SESSION I - REVIEWS ON THE POTENTIAL FOR BE UTILIZATION OF CROP RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS IN DEVELOPING COUNTRIES

GLOBAL REVIEW OF THE POTENTIAL OF CROP RESIDUES AS ANIMAL FEED

Vappu L. Kossila
Animal Production Officer
Animal Production and Health Division

FAO, Rome Italy

SUMMARY

The global situation on production of fibrous crop residues was described for the year 1981. The study was based on FAO statistics which were modified for this particular purpose. Results were given on regional and on individual country basis.

The quantity of fibrous crop residues in each country and region was observed in the light of the population of grass eaters (cattle, buffaloes, camels, sheep, goats, horses, mules, asses) since these animals have greater potential for the use of fibrous crop residues than grain eaters (pigs and poultry). Forages constitute some 85–94% of the metabolizable energy intake of grass eaters, 17.7% of that of pigs and 8.6% of that of poultry on the average in the whole world. The review indicated that about two thirds of crop residues were derived from cereal crops. In developed as well as developing countries crop residues account for about 24% of the total feed energy suitable for ruminant livestock while agro-industrial by-products account for only about one percent.

Asia is the leading region in the production of crop residues from wheat, rice, paddy, millet, buckwheat, sugarcane, nuts, oilplants and vegetables as well as fruit and berries. North and Central America is the leading region in the production of fibrous crop residues from maize, sorghum and pulses. Europe is leading in residue yields from barley, rye, mixed grain and roots and tubers. USSR leads in residue yield: from oats.

In 1981, global production of fibrous crop residues from different crops in trillion tonnes was: maize 1.0, wheat, rice and paddy, pulses each 0.5, sorghum and oilplants each 0.3, barley and sugarcane each 0.2, roots and tubers 0.17, millet and nuts each 0.13, fruit and berries 0.11, vegetables 0.08, oats 0.06 and rye 0.05. If all crop residues are counted, the world average would be 6166 Mcal ME and 3.4 tonnes of DM/LU of grass eater per year (1 LU = 500 kg live weight at maintenance level).

The amount of crop residues in tonnes DM/LU of grasseaters/year was: 6.66 in North and Central America, 3.56 in Asia, 3.54 in Europe, 2.94 in USSR, 2.20 in Africa, 1.87 in South America and 1.06 in Oceania.

Large difference were observed between individual countries. Much of these differences could be explained by climatic factors, level of technology in agricultural production systems, availability of natural pastures and forest lands for grazing, availability of drinking water, extent of livestock diseases, religious and cultural factors and political and economic regulation systems.

Yields of crop residues have risen proportionally more than livestock numbers from 1970 to 1981. The grain eater population in percent of total livestock population is the highest in Europe (33.7%) and the lowest in Oceania (3.3%). Countries which have high crop residues /LU of grass eaters tend to have also high grain eater numbers.

It is evident that at present there are more fibrous crop residues available per LU of grass eaters than a decade ago. From an economic and feed security point of view, research should be strongly directed towards improving the rate of utilization of fibrous crop residues as livestock feed.

RELATIVE IMPORTANCE OF CROP RESIDUES AS ENERGY SOURCE FOR RUMINANT LIVESTOCK

In some countries ruminant livestock is maintained mainly on pastures, forages and grains derived from arable land while in some other countries ruminants receive most of their energy needs from crop residues and/or natural pasturelands, meadows and wastelands. Studies on availability of crop residues as livestock feeds have been focused so far mainly on individual countries, groups of countries or regions.

(1) Forests, marsh, wasteland

There are hardly any global studies available on feed resources with special reference to fibrous crop residues so far.

Basic Foodstuff Service, FAO Commodities and Trade Division has very recently however, done a review on the World Feed Situation - Trends and Outlook (FAO 1984 in press). Main emphasis in this review is on the high density energy feeds utilization because information on forage resources and utilization is generally deficient in the case of many countries.

In a study produced at Winrock International Livestock Research and Training Centre, Fitzhugh et al (1978) give global figures on various feed energy resources available for ruminants. Origins of the different feed resources and their estimated total energy value (Meal Metabolizable Energy) given in that study for 1970 and the projections for 2 000 are referred to in Table 1. Table 1 shows that crop residues account for about 23 percent of all the feed energy resources available to ruminants in the world in 1970. Permanent pastures and meadows account for 38 percent, forages from arable land for 25 percent and agro-industrial by-products only for 1 percent. The relative importance of various energy sources remains more or less the same in the projections made for the year 2000.

In both developed as well as developing countries crop residues account for about 1/4 of the total feed energy suitable for ruminant livestock (Table 2). Compared to developing countries, in developed countries, more forages and grain are obtainable from arable land, while less forage is obtainable from natural pasturelands and meadows and nonagricultural land.

According to Fitzhugh et al (1978), forages constitute 84.5 percent of the metabolizable energy intake of cattle and buffaloes, 93.8 percent of that of sheep and goats, 17.7 percent of that of pigs, 8.6 percent of that of poultry and 93.3 percent of the ME intake of other animals (mainly draught animals).

FIBROUS CROP RESIDUES - GLOBAL REVIEW

A global review on the annual yields of fibrous crop by-products was recently done at FAO headquarters. The study involved some 100 commodities, 212 countries and a period covering the years from 1970 to 1981. The results of the study have been published from the regional and socio-economic group point of view (Kossila 1983b). It was not possible to handle individual countries in that connection. However the methodology applied is described in detail in that publication.

