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Biotechnology options for improving livestock production in developing countries, with special reference to sub-Saharan Africa

J.E.O. Rege

International Livestock Centre for Africa (ILCA)
P. O. Box 5689, Addis Ababa, Ethiopia

Abstract
Introduction
Overview of available biotechnologies
Need for biotechnology capacity in developing countries
References


Abstract

Techniques of modern biology such as molecular cloning of genes, gene transfer, genetic manipulation of animal and plant embryo transfer, genetic manipulation of rumen microbes, chemical and biological treatment of low quality animal feeds for improved nutritive value, genetically engineered immunodiagnostic and immunoprophylactic agents as well as veterinary vaccines, inter alia, are a reality today and are finding their ways into research and development programmes of developing countries. Biotechnology is offering unprecedented opportunities for increasing agricultural productivity and for protecting the environment through reduced use of agro-chemicals. The major thrust in biotechnology research is currently directed at solving immediate problems of industrialised countries, with major investments coming from transnational companies. However, many of the new discoveries and products will find their biggest markets in developing countries where the potential for improvement in agricultural productivity and health is greatest. The importance of biotechnology and its relevance is only slowly being accepted by policy makers in developing countries. In the presence of economic crisis, strong fiscal constraints, rapid social change and constant political instabilities, the difficulties associated with major policy changes in developing countries are enormous. This paper reviews available biotechnologies with potential application in livestock improvement and identifies those which have been or may be applied in developing countries in general, and Africa in particular. The review covers biotechnology applications in the areas of animal genetics and breeding, including conservation of animal genetic resources, animal health, physiology of lactation and growth, and animal nutrition.

Introduction

Developing countries are faced with the challenge to rapidly increase agricultural productivity to help feed their growing populations without depleting the natural resource base. Biotechnology is regarded as a means to meet both objectives through addressing the production constraints of small-scale or resource-poor farmers who contribute more than 70% of the food produced in developing countries.

Biotechnology can be defined as any technique that uses living organisms or substances from such organisms to make or modify a product, to improve plants or animals or to develop micro-organisms for specific purposes. Biotechnology is not new. Man has used it for thousands of years to manufacture products such as beer, wine and bread. Conventional plant and animal breeding which involves selection and mating of phenotypically preferred individuals is a good example of age-old application of biotechnology. What is new about biotechnology comes from more recent breakthroughs such as recombinant DNA technology and associated techniques, monoclonal antibody techniques, embryo manipulation technology etc. These have enhanced possibilities for manipulating biological systems for the benefit of mankind.

Among agricultural and allied fields, animal production and health have probably benefitted the most from biotechnology. But successful application of biotechnology has generally been limited to developed countries. Specifically, there are hardly any success stories of the application of biotechnology in the improvement of livestock production in Africa. The purpose of this paper is to review available biotechnologies with potential application in livestock improvement and to identify those which have been or may be applied in developing countries in general, and Africa in particular. In addition, the paper gives a "broad brush" examination of possible reasons for failure of those technologies which have been tried. The paper also presents examples of successful application of biotechnology in Africa and the potential role of biotechnology (both "old" and "new") in future livestock development in Africa. The paper starts by presenting an overview of biotechnologies with current and/or potential applications in the areas of reproductive physiology, genetics and animal breeding, animal health, physiology of lactation and growth and animal nutrition. Given the breadth of the topic, not much depth is given to the review of each area. Rather, an attempt is made to highlight the technologies considered to have current or potential application. The paper concludes with a fleeting coverage of issues concerning the potential environmental hazards of genetic engineering and other biotechnologies, and the need for their ethical evaluation and for an international regulatory mechanism.

Overview of available biotechnologies


Reproductive physiology
Animal genetics and breeding
Animal health
Animal nutrition


Reproductive physiology

One of the challenges for genetic improvement is to increase reproduction rates. Several reproduction techniques are available. The commonest of these are artificial insemination (AI), embryo transfer and associated technologies. Measurement of progesterone in milk or blood which is a widely used technique for monitoring ovarian function and for pregnancy tests is also an important technology for managing the reproductive function of the animal.

Artificial insemination

No other technology in agriculture, except hybrid seed and fertiliser use, has been so widely adopted globally as AI. Progress in semen collection and dilution, and cryopreservation techniques now enables a single bull to be used simultaneously in several countries for up to 100,000 inseminations a year (Gibson and Smith 1989). This implies that a very small number of top bulls can be used to serve a large cattle population. In addition, each bull is able to produce a large number of daughters in a given time thus enhancing the efficiency of progeny testing of bulls. The high intensity and accuracy of selection arising from AI can lead to a four-fold increase in the rate of genetic improvement in dairy cattle relative to that from natural mating (Van Vleck 1981).

A wider and rapid use of selected males through AI will accelerate the rate of gender improvement. Also, use of AI can reduce transmission of venereal diseases in a population and the need for farmers to maintain their own breeding males, facilitate more accurate recording of pedigree and minimise the cost of introducing improved stock. However, success of AI technology depends on accurate heat detection and timely insemination. The former requires a certain level of experience among farmers while the latter is dependent on good infrastructure, including transport network, and availability of reliable means of transport.

Though AI is widely available in developing countries it is used far less, particularly in Africa, than in developed countries. Its use has been limited largely to "exploratory" purposes mainly by research institutions. A few countries including Botswana, Ethiopia, Ghana, Malawi, Mali, Nigeria, Senegal and Sudan have taken the technology to the field, mostly for programmes of "upgrading" indigenous stock and as a service to a limited number of commercial farmers keeping exotic dairy cattle breeds. A few others have used the technology more widely. Kenya and Zimbabwe, for example, have elaborate AI systems which include national insemination services incorporating progeny testing schemes. However, even these have gone through periods of collapse or serious degeneration and have had to go through "rehabilitation" phases. The

Republic of South Africa is probably the biggest user of AI technology in terms of number of inseminations. This country also has what is perhaps the best organised progeny testing scheme on the continent.

AI technology use is still more generally associated with dairy cattle than other domestic livestock species. The limitations of AI use in beef cattle include the difficulty in detecting heat in large beef herds kept on ranches and the less frequent handling of individual cows. In sheep and goats the failure to develop a simple, non-surgical insemination procedure has prevented extensive exploitation of the technology in sheep (Robinson and McEvoy 1993). However, the technical success of laparoscopic intrauterine insemination has prompted research into less invasive transcervical procedures (Halbert et al 1990; Buckrell et al 1992). Also, in Africa, research to improve the freezing-and-thawing properties of sheep semen is underway in the Republic of South Africa. In pigs use of AI is hampered by the inability to successfully cryopreserve boar semen.

AI is credited for providing the impetus for many other developments which have had a profound impact on reproductive biotechnology. Foote (1982) noted that studies of oestrus detection and ovulation control which evolved out of a need to correctly time inseminations, led to the development of embryo-transfer technology.

Embryo transfer (ET)

Although not economically feasible for commercial use on small farms at present, embryo technology can greatly contribute to research and genetic improvement in local breeds. There are two procedures presently available for production of embryos from donor females. One consists of superovulation, followed by AI and then flushing of the uterus to gather the embryos. The other, called in vitro fertilisation (IVF), consists of recovery of eggs from the ovaries of the female then maturing and fertilising them outside the body until they are ready for implantation into foster females. IVF facilitates recovery of a large number of embryos from a single female at a reduced cost thus making ET techniques economically feasible on a larger scale. Additionally, IVF makes available embryos suitable for cloning.

