Table of Contents Next Page

Overview of needs and justification for use of roots, tubers, plantains and bananas in animal feeding
by D.H. Machin


Over the past twenty years many developing countries have experienced considerable difficulties in providing sufficient food to satisfy the ever increasing demands of expanding populations.

In order to meet these needs they have looked to transfer technology from developed countries. Often this technology has been developed for temperate rather than the tropical or subtropical environments common to most developing countries. Due to the close environments interaction between crops and their environment only certain aspects of temperate technology could be utilized. For this reason cropping systems that were developed had to be designed for each environment in order to function at all. However, in the case of livestock, which are less environmentally sensitive, it was possible to transfer not only technology but whole systems, including animals, building designs and feeds.

Many of the developing countries that followed this approach to resolving livestock production deficits were able to finance such activities through the export of primary products, such as oil, minerals, tea coffee, etc., or by borrowing.

Over the last decade the above practice has commonly proved to be financially unsustainable due to:

  1. escalating demands for livestock products, from expanding and increasingly urbanised populations, outstripping the amount of foreign exchange available to purchase the necessary inputs.

  2. reduced amounts of foreign exchange available for continued importation caused by falling earnings from the export of many primary products and the need to allocate greater amounts of foreign exchange to finance earlier borrowings.

For the above reasons FAO has on various occasions been requested by developing countries to assist in seeking effective means of resolving these problems. This expert consultation constitutes part of the initiative to try to resolve this problem.


The use of cereals for animal feeding in developing countries was recently considered at the meeting of the Intergovernmental Group on Grains (IGG), held in FAO, Rome in November 1990 (FAO, 1990). The report prepared for this meeting showed (Table 1) that of the total of 900 million tons of compound feed, in grain equivalents, used worldwide in 1988, around 280 million tons were used in developing countries (grain equivalent refers to the feed value of 1 kg of barley in terms of metabolisable energy and protein). Of this total more than half (149 million tons) consisted of cereals, including 127 million tons of coarse grains, 12 million tons of wheat and surprisingly 10 million tons of milled rice.

TABLE 1.Estimated World utilization of livestock feed in grain equivalents
  World Developing countries
Output Growth rate Output Growth rates
1988 1971–80 1981–88 1988 1971–80 1981–88
(m.tons) (percent/year) (m.tons) (percent/year)
Concentrates 900 2.4 1.8 279 5.8 3.3
Cereals* 623 2.4 1.1 149 7.1 2.8
Oil meals* * 119 4.8 3.3 36 4.7 4.0
Brans & by-products 110 2.3 2.1 74 3.7 2.8
Roots & tubers 32 -0.5 2.4 17 2.9 3.9
Pulses 17 -1.3 12.3 3 1.4 1.9

* Cereals including rice in milled form.

** Includes fishmeal, tonnages are expressed in grain equivalents.

Source: FAO 1990.

The IGG meeting also assessed the international trade in animal feed. The briefing report showed that whilst developing countries were net exporters of grains (approximately 5 million tons) in the early 1970s they had become net importers by 1988 to the extent of about 21 million tons. It is also of particular interest to note that estimates indicate that between 75 and 80 percent of all shipments to developing countries are cereals used for animal feed production.

The replacement of these imports by local alternatives would enable developing countries to save considerable foreign exchange, which would otherwise have been needed to purchase the imported material, as well as pay related shipping and transport charges. At the same time, the development of local industries to produce substitutes for imported feedstuffs could stimulate local industrial activity and help increase local employment opportunities.


It is predicted that the population of the world will rise to around 6.25 billion from a current estimate of 5.29 billion by the year 2000 (Table 2). As a consequence the world population will have doubled from that of 1960. Clearly more feed of every type will be required. The current systems of feed production seem to be largely unsustainable and in particularly those associated with the production of animal protein. The clearance of forests to produce land to graze animals, overgrazing of these and existing lands, together with methane and carbon dioxide produced by such activities are currently believed to be implicated in world environmental problems. It is therefore clear that more appropriate and sustainable systems of livestock production and feeding will need to be developed to meet both the current needs and future expansion.

World per capita protein production estimates are shown in Table 3. These show that total protein supplies in developing countries (57.6g in 1983) were around half those of developed countries (99.2g in 1983), of which approximately 20% was animal protein in developing countries but 50% in developed countries.

