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 Abstracts on Sustainable Agriculture (GTZ, 1992, 423 p.)
 Abstracts on integrated systems
1069 92 - 3/119
Latin America, Colombia, study, tropical deforestation, livestock production, cattle, small livestock, biomass production systems
 1. Intensive sustainable livestock production: an alternative to tropical deforestation.
AMBIO, 19, 1990, pp. 397-400
Extensive cattle grazing is the principal production system employed by the colonizers of rain forests and has been, and still is, encouraged by most state agencies for rural development and agrarian reform, even though scientific research has demonstrated clearly the failure of this system in most tropical ecosystems.
When cattle-grazing systems are the main activity of resource-poor farmers with insufficient capital and minimal access to credit, returns are usually insufficient to support the minimal needs of the family. The consequence is that the land is sold, usually to the rich landholders, who, through economies of scale, can continue with the extensive grazing systems; and the resource-poor farmer turns once again to the forest and the destructive process continues.
To solve the problem of tropical forest destruction demands a strategy which is of necessity complex, if the remaining tropical forest areas with their ecological riches and biological diversity are to be preserved.
An intensive livestock production model, based on the concept of using highly efficient energy- and nitrogen-fixing plants, promises to offer an appropriate technological solution to the problem of providing an alternative to extensive cattle-grazing systems.
An appropriate strategy is the rational use of the natural resources of the tropics, namely:
- solar energy captured by highly efficient crops through the processes of photosynthesis; and
- the genetic diversity of the nitrogen-fixing plants present in the forest flora.
In recent years, several Latin American countries, have directed research and development activities towards validating the hypothesis that sugarcane can be the basis of intensive animal production systems, thus assuming the role played by the cereal grains in the temperate countries. In a complementary way, it is increasingly being recognized that nitrogen-fixing trees and shrubs (leguminous and non-leguminous) can provide much of the protein needed to balance the carbohydrates from the sugarcane.
The model has the additional benefit of providing a comparative advantage for the resource-poor farmer with limited land area. The model employs fractionation of both the sugarcane and the forage trees to provide suitable diets for monogastric and ruminant animals in an integrated operation, which is proving to be technically, economically and ecologically sustainable.
The model developed in Colombia employs complementary livestock species (pigs and sheep) managed in confinement. Productivity is a function of sugarcane yield which depends on soil fertility, water availability and variety. For the world average yield of 50 tonnes per ha per year, total liveweight production per year from pigs and sheep can be 1500 kg per year. With appropriate management, sugarcane can yield up to 180 tonnes per ha per year, which will give 8000 kg liveweight per hectare per year.
During the last three years, this model has been subjected to continuous testing and adaption to Colombian conditions with extremely promising results. The crops used in the model (sugarcane and forage trees) are perennial, thus soil erosion is contained.
Implementing these models on a massive scale will result in a substantial reduction of the area required to support a resource-poor farmer. At the same time, existing grazing areas can be transformed into more productive units with obvious advantages in terms of job creation and economic stimulus to rural development.
A weakness of the system is the lack of certainty as to the best way to provide the protein input. Recent developments in this area are encouraging. And even at the present stage of development, the results are much more superior, in economic, sociological and ecological terms, than traditional grazing systems.
1070 92 - 3/120
Africa, Nigeria, humid tropics, study, snail utilization, traditional medicine, cultural values
AGBELUSI, E.A. and B.N. EJIDIKE
 2. Utilization of the african giant land snail in the humid area of nigeria.
Trop. Agric. (Trinidad), 69, 1, 1992, pp. 88-92
This paper examined the utilization of the giant land snail among the people of Ondo State in Nigeria. The study was carried out in ten of the 17 local government areas in Ondo State of Nigeria.
A questionnaire was used to obtain data on the pattern of utilization of this animal.
The climate is tropical with two distinct seasons, the wet season and a dry season. The vegetation of Ondo State ranges from mangrove swamp at the coast to derived savanna towards the northern boundary.
The African giant land snail is the largest among the terrestrial Gastropoda living in Africa. This snail species is found mostly in the high forest zone. A mature adult weights approximately 750 g and the foot, which constitutes the edible part, is about 30% of the live weight.
Snail meat is highly relished and considered a delicacy for the peasant population living in the rural area of the forest zone of West Africa, especially in Nigeria and Ghana. Apart from its nutritive value, it is also used in traditional medicine.
The results indicate that snails are used primarily as meat by the rural and urban people. This may be due to a downward trend in the economy of the nation which places frozen fish and chicken out of reach of the common citizen, so that wild animals are the primary source of protein.
Although some groups of people have taboo, religious and other reasons for not eating snails, the numbers are quite insignificant when compared with those who relish snail meat and consider it to be a delicacy.
Alternative uses for giant land snails do exist. The land snails are very important in traditional medicine throughout the areas. Various parts of this animal are utilized in preparing medicine for curing numerous ailments. When mixed with other ingredients, the fluid from giant land snails cured headache and malaria. This fluid also improved blood clotting on a fresh wound. The shells of giant land snails when smoked/burnt to a colourless condition are ground and mixed with other ingredients in preparing a medicine for pregnant women during labour and as fertility drug for women experiencing difficulty with conception.
The importance of giant land snails is also reflected in cultural values. Snails are one of the ingredients used in making a sacrifice to Ogun (the god of iron).
Snail shells, which are regarded as the trophy of the animal, are used as decorative objects, especially when painted with different colours.
Some rural people also store traditional medicine in giant land snail shells and some make use of the shells as an abrasive for washing utensils and brushing teeth.
Snails also provide employment for some people in the rural area. Owing to a high demand for this animal, some of the rural dwellers are now full-time or part-time gatherers of snails.
These results revealed that the snails were important not only as a source of animal protein to the population but also an important ingredient in their traditional medicine.
1071 92 - 3/121
Survey, developing countries, industrialized countries, livestock production, small-holders, development policies, environmental pollution, animals, extension, education
 3. Important issues of small-holder livestock sector worldwide.
Sustainable Agriculture, 3, 1, 1991, p. 5
Heifer Project International listed a comparison of important issues of the livestock world around the world.
Developing national and international policies which stress the importance that small scale farmer play in agriculture and environmental balance is important. Often, economies of scale are applied to agricultural situations leading to production efficiency at the expense of the environment, animal health and welfare of small farmers. Greater value must be placed on animals and crops raised by small scale producers to avoid monopolization of agriculture, increase agricultural diversity and keep rural populations viable.
The overriding issue listed was how are animals fed and cared for.
In non-industrialized countries, the concern for animals is more along the lines of how does one keep an animal fed during the lean months.
Farmer based technology such as agroforestry techniques, fodder banks, development of vegetative erosion control barriers, utilization of crop wastes, increased planting of leguminous trees and pasture crops are techniques that are readily adaptable. Farmers easily see how livestock and the land benefit from establishment of year-round reliable feed sources.
The most successful operations in non-industrialized countries are those that utilize livestock as waste converters. Ruminants, with their ability to digest cellulose, are especially suited to this task. Animals can be useful in using those things that are waste or inedible for humans and convert it into human food.