The principal benefit of embryo transfer is the possibility to produce several progeny from a female, just as AI can produce many offspring from one male. For example the average lifetime production of a cow can be increased from 4 to 25 calves. Increasing the reproductive rate of selected females has the following benefits: genetically outstanding animals can contribute more to the breeding programme, particularly if their sons are being selected for use in AI; the rate of genetic change can be enhanced with specially designed breeding schemes which take advantage of increased intensity of female selection combined with increased generation turnover; transport of embryos is much cheaper than that of live animals; risk of importing diseases is avoided; facilitates rapid expansion of rare but economically important genetic stocks; and the stress to exotic genotypes can be avoided by having them born to dams of local breeds rather than importing them as live animals.

Embryo transfer is still not widely used despite its potential benefits. In developing countries this is mainly due to absence of the necessary facilities and infrastructure. Even in developed countries, cost considerations still limit the use of commercial embryo transfer in specialised niches or for a small proportion of best cows in the best herds. Thus, in North America and Europe, only about one out of 500 calves born in the last decade was from ET (Seidel and Seidel 1992). Commercial embryo transfer is more popular with cattle than other species. This is mainly because ET is relatively easier in cattle than the other species and also because it is more economical in cattle (i.e. cattle are worth more). Additionally, the low reproductive rate and the long generation interval of cattle make ET much more advantageous in cattle.

Production of several closely related, and hence genetically similar, individuals through ET techniques can make critical contributions to research. For example a project at the International Laboratory for Research on Animal Diseases (ILRAD) to locate the genes responsible for tolerance of some cattle populations to trypanosomiasis required large numbers of closely related crosses of trypanotolerant and trypanosusceptible cattle. Use of ET has made it possible to generate such families thereby facilitating the search for genetic markers of trypanotolerance. Additionally, ET could be useful in studying the extent to which a trait is influenced by the embryo (direct component) or the reproductive tract (maternal component).

Embryo sexing and cloning

Although embryo sexing may not have dramatic effects on rates of genetic gain (Colleau 1991; Kinghorn et al 1991) it can considerably increase efficiency. Taylor et al (1985) concluded from a study that an all-female heifer system using ET was 50% more efficient than the highest achievable in a traditional system. It has been suggested that, if multiple sexed-embryo transfer became as routine an operation as AI is, beef operations based on this system could become competitive with pig and poultry production in terms of efficiency of food utilisation.

Clones may be produced by embryo splitting and nuclear transfer (Macmillan and Tervit 1990). These offer the possibility for creating large clone families (Woolliams and Wilmut 1989) from selected superior genotypes which, in turn, can be used to produce commercial clone lines (Smith 1989). However, some studies have concluded that cloning of embryos will not increase rates of genetic progress in the nucleus, but that it offers considerable advantages in increasing the rate of dissemination of tested superior genotypes in commercial populations (Woolliams 1989). Other potential applications of cloning include efficient evaluation of genotype x environment interactions and testing and/or dissemination of transgenics. From a research standpoint, production of identical siblings should, by eliminating variability among animals, greatly reduce the size and hence the cost of experiments.

Hormone use

Use of hormonal assays to monitor reproductive function can be rewarding for both research purposes and commercial livestock operations. Reproduction can also be manipulated using hormonal treatments. But while hormonal treatments have produced desirable results in some studies in Africa (Aboul-Naga et al 1992), lack of awareness about their use and the fact that they are not economically viable under most prevailing production circumstances limit their use. Progesterone and PMSG treatment and immunisation against androstenedione increased ovulation rate in Ossimi sheep. Also, exogenous melatonin treatment of barren Rahmani ewes resulted in increased proportion of ovulating ewes and a higher ovulation rate (Aboul-Naga et al 1992). These responses, however, did not result in increased litter size because of increased ova wastage. Thus, in addition to the impracticability arising from prohibitive prices of hormonal preparations and the problems with hormonal administration at farm level, there are other technical problems associated with the use of these technologies. For example, technologies aimed at increasing litter size in traditional small ruminant production systems should not be applied unless management, including nutrition, can be improved in concert to ensure the survival of the additional progeny.

Reproduction can also be manipulated without application of exogenous hormones. Aboul-Ela et al (1988) reported that exposing ewes to rams one week prior to mating ("the ram effect") increased the percentage of ewes in oestrus (and hence the per cent mated) by 27%. Such management approaches offer practical options for increasing annual lamb (or kid) production in situations where other technologies are either not available or not appropriate. "Accelerated lambing" - increasing the number of lambings per year - can also be used to increase annual productivity. However, in tropical and subtropical situations where animals depend on seasonally available natural pastures, this practice may not be sustainable. Under such circumstances the reproductive cycle tends to be dictated by availability of feeds.

Animal genetics and breeding

Genetic improvement of livestock depends on access to genetic variation and effective methods for exploiting this variation. Genetic diversity constitutes a buffer against changes in the environment and is a key in selection and breeding for adaptability and production on a range of environments.

In developed countries, breeding programmes are based upon performance recording and this has led to substantial improvements in animal production. Developing countries have distinct disadvantages for setting up successful breeding programmes: infrastructure needed for performance testing is normally lacking because herd sizes are normally small and variability between farms, farming systems and seasons are large; reproductive efficiency is low, due mainly to poor nutrition, especially in cattle; and communal grazing precludes implementation of systematic breeding and animal health programmes.

Multiple ovulation embryo transfer and open nucleus breeding system

Multiple ovulation embryo transfer (MOET) is a composite technology which includes superovulation, fertilisation, embryo recovery, short-term in vitro culture of embryos, embryo freezing and embryo transfer. Benefits from MOET include increasing the number of offspring produced by valuable females, increasing the population base of rare or endangered breeds or species, ex situ preservation of endangered populations, progeny testing of females and increasing rates of genetic improvement in breeding programmes. Genetic improvement of ruminants in developed countries has made much progress in the last 35 or so years through the use of large-scale progeny testing of males. As has been pointed out, the general failure of extensive use of AI in developing countries has implied that progeny testing schemes cannot be operated with much success. In any case the generally small herds/flocks and uncontrolled breeding in communal grazing situations preclude implementation of progeny testing. Smith (1988a) suggested that the Open Nucleus Breeding System (ONBS) may be especially valuable for developing countries where the use of AI has been a failure due to the reasons given above.

The ONBS concept is based on a scheme with a nucleus herd/flock established under controlled conditions to facilitate selection. The nucleus is established from the "best" animals obtained by screening the base (farmers') population for outstanding females. These are then recorded individually and the best individuals chosen to form the elite herd/flock of the nucleus. If ET is possible, the elite female herd is used through MOET with superior sires to produce embryos which are carried by recipient females from the base population. The resulting offspring are reared and recorded and the males among them are evaluated using, as appropriate, the performance of their sibs and paternal half sibs and their own performance. From these, an elite group of males with high breeding values for the specific trait is selected and used in the base population for genetic improvement through natural service or AI. It should be noted that, while MOET improves the rate of progress substantially, it is possible to operate an ONBS without ET technology, especially in species, such as small ruminants, with high reproductive rates. Such schemes are being tried for sheep in West Asia by FAO (Jasiorowski 1990) and in Africa (Yapi et al 1994). However, availability of AI and ET, in addition to increasing rates of genetic gain, enhance the flexibility of the system. For example, germplasm from other populations can be introduced easily through semen and/or embryos. One of the advantages of a nucleus herd is that it provides opportunity to record information on more traits than is possible in a decentralised progeny testing scheme.