TABLE 2. World Population Growth by Decade, 1950–90, with Projection to 2000.
Year Population (billions) Increase by decade (millions) Average annual increase (millions)
1950 2.515    
1960 3.019 504 50
1970 3.698 679 68
1980 4.450 752 75
1990 5.292 842 84
2000 6.251 959 96

Source: United Nations, Department of International Economics & Social Affairs, World Population Prospects 1988 (New York: 1989)

There is considerable discussion amongst human nutritionists and dieticians on the need to include protein of animal origin in human diets. It is however clear that animal protein is generally more digestible that plant protein, the amino acid balance of the animal protein more closely matches human requirements, other essential nutrients are more common in such products such as iron, calcium, phosphorus, etc. and there are generally less toxicological problems associated with the use of animal products. For these reasons, it is generally easier to obtain a balanced wholesome diet, where animal proteins provide a significant proportion of the total protein consumed.

Reference to Tables 3 and 4 indicates that in theory the amount of total protein available in developing countries should be sufficient to meet the overall populations needs. For this statement to be true it must be assumed that the protein is distributed according to the need and that the protein available is of adequate quality. Table 4 was prepared to indicate the total and variation in protein need by humans of varying age and sex. It is also particularly pertinent to note that the “Safe level of Protein Intake” referred to is based on protein having the quality and digestibil-

TABLE 3. Per Capita Supplies of Total and Animal Protein (in grams per day)
    Total Protein Total Animal Protein of which from
Meat Milk Fish Eggs
World 1971–73 65.1 21.5 10.0 6.6 3.3 1.6
1981–83 68.3 23.1 10.9 6.8 3.7 1.7
Developing 1971–73 52.7 9.2 4.1 2.5 2.1 0.5
Countries 1981–83 57.6 11.3 5.1 3.1 2.3 0.8
Developed 1971–73 96.0 52.3 24.6 16.8 6.8 4.1
Countries 1981–83 99.2 56.8 27.3 17.4 7.7 4.4

Source: FAO Economic and Social Development Paper, No. 80, aspects of the world feed-livestock economy; Structural changes, prospects and issues (Rome, 1989).

TABLE 4.Example of Safe Protein Intake for a Family Group of Varying Age and Weight
Family Group Member Age (yrs) Weight (kg) Safe Level of Protein Intake (g/day)*
Grandfather 60+ 65 49
Grandmother 60+ 50 37.5
Male 30–60 70 52.5
Female 30–60 55 41
Female (non pregnant) 18–30 55 41
" (pregnant) 18–30 55+ 47
" (lactating) 18–30 55+ 58.5
Male 14–16 55.5 52
Female 14–16 52 46
Male 10–12 34.5 34
Female 10–12 36 36
Male/Female 3–5 16.5 17.5
Baby under 1 7–10 14

* Based on protein with the quality and digestibility of milk or egg.

Source: Data extracted from: Energy and Protein Requirements, Report of a Joint FAO/WHO/UNU Expert Consultation, Technical Report Series, No. 724, World Health Organization, Geneva, 1985 ity of milk or egg. In practice it is likely that many of the most vulnerable members of societies in developing countries will be receiving the minimum (or less) quantity of protein and this will be mostly of vegetable origin. For this reason it is likely that a large proportion of such societies will be receiving diets deficient in many of the essential nutrients of proteinaceous origin.

It would therefore appear that increasing the production and availability of animal protein in developing countries is of significant importance if the human populations of such countries are to be adequately fed.


There is a range of measures that developing countries can implement in order to alleviate the above mentioned problem. These include:

  1. Maximizing the efficiency of current livestock production systems so that all existing resources, including human skills, animals, livestock facilities and feeds are used as efficiently as possible.

  2. Establishing what agro-industrial byproducts, that could be used in animal feeding in a country, are currently either unused or used inefficiently and if their use is economically viable use these to replace imported or human feeds.

  3. Developing local crops that can be grown to supply the nutrients currently obtained from imports or feeds that might be better used by humans.

The particular materials to be considered in this consultation clearly fall into the latter two categories, though all points should be considered in resolving the overall problem. In particular, the first measure listed above is particularly relevant to the application of the last two. Even in developed countries with well established traditions of byproduct utilization the value of “wastes” (byproducts) or non-traditional feedstuffs has till very recently been disdainfully undervalued. In many such countries this view has now been replaced with an appreciation of their true worth, to such a point, that the profitability of many livestock industries now depends on the use of feeds largely consisting of byproducts. This change in the traditional approach to livestock feeding has now led to a more commercial approach to nutrient supply, involving the use of crops on the basis of the yields of total nutrients per unit of land and the cost of production of each nutrient. On this basis alone this should result in the utilization of less cereal and more root and tuber crops in many traditionally cereal producing areas (it is of interest to note that the Netherlands are currently using less than 15% cereal in its feed industry).

