease pattern changes: important diseases in nomadic systems may be a minor problem in settled systems (Wilson et al, 1984). Research should be continued, as improvement in the knowledge of the immunological basis of disease resistance may ultimately lead to applicable innovations.
Small ruminants are an attractive export product for many African countries. Potential markets in North Africa, the Middle East and southern Europe are fairly close. For various reasons, live animal export has been preferred by these countries, thus enhancing the advantage of African producers over competitors in Australia and New Zealand (Holtzman, 1982). Production for export is risky, however, as demand may rapidly change, influenced by political considerations, currency changes and, most of all, by the quality of the product.
Animal health is important not only from a quality viewpoint, but also from a political one. Too often markets are closed for public health reasons whether justified or not. Governments interested in export of small ruminants should provide an infrastructure which reduces the risk of market changes for disease reasons. With respect to Europe and the USA this may be impossible, at least in the short term in most African countries but for nearby markets it should be feasible. Table 3 shows that many of the infectious diseases in producing countries in Africa are also present in most potential market countries. This should provide little comfort, however, as most Middle East countries are active in the development of animal health programmes, which include eradication of these diseases. Also, economic situations may change rapidly as was experienced by East African cattle producers in the 1970s when the beef market collapsed (Shapiro, 1980) and many countries imposed import restrictions to protect their livestock industry, often using "disease risk" as the justification. Fortunately, small ruminants are a special product and their marketing in Africa is not directly influenced by the world market.
Table 3. Prevalence of some contagious diseases of small ruminants in selected countries which import African livestock or are potential markets
United Arab Emirates
nd no data: * reported sporadic: ** reported commonly
Some of the restrictive diseases which prevent export of cattle or beef are, however, also carried by sheep and goats (e.g. foot-and-mouth disease, brucellosis and blue tongue) and restrictions aimed at cattle may affect export of small ruminants (Watson, 1984).
Understanding the constraints, developments and options of current small ruminant production systems allows a decision about change and/or improvements. In many respects we should be reluctant to make such decisions as there are still too many unknowns. Often, however, farmers themselves make changes without outside help or advice, using available means and remedies (Chavanduka, 1984). This is probably the best model of change: let the livestock owner decide and let all others involved in livestock support or research provide him with the information needed to make sound decisions, but not interfere with his decision making. This requires a good extension system backed up by research data.
Livestock extension is neither well developed nor well supported in many African countries. Agents are young and inexperienced and as such not accepted by producers. Often they are not kept up-to-date, especially in those extension services not connected with a university or research institute. Extension efforts combined with dipping services and/or vaccination campaigns have various advantages but may be less accepted when such services are enforced (Muriithi, 1984). A critical evaluation of the extension effort, especially in the area of small ruminant health and management, could lead to major improvements in the industry.
Few data are available on the cost/benefit ratios of health interventions in the tropics. A few crude data on the effects of certain interventions (Table 4) show that vaccination for PPR, anthelmintic treatment and mineral supplementation are beneficial in particular areas of study. Such data need to be developed at many sites in Africa as local conditions and diseases vary. Extrapolation from different countries as well as from different species may be risky and suggestions to introduce large scale vaccination campaigns for the control of PPR similar to those for rinderpest in cattle (Sumberg & Mack, 1985) may need further discussion considering the longevity and number of goats at risk and the logistics and costs involved. Based on earlier findings ILCA has introduced health packages in some trial villages (Mack, 1983) but still has to demonstrate that such packages will, in the long run, be accepted (i.e. paid for) by livestock owners. Comparable packages which included anthelmintic treatment and dipping for mange were popular in Nigeria during the 1950s, indeed so popular that they became a drain on government resources (Schillhorn van Veen, 1978). For some time they were then offered by private suppliers but were later discontinued. It is clear that ultimately it is not the role of government fully to care for the livestock sector but rather to provide information and incentives for producers to sustain and expand production. In this respect, governments should take a closer look at livestock development support structures which are often divided over different ministries and are poorly supported.
Table 4. Effect of technical interventions on small ruminant production
Effect on production
|Vaccination:||PPR||-19%||n.d.||Wilson et al, 1984|
|Pasteurellosis||-2%||n.d.||Wilson et al, 1984|
|Monthly in wet season||-90%||+40-60%||Schillhorn van Veen & Brinckman, 1975|
|Twice per year||-75%||+30%||Specht, 1982|
|Supplementation: Cobalt||n.d.||+||Gyang, unpubl.|
Government support for the livestock industry is poor in most African countries (Anteneh, 1985). Indirect, non-measurable, support such as stimulation of private industry, improved transport (roads and railways from rural areas), marketing and export facilities can also be improved. Livestock marketing systems work but are not very beneficial to the producer. Private veterinary services (partly subsidized) and supplies of feed and supplements are also deficient or at least unreliable. Data on livestock experiments are either not published or written up in cryptic reports not available to the general public. Provision of such services should have high priority for without these there is little hope of sustained improvements.
Most of the livestock industry in Africa is still out of-date. Changes proposed are often expected to be applicable across the board in a particular country, if not in most of Africa. Innovations which make use of local opportunities are rarely initiated. Breeding and marketing sheep for Muslim festivals, for instance, tried in Nigeria in the early 1970s did not receive wide application. The profitability, however, was demonstrated and has recently been confirmed (Kolff & Wilson, 1985). Other opportunities with respect to marketing (religious festivals, proximity of urban markets), availability of fodder (river flood plains, crop residues), use of by-products, availability of expertise, etc., should be considered and stimulated at the local level. Examples of such opportune foci of small ruminant production are abundant in other parts of the world and could provide a sound base for production in a given area. Computer model data as well as field observations (Spharim & Seligman, 1983) demonstrate the viability of different systems in a limited geographical area. Existing opportunities are however not always utilized because of government constraints or inflexibility of local social structures.
Identification of opportunities requires considerable effort and cannot be achieved on research stations. Cooperation between extension and research staff is paramount in these, as well as in other, efforts to improve the small ruminant industry.
Stall-fed ram (Sahel x West African Dwarf) being fattened for slaughter at Muslim festival