The ONBS can be used for the improvement of an indigenous or exotic breed. It can also be used to improve a stabilised crossbred population. The level of the genetic response depends on the size of the scheme (that is, number of participating herds/flocks and total number of animals) and the selection intensity.

An ONBS can initially be developed to form a focus for national sire breeding and selection activities. In time, and with experience, the capacity can be expanded and ET introduced to increase the rate of genetic progress.

At one time it was suggested that application of MOET in nucleus breeding schemes could increase animal genetic gains by 30-80% (Nicholas and Smith 1983). More recently it has been concluded that the earlier figures were over-predictions (Keller et al 1990). The over-predictions arose partly because the assumed average number of progeny (eight) per donor female was unrealistically high and partly because of wrong assumptions made about genetic parameters (Keller et al 1990). The realistic average number of live progeny per donor flushed is in the range of 2-3 in sheep and cattle and 6-8 in goats (Macmillan and Tervit 1990). Consideration of these figures suggest that MOET could increase annual genetic gains by 1020% in large nucleus breeding schemes. However, costs of operating such schemes in developing countries need to be evaluated before they can be recommended.

Indicator traits

Indicator traits are characteristics which are genetically correlated to traits of economic importance and are easier to measure than the latter. Such traits are usually not the target of genetic improvements but provide an indirect means of improving a targeted trait. Blair et al (1990) reviewed some physiological and/or metabolic characteristics which might be considered as potential indicator traits. Traits such as testicular size in rams or bulls or FSH in ewe lambs (Bodin et al 1986) have potential as indirect predictors of fertility. Indicator traits can improve genetic response by increasing accuracy of selection and reducing generation interval. The value of an indicator trait will depend largely on the magnitude of co-heritability (square-root of the product of heritability of the indicator and of the target trait) and the genetic correlation between the two traits (Woolliams and Smith 1988). Woolliams and Smith (1988) concluded that, with high co-heritability, selection for the indicator trait alone can result in greater rates of response than is possible with progeny testing, especially when breeding values are not accurately measured by progeny testing.

Packed cell volume (PCV), an indication of the extent of anaemia, is widely used as an indicator trait for pathological conditions associated with anaemia. For example, PCV is currently used at ILRAD and ILCA (International Livestock Centre for Africa) as an indicator of the effect of trypanosomiasis and hence of trypanotolerance, and at ILCA as an indicator of effect of the endoparasite Haemonchus contortus and hence as an indicator of resistance to the parasite.

Genetic markers and marker-assisted selection

A genetic marker for a trait is a DNA segment which is associated with, and hence segregates in a predictable pattern as, the trait. Genetic markers facilitate the "tagging" of individual genes or small chromosome segments containing genes which influence the trait of interest. Availability of large numbers of such markers has enhanced the likelihood of detection of major genes influencing quantitative traits. The method involves screening the genome for genes with a large effect on traits of economic importance through a procedure known as linkage analysis (Paterson et al 1988). The chances of major genes existing for most traits of interest, and of finding them are considered to be high (Mackinnon 1992). The process of selection for a particular trait using genetic markers is called marker assisted selection (MAS). MAS can accelerate the rate of genetic progress by increasing accuracy-of selection and by reducing the generation interval (Smith and Simpson 1986). However, the benefit of MAS is greatest for traits with low heritability and when the marker explains a larger proportion of the genetic variance than does the economic trait. Lande and Thompson (1990) suggest that about 50% additional genetic gain can be obtained if the marker explains 20% of the additive genetic variance and the economic trait has a heritability of 0.2. MAS also facilitates increased rate of genetic gain by allowing measurement in young stock thereby reducing generation interval.

Marker identification and use should enhance future prospects for breeding for such traits as tolerance or resistance to environmental stresses, including diseases. Already, identification of carriers of genes for resistance and introduction of such genes into a population seems feasible for resistance against Trichostrongylus colubriformis and Haemonchus contortus (Gogolin-Ewens et al 1990). It should also be possible to eliminate factors predisposing sheep to Listeriosis or Salmonellosis (Blancou 1990). There is also evidence for a major gene for resistance to the cattle tick (Boophilus microplus) in a Hereford x Shorthorn cattle line called Belmont Adaptaur (Kerr et al 1994). Research is currently underway at ILRAD to identify genetic markers for tolerance to African trypanosomiasis in N'Dama cattle and at ILCA for resistance to endoparasites in Red Maasai sheep.

Transgenic animals

A transgenic animal is an animal whose hereditary DNA has been augmented by addition of DNA from a source other than parental germplasm through recombinant DNA techniques. Transfer of genes or gene constructs allows for the manipulation of individual genes rather than entire genomes. There has been dramatic advances in gene transfer technology in the last two decades since the first successful transfer was carried out in mice in 1980 (Palmiter et al 1982; Jaenisch 1988). The technique has now become routine in the mouse and resulting transgenic mice are able to transmit their transgenes to their offspring thereby allowing a large number of transgenic animals to be produced. Successful production of transgenic livestock has been reported for pigs, sheep, rabbits and cattle. The majority of gene transfer studies in livestock have, however, been carried out in the pig. Although transgenic cattle and sheep have been successfully produced, the procedure is still inefficient in these species (Niemann et al 1994).

Transgenesis offers considerable opportunity for advances in medicine and agriculture. In livestock, the ability to insert new genes for such economically important characteristics as fecundity, resistance to or tolerance of other environmental stresses would represent a major breakthrough in the breeding of commercially superior stock. Another opportunity that transgenic technology could provide is in the production of medically important proteins such as insulin and clotting factors in the milk of domestic livestock. The genes coding for these proteins have been identified and the human factor IX construct has been successfully introduced into sheep and expression achieved in sheep milk (Clark et al 1990). Moreover, the founder animal has been shown to be able to transmit the trait to its offspring (Niemann et al 1994). To date, the majority of genes transferred into sheep have been growth hormone encoding gene constructs. Unfortunately, in most cases the elevated growth hormone levels have resulted into a clinical diabetes situation leading to an early death of the transgenic sheep (Rexroad et al 1990). Transgenic sheep have recently been generated which express the visna virus envelope gene (Clements et al 1994).

The first reports of the production of transgenic animals created a lot of excitement among biological scientists. In the field of animal breeding, there were diverse opinions on how the technology might affect livestock genetic improvement programmes. Some (Ward et al 1982) believed that it would result in total reorganisation of conventional animal breeding theory while others (Schuman and Shoffner 1982) considered the technology as an extension of current animal breeding procedures which, by broadening the gene pool, would make new and novel genotypes available for selection. Application of the technology in animal improvement is still far from being achieved. However, consideration needs to be given to its potential role in this field. Smith et al (1987) presented a comprehensive evaluation of strategies for developing, testing, breeding and disseminating transgenic livestock in the context of quantitative improvement of economic traits.