Finally a system that involves people, land, plants and animals is the paradigm for animal agricultural development for the 90s.
1072 92 - 3/122
Review, book, developing countries, arid zone, semi-arid zone, tropics, small ruminant production, sheep, goats, breeding, nutrition, management, feeds, FAO
TIMON, V.M. and J.P. HANRAHAN
 4. Small ruminant production in developing countries.
FAO Animal Production and Health Paper No. 58, FAO, Rome, ISBN 92-5-102343-3, 1985, price DM 33,-
FAO organized an Expert Consultation on Small Ruminant Production in Sofia, July 8/12, 1985. The papers published in these proceedings represent the technical contributions and discussions at the meeting.
Separate to these discussions the consultation addressed some of the broader issues of importance to the advancement of small ruminant production, particularly in the developing countries, and at the end of the meeting agreed a set of recommendations.
Twenty papers were presented and discussed in the consultation and are reproduced in these proceedings. Strategies in breeding and breed development, nutrition and management, the development and utilization of indigenous grasses, shrubs and forest feeds for the production of sheep and goats, in arid, semi-arid and tropical conditions.
Small ruminants such as sheep and goats have adaptive capacities to survive and produce in difficult environments be they arid, high altitude or extremely cold. Generally, small ruminants are efficient converters of forage feeds whether they are farmed in temperate, arid or semi-tropical conditions. Perhaps their greatest advantage relative to large ruminants is their low cost, small size, their suitability to small holdings and in many of the developing countries, their triple purpose use for meat, milk and fibre.
There is a steady increase in sheep and goat numbers; sheep numbers are in excess of one billion head and goat numbers globally are now approaching half a billion head.
Increasing numbers is not enough. The fundamental issues are increased efficiency of production, biological efficiency, structural/organizational efficiency or more effective use of basic feed resources.
The recommendations are set down under the following broad headings:
- Research and development in small ruminant production. In view of the very significant contribution of small ruminants to the economy and livelihood of peoples in almost every country around the world, and particularly in the developing countries, the consultation strongly recommends that much greater priority and much larger investment should be made by national and international institutions in the promotion of small ruminant production. - Coordination - linkages. The consultation recommends that there is need for much more effective coordination and closer linkages between institutions involved in small ruminant production throughout the world and in particular involving research and development centres in the developing world. - Support services/infrastructure. The expert group considered the likely success of development in small ruminant production and recommends that an adequately planned infrastructure and support services must form an integral part of all development programmes in small ruminant production. - Genetics and breed improvement. Very serious consideration should be given to the choice of species (and/or mixture of species) and the choice of breed in the very first stages of planning the development of small ruminant production.
Adaptation of breed to local environment should be a key element in breed choice and breed development strategies. This means paying particular attention to indigenous breeds.
The consultation considered that many of the developments in the technologies of reproduction in small ruminants are not and will not be relevant to small ruminant production in the developing countries until levels of nutrition and management are substantially increased, and market prices dictate more cost effective results.
1073 92 - 3/123
Review, book, microlivestock, animals, economics, future, microbreeds, poultry, rabbits, rodents, deer, antilope, lizards, bees
 5. Microlivestock little-known small animals with a promising economic future.
Publ. of the Board on Science and Technology for International Development (BOSTID), Nat. Research Council; Nat. Academy Press, Washington, D.C., ISBN 0-309-04437-5; 1991, 370 p. + annexes
The purpose of this report is to raise awareness of the potential of small livestock species and to stimulate their introduction into animal research and economic development programs. It is geared particularly towards benefiting developing countries.
'Microlivestock' is a term suggested for species that are inherently small, such as rabbits and poultry, as well as for breeds of cattle, sheep, goats and pigs that are less than about half the size of the most common breeds. These miniature animals seem to have a promising future.
The book was prepared after an intensive survey of more than 300 animal scientists in 80 countries. They suggested more than 150 species for inclusion. The staff then drafted chapters on about 40 species and these drafts were reviewed by more than 400 researchers worldwide.
This study covers many species, but it by no means exhausts all the microlivestock possibilities.
As well as dwarf breeds of cattle, sheep and goats, the book covers more unusual species that can be farmed profitably including deer, the giant rat, coypu and guinea pig are dealt with.
Each potentially useful breed is analyzed and useful information set out under headings, including appearance, husbandry, behaviour and uses.
The muscovy duck, for example, is shown to have several advantages over the domestic duck, in that it is a good forager, is not so susceptible to disease and produces a lean carcass.
Not much space was allocated to the inclusion of aquatic food sources or edible insects, snails, worms, turtles, birds or bats, highly regarded food sources in some regions.
A warning was issued about the introduction of certain species, especially rodents, into regions where they do not exist. Such schemes can, obviously, have dramatic negative consequences.
This report is addressed to government administrators, technical-assistance personnel, and researchers in agriculture, nutrition, and related disciplines who are concerned with helping developing countries achieve a more efficient and balanced exploitation of their biological resources.
The book is easy to read, and with little technical language, the book will be particularly useful in those areas where good grazing is in short supply.
This is an extremely interesting book and is highly recommended for all those engaged in livestock production.
The Board on Science and Technology for International Development (BOSTID) of the Office of International Affairs addresses a range of issues arising from the ways in which science and technology in developing countries can stimulate and complement the complex processes of social and economic development. It oversees a broad program of bilateral workshops with scientific organizations in developing countries and conducts special studies.
This report was prepared by an ad hoc advisory panel of the Advisory Committee on Technology Innovation, Board on Science and Technology for International Development.
1074 92 - 3/124
Review, book, Africa, subhumid zone, arid zone, Nigeria, Sudan, Kenya,
Botswana, livestock production, projects, multilateral agencies, NGO's, animal health, range management, livestock feed, restocking systems, ODI
 6. Assisting African livestock keepers.
Overseas Development Institute (ODI), Regents College, Inner Circle Regent's Park, London NW1-4NS, UK; ISBN 085003-143-5, 1991, 61 pp., UK Â£5.95
Â‘Assisting African livestock keepers' is a collection of four papers which were originally published in the Overseas Development Institute
(ODI) Pastoral development network. They refer to a range of subjects within pastoral development; animal health, animal feed, range management, and post-drought recovery. All emphasize the need for the participation of livestock-keepers in project management. They describe projects in Nigeria, Sudan, Kenya and Botswana which cover both subhumid and semi-arid regions. The development institutions involved range from large multilateral agencies to a small Sudanese NGO.
The first paper, on animal health, describes an example of an increasingly popular approach to the delivery of veterinary services, namely the training of herder specialists. The project was a notable success in terms of the number of livestock vaccinated. The second paper is about range management and lists the conclusions to be drawn, and the problems that arose, during six years of work in Botswana on establishing fenced grazing areas radiating out from a central water point. Improvement of livestock feed in the subhumid zone of Nigeria is the subject of the third paper. It describes the achievements and problems faced during the course of a research project set up to involve livestock keepers in fencing off a small plot of land near their homestead and in supplementing the natural pastures therein with a forage legume for use during the dry season. The fourth paper is an evaluation of four restocking projects set up in various parts of Kenya.