The amounts of fibrous crop by-products, derived from cereals and other crops, in different regions in 1981 are shown in Fig. 1. It also gives the quantities of livestock units (LU) for grass eaters (cattle, buffaloes, camels, horses, mules, asses, sheep, goats) and grain eaters (pigs, poultry) separately for each region. Asia is the leading region as far as the livestock numbers and production of fibrous crop residues are concerned.

In North and Central America, Europe, and South America the size of livestock population is similar but North and Central America has a very high fibrous crop residue figure (Fig. 1). Quantitatively taken in Africa and USSR the fibrous crop residue situation is quite similar to each other. In Oceania, on the other hand, very little residues are produced.

The amounts of fibrous crop residues produced per LU of grass eaters in different regions are given in Table 3. The World's “grainstorehouse” North and Central America produced 6.66 tonnes of fibrous crop residues per LU of grass eaters in 1981. Europe and Asia ranked the second in this respect with some 3.5 tonnes/LU. Europe, however, has a very large grain eater population - 33.7 percent of the total LU numbers, compared to Asia's 17.1 percent. USSR produced 2.94 tonnes of fibrous crop residues per LU of grass eaters. Like Europe, USSR also has a high grain eater population (26.1 percent of total LU number).

Figure 1: Regional differences in the yield of fibrous crop residues from cereals and other crops, and in the numbers of grass eaters and grain eaters in 1981.

Figure 2: Production of fibrous crop residues in different countries of the world in 1981 (metric tons of dry matter per livestock unit of grass eaters per year).

In Africa and South America near to 2 tonnes of fibrous crop residues were produced per LU of grass eaters. In both regions the number of grain eaters is very moderate (Table 3). In Oceania, which is a typical area for grazing ruminants, only 1 tonnes of fibrous crop residues was produced per LU of grass eaters in 1981. The grain eater population was only 3.3 percent of total LU in Oceania.

In Appendix 1, production of fibrous crop residues from individual cereals and certain groups of crops are given separately for each region and for different market economies as well as for the whole world in 1981. North and Central America is the leading region in the production of fibrous byproducts from maize, sorghum and pulses. Asia is the leading region in the production of residues from wheat, rice and paddy, millet, buckwheat, sugarcane, nuts, oilplants, vegetables as well as fruit and berries. Europe leads the residue fields from barley, rye, mixed grain and roots. USSR leads in residue yields from cats.

Referring to the world's total crop residue figures (in Appendix 1) maize yielded the largest amount of fibrous crop residues (1.0 trillion tons). Wheat, rice and paddy and pulses, each yielded about half of the amount compared to maize (0.5 trillion tonnes), sorghum and oilplants each yielded 0.3 trillion tons, barley and sugarcane each yielded 0.2 trillion tons, roots and tubers 0.17 trillion tons, millet and nuts, each about 0.13 trillion tons, fruit and berries about 0.11, vegetables 0.08, oats 0.06 and rye yielded 0.05 trillion tons of fibrous residues. If all given crop residues are counted this would give 3.4 tonnes and 6166 Meal ME/LU of grass eaters per year on an average in the whole world.

CROP BY-PRODUCT SITUATION IN DIFFERENT REGIONS

Africa:

In 1981, Africa carried about 12 percent of the world's grass eater population and it produced some 343 million metric tonnes of DM from crop residues which accounts for 7.7 percent of the world total. 68.8 percent of the African crop residues were derived from cereals, 12 percent from oilplants and pulses, 4.9 percent from sugarcane etc. Africa has clearly defined areas with rather definite preferences for certain cereals. Maize is prevalent in South-East Africa, in Egypt and in a few South-Western countries (Ivory Coast, Ghana, Benin). Millet and sorghum are prevalent in Middle and West Africa. Wheat is popular in North Africa. Rice is preferred in several countries on the South West coast and in the East Coast Islands (Comoros, Madagascar). Two countries, i.e. Reunion and Mauritius are specialized primarily in sugarcane production.

The quantities of DM from fibrous crop residues, produced per LU of grass eaters in different African countries in 1981 are shown in Fig. 2. There is a definite belt of countries beginning from the South East coast (Mozambique) and extending to the South West African coast line, which have produced over 2 tonnes/LU of grass eaters of fibrous crop residues.

On the other hand, North African countries (with exception of Egypt and Tunisia) as well as Botswana and Namibia in the South had very low crop residue figures.

One can list, as an example, a few African countries which had rather high amounts of crop residues and a few of those which had very limited amounts of crop residues per LU of their grass eater population in 1981.

LU = Livestock units of grass eaters.,
DM = dry matter from fibrous crop residues.

Such factors as quantity of rainfall, soil conditions, amount of water available for livestock, animal health problems (tsetse) play a significant role as far as the above figures are concerned.

South America:

In 1981, South America produced 8.6 percent of fibrous crop residues and it carried about 15.7 percent of the grass eater population of the world total figure. 47 percent of the fibrous crop residues were derived from cereals, some 14 percent from sugarcane, 20 percent from pulses and the rest from other sources.

In most of the South American countries, maize was the main cereal producing fibrous crop residues. However, in Suriname and Guyana, the main cereal was rice and in Venezuela it was sorghum. Several South American countries produced considerable quantities of fibrous crop residues from sugarcane (Brazil, Colombia, Peru, Ecuador, Bolivia, Guyana). The total quantities of fibrous crop residues/LU of grass eaters was less than one tonne in Bolivia, Uruguay, Venezuela, and Colombia. On the contrary, high figures were observable in Guyana (5.38 tonnes/LU) and Suriname (10.8 tonnes/LU) (Table 4, Fig. 2).