An important contribution of transgenic technology is in the area of basic research to study the role of genes in the control of physiological processes. The understanding of the molecular control of life processes has important implications for both medicine and agriculture. For example, the generation (through mutation of an endogenous gene) of an organism which lacks a specific gene is a powerful tool to investigate the function of the gene product. This type of genetic analysis has been facilitated by the availability of in vitro cultures of embryonic stem cells from mice (Bradley 1994).

Recent advances in in vitro technology (in vitro fertilisation and maturation) will increase the number of zygotes available for gene transfer purposes. This, plus the utilisation of embryonic stem cell (Stice et al 1994) and primodial germ cell (Stokes et al 1994) technologies should enhance the efficiency of gene transfer in cattle and sheep considerably.

Genetic characterisation of animal genetic resources

Developing countries are endowed with the majority of the global domestic animal diversity - landraces, strains or breeds. Some livestock breeds in these countries are in immediate danger of loss through indiscriminate crossbreeding with exotic breeds. The importance of indigenous livestock breeds lies in their adaptation to local biotic and abiotic stresses and to traditional husbandry systems. However, most of these animal genetic resources are still not characterised and boundaries between distinct populations are unclear. In such cases breeds are defined on the basis of subjective data and information obtained from local communities. Reliance on these criteria as the basis for classification for utilisation and/or conservation may be misleading. Additionally, historical evidence is not always accurate, relying as it often does on subjective judgements. Archival research can reveal much about the original type of a breed or strain but it is molecular genetic evidence which is factual and precise. It is in this sphere that biotechnology has an important role.

Genetic uniqueness of populations is measured by the relative genetic distances of such populations from each other. Polymorphism in gene products such as enzymes, blood group systems and leukocyte antigens which have traditionally been used for measuring genetic distance are being rapidly replaced by polymorphism at the level of DNA, both nuclear (Jeffreys and Morton 1987) and mitochondrial (Loftus et al 1994) as a source of information for the estimation of genetic distances. The first DNA polymorphism to be used widely for genome characterisation and analysis were the restriction fragment length polymorphism (RFLP) (Southern 1975) which detect variations ranging from gross rearrangements to single base changes. Minisatellites sequences of 60 or so bases repeated many hundreds or thousands of times at one unique locus within the genome have been used to generate DNA fingerprints typical of individuals within species (Jeffreys and Morton 1987). Microsatellites (Weber and May 1989) repeats of simple sequences, the commonest being dinucleotide repeats are abundant in genomes of all higher organisms, including livestock. Polymorphism of microsatellites takes the form of variation in the number of repeats at any given locus and is generally revealed as fragment length variation in the products of polymerase chain reaction (PCR) amplification of genomic DNA using primers flanking the chosen repeat sequence and specific for a given locus (Kemp and Teale 1991). Ease of identification and of sequence determination (Moore et al 1992) and need for only small amounts of DNA, are some of the advantages of microsatellites. Additionally, because microsatellite polymorphism can be described numerically, they lend themselves to computerised data handling and analyses (Teale et al 1994). Microsatellites can be used in non-PCR systems in a way similar to minisatellite probes (Haberfeld et al 1991).

Randomly amplified polymorphic DNA (RAPD) (Williams et al 1990) has been extensively used for genetic characterisation of a wide range of organisms. The technique uses short (up to 10 bases) primers to amplify nuclear DNA in the PCR. The procedure does not require knowledge of the sequence of DNA under study; primers are designed randomly. The basis of the polymorphism detected by this method is that products are either generated in PCR or not.

Complete sequencing of the genome is the ultimate form of genetic characterisation. Sequencing has traditionally been expensive and laborious, but with the advent of automated sequencing this is changing rapidly. However, sequencing is unlikely to be used as a technique of choice for genetic characterisation.

Nei and Takezaki (1994) reviewed statistical methods for estimating genetic distances and for constructing phylogenetic trees from DNA sequence data and concluded that different analytical methods may produce different results. Teale et al (1994) commented on what considerations to be made in using DNA polymorphism data for genetic distance estimation and cautioned that great care has to be taken in selecting characterisation methods and in interpreting the resulting data. While recognising the importance of the uniparental mode of inheritance of mitochondrial DNA in detecting underlying population structure not discernible from analyses of nuclear DNA, Loftus et al (1994) concluded that mitochondrial DNA analysis may not be sufficient to resolve breed differences within Africa. MacHugh et al (1994) suggested that microsatellite polymorphism may be more suitable when trying to discriminate between closely related populations. Regardless of which method is used, the ultimate goal in genetic characterisation for conservation is to obtain a measure of available diversity.

Conservation of animal genetic resources

The terms conservation, preservation, ex situ and in situ are used here according to the definition given by FAO (1992). There are several ways, differing in efficiency, technical feasibility and costs, to conserve animal genetic resources. Developing and utilising a genetic resource is considered the most rational conservation strategy. However, there are cases where ex-situ approaches are the only alternatives. Ex-situ approaches include: maintenance of small populations in domestic animal zoos; cryopreservation of semen (and ova); cryopreservation of embryos; and some combinations of these. Brem et al (1989) reviewed biotechnologies for ex-situ conservation.

Cryopreservation of gametes, embryos or DNA segments can be quite an effective and safe approach for breeds or strains whose populations are too small to be conserved by any other means. The safety of these methods has been demonstrated by background irradiation studies. For example, studies based on irradiation of mouse embryos exposed to the equivalent of hundreds of years of background mutation showed no detectable damage (Whittington et al 1977).

Regeneration of offspring following transfer of frozen-thawed embryos has been successful for all major domestic species, except the buffalo (Teale et al 1994). In cattle, the transfer of frozen-thawed embryos is now a commercial practice and embryo survival rate after thawing can be as high as 80% with a pregnancy rate of about 50%. Cryopreservation of oocytes followed by successful fertilisation and live births have been achieved in the mouse. Cryopreserved bovine oocytes have been successfully matured and fertilised in vitro and zygotes developed to blastocyst stage (Lim et al 1991). These trends strongly suggest that long-term cryopreservation of mammalian oocytes is possible (Teale et al 1994).

Respective pregnancy rates of 58 and 50% for fresh and frozen-thawed in vitro produced embryos have been reported (Lu et al 1990). Also, calves have been produced from transfer of both split and frozen-thawed in vitro produced embryos.

Economic aspects of genetic conservation in farm animals has been assessed by Brem et al (1984). The study concluded that costs of ex situ live animal conservation was moderate to high while costs of long-term cryopreservation of gametes were low.

Development in genetic engineering, cryobiology, cell biology and embryology will provide techniques that may enhance our ability to preserve germplasm in vitro. Techniques such as transfer of DNA within and between species and the production of viable transgenic animals are far from practical application. However, biotechnology will certainly contribute newer and cheaper methods for preservation such as storage of catalogued DNA. At present, other than live animal and embryo preservation, the other techniques do not allow preservation of genomes in a form which can be reactivated in toto at a later stage, but they permit the preservation of individual genes or gene combinations for possible future regeneration.

Conservation of indigenous animal genetic resources should be one of the priority livestock development activities for developing countries. The critical importance of these resources to their owners in developing countries need not be emphasised. Their importance to developed countries is also becoming evident as indicated by the increasing importation of tropical germplasm by these countries. It is highly likely that these resources will become of increasing importance to the industrialised countries either as sources of unique genes or when environmental concerns necessitate change in production systems. Developed countries should, thus, assist in the conservation and development of these resources. Technology for cryopreservation of semen and embryo is sufficiently developed to be applied in developing countries. What is missing is financial support to implement conservation programmes. Such support has been provided for world-wide conservation activities for plant germplasm. There is also a strong case for support of animal genetic resources conservation.