1075 92 - 3/125
Review, book, Europe, deer farming, research, development, practical aspects, theory, nutrition, health, selection, breeding, farming systems, marketing, economy
 7. Deer farming.
Farming Press Books, Ipswich, UK, ISBN 0-85236-206-4; 1990; Â£15.95
In the quest for alternative forms of livestock production to sheep and cattle in northern Europe, deer farming has been strongly advocated. It is environmentally friendly with low inputs of fertilizers and pesticides and farmed venison is a lean and natural meat with a distinctive flavour desired by consumers. It has also an advantage over other proposed alternatives in that there is a strong body of scientific knowledge on the biology of deer and a resource of information on farming techniques which has been collected in the last 20 years.
This book draws on such research and development work carried out between 1970 and 1985 in Germany and elsewhere and decribes how to farm fallow deer in Germany, covering both theoretical and practical aspects in a comprehensive manner. Nutrition, health, selection and breeding, farming systems, marketing and economics are convincingly dealt with.
This translation from the German into English is generally of a good standard. While the book offers a valuable insight into the state of the deer farming industry and agriculture in West Germany in the mid-1980s, it could have had a broader appeal if some of the detail only relevant to German conditions had been omitted in the English edition.
The major strength of the book is its wealth of information on fallow deer and their farming which will be valuable to scientists, lecturers, advisers and consultants in many European countries. Although reference is made to the farming of other species, such as the red deer, where information on the fallow deer is lacking, there clearly exists a need for a companion volume on the farming of the red deer under European conditions. This book sets a high standard for future publications on deer farming which will no doubt appear as the potential of deer farming as an alternative livestock enterprise is realized.
Abstract by J.A. Milne
1076 92 - 3/126
Study, developing countries, Africa, Asia, Latin America, sheep, goat, economic constraints, feed shortages, trade, policies, capital, flock size, risks, labour, FAO
 8. Economic constraints on sheep and goat production in developing countries.
In: FAO Animal Production and Health Paper No. 58, FAO, Rome, Italy; 1985, pp. 138-147
This paper discusses some economic factors that have affected the efficiency of production, documents selected cases, and offers some solutions to the problems.
Sheep and goats are important livestock species in developing countries.
Fifty-three percent of the total small-ruminant population in the developing countries is found in Asia, particularly in India and Pakistan, 33% in Africa, and 14% in Latin America.
The total product from small ruminants increased in developing countries because their numbers increased.
Sheep and goats are important in development because of their ability to convert forages and crops and household residues into meat, fibre, skins and milk. The economic importance of each of the products varies between regions, especially in the developing countries.
Goats are hardy and well-adapted to harsh climates. Due to their grazing habits and physiological characteristics, they are able to browse on plants that would normally not be eaten by other livestock species. The presence of goats in mixed species grazing systems can lead to a more efficient use of the natural resource base and add flexibility to the management of livestock. This characteristic is especially desirable in fragile environments.
Sheep and goats contribute to a broad range of production systems.
The most common production system throughout the developing countries involves either the extensive system with large herds and/or flocks grazing on arid and semi-arid rangelands or the intensive system with smaller herds and/or flocks kept in confinement, mostly in the humid tropics. Both systems are characterized by low input use.
Most of the world's sheep and goats are produced on mixed-species farms rather than in species-specific units.
Technological development studies of small-ruminant production as it relates to other farming systems have been limited. Therefore, the target, in terms of research, has to be integrated production systems rather than isolated sheep and goat components. By using a multidisciplinary research approach, the problem can be addressed in a realistic and practical way.
The problems of sheep and goat production can neither be efficiently nor successfully solved until research concentrates on studying all of the related and interrelated components involved. For too long, research has focused on one discipline at a time, ignoring the developing country's culture, environment, educational level of its producers, and the availability and dependability of local technology transfer.
It is important to know that an increase in sheep and goat activity in an integrated system could increase the total productivity of a farm through more efficient labour and available resources and generate more income per unit of time.
If developing countries could increase herd productivity, they could increase production. To increase production in developing countries, existing constraints must be overcome.
1077 92 - 3/127
Review, books, sheep, pigs, animal production, tropics, subtropics, CTA
GATENBY, R. and HOLNESS, D.H.
 9. Sheep. Pigs.
The Tropical Agriculturist Series; Macmillan and CTA, Sheep 0-333-52310-5; Pigs 0-333-52308-3; 1991, available from CTA, Postbus 380, 6700 A.J., Wageningen, The Netherlands
Sheep is the second volume in this series to be produced in the field of animal production: it follows the volume on 'Poultry'. The importance of sheep in tropical countries is often overlooked. They are, in fact, very important: over 600 million of them are to be found in the developing world. Sheep will thrive under conditions where either crops or other forms of livestock would not because the climate is too arid or the soil too poor.
However, they can be integrated well with both crops and other forms of animal production and, because of their relatively small size, they can provide a more convenient source of meat than cattle and they are often kept by farmers as a kind of insurance for quick sale or slaughter for festivities.
The third book in the series, 'Pigs', considers some of their advantages. The world trend is towards the consumption of more white, rather than red meat. Pigs produce meat without contributing to the deterioration of natural grazing lands.
This is of paramount importance in relation to the current desertification, soil erosion and loss of productive land in tropical and subtropical parts of the world. However, there are problems, particularly those associated with feed supplies; and inadequate control of disease may make intensive pig production unprofitable or even untenable. Religious considerations may make pig-keeping unacceptable, and the possibility of transfer of disease and parasites to the human population may make extensive pig production unwise.
This book considers these problems to see which systems of pig production are most acceptable in various regions of the tropics and which should be avoided. It approaches the subject from the point of view of both the commercial producer and of the village pig-keeper. As with all the books in The Tropical Agriculturist series, these are readable, informative and practical guides.
Abstract from SPORE
1078 92 - 3/128
Africa, Rwanda, Kenya, Sudan, Nigeria, Ethiopia, Mali, sheep production, traditional systems, farming systems development
 10. Strategies to increase sheep production in East Africa.
In: FAO Animal Production and Health Paper 58; FAO, Rome, Italy; pp. 118-123
Sheep in eastern Africa are managed in traditional systems. The end product is almost entirely meat, either for home consumption or to an internal or external market through sales. In parts of Sudan, sheep are also kept to provide milk.
In most traditional societies, first lambing occurs at 15-18 months when ewe weights are 80-85 per cent of mature size. Control of age at first breeding usually means delaying this and may result in first lambing not taking place until 2 years or older.
Total lifetime production of young can be increased by encouraging first lambing at early ages.
The growth rate is an important factor in livestock productivity. In traditional systems, because of overstocking, genetic potential is rarely expressed. Growth rates vary from as little as 40 g per day in Kenya Masai sheep to as much as 70 g per day in Sudan Desert type from western Sudan.
