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Cassava as animal feed
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CASSAVA Cassava As Animal Feed. B. Nestel and ,lYI.Graham (Editors). Proceedings of a Workshop, University of Guelph, 18--20 April 1977. Organized by the International Development Research Centre and the University of Guelph. I.D.R.C., Ottawa, Canada, 1977, 147 pages, 86 tables, 8 figures, price $8.75. ISBN: 0-88936-i42-8.
This b o o k is a compilation of 14 papers presented during a workshop held at the University o f Guelph (Ontario, Canada), 18--20 April 1977, and sponsored by the I.D.R.C. and the University of Guelph. The papers present a review of recent knowledge on the various utilizations of roots, harvested foliage or whole plant cassava in the feeding of several species o f ruminant or non-ruminant animals. The first 3 papers are connected with the basic knowledge o f nutritional limiting factors of cassava (roots and leaves) identified with the chemical analysis: D.M. protein, amino acids, minerals, crude fiber, ether extract and N-free extract. Raw cassava is a bulky feed and the first limiting factors are for roots the very low protein c o n t e n t and for the whole plant a limitation in the energy and protein intake of animals. Zinc and iodine deficiencies were also studied in cassava grown inseveral countries. Further details about vitamin content and deficiencies are discussed. From the chemical analysis, recommendations could be given in order to indicate a protein--minerals--trace elements and vitamin supplement adequate to balance a diet based on cassava. Various toxic components in cassava have been k n o w n for a long time. Hydrocyanic acid is the most toxic substance, b u t cyanogenic glucosides, such as linamarin, are present in m a n y cases. Long-term physiological effects of feeding cassava products containing high concentrations of cyanogenic compounds were studied only with the rat. Conclusions which were drawn show a lack of information on the tolerance to these substances of r u m i n a n t and nonruminant animals and an urgent need for further investigations. The supplementation of cassava based diets (mainly roots) by essential amino acids such as methionine in experiments with chicks, was discussed in terms of balancing, as well as in terms o f detoxification, of the diet. For monogastric animals (broilers and layers, growing--finishing pigs, pregnant or suckling sows) and for polygastric animals (dairy and beef cattle, goats and sheep) the practical utilization of cassava is presented in 6 fundamental chapters. Attention is always on the nutritional value of different parts of the plant; on roots and leaves in particular. Discussions are devoted to toxicity, chemical composition, amino acid profile, digestibility in vivo for ruminants and nutrient availability according to the type of processing (sun drying, silage, hay making). From the numerous data obtained, mainly in experiments performed in developing countries, it was possible to give provisional recommendations about the o p t i m u m quantity o f cassava in the diet of farm animals according to species, age and kind of
390
production (milk, eggs and/or meat). Particular attention is given to the economical interests of cassava utilization instead of cereals in the countries where cassava is grown. The use of roots as an energetic substrate for single cell protein production was presented. The nature of different strains of fungi and bacteria was detailed and discussed. The final product, elaborated in an experimental plant, contained 40--50% of crude protein (35--38% of true protein) on a D.M. basis. A 3-stage continuous flow fermentation system is described through theoretical and practical performances. The nutritive value of the final product obtained from different fungi growing on cassava was studied. A permanent deficiency in sulfur amino-acids was observed in the rat but no toxicity. The last chapter is devoted to the available technological processes for improving the food value of cassava. Various processes were presented, with particular attention to energy-saving (sun drying, detoxification processes, and pelleting of the product). Finally, extraction of the protein fraction from leaves was discussed. In a short and precise discussion and conclusions chapter, different problems were put together; the lack of knowledge as well as the unsolved problems for which further investigations are urgently needed. Moreover, a particularly useful bibliography of 16 pages of references on cassava or its components made this book a basic work on "cassava science". Research workers as well as feed manufacturers and advisers in animal nutrition could find sufficient information in this book to develop the production, the technology o f treatments, and the use of cassava for animal feeding. A. A U M A I T R E a n d J. LE D I V I D I C H
(Jouy-en-Josas, France)
CASSAVA Cassava As Animal Feed. B. Nestel and ,lYI.Graham (Editors). Proceedings of a Workshop, University of Guelph, 18--20 April 1977. Organized by the International Development Research Centre and the University of Guelph. I.D.R.C., Ottawa, Canada, 1977, 147 pages, 86 tables, 8 figures, price $8.75. ISBN: 0-88936-i42-8.