Animal health

Disease diagnosis

Successful control of a disease requires accurate diagnosis. This has been greatly improved in recent years through developments in biotechnology. The most recent major development, the finding that it is possible to immortalise individual antibody-producing cells by hybridisation to produce antibodies of a given class, specificity and affinity (i.e. monoclonal antibodies) has provided a tool that permits the analysis of virtually any antigenic molecule (Kenneth et al 1980). The use of monoclonal antibodies has revealed that the failure of vaccines (e.g. of rabies) to provide protection in all parts of the world was due to the diversity in the antigenic composition of the causative virus (Wiktor and Koprowski 1980). The (monoclonal antibody) technology is relatively simple and can readily be applied in developing countries. Monoclonal antibodies are currently supplied to developing countries directly or in the form of kits and simple reagents for completion of the tests (Ferris et al 1988). For example, kits for rinderpest virus diagnosis used in African countries come in this form.

The ability to generate highly specific antigens by recombinant DNA techniques has made it possible for an increasing number of enzyme-linked immunosorbent assays (ELISA) to have the capacity to differentiate between immune responses generated by vaccination from those due to infection (Robinson and McEvoy 1993). This has made it possible to overcome one of the major drawbacks of antibody detection tests: the fact that, because antibodies can persist in animals for long periods, their presence may not indicate current infection. ILRAD has developed a technique to overcome this problem in diagnosis of trypanosomiasis. The parasite antigen detection test uses monoclonal antibodies raised in laboratory mice (Nantulya and Lindqvist 1989) to capture the parasite antigens which are then revealed by their reaction with a second layer antibody to which is conjugated an easily detectable enzyme. This test reveals current infections and facilitates differentiation between the major trypanosome species. This has important implications for disease control, especially because of the association of different parasite species with different epidemiological and disease circumstances.

The advent of PCR has enhanced the sensitivity of DNA detection tests considerably. For example, PCR used in combination with hybridisation analysis, has been shown (Brandon et al 1991) to provide a sensitive diagnostic assay to detect bovine leukosis virus.

Other diagnostic techniques include nucleic acid hybridisation (NAD) and restriction endonuclease mapping (REM). As has been indicated above, one of the most valuable features of these molecular techniques is their specificity and sensitivity. A good example of the specificity of NAD is its application in distinguishing infections caused by peste des petite ruminants (PPR) virus from rinderpest (Lefevre and Diallo 1990), diseases whose symptoms are clinically identical and which cannot be distinguished antigenically with available serological reagents. This technique also allows comparison of virus isolates from different geographical locations. Detailed overview of biotechnological tools for diagnosis of livestock diseases has been provided by Bourne and Bostock (1992) and Robinson and McEvoy (1993).

Other available diagnostic techniques which may have application in small ruminants and/or cattle include: nucleic acid probes (NAP) for heartwater (Cowdria ruminantium), chlamydia psitacci, Paratuberculosis and Bluetongue (Blancou 1990; Knowles and Gorham 1990); restriction endonuclease reaction (RENR) for diagnosis of Corynebacterium pseudotuberculosis (Knowles and Gorham 1990); PCR for characterising subtypes of Bluetongue from different geographical regions (Osburn 1991); monoclonal antibodies (MAB) for differentiating false positive anti-Brucella titres caused by Yersinia enterocolitica and true positive anti-Brucella titres in latent infected animals (Haas et al 1990); and MAB for diagnosis of Toxoplamosis, Pasteurellosis, Mycoplasma spp, PPR and Boder Disease (Blancou 1990; Lefevre and Diallo 1990). Examples of tropical diseases for which diagnostic tests are available are presented in Table 1. Teale (1991) reviewed the diagnostic techniques that are currently available or which could be developed in the near future.

Table 1. Tropical diseases for which probes and monoclonal antibodies (MAB) are available.

Viral diseases

Bacterial diseases

Rinderpest

Cowdriosis

Peste des petite ruminants

Contagious bovine pleuropneumonia

Bluetongue

Contagious agalactia

African horse sickness

Contagious caprine pleuropneumonia

Foot-and-mouth disease

Anaplasmosis (A. centrale and A. marginale)

Vesicular stomatitis

Haemorrhagic septicemia (only MAB available)

Source: Lefevre (1992).

Vaccines

Conventional means of controlling major livestock diseases include chemotherapy, vector control, vaccination, slaughter of infected stock, and other management practices (including grazing management and controlled stock movements). Vector control requires continuous application of pesticides. These are often unaffordable to farmers in developing country. Moreover, where these drugs or pesticides are used, resistance by parasites is often encountered and reinfection following administration of drugs against parasitic diseases usually occurs. Additionally, in many cases drugs are not readily available locally. In some cases where they are available, they are ineffective, either because they have been partly preserved or they are not genuine.

Immunisation remains one of the most economical means of preventing specific diseases. An effective vaccine can produce long-lasting immunity. In some cases, vaccination can provide lifetime immunity. Moreover a small number of doses is usually required for protection. Level of infrastructure and logistical support required for a large-scale vaccination programme is such that a successful vaccination campaign can be implemented in remote rural areas. In general, vaccines offer a substantial benefit for comparatively low cost, a primary consideration for developing countries.

Vaccines have conventionally been produced by several methods some of which have become rather static with regard to efficacy, safety, stability and cost. Very effective vaccines against animal diseases such as rinderpest and pig cholera have been in use for more than 20 years and have helped to significantly reduce the incidence of these diseases world-wide. However, vaccines of questionable efficacy also exist. Impotency, instability, adverse side effects, and reversion of attenuated organisms to wild (disease-causing) forms represent some of the problems. However, research strategies for the development of better, cheaper and safer vaccines are constantly being sought. Through the use of monoclonal antibodies and recombinant DNA technologies, it is now possible to define and produce immunogenic components much more rapidly. These technologies are increasingly being used to clarify the pathogenetic mechanisms and immune response to microbial diseases (Wray and Woodward 1990; McCullough 1993). This should lead to the production of more effective vaccines in the future. To date many candidate vaccines have been produced by these techniques. However, only few of these are being produced commercially.

Table 2 summarises some vaccines developed by recombinant DNA technology. There are other vaccines under various stages of development. The following are of particular relevance to small ruminants: recombinant vaccines against Bluetongue and Rift Valley Fever may soon be available for field use (Osburn 1991); a hybrid virus vaccine against Orf (Reid 1989), a thermostable recombinant vaccine against PPR (Lefevre and Diallo 1990) and recombinant vaccines against Taenia ovis and Echinococcus (Blancou 1990); tick gut antigens and Haemonchus gut antigens produced by molecular techniques offer ways for prophylaxis against these parasites. Progress is also being made towards the development of vaccines against Babesiosis and Theileriosis in cattle (Wright 1990) which may indicate prospects for similar immune-prophylaxis becoming available for sheep and goats as well.

Table 2. Example of some novel animal vaccines.