As an example of the potential for increased growth under improved conditions of nutrition and management, the "Mouton de Case" sheep in West Africa achieves a growth rate of 117 g per day to 40 weeks of age compared with only 60 g for its range-reared contemporaries.
Management practices in many traditional societies are such that the best adapted sheep or those with superior genetic potential are not used as breeding stock. This is because of the cultural or religious requirements for large fat sheep for slaughter at social and sacrificial occasions.
Pre-weaning mortality has been shown to be an extremely important constraint on productivity of sheep. Levels of up to 30 or even 40 per cent losses before weaning are not uncommon.
The standard approach to improving the supposedly unproductive indigenous African sheep types has been to import exotic breeds, usually of European origin.
There have rarely been successful transfer of these breeds to traditional systems. In East Africa, successes have almost entirely been confined to those cases where modern management practices can be assured and high levels of veterinary and nutritional inputs maintained.
Identifying these practices and abilities and extending them to other owners would lead to overall improvement. A plan for improvement of a traditional flock with the minimum of outside and costly interventions is shown in this paper.
1079 92 - 3/129
Pacific, Solomon Islands, pig production, compound feeds, pig feeds
 11. Alternatives to imported compound feeds for growing pigs in solomon islands.
Trop. Agric. (Trinidad), 69, 2, 1992, pp. 141-143
The developing island nations of the Pacific region are often at a disadvantage as locally available feed resources are limited and technical expertise to facilitate their use may be lacking. Importation of feeds into these countries greatly increases the pig farmer's cash outlay and, in many cases, can render intensive pig-keeping a rather marginal activity.
The small-scale pig farmer has markedly different requirements from those of the intensive pig producer. As an alternative to the use of compound feeds, it may be possible to supply locally-produced protein concentrates to pig farmers operating under village conditions. These can supplement the low nutrient-dense energy feeds (e.g. root crops, fresh coconuts) that are widely available and allow levels of production not greatly below those of intensive pig producers. Such systems, based on sweet potato and cassava as the principal energy source have been evaluated experimentally with encouraging results.
Therefore an experiment was carried out to consider the use of locally available raw materials in the diets of fast-growing pigs either as a complete compound feed or as a protein concentrate to supplement low nutrient-dense energy feeds.
Three dietary treatments were tested in the experiment. An imported pig-grower diet was compared with an equivalent compound diet of local origin and a semi-intensive system in which low nutrient-dense energy feeds (cassava and coconut) were supplemented with a 50% crude protein concentrate designed to be fed at approximately 20% of dry matter intake.
An imported compound pig grower diet resulted in slower growth (P=0.075) and poorer feed conversion ratio (P=0.001) than a similar diet compounded from locally available raw materials. The economic advantages of the local compound feed were marked (P<0.001) with cost per kg of liveweight gain being little over one third (SI.36 vs SI.11) of that observed with the imported feed. An alternative system employing a combination of a locally-produced protein concentrate and fresh cassava and coconut resulted in slightly poorer growth rates than the compound feeds but was still competitive in economic terms. The use of concentrate, cassava and coconut did, however, result in fatter carcasses in terms of back-fat measured at the mid-back (P=0.005) and the loin (P=0.007).
The true value of any livestock feed is only revealed when the economic advantages associated with its use are taken into account. A feed which results in fast and efficient growth but at excessive cost may be just as unsuitable as a cheaper feed which satisfies few of the animal's requirements and results in poor growth rates. The most suitable feed will invariably lie between these two extremes.
From these results it seems likely that pig production using imported feed might become uneconomic if high labour and service costs are incurred.
The locally-produced compound diet which combined fast, efficient growth with low cost therefore resulted in the highest returns.
The costings discussed above are based on pigs produced for commercial sale. The economics of pig sales in or between villages are likely to differ somewhat because of generally lower and more variable prices.
Under these conditions, the benefits of intensification by improved nutrition using purchased feedstuffs may not always materialize. Before recommending the use of purchased feeds to any farmer with a pig project, extension workers should consider what reliable markets are available for animal products.
Concluding, it can be said that raw materials are available in Solomon Islands which ought to allow local production of compound pig feeds with several potential advantages: feed costs are dramatically reduced when local ingredients are used; the quality of local feed ingredients is more easily assured than that of imported feeds as more local control is possible and import substitution is of general benefit to Solomon Islands' economic development.
1080 92 - 3/130
Asia, India, on-farm research, dairy animal, sustainable development, economic analysis, crossbred-cows, green fodder, fodder production, technology transfer
 12. Economic analysis of on-farm dairy animal research and its relevance to development.
In Proc. of on-farm animal research/extension and its economic analysis; Winrock Int. Inst. for Agric. Development, Los Baï¿½os, Laguna, Philippines; 1987, pp. 45-52
An economic analysis of on-farm research trials conducted in India on crossbred cows and fodder crops on rural farms was done.
Figures indicate a wide gap between availability of and need for milk in the country.
Low production and per capita availability of milk in the country are due to poor productivity of milk animals, which can be attributed to poor genetic potential, poor nutrition, widespread disease, and lack of organized marketing and credit facilities. The average annual milk yields of Indian cattle and buffalo are only 181 kg and 438 kg, respectively.
To improve animal productivity and increase milk production, concerted research and extension are needed.
Results showed the economic viability and superiority of crossbred cows over animals kept by the rural households. Three crossbred cows kept on an acre of irrigated land generated net and family labor incomes of Rs. 1,345 and Rs. 2,772 per cow per annum, respectively. A three plot system of fodder production on small farms gave an average yield of 61,803 kg green fodder which was sufficient to feed four adult crossbred cows in one year. This indicates that three crossbred cows can be maintained profitably on one acre if intensive fodder crop rotations are followed.
Highest average yields were obtained from a multi-cut mixture of fodder crops like sweet sudan, cowpea, teosinte, sorghum and pearl millet sown in summer (5,316 kg/ha) and berseem + mustard in winter (7,835 kg/ha).
The analysis revealed that on-farm trials can help small farmers in selecting fodder crops for economical milk production.
Dairy farming that uses high-yielding animals and scientific practices has great potential to increase income and employment levels; therefore, on-farm research trials are important for disseminating new innovations and technology to the farmers.
One can conclude that the technology demonstrated through on-farm research trials was technically feasible and economically remunerative and it can uplift the poor of India.
1081 92 - 3/131
Review, book, UK, New Zealand, grazing management, grasslands, animal production, animal feed, low-input systems, herbage intake, grazing methods, sward monitoring, enterprise planning
 13. Grazing management: science into practice.
Publ. of Longman Group, UK; ISBN 0-582-45010-1; 1990; Â£11.95
This is the latest book in the series 'Longman Handbooks in Agriculture'. It is an opportune time for the book to be published as research has advanced knowledge of grazed grassland considerably in the past 15 years. The author has been at the forefront of these advances.
In particular, the understanding of sward dynamics and the animal behavioural factors influencing intake have been clarified by research.