The share of grain eaters in percentage of total LU number was particularly low in Argentina (2.6 percent), Colombia (3.5 percent) and Uruguay (1.7 percent) but rather high in Ecuador (23.9 percent), Guyana (42.2 percent), Suriname 32.7 percent and French Guyana (30 percent) (Table 4).

Asia:

In FAO statistics and in this article USSR is handled separately from the rest of Asia.

In 1981 Asia carried about 35.2 percent of the grass eaters of the world. In the same year 1 628 882 thousand metric tonnes of fibrous crop residues were produced in Asia, which represents 36.8 percent of the world total (Kossila 1983a). Sixty-eight percent of these residues were derived from cereals, 14.5 percent from oilplants and pulses, 4.5 percent from sugarcane. The most important cereal crop was rice and paddy, the next in order were maize and wheat. The average amount of crop residues per LU of grass was 3.56 tonnes per year in 1981. There are however very large differences in this respect between individual countries:

LU = Livestock units of grass eaters
DM = dry matter from fibrous crop residues

Generally speaking Near and Far Eastern countries had more crop residues available per LU of grass eaters compared to Middle East figures (Fig. 2).

The average grain eater population is very modest in Asia (Table 3). However, there are great differences between areas and countries in this respect. For instance, the majority of the Middle Eastern countries have less than 5 percent of grain eaters while most of the Far Eastern countries have a large proportion of grain eaters (45 to 70 percent). In some special cases (Hong Kong and Singapore) there are 97 percent of grain eaters. Moreover, several Near Eastern countries (Jordan, Israel, Lebanon, Cyprus) have a considerable grain eater population in relation to the total livestock population. A high proportion of grain eaters is often associated with a high availability of fibrous crop residues (i.e. in Korea DPR, Korea Rep., Malaysia, Philippines, Indonesia, China, Vietnam, Japan). Since Asia is a very large region, it is understandable that extremes in climatic and soil conditions are found in that area, which greatly influence crop and livestock production and are reflected in the figures obtained for different countries.

USSR:

USSR carried about 9.4 percent of the total livestock units and produced 7.2 percent of the fibrous crop residues of the world in 1981. Crop residues accounted for about 2.94 tonnes per LU of grass eaters. More details concerning the sources of crop residues are found in Appendix 1. See also Table 3.

Oceania:

In 1981, Oceania yielded 1.2 percent of the fibrous crop residues while they had 3.9 percent of grass eaters of the world total. 41 percent of the fibrous crop residues were derived from wheat, 13.7 from cane, and some 9 percent from barley, sorghum and nuts each. 83.7 percent of the crop residues came from Australia and the rest from the other islands of Oceania (Table 5). The quantity of residues per LU of grass eaters was 1.95 tonnes (Fig. 2).

Nuts were the main crop in most of the small islands. The grass eater production systems depend heavily on grass in this region. The grain eater population as a percentage of total livestock quantity is very high in some of the small islands while the average for the whole region is very low (Tables 3 and 5). Also the quantity of fibrous by-products per LU of grass eaters is high in some islands. Some of the smaller islands belonging to Oceania were left out because there was not enough information available.

North and Central America:

In 1981, North and Central America produced about 27 percent of fibrous crop residues and had about 13.8 percent of grass eaters of the world total figure. 96 percent of the crop residues were produced by USA, Canada and Mexico. In this region 68.6 percent of crop residues were derived from cereal crops (40% from maize), 20 percent from pulses, 3.5 percent from sugar cane and the rest from other sources.

Maize was the main residue producing cereal crop in USA, Mexico, El Salvador and Guatemala, wheat in Canada and sugarcane in most of the Caribbean Islands and in the Central American mainland (Table 6). In this region 6.66 tonnes DM was yielded per LU of grass eaters on an average. Fig. 2 shows that there are more residues available per LU in USA and Canada compared to Central American countries although many of the last mentioned countries have sugarcane as their main crop. Cane has very high potential for production of fibrous byproducts.

Canada and many of the Caribbean Islands have a rather high grain eater population in percent of the total LU number.

Europe:

European countries produced 11.4 percent of fibrous crop residues and carried 11 percent of grass eater population of the world total. 67 percent of the crop residues were derived from cereals, 11.2 percent from roots and tubers, and 10.7 percent from oilplants (Appendix 1). Crop residues were derived mainly from barely and oats in North Europe, from rye in Poland, from wheat and maize in Middle Europe and in the South where also oilplants play a significant role. In the Northern Islands (Iceland, Faeroe Islands) crop residues are derived mainly from roots and vegetables and yield per LU is very low. The average figure for Europe was 3.54 tonnes DM/LU of grass eaters in 1981. In 78 percent of the European countries this figure fits between 1 and 6 (Table 7, Fig. 2) while for instance in Asia only 45 percent of the countries fit within this range.

Europe has a very high grain eater population compared to other regions (Table 3). The percentage of grain eaters in percent of total LU population, however, fits between 20 and 60 in 78 percent of European countries.

Summary and conclusion

The global situation on production of fibrous crop residues is described for the year 1981. The study is based on FAO statistics which have been modified for the said purpose. Results are given on a regional and on an individual country basis for the whole world.

The quantity of fibrous crop residues in each country and region is observed in the light of the population of grass eaters (cattle, buffaloes, camels, sheep, goats, horses, mules, asses) since these animals have greater potential for the use of fibrous crop residues as their energy sources than grain eaters (pigs and poultry).