Species

Disease

Producer

Avian


Coccidiosis,

Genex and A.H. Robins

Newcastle virus

Codon and Salsbury labs

Bovine




Papilloma virus

Molecular genetics

Viral diarrhoea

California Biotechnology

Brucellosis

Ribi ImmunoChem

Rinderpest

USDA and University of California, Davis

Swine


Parvovirus

Applied Biotechnology

Dysentery

Codon

Equine


Influenza, Herpes

California Biotechnology


Applied Biotechnology

Companion

Canine parvovirus

Applied Biotechnology

Sources: Van Brunt (1987); Cunningham (1990).

Physiology of lactation and growth

Recombinant bovine somatotropin (BST) is a genetically engineered synthetic analog of the natural growth hormone (Bauman et al 1985). Since the 1970s there have been a number of studies on the effects of BST on milk yield, reproductive performance and health as well as its likely effect on humans who consume such milk. Under good management and feeding, regular BST administration to lactating dairy cows increases milk yield by 15-30% and also increases efficiency of milk production.

BST is now readily available and is already in commercial use in the United States. However, the appropriateness of BST use to increase milk production in the USA is doubtful as the country already has a milk surplus and the public is also concerned about its effects on health. Indeed, the benefit of BST in the USA is perceived to be towards reducing the production costs of large dairy farms, but this could push smaller farmers out of the market. The appropriateness of BST use for developing countries is still a matter of debate. Those supporting its introduction argue that its use in commercial dairy farms could increase the national milk output. Those opposed point out the fact that BST does not improve milk yield in indigenous non-dairy breeds and that its use on crossbred and exotic dairy cattle will require more feeding, and that provision of adequate nutrition is already a problem for most dairy operations in developing countries.

Whether or not BST affects reproductive performance has not yet been conclusively established. Although most reports have indicated nonsignificant effects of BST on reproductive performance, most such studies have been on single lactations; the effect of BST on lifetime productivity needs to be investigated. Some studies (McBride et al 1990; Phipps et al 1990) have shown that feed conversion efficiency declines in subsequent lactations. The study by Phipps et al (1990) also indicated a decline in the incremental amount of milk yield from BST application in subsequent lactations. Additionally, the effect of BST on reproductive performance is likely to be more adverse in the presence of higher biotic and abiotic stresses, including nutritional stresses (Burton et al 1990; Lormore et al 1990). There is also need to examine the economics of BST application in view of the known association of its use with mastitis (Burton et al 1990) and other infections. BST use is thus bound to be associated with increased use of antibiotics and other veterinary drugs. Thus, in evaluating the potential role of BST in developing countries, one needs to consider not only the possible response levels of the cattle in these countries to BST treatment, but also the cost of BST, the amount and cost of other incremental inputs required for effective use of BST, and the milk prices. Ultimately, the main technical constraint to BST use in developing countries will not only be its cost, but the absence of an efficient delivery system; current use of the technology requires regular injections.

Porcine somatotropin (PST) and recombinant growth hormone stimulatory peptides (e.g. growth hormone releasing factor, GRF) along with BST have been shown to increase growth rates by 8-38% in cattle, sheep and pigs. In almost all cases, administration of exogenous growth hormones have been associated with increased carcass protein and reduced carcass fat (Hart and Johnson 1986). Other growth-promoting agents (e.g. anabolic steroids and beta agonists) have been shown to have even larger effects but public concerns over the possible residual effects in meats have led to their being banned in most developing countries. The use of anabolic implants is, however, permitted in some countries such as the USA.

Animal nutrition

Nutrition represents one of the most serious limitations to livestock production in developing countries, especially in the tropics. Feed resources are inadequate in both quality and quantity, particularly during the dry seasons. Biotechnological options are available for improving rumen fermentation and enhancing the nutritive value and utilisation of agro-industrial by-products and other forages (Kundu and Kumar 1987).

Fibrous feeds, including crop residues, of low digestibility constitute the major proportion of feeds available to most ruminants under smallholder situations in developing countries. The associated low productivity can be overcome to some extent by several means, among which are: balancing of nutrients for the growth of rumen microflora thereby facilitating efficient fermentative digestion and providing small quantities of by-pass nutrients to balance the products of fermentative digestion, enhancing digestibility of fibrous feeds through treatment with alkali or by manipulating the balance of organisms in the rumen and genetic manipulation of rumen micro-organisms, currently acknowledged as potentially the most powerful tool for enhancing the rate and extent of digestion of low quality feeds. Rumen micro-organisms can also be manipulated by adding antibiotics as feed additives, fats to eliminate or reduce rumen ciliate protozoa (defaunation), protein degradation protectors, methane inhibitors, buffer substances, bacteria or rumen content and/or branched chain volatile fatty acids.

Increasing digestibility of low-quality forages

Low-quality forages are a major component of ruminant diets in the tropics. Thus, much progress can be made by improving the forage component of the ration. The characteristic feature of tropical forages is their slow rate of microbial breakdown in the rumen with the result that much of the nutrients of the feed are voided in the faeces. The slow rate of breakdown also results in reduced outflow rate of feed residues from the rumen which consequently depresses feed intake. At present, the main treatment methods for forages such as cereal straws are either mechanical (e.g. grinding), physical (e.g. temperature and pressure treatment) or a range of chemical treatments of which sodium hydroxide or ammonia are among the more successful (Greenhalgh 1984).

The lignification of the cell walls prevents degradation by cellulase or hemicellulase enzymes. Fortunately, it is possible to use lignase enzyme produced by the soft-rot fungus (Phanerochaete chrysosporium) which causes a high degree of depolymerisation of lignin (Tien and Kirk 1983). The enzyme acts like a peroxidase and causes cleavage of carbon-carbon bonds. At present the levels of the lignase enzyme produced by the basidiomycete fungi are insufficient for the treatment of straw on a commercial scale. However, it is conceivable that the use of recombinant DNA engineering techniques will allow the modification of the lignase genes and associate proteins to increase their efficiency and stability. The lignin gene has to date been cloned and sequenced from P. chrysosporium (Zhang et al 1986; Tien and Tu 1987).

Improving nutritive value of cereals

Moderate protein content and low amounts of specific amino acids limit the nutritive value of cereals and cereal by-products (e.g. barley is low in Iysine and threonine). This is a major limitation in the ration formulation for non-ruminant livestock which necessitates addition of expensive protein supplements. There are on-going studies to enhance the low level of Iysine in barley by genetically engineering the grain genome (Miflin et al 1985; Shewry and Kreis 1987). Genetic modification through insertion of genes into rice protoplasts and generation of transformed plants has already been achieved.

Removing anti-nutritive factors from feeds

Anti-nutritive factors in plant tissues include protease inhibitors, tannins, phytohaemagglutinins and cyanogens in legumes, and glucosinolates, tannins and sanapine in oilseed rape (Brassica napus) and other compounds in feeds belonging to the Brassica group. As with amino acid deficiencies, the adverse effects of these compounds are more marked in non-ruminants than in ruminants (Chubb 1983). Conventional plant breeding has been used to reduce and, in some cases, eliminate such anti-nutritive factors. An example is the introduction of cultivars of oilseed rape which are low in, or free from erucic acid and glucosinolates. A combination of genetic engineering and conventional plant breeding should lead to substantial reduction or removal of the major anti-nutritive factors in plant species of importance as animal feeds.