This has enabled the limitations to animal production from grazed grassland to be implemented to increase output. Reductions in government financial support for agricultural food products in developed countries will accelerate the move to lower input systems of production, which for ruminant animals means a greater reliance on grazing.
There are 20 chapters liberally sprinkled with tables and figures. Ten chapters deal with the principles of grazing including the grazed sward, the grazing animal, factors affecting herbage intake, food conversion efficiency and output from grazing systems. The resources of plants, soils, fertilizers and supplements are covered in four chapters. The final six chapters are devoted to applications, including grazing methods, sward monitoring and control and enterprise planning.
The book is written to answer the question of how the science behind grazing can be used by management to increase output, rather than how grazing management can draw on science to assist it, that is, it is science-driven rather than management-driven. Great reliance is placed on research experience in the UK, although the penultimate chapter on 'Enterprise planning and feed budgeting' reflects the author's more recent New Zealand experience. Extensive grazing on hills or rangeland is not covered, nor are grazing and plant species diversity.
The book is stronger on the principles of grazing mainly with intensive grazing. Being strongly research-based, it is directed more at the enthusiastic learner than at the superficial reader. Nevertheless this is an up-to-date, comprehensive account of the principles of grazing management, written by a world expert, which should make an important contribution to teaching in agricultural and applied biology.
1082 92 - 3/132
Review, research report, Africa, Sub-Sahara, case studies, fish farming
LAZARD, J. et al.
 14. Fish-farming in sub-Saharan Africa: case studies in the francophone countries - proposals for future action.
AGRIDOC Inst. BDPA SCETAGRI, 27 Rue Louis Vicat 75738, Paris cedex 15, France; ISBN 2 11-086732-9; price 120 ff
Fish farming is a long-standing and traditional activity in Asia, but it is relatively new to Africa, arriving only in the last half century or so. Its potential has yet to be developed: the annual tonnage of fish, approximately 10,000 t, accounts for only 0.1% of world production. But the increasing demand for fish, especially in urban areas, means that there is likely to be a boom in aquaculture.
African fish-farming can be classified into several categories. At the lowest end of the scale is "family" aquaculture: the peasant farmer will dig out a pond by hand, with the help of family members, to rear tilapia for his domestic consumption only. This practice is common in many francophone African countries and often receives considerable aid from international organizations or NGOs for the breeding of young fish, extension and training work, personnel, etc. However, the results are universally disappointing, the farmers are not motivated, yields are low and incomes poor.
The second category is small-scale commercial aquaculture, which is beginning to be a significant factor, especially close to cities. The difference between this and family fish-farming is that it is essentially business concern which necessitates buying in materials and marketing the produce. For this reason fish-farmers establish their businesses close to town in order to make use of the urban infrastructure and the marketing potential. FAO has developed a project of this type in C_te d'Ivoire, in the Bouak_ and Daloa regions. About 50 farmers have dug out their own ponds and now breed their own young stock and rear them with the help of the project staff. Research has shown that it is these small or medium-scale ventures which seem to have the best chance of succeeding.
The characteristic of the third category, 'network' aquaculture, is that its different stages (hatcheries, fish-feed processing, fish production) are separated.
This system is well-suited to some areas, for example where there are lakes, lagoons or water courses. The lagoons of Cï¿½te d'Ivoire have rearing projects in enclosures and cages, and Niger has set up cage culture schemes in the river. It particularly suits some sectors of the population - for example it can provide an alternative living for fishermen when their traditional sources of income are insufficient, and city businessmen are able to invest capital in the hope of significant returns. However, further research into the ideal environment for fisch-rearing and into improving feed is still necessary.
The final category - 'industrial', large-scale aquaculture - is carried out in sizeable production units. It depends on high productivity and, for example, raceways, tanks or cages, which demand considerable capital outlay. Burkina Faso set up the Banfora Aquaculture project of intensive-system fish production with cages and raceways, but hatchery and feed problems forced it to close down in 1986. An industrial fish farm in Brazzaville (Congo) forecast tilapia production of 500 tonnes per annum in concrete raceways using water pumped up from the nearby river. This enterprise was also bedevilled by numerous technical problems which slowed production, and financial results were well down on the forecasts. At present this type of fish culture is extremely problematic in that the cost of production is still considerably higher than the sale price.
All these categories of fish-farming are surveyed in this report, which has just been published by the French Ministry of Cooperation. It analyses the current state-of-the-art and suggests some future directions. Particularly useful are the many case studies used to support the theories put forward by the authors, and the analysis of socio-economic factors, especially the market study comparing farmed and wild fish. Also described in this book is 30 years' experience of experimental research done in the field. It addresses the problems of the training need to improve the technical and professional skills of African aquaculturalists.
1083 92 - 3/133
Review, book, tropics, integrated crop-livestock-fish farming, concept, research framework, education, institutional framework, ICLARM, UNDP
EDWARDS, P. et al.
 15. Research and education for the development of integrated crop-livestock-fish farming systems in the tropics.
Publ. by ICLARM, MC P.O.B. 1501, Makati, Manila, Philippines; ISBN 971-1022-46-x; 1988, 47 p. + annexes
In this publication, an attempt is made to create a framework for a truly interdisciplinary approach to research and education in integrated farming - a fusion of agricultural and aquaculture sciences.
Hunting/gathering/fishing preceded the development of agriculture but are still of importance in many third-world countries, particularly with regard to fish. Indeed, the capture of wild fish, as opposed to aquaculture, is still the major source of fish in most third-world countries.
The crop, livestock and fish subsystems may function independently in certain farming systems, and their products be only additive. An output from one subsystem in an integrated farming system, which otherwise may have been wasted, becomes an input to another subsystem resulting in a greater efficiency of output of desired products from the land/water area under a farmer's control. There is synergism in integrated farming since the working together of the subsystems has a greater total effect than the sum of their individual effects.
That means the word integrated is derived from the Latin verb "integrare", which means to make whole, to complete by addition of parts, or to combine parts into a whole.
The main biological feature of an integrated farming system is byproduct recycling; but improved space utilization, in which two subsystems occupy part or all of the space required for one subsystem, may be an important aspect of increased productivity. A major socioeconomic benefit of integrated farming is that inputs to the various subsystems that comprise the farming system tend to be intra-farm, with a diminished reliance on inter-farm or agro-industrial inputs. Integrated farming systems also spread the risks associated with farming because of the increased diversity of produce. They also lead to a more balanced diet for the farming family that chooses to eat some of its own produce.
A schema is presented in this study of the possible evolutionary development of integrated farming systems to set the research framework recommended here in an appropriate context.
Aquaculture science is a relatively new field of study.
The attention normaly remains narrowly focused on the fish and the aquatic environment rather than on the farmer and the whole farm.
The greatest scope for the development of integrated crop-livestock-fish farming systems is in the humid tropics. This is where the need is also greatest.
This climate allows tropical fish to grow year-round.
The integrated farming systems discussed in this study make use of tropical fish, particularly the omnivorous tilapia which has been hailed as the "aquatic chicken" of the future. Tilapias breed and grow year-round in the tropics.