Production of fibrous crop residues per LU of grass eaters varies greatly between regions and countries. Some of these variations could be explained by such variables as availability of other energy resources (natural pastures, forestland, grazing, cultivated fodder resources, concentrates etc.), climatic factors (rainfall, temperature, etc.), water resources, soil conditions, land topography, animal diseases (tsetse, ticks, other parasites, etc.), cultural and religious factors (prohibition of cattle slaughter, prohibition of consumption of pig meat, etc.), type of ruminant production system (intensive, extensive), number of draught animals required for agricultural work, even animals needed for manure production, level of modern technology in agricultural production systems, political and economic regulation systems (price policy, imports/exports) etc.

Large quantities of fibrous crop residues are already used as animal feed in many countries but much is still wasted for various reasons or used for other purposes (paper making, bedding etc). At the same time there are many areas where ruminant livestock is starving to death due to lack of feed.

There are many countries where the amount of crop residues per LU of grass eaters exceeds the amount that can actually be used as feed : USA Canada, most of the European countries, a few Near Eastern countries (Cyprus, Jordan, Israel, Lebanon), a belt of countries from Mozambique to the South-West coastline in Africa, China, Korea DPR, Korea Rep., and most of the countries in the Islands of South-East Asia (Fig. 2).

There are also countries or groups of countries which have very limited amounts of fibrous crop residues available per LU of grass eaters, like many countries in Northern, Eastern and Southern Africa, many countries in the Middle East as well as Mongolia in Asia, Australia, Iceland and Ireland in North and West Europe, and a few countries in Northern and Western South America (Fig. 2).

During 1970 to 1981 the world total of fibrous crop residues rose by 36.8 percent while the grass eater population increased only by 10.1 percent at the same time (Kossila 1983b). It is evident that at present there are more fibrous crop residues available per LU of grass eaters than a decade ago. From the economic and feed security point of view research should be strongly directed towards improving rate of utilization of fibrous crop residues as livestock feed.

REFERENCES

FAO World Feed Situation - Trends and Outlook, 1984. Basic Foodstuff Service, FAO Commodities and Trade Division. (In press)

Fitzhugh, H.A., Hodgson, H.J., Scoville, O.J., Nguyen, T.D. and Byerly, T.C., 1978. The role of ruminants in support of man. Winrock Intern. Livest. Res. & Train. Center, USA Arkansas, 135 pp.

Kossila, V. 1983a. Problems related to effective utilization of feed resources in developing countries, Proc. FAO PARC Workshop on Least Cost Ration Formulation, 12–24 March 1983, Islamabad, Pakistan pp.16–24

Kossila, V. 1983b. Location and potential feed use. In: Straw and other fibrous by-products for food, Chapter 2, Editors: F Sundstol and E. C. Owen, Elsevier, Amsterdam, pp 4-24.

PRACTICAL EVALUATION OF CROP RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS FOR RUMINANTS IN DEVELOPING COUNTRIES WITH EMPHASIS ON EAST AFRICA

M H Butterworth and A K Mosi

International Livestock Centre for Africa
PO Box 5689
Addis Ababa, Ethiopia

SUMMARY

A brief history of the evaluation of crop residues as animal feeds in developing countries, including those of East Africa, was presented. It was pointed out that in some cases data had been collected over a period of more than 60 years. A large quantity of crop residues is produced annually in East Africa which amounts to about 700–800 kg per livestock unit. However, there are considerable difficulties in making precise estimates because of uncertainty both as crop production figures and extraction indices.

Recent work in East Africa was reviewed, emphasis being placed on the chemical treatment of crop residues that has been intensively investigated in various countries of the region.

Work carried out at ILCA in Addis Ababa has stressed the use of legume forages as supplements to fibrous crop residues. Different levels of Trifolium tembense, a clover native to the Ethiopian Highlands, have been fed with oat, wheat, teff and maize straws. In all cases both intake and digestibility were increased. The average digestibility of the crop residue when fed alone was 48.3% and the intake was 49.8g/kg liveweight 0.75. The provision of 45% (on average) legume hay improved digestibility to 65% and intake to 58g/kg liveweight 0.75 equivalent to improvements of some 35 and 15% in digestibility and intake respectively.

INTRODUCTION

This paper will give a brief background to the history of the evaluation of crop residues in developing countries including those of East Africa, and an indication as to amounts and types of crop residues available in the area. Some recent studies will be highlighted and finally recent work from ILCA will be reviewed. The main emphasis of the paper will be on crop residues.

The evaluation of crop residues in the tropics and subtropics using in vivo experimentation started sixty years ago with the work of Lander and Dharmani (1924) in India. Steers were used to determine the digestibility of wheat straw and later, the digestibility of rice straw was determined with cows. Carbery et al (1934) also working in India used steers to carry out digestibility trials on rice straw and linseed oil meal. Work (1937) determined the digestibility of Hawaiian feedingstuffs using steers and in Trinidad, Harrison (1942) carried out a series of trials on forages using cows. Later work at the Imperial College of Tropical Agriculture was carried out by Duckworth (1946) who made a statistical comparison of the effects of crude fibre on the digestibility of roughage by both Bos indicus and Bos taurus cattle.

In East Africa, early work was carried out by French (1931) at Mpwapwa in Tanganyika. French published the results of a long series of trials on crop residues and by-products which culminated in an attempt to establish fundamental relationships between chemical constituents and digestibility (Glover et al 1957). However, such attempts by French and his colleagues and others were only of limited value because of the empirical nature of the methods then in use for the determination of the fibre (and other) fractions of the diet. In fact, it was shown by Quarterman (1961) working at Muguga in Kenya that the digestibility of crude fibre in tropical feeds was consistently and significantly higher than that of the nitrogen free extractives.