Transgenic rumen microbes (see below) could also play a role in the detoxification of plant poisons (Gregg 1989) or inactivation of antinutritional factors. Successful introduction of a caprine rumen inoculum obtained in Hawaii into the bovine rumen in Australia to detoxify 3-hydroxy 4(IH) pyridine (3,4 DHP), a breakdown product of the non-protein amino acid mimosine found in Leucaena forage (Jones and Megarrity 1986) demonstrates the possibilities.

Improving nutritive value of conserved feed

The conservation of plant material as silage depends upon anaerobic fermentation of sugars in the material which in turn is influenced by the ability of naturally occurring lactic acid bacteria to grow rapidly on the available nutrients under the existing physical environment. Unless the ensiled material is sterilised, lactic acid bacteria are always present. However, the ensiling conditions may not always be ideal for their development. In addition to the number and type of bacteria, other interrelated factors may affect quality of silage, including availability of water-soluble carbohydrates, the dry-matter content, the pH and extent of air exclusion. For example, lack of water-soluble carbohydrates may be overcome by wilting the material to raise the dry matter to a level at which less acid is required to stabilise the fermentation. The availability of sugars in the material and the rate at which the different micro-organisms multiply also influences the ensilage process.

Throughout this century, research workers have investigated ways through which the fermentation process in silage making can be controlled in order to improve the feeding quality of the resulting silage. Use of additives, to restrict the activity of the microorganisms, to stimulate the fermentation by the lactic acid bacteria or simply as nutrients has been one of the approaches. Additives used in the early studies included chloroform, toluene and cresol (to inhibit bacterial growth) and sulphuric acid and hydrochloric acid (to reduce the pH). Indeed, over the last 40 to 50 years, corrosive, acid-containing additives have been widely used in silage making. Other fermentation inhibitors which have been studied include organic acids, salts of acids, formaldehyde and other aldehydes, sodium hydroxide, and antibiotics. Of these, formic acid is probably the most widely studied and has been reported to have a beneficial effect on the fermentation process and on the nutritive value of silage. Sulphuric acid is cheaper than formic acid and is popular in some countries. However, acids are a hazard on the farm and can be particularly dangerous if recommended to uninformed farmers. Salts of acids are safer to handle but are less effective than the acids from which they are derived.

The hazardous nature of some of the chemical additives has necessitated a search for alternative compounds for improving the ensilage process. A group of compounds classified as fermentation stimulants have been widely studied. These include sugar sources (e.g. molasses and whey), enzymes and inocula of lactic acid bacteria. Molasses is of particular relevance to smallholder farmers in developing countries in the tropics where sugar-cane is produced and processed. Enzymes are essential for the breakdown of cell-wall carbohydrates to release the sugars necessary for the growth of the lactic acid bacteria. Although resident plant-enzymes and acid hydrolysis produce simple sugars from these carbohydrates, addition of enzymes derived from certain bacteria, e.g. Aspergillus niger or Trichoderma viridi (Henderson and McDonald 1977; Henderson et al 1982) increases the amount of available sugars. Commercial hemicellulase and cellulase enzyme cocktails are now available and improve the fermentation process considerably (Hooper et al 1989). However, prices of these products preclude their viability for farm level application, especially in developing countries.

There are two forms of indigenous lactic acid bacteria: the homofermentative type which converts hexose sugars to lactic acid with no loss of dry matter and the heterofermentative type which produces a range of compounds accompanied by loss of dry matter as carbon dioxide. Thus, the native bacteria are not the most efficient. Considerable research in the USA and Europe has been directed towards the development of microbial silage additives (inoculants). Commercial bacterial inoculants designed to add sufficient homofermentative lactic acid bacteria to dominate the fermentation are now available The objective of using such additives is to ensure the rapid production of the required amount of lactic acid from the carbohydrates present to preserve the ensiled material. Most such inoculants contain Lactobacillus plantarum with or without other bacteria such as L. acidophilus, Pediococcus acidilactive and Streptococcus thermophilus. In general, the results with bacterial inoculants have been quite variable. However, with an effective product, it is possible to improve the fermentation of low dry-matter silages and to enhance the efficiency of their utilisation.

In order to improve the effectiveness of microbial inoculants in breaking down structural carbohydrates to glucose, detailed knowledge of the lactobacilli bacteria is essential. Work already undertaken on the molecular biology of Lactobacillus plantarum and other species (Armstrong and Gilbert 1991) suggest that the rapid progress in this area will make it possible to construct novel genes encoding highly active fibre-degrading enzymes. Such genes could then be inserted into strains of L. plantarum.

Successful silage making incorporating these technologies can only be achieved with strict adherence to recommended application procedures, including rates of additives, inoculants etc. This technology is available in most developing regions including Africa. However, it is not fully exploited. Indeed, in Africa silage making is still generally restricted to large-scale commercial farms.

Improving rumen function

Armstrong and Gilbert (1985) and Forsberg et al (1986) have reviewed the major areas of rumen function which might benefit from transgenic technology. These include development of transgenic bacteria with enhanced cellulotic activity, capability to cleave lignohemicellulose complexes, reduced methane production capability decreased proteolytic and/or deaminase activities, increased capability for nitrogen "fixation" and increased ability for microbial production of specific amino acids. The first successful transfer of foreign genes into rumen bacteria (Bacteriodes ruminicola) was reported by Thomson and Flint (1989). However, we are still a long way from commercial production of genetically engineered rumen bacteria.

Although several workers have isolated genes encoding plant structural carbohydrate-degrading enzymes from rumen bacteria, there are limited reports (Hespell and Whitehead 1990) on the genetic engineering of these microorganisms. In contrast to conditions in which single species of organisms are grown in controlled environments and where the energy supply is usually in excess of demand, the rumen environment is very complex, competition between different microbial species is intense and energy is usually the limiting growth factor (Russell and Wilson 1988). This is probably the main reason why reintroduction of genetically modified rumen bacteria into their natural habitat has met with variable success (Flint et al 1989). Advances being made in transformation methods for obligate anaerobic bacteria will certainly result in successful genetic engineering of a range of rumen bacteria. However, it is not possible to predict if any of these bacteria will be capable of colonising the rumen.

It can be concluded that there are several potential opportunities for improving the efficiency of ruminant digestion and possibilities for utilising a wider range of feeds than is currently possible. Modification of rumen microbial population (Hespell 1987; Russell and Wilson 1988; Flores 1989) is one such opportunity. However, technical difficulties associated with making genetic modifications to individual species of rumen bacteria (Armstrong and Gilbert 1991) hinder progress in this area.

Need for biotechnology capacity in developing countries


Biotechnology adoption and adaptation
Environmental concerns about biotechnology
Acknowledgement


For the developed countries, the need for biotechnology may be to increase the level of affluence, but for developing countries, it could reduce hunger and starvation. The use of bovine somatotropin to increase milk production in economies where farmers are being paid to produce less milk illustrates this point. However, not all available biotechnologies are appropriate or relevant to all countries. Developing countries may need to adapt some of these technologies before they can use them. It is therefore important that developing countries develop capacity to maintain a strong base of applied and adaptive research and some level of training to keep abreast with new developments.

Biotechnologies which could have application in developing countries are summarised in Table 3. While the applications of some of the available technologies are relatively simple, it is unlikely that developing countries will be able to retain those trained to support implementation of biotechnology programmes if adequate financing is not available to provide required equipment, chemicals etc to expand or even maintain such programmes.