Integration of aquaculture with agriculture is more developed in Asia than in any other region of the world. Integrated farming systems are presently used by only a very small minority of farmers in a few countries and have not progressed far in terms of productivity and efficiency from their traditional beginnings.
A vast potential still exists for many more of Asia's numerous and needy small-scale farmers to enjoy the benefits of integration of aquaculture into farming systems. To realize this potential requires a new research and education program, as is proposed in this publication.
For Africa, the potential for aquaculture and integrated farming development is far less certain.
For many African nations there are serious constraints to aquaculture and integrated farming development.
A holistic view of the farm is essential. Aquaculturists must learn to understand existing crop and crop-livestock farming systems and agricultural researchers the fish farming subsystem. The processes of research and education for the development of integrated farming systems are therefore closely interlinked. This calls for an innovative approach to bring aquaculture into the mainstream of agriculture.
A cautious approach to aquaculture development is needed; not a rush into development by transfer of foreign technologies. Such a cautious approach should best be undertaken in parallel with further research for the development of Asian integrated crop-fish and crop-livestock-fish systems for which reliable management guidelines are still lacking.
1084 92 - 3/134
Asia, Philippines, study, goat/fish farming, culture periods, tilapia
 16. Goats/fish integrated farming in the philippines.
AMBIO, 19, 8, 1990, pp. 408-410
This paper presents preliminary findings from the two 120-day fish-culture periods in a 240-day goat rearing cycle in the Philippines.
There is a government program for an effective approach to improving the quality of life of the people, not only in the urban communities but also in the rural areas through the livelihood project. The project is a centerpiece program and seeks to boost livelihood opportunities nationwide. Goat raising has become one of the priorities of the program. The small size of goats, their early maturation, inquisitive feeding habits and low capital investment must be exploited to spur development of intensive goat production including the utilization of the manure in fish culture.
The present project was initiated to determine the maximum rate of goat-manure loading and stocking density of Nile tilapia (Oreochromis niloticum) per unit area of fishpond and design a goat/fish integrated farming system that could give the highest economic return, with manure as the only added nutrient source.
This study was conducted in twelve 200 m2 fishponds. The goat houses had a floor area of 0.75 m x 1.5 m per goat and were built partially overhanging the surface of the pond.
An integrated farming system offers several potential advantages, i.e. increased productivity, greater income, improved cash flow, fuller employment, a better diet for the farmer and his family and the spread of both biological and economic risks, since two subsystems are involved as opposed to one in a single commodity farming system. This strategy, however, requires knowledge and management skills.
The major constraint for small-scale farmers involved in aquaculture is the shortage and high cost of pond fertilizer and commercial feeds for the fish.
In the Ilocos Region, Philippines, intensive goat raising is possible due to the high demand for chevron (goat meat) which is the main delicacy of the Ilocanos. Intensification is greatly limited by the problem of waste disposal. Many Ilocanos are engaged in small-scale aquaculture, but operations are hindered by the shortage and high cost of commercial feeds and fertilizer for their fish ponds. This goat/fish production trial described employ 0, 200, and 300 goats with fish-stocking densities of 10,000 and 20,000 of Nile tilapia
(Oreochromis niloticus) per ha. The highest individual fish weight (78.05 g), in a 120-day fish-culture period, was recorded for the combination of 300 goats and 10,000 O. niloticus per ha, whereas the lowest gain (45.95 g) was obtained at the stocking density of 20,000 O. niloticus per ha without goat manure. The highest total fish yield of 1170 kg x ha 1 was recorded for a combination of 20,000 O. niloticus and 300 goats per ha. Currently, the goat manure loading per ha is increasing to 400, 500, and 600 goats.
Concluding in the two trials conducted, the growth of tilapia increased with the rate of goat manure loading. This indicates that the fish feed produced in the ponds with goat manure is being efficiency utilized by the fish biomass. The analysis shows that the highest net return of Philippine dollars 129872 was obtained from the 300 to 20,000 combination followed by the 300 to 10,000 per hectare (PD 108952.50). If the present trend in some local markets prevails where large fish fetch significantly higher prices than small-size fish, the 300 goat to 10,000 fish per hectare combination would be more profitable.
Raising goats and developing a family-level fishpond for small-scale use could help to decrease protein malnutrition.
The integration of goat with tilapia production is a means of establishing a sustainable farming system aimed at maximizing productivity and minimizing operational costs. There is great potential for this production as the demand for milk and meat is high.
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Africa, Rwanda, aquaculture, project, techniques, extension, organization, farm structure, USAID
 17. The sustainability of aquaculture as a farm enterprise in Rwanda.
J. of Applied Aquaculture, 1, (2), 1991, pp. 37-62
The objective of this article is to identify correlates of self-sufficient practice of fish culture by Rwandan farmers. It focuses on the degree to which fish farmers have achieved autonomous confidence in growing tilapia and on their relative willingness to forego dependence on government services.
Data were obtained from a sample of active Rwandan fish farmers randomly selected from project rolls.
Fish culture is one of many diverse efforts to increase food production and food security by producing a much-needed protein crop.
Although first introduced by Belgian colonialists in the 1950's, in the past decade fish culture has experienced a renaissance in Rwanda.
Beginning in 1983, the Rwanda National Fish Culture Project has assisted farmers with the upgrading of their ponds and identified the Nile tilapia, Oreochromis niloticus, as a species suitable for the high-evaluation, cool-water environment. Average annual yield among project participants was raised from an initial annual of 300 kg/ha to 1,550 kg/ha.
The purpose of the USAID Rwanda Fish Culture Project was to assist the Ministry of Agriculture in the development of an Aquaculture Extension
Service to provide technical assistance to Rwandan farmers. In its seven years of operation, the project has established four fish stations, trained over 60 extension agents, and helped establish over 1,150 private ponds. Aquacultural extension representatives assist farmers with pond construction, fish production, and related activities.
A tilapia production system has been implemented by farmers, utilizing readily-available inputs to grow fingerlings to market-sized fish.
Nearly 20,000 farmers and family members are associated with the project.
Most respondents planned new ponds; most felt capable of doing without extension assistance; and very few reported conflicts with other enterprises. When extensionists visited more frequently, farmers attented to their ponds more frequently. Wealthier farmers were less happy with the technical assistance they received. Women gave the male extension representatives lower helpfulness ratings. The results showed the advanced degree to which farmers have grasped the technical aspects of fish culture and their relatively favorable perceptions of the extension assistance.
The survey responses suggest that farmers expect to continue growing fish. Many of the factors that affect the independent practice of fish farming depend on the government and are beyond farmer control.
Several contextual factors not measured in this study affect the prospects of aquaculture in Rwanda, regardless of its ecological, socioeconomic, or nutritional merits. The commitment of the Rwandan government may shift to other priorities, not the least of which is threats to national security. Donor priorities about environmental and natural resource issues may induce reallocations of scarce internal funds. The financial condition of the country may disrupt the payment of salaries of fail to provide sufficient resources to recruit and train additional staff or replacements. The extension administration may fail to allocate sufficient travel funds for the moniteurs. Farmers have little way of knowing or understanding the larger national questions about the direction of agricultural policy or the status of foreign exchange and the need to redirect spending to produce export crops.