AVAILABILITY OF CROP RESIDUES

It is useful at this point to give an indication of the quantities and variety of crop residues available in East Africa. Some estimates are given in Table 1. It must be emphasised however, that these values are subject to considerable variation. The crop production figures from which they have been calculated are approximate and furthermore, the relation between grain yield and that of crop residues depends on many factors particularly rainfall and time of planting. However, it may be seen that the total amount of residue is considerable; it is equivalent to about two thirds of a tonne per head of cattle in the region. East Africa is also noted for the variety of crop residues to be found. These include sisal, pyrethrum, sunflower, ramie, pineapple, coffee, and many others. Tef (Eragrostis tef)and Niger or Noug seed (Guizotia abyssinica) are grown almost exclusively in Ethiopia.

^* Based on the following ratios of residue to grain, Maize 1.6;Millet 4.5; Sorghum 3.7; Groundnut 1.2; (Powell, personalcommunication) wheat 1; Rice 1 (Kategile 1982)

Data from FAO (1981) production year book vol. 35.

RECENT WORK IN EAST AFRICA

This section does not set out to review comprehensively work that has been carried out in the zone, but rather highlights some of the more important findings particularly those which might be put into use by small farmers.

Several authors have evaluated untreated crop residues and it has been shown that these cannot be expected to do more than maintain an animal when fed alone (see for example, Nangole et al 1983; Kevelenge et al 1983; Butterworth et al 1984). However, when suitably supplemented, they can form the basis of a production ration which supports adequate daily gains in stallfed cattle. Some examples are given in Table 2. They have formed the basis for highly successful stall-feeder operations in Malawi (using maize stover and ground nut haulms; see for example: Spurling and Spurling 1972; Addy and Thomas 1977; Thomas and Addy 1977; Butterworth et al 1984) and commercial operations in Kenya (Creek 1973).

Other methods have been sought to improve the performance of cattle fed high levels of crop residues, without the use of supplementary concentrate feed which might perhaps be used more profitably for other classes of stock.

It has been demonstrated elsewhere that the treatment of highly lignified crop residues with alkalis can improve both digestibility and intake. This is achieved by the decoupling of lignin-carbohydrate linkages. A considerable amount of work has been carried out on this theme in East Africa, much of which has been summarised by Kategile et al (1981). Said et al (1982) have reviewed the methods of treatment which have been used in Kenya. Sodium hydroxide has been employed by small farmers in a dip-treatment method using a horizontally-cut 200 litre drum. Trials on the treated material fed to feedlot cattle showed that daily gain was higher than that in control animals over a 130 day period. Alternatively, when NaOH solution was sprinkled over chopped stover/straw and allowed to ripen overnight, the resulting product was equivalent in feeding value to medium quality Chloris gayana hay. An interesting compound which has been used for alkali treatment in East Africa is “Magadi”, a natural deposit of sodium sesquicarbonate (Na₂CO₃NaHCO₃2H₂O) which is found in the Rift Valley. It was shown that wide differences occurred according to the methods of residue treatment used. However, Magadisoaked maize cobs supported a higher rate of gain when fed to Friesian heifers grazing a Setaria sphacelata/Desmodium uncinatum pasture than unsoaked cobs (Nangole et al 1983).

^* Data taken from: IAR Holeta Progress Report 1974/75 andO'Donovan (1979)

Treatment with ammonia has the advantage that a mild alkaline effect is combined with the addition of non-protein nitrogen to the diet. Dorper sheep fed untreated maize cobs as well as 400 g/head/day concentrate gained 79 g/day compared with sheep fed treated roughage which gained 130 g/day. Similar values for untreated and treated maize stover were 62 and 69 g/day (Said et al 1982).

Kategile (1982) has reviewed recent work carried out in Tanzania. Maize cobs (100 kg) were treated with NaOH (5 kg) for a period of 48 hours. Both dry matter intake and rate of gain of heifers were significantly improved by feeding treated rather than untreated cobs. Rates of gain were higher in Boran steers fed treated cobs than in those fed the untreated roughage. Kategile (1982) also described the use of a flail forage harvester for alkali treatment, cutting and collection of straws after harvesting.

Recent work carried out at ILCA, Addis Ababa

Work on crop residues at ILCA has also involved the use of chemical treatment but in the latest series of trials, different amounts of legume hay were fed with various residues.

Sheep were used to assess the nutritive value of (a) tef straw ensiled for either 3 or 6 weeks with 4% urea, (b) a mixture of haricot bean and horse bean haulms ensiled as above or (c) oat straw ensiled for 3 weeks with urea solution or sprayed just before feeding. Untreated straws were fed as controls in all cases. It was shown that the digestibility of the tef straw was significantly improved by treatment with urea and that this was associated with a decrease in both ADF and NDF fractions of the forage and a relatively low level of lignin. The legume straws did not respond to treatments and this was associated with the higher level of lignin in these forages. The longer period of ensiling in the case of the oat straw was accompanied by lower protein digestibility associated with a higher level of ADF-N caused by Maillard reactions during ensiling.

Columns within straws with different superscripts are significantly(P<0.05) different

In a further experiment, the above crop residues were treated with a solution of 1 or 10% Ca(OH)₂. However, this did not improve the nutritive value of any of the treated material. Later work has emphasised the use of legumes to improve the digestibility and intake of crop residues. Chemicals are often expensive and difficult to obtain and may also be dangerous. Legumes are beneficial to soil structure and yields of food crops are improved on subsequent cultivation.