This b o o k is a compilation of 14 papers presented during a workshop held at the University o f Guelph (Ontario, Canada), 18--20 April 1977, and sponsored by the I.D.R.C. and the University of Guelph. The papers present a review of recent knowledge on the various utilizations of roots, harvested foliage or whole plant cassava in the feeding of several species o f ruminant or non-ruminant animals. The first 3 papers are connected with the basic knowledge o f nutritional limiting factors of cassava (roots and leaves) identified with the chemical analysis: D.M. protein, amino acids, minerals, crude fiber, ether extract and N-free extract. Raw cassava is a bulky feed and the first limiting factors are for roots the very low protein c o n t e n t and for the whole plant a limitation in the energy and protein intake of animals. Zinc and iodine deficiencies were also studied in cassava grown inseveral countries. Further details about vitamin content and deficiencies are discussed. From the chemical analysis, recommendations could be given in order to indicate a protein--minerals--trace elements and vitamin supplement adequate to balance a diet based on cassava. Various toxic components in cassava have been k n o w n for a long time. Hydrocyanic acid is the most toxic substance, b u t cyanogenic glucosides, such as linamarin, are present in m a n y cases. Long-term physiological effects of feeding cassava products containing high concentrations of cyanogenic compounds were studied only with the rat. Conclusions which were drawn show a lack of information on the tolerance to these substances of r u m i n a n t and nonruminant animals and an urgent need for further investigations. The supplementation of cassava based diets (mainly roots) by essential amino acids such as methionine in experiments with chicks, was discussed in terms of balancing, as well as in terms o f detoxification, of the diet. For monogastric animals (broilers and layers, growing--finishing pigs, pregnant or suckling sows) and for polygastric animals (dairy and beef cattle, goats and sheep) the practical utilization of cassava is presented in 6 fundamental chapters. Attention is always on the nutritional value of different parts of the plant; on roots and leaves in particular. Discussions are devoted to toxicity, chemical composition, amino acid profile, digestibility in vivo for ruminants and nutrient availability according to the type of processing (sun drying, silage, hay making). From the numerous data obtained, mainly in experiments performed in developing countries, it was possible to give provisional recommendations about the o p t i m u m quantity o f cassava in the diet of farm animals according to species, age and kind of
390
production (milk, eggs and/or meat). Particular attention is given to the economical interests of cassava utilization instead of cereals in the countries where cassava is grown. The use of roots as an energetic substrate for single cell protein production was presented. The nature of different strains of fungi and bacteria was detailed and discussed. The final product, elaborated in an experimental plant, contained 40--50% of crude protein (35--38% of true protein) on a D.M. basis. A 3-stage continuous flow fermentation system is described through theoretical and practical performances. The nutritive value of the final product obtained from different fungi growing on cassava was studied. A permanent deficiency in sulfur amino-acids was observed in the rat but no toxicity. The last chapter is devoted to the available technological processes for improving the food value of cassava. Various processes were presented, with particular attention to energy-saving (sun drying, detoxification processes, and pelleting of the product). Finally, extraction of the protein fraction from leaves was discussed. In a short and precise discussion and conclusions chapter, different problems were put together; the lack of knowledge as well as the unsolved problems for which further investigations are urgently needed. Moreover, a particularly useful bibliography of 16 pages of references on cassava or its components made this book a basic work on "cassava science". Research workers as well as feed manufacturers and advisers in animal nutrition could find sufficient information in this book to develop the production, the technology o f treatments, and the use of cassava for animal feeding. A. A U M A I T R E a n d J. LE D I V I D I C H
(Jouy-en-Josas, France)