Production schemes that fail to gain the confidence and enthusiasm of farmers will generate neither food nor revenue. As a consequence, a central aspect of sustainability of fish culture is the extent to which the farmers understand and use the technology in their normal pattern of farming.
One threat to the evolution of fish culture in Rwanda is that improperly constructed ponds will undermine the success achieved by project participants. Ponds that are too small, leaky, or have continual water flows that waste nutrients and chill pond waters create negative examples that undermine the reputation of the enterprise.
To summarize, the Rwandan farm data showed only limited connections between the sustainability indicators and the variable sets identified.
The results showed the advanced degree to which farmers have grasped the technical aspects of fish culture and their relatively favorable perceptions of extension assistance.
An important next step in the evolution of aquaculture in Rwanda is to identify spontaneous emulators and provide the necessary corrective assistance to assure the proper realization of fish culture. It also will be important to understand why some farmers did not undertake aquaculture and others turned pond land to other uses.
1086 92 - 3/136
Asia, Malaysia, aquaculture, prawns, crawfish, ponds, rice production, aquatic macrophytes, grass carp, water quality
GRANADOS, A.E. et al.
 18. Double-cropping malaysian prawns, macrobrachium rosenbergii, and red swamp crawfish, procambarus clarkii.
J. of Applied Aquaculture, 1, (1), 1991, pp. 65-77
The objectives of this study were:
- to determine the effects of three crawfish stocking densities on survival, growth, and yield of prawns and crawfish cultured in a double-cropping scheme; - to contrast survival, growth, and yield of prawns cultured with crawfish with those when prawns are cultured in a monoculture system; and - to compare survival, growth, and yield of prawns fed a commercially formulated diet in the double-cropping system with those of prawns that are cultured in double-cropping systems that receive no formulated feed.
Prawns, Macrobrachium rosenbergii, and crawfish, Procambarus clarkii, were alternatively grown in ponds to determine if they were compatible and if total production could be increased. Brood crawfish were stocked into replicated ponds at rates of 0, 60, 120 or 180 kg/ha on 18 April.
Water was removed to encourage burrowing. Following this, rice was planted as forage. Post-larval prawns (0.02 g) were stocked 3 July in all ponds at 17,500/ha. Prawns in half the ponds were fed and those in the other ponds were not. Ponds were drained from 7 to 11 October. Prawn production ranged from 157 to 248 kg/ha; survival ranged from 69% to 88%, and average size ranged from 11 to 17 g. There was no significant difference (P > 0.05) between fed and non-fed treatments. The ponds were reflooded and crawfish were harvested by trapping from 15 January to 15
May. The average yield of crawfish ranged from 746 to 1,266 kg/ha.
Stocking rate had no effect on crawfisch yields (P > 0.25). Total yield, with prawns and crawfish combined, ranged from 1,037 to 1,237 kg/ha.
Overall, prawns and crawfish were compatible in rotation.
This study demonstrated that prawns and crawfish are compatible in pond production and that one crop of each can be produced annually in the same pond. To achieve this, pond management strategies had to be modified. For example, rice was planted as forage only in the shallow area of the pond, and a deep portion was left open for initial stocking of prawns. While the crawfish yield in ponds was acceptable (1,000 kg/ha), prawn yield was low due to small size at stocking (0,02 g), low stocking rate (17,500/ha), and short growout period (93 days).
The ongoing goal of most commercial prawn growers is to produce a large prawn (30 g+), but when prawns exceed approximately 17 g they begin to segregate into different size groups. Up to 17 g, there is virtually no size distinction, even between males and females. Successful marketing of such small individuals would produce additional revenue.
Crawfish are normally not available during summer and early fall, but prawns can be harvested during this period. The ideal size of prawns for molting troughs is about 17 g. Thus, prawns could possibly fill both a biological niche (rotation with crawfish in ponds) and a market niche (soft shell). Preliminary research indicates that prawns can be molted in the same shedding tanks as crawfish, and this could allow year-round production of a soft-shell product. The implementation of this would require new management strategies. Crawfish may have to be cultivated differently by introducing a formulated diet instead of allowing them to feed on rice forage. This management strategy could also produce a larger, more valuable crawfish (33 or less per kg), especially for the European market. Additionally, stocking systems will have to be developed to produce a 17-g prawn during those months when crawfish are normally not available. This study suggests that production of 17-g prawns is possible. Future research should concentrate on stocking dates, stocking sizes, stocking rates per hectare, and length of grow-out period.
1087 92 - 3/137
Asia, Malaysia, study, rice, fish, farming systems, resource utilization
 19. Rice/fish farming in Malaysia: a resource optimization
AMBIO, 19, 8, 1990, pp. 404-407
This paper summarizes and discusses the ecology as well as rice/fish farming system as practiced in North Kerian, Perak, Malaysia.
In Malaysia, where arable land is limited, integrated farming systems are widely practiced to optimize land use. Integrated rice/capture-fish farming is an example and is an important source of freshwater fish.
Capture-fish farming is practiced in North Kerian, Perak, Malaysia, where wild fish are retained and grown in the rice fields and later harvested at the end of the rice-growing season. Sump ponds, dug at the lowest part of the rice fields, provide refuges for fish during periods of low water availability or quality and facilitate fish harvest.
Before the early 1970s, when single cropping of rice was practiced, the system was the major supplier of freshwater fish, especially snakeskin gouramy (Trichogaster pectoralis), catfish (Clarias macrocephalus), and snakehead (Channa striata). But when double cropping of rice began in the 1970s followed by the widespread use of herbicides and pesticides, fish harvest began to decline.
The system described here requires no biological and little economic input, and native fish are found to be both biologically and economically suitable. The system can utilize different specific habitats, the fish are tolerant to extreme physiochemical changes, and command good market prices. The different feeding habits of the predatory snakehead (Channa striata), omnivorous catfish (Clarias macrocephalus), insectivorous climbing perch (Anabas testudineus), and plantivorous-omnivorous gouramies (Trichogaster pectoralis and T. trichopterus) indicate possible yield improvements through rice/fish polyculture. Aquatic productivity of the prevailing ecosystem is low despite repeated seasonal fertilization. Productivity is probably low due to shading and competition with aquatic weeds and rice plants.
Zooplankton is not readily available to the fish larvae and fingerlings because aquatic weeds provide easy refuge. This lack of food results in fish below marketable size. The short growing season resulting from double cropping, coupled with widespread use of herbicides and pesticides, also affects fish production.
The shorter growing due to double cropping of rice cannot be avoided since it is the policy of the government to increase rice yields.
Increasing the system's productivity is the only way to increase fish yields.
Integration of other farming activities into the rice/fish-capture farming system are being tried in order to fully optimize land use.