The latest series of trials has used the legume (Trifolium tembense), which is native to the Ethiopian highlands, as a supplement to various crop residues which are common in the country. Groups of five Ethiopian rams were fed the various diets and digestibility trials were carried out following the usual procedures. Animals were given different levels of Trifolium hay (these were calculated to be 15, 30 and 45% of ad libitum roughage consumption) and values were compared with those from both sheep given the crop residue without supplement and the legume hay fed alone. The crop residues were maize stover, wheat straw, tef straw and oat straw. The only procedural point which deserves mention is that the legume was fed as a separate meal after which the roughage was given ad libitum as it had been found in an earlier trial that if both forages were given together, selective eating prevented the consumption of the full ration of legume.

In all cases, digestibility was increased by the addition of legume but the magnitude of this difference varied somewhat among crop residues. Similarly, total consumption of dry matter was increased in all cases although this was accompanied by a reduction in the consumption of the crop residue. Average values are given in Table 3 together with the significance of differences. The average digestibility of the crop residue when fed alone was 48.3% and the intake was 49.8 g/kg liveweight 0.75. When on average 45% of the legume was added, corresponding values were 65% digestibilty and intake of 58 g/kg liveweight 0.75 equivalent to improvements of some 35% and 16% in digestibility and intake respectively. Analyses of nitrogen, phosphorus, ADF, NDF, ADF-ash, lignin and energy were carried out. Digestibility of nitrogen was significantly improved by the addition of legume hay and, with the exception of the highest level in the oat straw-based group, each successive increment caused an increase in digestibility. Such an increase is to be expected in view of the generally accepted finding that the digestibility of crude protein is positively correlated with the level of crude protein in the diet (see for example Butterworth and Diaz 1970). Energy digestibility was improved in all cases. NDF digestibility was improved in maize and oats and that of ADF only in the case of oats. Cellulose digestion was improved in tef and oats and that of hemicellulose in the case maize and oats. It appears that the supplement was least effective in the case of wheat straw. This is associated with the fact that wheat straw was the crop residue with the highest content of both ligning and silica (estimated as ADF-ash). Significance of difference is given in Table 4.

Different letters indicated significant differences (P<0.05) amongcontrol, low, medium and high levels of supplementation respectively

REFERENCES

Addy, B L and Thomas, D. 1977. Intensive fattening of beef cattle by stall feeding on the Lilongwe Plain, Malawi II. Utilisation of crop residues, crop by-products and leucaena. Trop. Anim. Hlth. Prod. 9:197–202

Butterworth, M H, Chintsanya,1984. N C C, Phiri, K M J and Mitengo Gama, P W S, Stall feeding beef cattle with agricultural by-products in Malawi. Trop. Agric. (Trinidad) 61:25–28

Butterworth, M H and Diaz, J A 1970. The use of equation to predict the nutritive value of tropical grasses. J. Range Manag. 23:55–58

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POTENTIAL FOR THE BETTER UTILIZATION OF CROP RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS IN ANIMAL FEEDING IN NORTH AFRICA, WITH SPECIAL REFERENCE TO METHODOLOGY, EQUIPMENT, FACILITIES AND PERSONNEL INVOLVED, AS WELL AS AN OUTLINE OF RESEARCH PRIORITIES OF THE REGION

M A El Naga
Faculty of Agriculture, University of Alexandria
Alexandria, Egypt

SUMMARY

The northern countries of Africa are deficient in animal feeds, estimated to be some 27% of calculated requirements. The available feed amounts are not consumed at a regular rate over the whole year. The more nutritious 65% of available feeds are consumed during the winter (rainfall)season. The animals suffer during the summer (dry) season from severe shortage of feed reflected in many imbalances due to deficiencies in nitrogen, soluble carbohydrates, vitamin A precursors and minerals. At the same time, these countries have considerable amounts of crop residues and agro-industrial by-products which are under-utilized. The amounts of unused by-products need to be surveyed. The fractions which could be directed to animal nutrition should be identified.

Improving the nutritive value of low quality roughages (conventional and non-conventional) can be achieved by arranging the consumption of nutritious and low quality ingredients to be regular over the whole year. Some of the winter materials (preserved as hay or silage) could be shifted to the summer season and vice versa. This will provide the animals with a more balanced diet over the year. Moreover, the non-traditional by-products should be used after proper processing (chopping and mixing) and supplementation with the deficient nutrients in the form of urea, molasses, vitamin A and minerals.

Simple machinery to conduct this work could be fixed on mobile trailers and driven by tractors to the farmers' sites to treat their local ingredients. Chopping and supplementation can result in doubling the daily body weight gain of animals given the same ingredients without any treatment. In milk production a diet based on chopped and supplemented by-products resulted in a similar level of milk yield as that obtained on a 1:1 concentrate to green roughage diet (on DM basis). The mechanization of processes involved in the improvement of the nutritive value of such ingredients needs to be evaluated economically.

Animal species should be compared in respect of their ability to utilize by-products more efficiently. Buffaloes proved to be more efficient in this respect. The camel may even exceed buffaloes in this ability.