The development of biotechnology capacity in developing countries is also justified in order to support research which is only of interest to them or that which, because of restrictions in developed countries, can only be done in developing countries. For example, veterinary regulations in most developed countries generally prohibit the introduction of biological material (e.g. infectious agents required for vaccine development) or live animals for research purposes. Therefore developed countries must develop the capacity to undertake such research in the relevant countries.

The disparity between industrialised countries and developing regions of the world in terms of veterinary biotechnology has been summarised by Lefevre (1992): Out of 152 laboratories involved in veterinary biotechnology in 1991, only 26 are located in 17 countries in Asia, Africa and South America. Moreover, some of these laboratories may not be actively involved in biotechnology but are merely interested in it. In sub-Saharan Africa (excluding the Republic of South Africa), only ILRAD (based in Kenya) is actively involved in biotechnology research. However, ILRAD's biotechnology work is focussed on only two diseases, trypanosomiasis and theileriosis. Because the well-equipped and adequately funded laboratories doing research in molecular biology are found almost exclusively in developed countries, the gap between the industrialised and developing countries in technical expertise and relevant research capacity is getting wider and motivated scientists from developing countries with the expertise to carry out sophisticated research are opting to work in laboratories in industrialised countries.

Table 3. Possible applications of biotechnology to the solution of problems of livestock production in developing countries.

Problem

Possible solution1

Scale of economic impact

Probable time to commercial use, years

Animal diseases

New vaccines and new diagnostics

Large

<5

Poor quality forages



Microbial treatment of forages

Moderate

5-10

Modification of rumen microflora

Moderate/large

>10

Genetic improvement of forages and their symbionts

Moderate

5-10

Difficulty of implementing selection programmes


Selection in nucleus herds, using Al, ET, embryo sexing

Large

5-10

Marker-assisted selection

Moderate

5-10

Difficulty of maintaining dairy cattle performance after F1 cross


Use of IVF, ET and embryo sexing Selection among local breeds using AI, MOET

Large Medium/large

>10
>10

Development of composite breeds

Large

>10

Cost and environmental challenge to imported cattle

Use of ET to import embryos

Small

<5

Need for increased efficiency in intensive systems

Use of rBST and rPST in dairy and pig production

Large

<5

1 Definitions: Al: artificial insemination; ET: embryo transfer; IVF: in vitro fertilisation; rBST: recombinant bovine somatotropin; rPST: recombinant porcine somatotropin.

Sources: Adapted (with additions) from Cunningham (1990); Doyle and Spradbrow (1990).

Another justification for local capacity in biotechnology research is to provide a home for orphan commodities. From biotechnology research standpoint, an orphan commodity may be defined as a commodity in which there is or is likely to be little or no investment in modern biotechnology in industrialised countries either because the commodity is not important in temperate areas or because there are no likely profits for transnational companies. Thus an orphan commodity is not necessarily a small commodity. Banana, plantain, cassava, coconut and tropical fruits are examples of orphan crops (Persley 1990). Most African indigenous animals, especially chickens, pigs and goats probably fall in this category although some basic research on these species in the developed countries may benefit the African populations as well. There is thus a need for biotechnology research capacity for problems that may be unique to developing countries. Persley (1990) suggested the establishment of a special funding mechanism to provide support for research on orphan commodities by public and private sector institutions in industrialised and developing countries.

Biotechnology adoption and adaptation

The case of artificial insemination

One of the reasons why technologies developed in the industrialised countries tend not to be implemented with much success in developing countries is the failure to recognise the importance of adapting technology to local conditions. AI is a good example. Where AI technology has been adopted in Africa, not much consideration has been given to adapting it to the circumstances in which it is to be applied to ensure sustainability. Instead, AI uses have been based on sophisticated models intended for countries with good communication and transport systems and with adequate and reliable operating budgets. Such AI use programmes have often collapsed and have had to go through several phases of foreign-aid-supported "rehabilitations" and, in some cases, have eventually collapsed. Government subsidies of the AI system are considered to be another main cause of failure of AI in developing countries. Privatisation of the services may change the situation. For example, in some of these countries, the concept of farmer co-operatives is well developed and applied for specific cash crops or milk marketing. AI could easily be run by co-operatives organised in schemes in which farmers are "grouped" on the basis of such factors as transport requirements and similarity of systems of production. Semen can easily be delivered over short distances by motorbikes, bicycles, horses, donkeys etc. Under such circumstances, use of fresh semen collected from bulls belonging to the co-operative could be considered. This would eliminate the cost of freezing semen. Such schemes would make it easier to match genotypes to production systems within a country. Indeed, such a scheme could form the basis for the genetic improvement of localised indigenous breeds.

The case of embryo transfer

Embryo transfer (ET) could have a major impact on cattle breeding in developing countries (Cunningham 1990) especially as part of a nucleus breeding scheme (Smith 1988b). However, successful ET requires highly motivated, experienced staff and a high capital investment in facilities, equipment and drugs.

In general, the inappropriateness of ET for developing countries is ascribed to lack of infrastructure. However, in some instances, ET represents a solution to a lack of infrastructure. Thus, establishment of multiple ovulation embryo transfer (MOET) is considered an attractive means of genetic improvement where infrastructure for progeny testing is not available.

Most developing countries have limited financial resources. In addition, equipment and supplies tend to be more expensive than they are in developed countries due to transportation costs, import tariffs, lack of hard currency etc. These make ET technology prohibitive in these countries. However, it is possible to adapt ET techniques to local conditions thereby reducing the cost. Seidel and Seidel (1992) pointed out that a lot of the fancy equipment associated with ET are not essential for successful utilisation of the technology. For example, fancy freezing equipment are no more effective than dry ice/alcohol baths for freezing embryos as these save labour and are more convenient. Similarly, filters are not essential for isolation of embryos, neither are disposable sterile syringes and fancy plastic dishes. Thus, by combining good imagination with knowledge of basic principles, the technology can be successfully adapted to local conditions. Therefore research, especially of an applied nature, on such technologies by institutions in developing countries is always justified and often essential. Moreover, researchers need to be exposed to new technologies or procedures to appreciate the power and limitations of such technologies.

Environmental concerns about biotechnology

There is much euphoria about developments in biotechnology and potential benefits, but little is said about the risks associated with biotechnology. For example genetically modified organisms could create ecological disaster if released into the environment.

Biosafety is, therefore, an issue of great concern for many developing countries. In a recent (June 1994) meeting of the Intergovernmental Committee on the Convention on Biological Diversity (CBD 1992), representatives of developing countries pointed out that biotechnology was evolving more rapidly than the capacity of their countries to install effective safety procedures for the handling and use of living modified organisms and that there was need for adequate and transparent safety procedures to manage and control the risks associated with the use and release of such organisms. To deal with the basic ethical questions and the risks associated with genetic engineering, regulatory mechanisms should be created and internationally acceptable guidelines or regulations put in place. The political and regulatory processes affecting biotechnology and its products must draw upon professional competence of the highest standard. In general, however, developed countries are lukewarm to the idea of a legally binding international protocol on biosafety, possibly because it is a heavy responsibility with potentially massive cost implications for the technology-rich countries. However, biosafety is an issue which must be addressed sooner than later.

Acknowledgement

I wish to thank Dr R.L. Baker for assisting me, at a time of immense pressure, in obtaining several critical references used in this paper.

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