It is therefore quite clear that wholesale transfer of livestock systems from dissimilar environments is not likely to be either the most economically, nor productively efficient. Most situations, even at individual farm level, are sufficiently different to merit the development of individually designed systems, taking into account local factors and applying fundamental scientific and economic principles.


Cereals generally make up between fifty-five and eighty-five percent of most conventional compounded animal feeds, where they supply a major part of the nutrients provided. Tables 5 and 6 respectively, show a range of compositions for the most commonly produced feeds and cereals. From these it is possible to see that cereals, used at the levels indicated above, will provide not only the main part of the energy in feeds, but a significant part of the total protein, together with minerals and vitamins.

Proteins and essential fatty acids are generally supplied from oilseed cakes and meals and animal and fish protein products, many of which originate from the regions of the world in which most developing nations are located. Developing countries are in fact net exporters of these materials. Over the last two decades these exports expanded at the rate of 6.8 percent a year to reach a level of 29 million tons in the late 1980s.

Considering the above points it would appear that replacement of the cereal component of feeds is likely to offer a beneficial first step towards alleviating animal feed supply problems. The second step should then be to increase the supply of feedstuffs so that animal production can be increased and greater amounts of meat and livestock products made available to all.

TABLE 5.Compositions of a range of typical compounded animal feed
Feed Protein % Energy MJ/kg* Oil % Fibre % Calcium % Phosphorus %
Broiler Starter 23.0 12.7 3.0 3.0 1.0 0.7
Broiler Finisher 19.0 13.1 3.0 3.0 1.0 0.6
Layer 17.0 11.7 2.0 3.0 3.5 0.6
Pig Breeder 15.0 12.7 3.0 5.0 0.8 0.6
Pig Fattener 16.0 13.0 3.0 3.0 0.8 0.6
Calf Rearer 15.0 11.0 2.0 6.0 1.0 0.7
Dairy Cow 15.0 10.7 2.0 8.0 1.0 0.6

* Metabolisable Energy, monogastric or ruminant

TABLE 6.Composition of a range of cereal grains used in animal feed production
Cereal Protein % Energy MJ/kg* Oil % Fibre % Calcium % Phosphorus %
Maize 9.0 14.2 4.0 3.0 0.02 0.25
Millet 11.0 12.5 3.5 8.0 0.03 0.30
Sorghum 10.0 13.8 3.0 2.5 0.04 0.25
Rice (rough) 8.0 11.2 1.5 9.0 0.10 0.32
Wheat 11.0 13.0 2.0 3.0 0.05 0.35

* As for table 1

TABLE 7.Composition of a range of root, tuber, plantain and banana products (dry matters)
Product DM* % Protein % Energy * * MJ/kg Oil % Fibre % Calcium % Phosphorus %
Cassava Root (whole) 36.2 2.8 14.0 0.7 1.6 0.1 0.02
Cassava Leaf 17.8 25.4 9.9 3.7 10.2 1.5 2.4
Sweet Potato Root (whole) 59.0 5.2 13.5 1.2 2.6 0.2 0.2
Sweet Potato 10.8 19.4 5.8 3.6 12.6 1.8 0.2
Leaf     (10.0)        
Plantain Fruit (mature) 29.4 4.0 14.5 0.8 1.1 0.8 0.3
Banana Fruit (ripe) 31.0 5.4 15.2 0.9 2.2 0.2 0.1
Banana/Plantain 16.0 6.4 3.5 0.8 23.7 0.9 0.3
Plant     (9.9)        

* DM = Dry Matter

* * Metabolisable Energy values for monogastrics, ruminant values in brackets

The plant materials identified for particular consideration in this consultation, to replace cereals, are listed in table 7. This table also includes an example range of compositions of primary raw materials that may be derived from these plants. A comparison of the compositions of the cereals and the possible substitutes being considered here produces the following conclusions:

  1. That, on the basis of their composition alone, the roots, tubers and fruits of plants being considered here would appear to have considerable potential to provide a considerable amount of the nutrient at present provided by cereals in animal feeds.

  2. Although the materials refered to in 1. would appear to be able to completely replace the energy component in livestock feeds, they would be unable to provide other nutrients as well as cereal grains. However, the use of a combination of such materials with leafy material from the same plant, although reducing the energy component, could produce a blend of nutrients that could largely substitute for cereals.

  3. The lower protein content of possible alternatives referred to in 1. could also be compensated for by better utilization of locally produced protein sources, which are at present exported, or the use of proteinaceous agro-industrial byproducts, azolla, etc.

Top of Page Next Page