DESCRIPTION OF THE PRESENT SITUATION OF THE ANIMAL NUTRITIONAL STATUS IN NORTH AFRICA

The northern countries of Africa (Egypt, Libya, Tunisia, Algeria and Morocco) are all in short supply of animal feeds (Table 1). Pasture plants are the main sources of animal feeds in these countries with the exception of Egypt. It is very difficult to increase the land areas producing these ingredients due to limitations of water resources, soil fertility and inefficiency of the human element involved in agricultural activities. The magnitude of the animal feed deficiency in these countries is increased by expressing the gap between available and required feed in units of TDN and DP. The majority of available feed ingredients in such areas are of low quality due to deficiencies in nitrogen, easily fermentable carbohydrates, vitamin A or its precursor and minerals. Intensive lignification and/or silication are also additional factors which may considerably contribute to the poor digestibility of these materials.

Due to social reasons it is almost impossible to think of solving the problem of feed deficiency through reducing the size of the animal population. The farmers refuse to reduce the number of their animals. Moreover importing animal feeds is not economically feasible as it is in the case of importing poultry feed ingredients. The kilograms of feed needed to provide an increase of one kg in the live weight is about 8–12 kg in ruminant animals while it is around 2.25 kg for poultry.

* Studies of the Arab Organization for Agricultural Development

* Reports of the Arab Organization for Agricultural Development andFAO publications.

* The Winrock International report.
** Records of the Dept. of Animal Prod., Alexandria Univ.

It seems that there is no choice other than finding the proper way to deal with the locally produced ingredients so as to maximize their nutritive value. This should be implemented as simply, cheaply and efficiently as possible because most of the farmers (or nomads) are not trained to adapt modern technology to their environment, and they are poor. This situation has reflected its effects significantly on the levels of productivity and reproductivity of animals in north Africa (Table 2). The animal unit (about 350 kg live body weight) in north Africa produces at the rate of about 73% of the world's average productivity. The low nutritional status of animals in this area has resulted in the low level of their immunity against diseases and parasites which, in turn, causes more depression of productivity.

Due to the irregularity of feed resources consumption (about 70% of feed is consumed in winter leaving the poorest 30% to be consumed during summer), the animals show less than one third of their productive potential. This can be visualized from data presented in Table 3. In 1979, the Winrock International report on the dominating practice of feeding animals in Egypt and the resultant level of performance agreed with the locally prepared descriptions provided by Egyptian investigators. On the other hand when these native animals were properly fed, as in the experimental farm of the Faculty of Agriculture of Alexandria, their performance was considerably improved (Table 3).

VARIOUS APPROACHES FOR THE IMPROVEMENT OF THE NUTRITIVE VALUE OF FEEDS IN THE COUNTRIES OF NORTH AFRICA

The well known methods of improving nutritive value of animal feeds are the same everywhere; however, it requires some sort of adaptation to fit in with the conditions in various environments.

In the northern African countries, there are few local facilities for producing sodium hydroxide. The situation for ammonia, ammonium hydroxide or urea is somewhat better. However, prices are always high. Moreover, with the exception of urea, the farmers (and nomads) would be exposed to severe hazards when dealing with alkali materials like sodium or ammonium hydroxides.

After 6 years of work on alkali treatments in our Department, it was realized that supplementing the feed with the deficient nutrients resulted in a superior improvement with much less cost. This concept was clarified by El-Shazly and Naga in the meetings held in Arusha in 1981 and Nairobi in 1982. The cost of supplementation was less than alkali treatment. A tonne of straw requires 35 kg of ammonia (gaseous) which cost (x 0.15 L.E./kg) 5.3 L.E. per tonne of straw.

Supplementation of one tonne of straw with urea, molasses and mineral (15 kg of urea × .123 L.E./kg + 50 kg of molasses × .03 L.E./kg + 1 one kg of mineral mixture × .180 L.E./kg = 1.845 + 1.5 + 0.18 = 3.6 L.E./ton of straw) cost just 68% of the alkali treatment cost, as far as the prices of used materials are concerned. The supplement is added to the diet by spraying it manually after mixing the urea and minerals in the molasses portion. The molasses is then diluted by an equal weight of water to facilitate its handling. This method may suit small scale farmers having up to 15–20 head of buffalo and/or cattle or 50–60 head of sheep and goats. Bigger herds and flocks need machinery to achieve this job properly, because the amounts will then become more than a quarter of a tonne of roughages. Mechanizing this process has additional benefit. The effect of the additives and that of chopping and proper mixing is presented in Table 4. About 48% higher profit is earned through combining addition of supplements with chopping + mixing of the ingredients. A herd of 150 head of cattle of an average weight of 180 kg at the start of the experiment was kept on a whole roughage diet made of : 40% rice straw, 22% horse bean straw, 20% corn stalks, 15% molasses, 1.5% urea, 1.5% normal salt enriched with 0.1% microelements. The experimental period extended over 180 days. The average daily gain was 0.76 kg with an average daily feed consumption of 10.5 kg (kg feed/kg gain = 13.8). The cost of production one kg of live weight (on basis of 0.03 L.E./kg feed and 0.35 L.E./head/day as costs of labour, depreciation etc.) = 0.78 L.E. This production cost seems to be 17% higher than that reported in Table 4 where the diet contained 30% concentrates. This difference is false due to the heavy subsidy given to concentrate diets in Egypt. The international price (160 L.E./tonne is four times the subsidised Egyptian price (37.5 L.E./tonne factory-gate delivery).

* The roughage fraction : 40% rice straw, 20% horse bean straw and 10% of cornstalks.

* concentrates were a mixture of: 35% cottonseed cake, 30% corn, 25% wheat bran,7% molasses and 3% salt and calcium carbonate.