Extra income could be obtained by properly planting the large dikes surrounding sump ponds with valuable fruit trees such as coconuts (Cocos nucifera), bananas (Musa spp.) and mangoes (Mangifera spp.).
Farmers also planted the perimeter dikes with produce such as tapioca (Manihot spp.),squash (Cucurbita spp.), and sweet potato (Ipomea batatas) that can either be used at home or sold at the local market.
These and other activities are a recent addition to the traditional rice/fish-farming system and further investigations should be undertaken to determine their economic feasibility.
1088 92 - 3/138
Review, fishfarms, farming, biotechnology, transgenic fish, aquacultural genetics, feed conversion, environmental impact
BIOTECHNOLOGY AND DEVELOPMENT MONITOR
 20. Biotechnology in fishfarms: integrated farming or transgenic fish?
Biotechnology and Development Monitor No. 7, 1991, pp. 3-6
For many developing countries fish trade represents a significant source of hard currency. Although the developing countries' share in world fish exports remained stable at 45 per cent, net fish exports from developing countries doubled between 1985 and 1989 to US,5 billion.
Industrialized countries accounted for about 90 per cent of total fish imports in 1989. Aquaculture had already its share in the net export increase, and the application of biotechnology may boost fish exports even more.
Demand for fish is soaring worldwide. It appears unlikely that the increasing demand can be met through increased natural harvest.
Aquaculture could help to meet increasing demand, and biotechnology can make a contribution to improve aquaculture yields.
In Asia, where the bulk of aquacultural products is produced, aquaculture has a long-standing tradition as an extensive low input production system, practiced by resource-poor farmers. Recent interest in aquaculture biotechnology in industrialized countries could have a positive spin-off for these systems.
To be effectively applied to small-scale systems, aquacultural biotechnology methods should start from the more traditional technologies already in use. The efficiency and relevance of these technologies are impressive.
Organic agricultural wastes can be recycled as fish feed. Rice bran, for example, or the brown crust of rice which become available after rice polishing, possibly mixed with mustard or ground nut oil cake, is a very good feed for fish. Soybean cake and wine residues are also given as feed to carps, while grass carps are fed with chopped soft grass and vegetable tops. Wastes from livestock and poultry are recycled too, in some systems by dropping the manure directly into the ponds, thereby raising the production of algae, protozoa and zooplankton.
Mahua oil cake, a residue from oil extraction, is used in India to kill predators in the ponds before fingerlings are stocked. Mahua cake works as poison at the initial stage, but loses all its toxicity after 15-20 days and is then valuable as fertilizer. In Malaysia teaseed cake is used to kill predators.
For cleaning the ponds, duck weed is used in India. To increase alkalinity, banana stem cuttings are allowed to rot in the water.
Planting of tamarind leaves and stems have the effect of decreasing alkalinity of pond waters. Lotus plants maintain oxygen balance in ponds.
Widely adopted in southeast Asia also, is polyculture. In this system, a compatible group of 3 to 6 non-predator fish species of different feeding habits are introduced together in the same pond so that all types of food produced either at column, bottom or surface, are effectively consumed by fishes.
In order to be helpful, biotechnology should be integrated with these traditional methods. Newly introduced techniques must be comprehensible to farmers, and should use materials locally available.
Much of the current biotechnology research, however, seems to be directed at high input aquaculture production that requires, e.g. a well trained staff, pumps, tubewells and formulated feeds. To justify these costs, farmers need to produce high value products which often go for export, since in developing countries only the relatively wealthy can afford to eat their products. In poor communities, even the costs involved in building a small pond might be beyond financial reach of the farmer.
The impact of aquaculture on the environment varies by rate of intensity of the production system. According to ICLARM, even the more extensive aquaculture systems (where little or no feed or fertilizer inputs are used) may lead to the destruction of eco-systems, and pose health risks to workers from water borne diseases. Especially in integrated agriculture-aquaculture systems, toxic substances in livestock feeds (e.g. heavy metals, pesticides, or antibiotics) may accumulate in pond sediments and fish.
Intensive aquaculture systems, mainly reliant on external feed and fertilizer inputs, will have additional abusive effects because of pollution by effluents. Escapes of exotic modified, or genetically modified organisms on ecosystems may have an unpredictable impact as well.
Increased aquaculture productivity may lead to oversupply and declining world prices in specific markets. Shrimp trade is the most significant example. Shrimp trade amounts to over 20 per cent of world fishery trade, with more and more supplies coming from culture ventures. Main exporters are China, Taiwan, Thailand, Indonesia, and Malaysia. Shrimp breeding has recently also been taken up in India, Bangladesh, Sri Lanka, Ecuador, and Mexico.
Prices are likely to remain weak in the future, as shrimp farming is expanding enormously throughout developing countries.
1089 92 - 3/139
Review, book, semi-arid zones, case studies, agricultural engineering, crop production, tillage systms, dry farming, soil properties, soil erosion, management systems, tillage equipment, FAO
 21. Agricultural engineering in the development: tillage for crop production in areas of low rainfall.
FAO Agricultural Services Bulletin 83, FAO, Rome, Italy; ISBN 92-5-102542-8; 1990, 119 p. + annex
The objective of this publication is to provide perspectives and guidelines in the formulation of tillage strategies for the low rainfall areas, where dry-farming is practiced.
A better understanding is needed of the effects of tillage on the soil physical, chemical, and biological environments and how these environments are altered by various tillage practices.
Conservation tillage systems have been developed in a number of countries where dryland farming is practiced, but the scope of development considerably lags behind that for more humid regions.
There is little published material available concerning the efficiency of traditional dry farming systems that have been developed in Africa and Asia.
The primary objectives of tillage in any cropping system are to control weeds, enhance soil water storage and retention, reduce erosion, and to prepare a desirable seedbed.
The success of dry-farming depends heavily on the ability of the farmer to conserve water, and also to establish a suitable environment for seed germination, root growth, and control of soil erosion.
Dry-farming is practiced in the low rainfall or semiarid regions, where average annual precipitation is generally less than 500 mm.
Soils are often shallow, sandy, low in organic matter, and highly vulnerable to erosion when the surface is unprotected. During the wet season high intensity rains may result in severe runoff and erosion, and this is often followed by dry periods and severe wind erosion.
Tillage systems are generally referred to as reduced, minimum, or low tillage systems and zero till.
Conservation tillage is a term that is widely used to denote tillage systems that emphasize water conservation and erosion control.
The chapters carefully analyze:
- tillage effects on soil physical properties,
- organic matter dynamics,
- plant response,
- alternative tillage,
- planting equipment.
Conclusions and recommendations are drawn specifically to:
- tillage practice,
- water infiltration and conservation,
- erosion control,
- soil fertility,
- crop response,
- tillage implements,
- planting equipment.
An integrated approach is required to meet the tillage objectives for optimum seed preparation, weed control, erosion control, water conservation, and preservation of organic matter.
This is a reference book to assist scientists and extension workers in explaining alternative tillage practices.