When this whole roughage diet was tried with lactating cows and buffaloes (20 head) in a comparision with 4 other diets in a latin square design the results shown in Table 5 were obtained. The combination of whole roughage (chopped + supplemented) diet strengthened with 17% concentrate mixture (Diet 5) showed the highest profit.

These diets of whole roughage or those containing as little as possible of concentrates after having been properly balanced, supplemented with deficient nutrients, chopped and well mixed become equivalent to almost double the amount of the raw ingredients before these mentioned arrangements. Concentrates for animals are scarce in the countries of north Africa. The main ingredients to build a feed formula should be roughages.

With the exception of Egypt, of pastures provide more than 60% of all the available animal feeds. During the rainy season, e.g. winter, animals face no problem. The real challenge of animal nutritionists is the assurance of reasonable nutritional status for the existing animal population during the dry season (summer) when the performance of animals drops to below the critical level. Two main reasons contribute to this bad effect:

1. The pasture plants burn out with an increase in fiber and decrease in protein contents.

2. The heat stress results in reducing the grazing period (from 4.12 to 2.87 h/day) especially if the animals (sheep & goats) are of the dark or black color. The animals cannot consume enough during the period when the climatic conditions allow grazing. Feed intake (on DM asis) decreases from 1433 to 907 g/head/day.

The animals at a pasture show clear symptoms of vitamin A deficiency, besides recognizable deficiencies of nitrogen, easily fermentable carbohydrates and some minerals. In some cases, where the soil is calcarious, the plants become extraordinarily rich in calcium. High Ca intake presents a real problem in many areas of the north African pastures. Table 6 presents the performance of a sheep flock grazing at El-Omayed site (94 km to the west of Alexandria), in response to vitamin A and to mineral + urea supplements. Sheep females and goat kids benefitted from this supplementation at higher rates than those shown by sheep, lambs and goat females. However, in both types of animals the placental drop after delivery occurred within a few hours instead of 2–4 days, due to supplementations. Distributing these molasses, mineral and vitamin A licking blocks at the water wells and spreading in the pasture area during the summer season would save a lot of mortality especially in the newly born lambs and kids and would help the mothers to produce more milk. The performance of the flock would considerably improve. It was found that these supplements resulted in increasing the digestibility of the pasture's dry matter by 28%

* Daily gain as % of initial weight

There are certain pasture areas where bushes are dominant. In summer these drop their leaves and become just a standing woody object. Cutting the ends of the branches of these bushes, grinding this material and using it as bedding spread over a plastic sheet for cultivating some sort of seeds or grains with the least water amount (because the wood particles will hold water efficiently) would enable production of nutritious green, protein-rich sprouts to be fed together with the bedding material. This open-air soil-less sprouting system can be established during summer adjacent to the water wells to be distributed to the nomads when they come to water their animals. The sprouts were able to make use of the mineral and perhaps other organic contents in the woody material used as a bedding. They reach a height of 20– 25 cm doubling the DM of the seeds or grains within two weeks instead of the one week obtained by using the sophisticated hydroponic conditioned chambers which are very expensive relative to the financing capacity of such countries. The character of holding amounts of water that reach 2–4 times the weight of the woody bed avoids the need for frequent irrigation under desert pasture conditions.

FACILITIES, PERSONNEL AND RESEARCH PRIORITIES FOR SUCH ACTIVITIES

A mobile chopper mixer of half a ton capacity driven by a tractor can efficiently serve a village or location of nomads enabling them to chop and mix their roughages with the proper supplement. When the roughage material will be rice straw, horse bean straw or similar ingradients, the driving motor should be more than 65 horse power. Milling will be more successful if the hammers of the grinder are hardened knives. The speed of the milling knives should be higher than 550–600 rpm to create a centrifugal power pushing the material through the sieve holes without turning it into fine particles (less than 3 mm) which can escape ruminal fermentation. Digestion of fiber materials occurs mainly in the rumen. The mixer should be horizontal to avoid the problems of mixing which originate from its different densities. The mixing period should extend long enough to allow complete absorption of molasses (especially when it is added at high percentage, i.e. more than 10%) and to prevent diarrhea in the animals consuming it.

A premixer is required at each location with a connected licking block facory to produce these for nomads especially in the summer season.

These activities could be achieved by mechanical and agricultural engineers. Veterinarians should provide their input especially against parasites and specialists of rural sociology and agricultural extension services should all cooperate in this respect.

The suggested research priorities perhaps would be as follows:

1. Surveying the really available by-products for use in animal feeding. There are competing usages for these by-products such as using them as fuel.

2. Studying the characteristic deficiencies in plants of each site so as to formulate the best supplement to be used these. In the cases where plants contain excessive amounts of any nutrient, like Ca or Si, means should be investigated to find out how to challange these or counteract their bad effect on the animal.

3. Economical comparisons between the expenditure in mechanization and the earned improvements in nutritive and feeding value of treated ingredient. If mechanization is to be recommended, the length of chopping and the proper integrating mixture of ingredients should be given specific care. Preliminary observation drew attention to the differences in the amount of each ingredient needed. If pelleting would pay for its costs it should be seriously considered. This last point may become vital for huge feed milling plants dealing with roughages to enable it to be transported economically.

4. Buffaloes have been shown to exceed cattle, sheep and goats in making use of roughages (Table 7). Camels may be even better than buffaloes in this respect. It is high time to focus some research on the nutritional characteristics of the camel. This animal has so many unique physiological charachters but still we know almost nothing about its productive potentiality, especially on low quality type of roughages.

The feed was a chopped, mixed and supplemented whole roughage diet.