SESSION I (contd.)

POTENTIAL FOR THE BETTER UTILIZATION OF CROP RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS IN THE MIDDLE EAST WITH SPECIAL REFERENCE TO METHODOLOGY, EQUIPMENT, FACILITIES AND PERASONNEL INVOLVED, AS WELL AS AN OUTLINE OF RESEARCH PRIORITES IN THE REGION

Miltiades Hadjipanayiotou

Agricultural Research Institute
Nicosia, Cyprus

SUMMARY

Crop residues and agro-industrial by-products can and should play a more significant role in the nutrition of ruminants in Middle East countries.

Supplementary feeding with nitrogen, energy and minerals as well as chemical and physical methods of treatment have been used in order to improve feeding value. The chemicals are: NaOH, Ca(OH)₂, NH₄ OH, CaO, urea, O₃ and SO₂. Based on the existing knowledge, it is concluded that treatment with NaOH is currently too expensive, and more emphasis should be put on ammonification; and that urea might be preferable to NH₃especially for developing countries. Treatment with a mixture of Ca(OH)₂and urea deserves further attention.

By-products such as citrus pulp, grape marc, and others with a high moisture content, should be processed to improve their storage quality. Processing of animal wastes is also important as a means of destroying pathogens. Dehydration of by-products results in a stable product which is flexible to use, but it should not be recommended because of costs and loss of nitrogen. Ensiling is less flexible but is preferred to dehydration because it requires less energy.

In many countries there are no data on by-products. If we are interested to make better use of them as animal feeds, it is important to know the quantities, seasonal availability, alternative uses, nutritive value and their location versus that of livestock industries.

Processes for improving by-products must be practical and economical and, if possible, should use existing farm machinery and not require new and expensive equipment. Countries in the region must make use of the prevailing high ambient temperatures for drying by-products and for enhancing chemical treatment of crop residues.

Finally, it is recommended that before setting research priorities, possible beneficiaries should be identified, and that governments, through various means, should promote use of by-products and technology for which there is sufficient knowledge.

INTRODUCTION

The Middle East countries raise some 99 million sheep and goats, 104 million beef cattle and 202 million dairy cattle (FAO 1981a). In some countries, the productivity of the animals is very low, although experimental data suggest that their production potential is higher. The greatest constraint to livestock productivity is the shortage of feeds and forages. Some countries of the region import cereal grains (Table 1) in an effort to increase livestock production and meet the ever-increasing demand for animal products. Higher livestock productivity, however, should be sought through better use of locally available feed resources. Crop residues, agro-industrial by-products and animal wastes, which are available in appreciable quantities (Table 2) in the region, can play a significant role in the nutrition of ruminants.

CROP RESIDUES

Supplementary feeding with nitrogen, energy and minerals (Hadjipanayiotou et al 1975; Economides et al 1981; Naga and El-Shazly 1983) and biological, chemical and physical methods of treatment (Jackson 1978) have been used to improve voluntary intake and digestibility of crop residues. Methods of chemical treatment of poor quality roughages tried in Middle East countries are:

* FAO 1981a,b

* Ratio of residue to either grain or fruit

Daily spray treatment: Crop residues were sprayed with NaOH solution so that they were uniformly wetted. The material was fed either 24h later or stored. Storing of treated straw did not further improve digestibility.

Treatment with NaOH, ozone, NH₄OH and SO₂: These chemicals were used at the Volcani Center, Israel (Ben-Ghedalia and Miron 1981; Ben-Ghedalia et al 1980). The in vitro organic matter digestibility of the residue was increased by 80% with SO₂, whereas NaOH and O₃ improved IVOMD by only 50%. The NH₄OH treatment had a small effect.

Industrial method: This methode is currently applied in Israel (Holzer et al 1980) and is similar to the one followed by the Biotechnical Institute at Kolding, Denmark, and BOCM-Silcock UK.

Treatment with Ca(OH)₂, NaOH or urea: The use of Ca(OH)₂ in improving digestibility has been of interest because of its low cost. However, there was considerable mould in many of the silages treated with Ca(OH)₂ alone (Hadjipanayiotou 1984b). Digestibility of straw treated with a mixture of Ca(OH)₂with NaOH or urea improved with ensiling (Table 3). CaO was not very effective.

Ammoniation by urea: An indirect NH₃ treatment, where straw is ensiled with an aqueous solution of urea, has been tested (Hadjipanayiotou 1982b). Straw was ensiled in steel drums, plastic bags or stacks covered with plastic (Sundstol et al 1978). Ammoniation improved digestibility of both long and chopped straw (Hadjipanayiotou 1983).

a Increase over the digestibility of treated straw tested 48 h aftertreatment.

b Together with 3.5 kg NaOH

c Same improvement for each ensiling period.

AGRO-INDUSTRIAL BY-PRODUCTS

Citrus pulp: Dried citrus pulp replaced considerable amounts of barley in the diets of fattening cattle (Hadjipanayi0t0u and Louca 1976) and lactating cows (Economides 1974). Drying,however, adds to overhead costs. About 67 gallons of fossil fuel and 200 kwh of electricity are required to dry 1 tonne of citrus pulp. Ensiling of citrus pulp either alone or in combination with poultry litter (Tagari 1977; Hadjipanayiotou 1982a, 1934a), rice straw, date stones, grape waste, groundnut hulls or cattle excreta (Kiflewahid 1983) are some economical and promising methods.

Grape marc: Although this product contains less moisture (50%) than citrus pulp (80%) its dehydration is still costly (requires about 16.5 gallons of fossil fuel and 109 kwh/tonne of dried product) primarily due to its low nutritive value (Hadjipanayiotou and Louca 1976; Economides 1974; Mavrogenis et al 1973). Ensiling of grape marc in earthen pits either alone or in combination with poultry litter gave good quality silages, which were eagerly consumed by dairy cows, growing heifers and Chios weathers.

Olive by-products: Extraction of oil from olive cake (residues after the first extraction of olive fruits) is an essential step because not only is oil a valuable product, but also it improves the storage quality and digestibility of the residue. Non-screened olive cake (extracted or not) is of low nutritive value whereas screened extracted olive cake is of better nutritive value. Separation of crushed kernels is achieved either by screening or by a strong air draught or by a combination of the two. There are factories in Europe (i.e. ABEA; China; Greece; and Dalmolive, Bari, Italy) merchandizing screened solvent extracted olive cake. Removal of kernels is recommended, not only to improve nutritive value of pulp but to improve available combustion energy.

Animal wastes: Processing of wastes is important as a means of destroying pathogens and in some instances to improve storage quality. Dried poultry litter has been used successfully in many parts of the world. However, because of increased cost of fossil fuel, processes such as drying using solar dryers, similar to greenhouses with a plastic covering, “in house” drying by incorporating slats below the cages, deep stacking, ensiling and chemical treatment with formalin have been tested (Tagari 1977; Hadjipanayiotou 1982a, 1984a; Fontenot 1981; Shah and Muller 1983). In our studies, earthen pits, existing barns and empty drums were used as silos. Individual ingredients were mixed in concrete mixers before entering the silo pit or silages were made by adding ingredients layer by layer using a tractor scoop. The material was pressed before being covered with plastic sheet and soil.

Slaughter-house by-products: In many countries of the region, abattoirs are little developed or have no facilities for the processing of by-products, and it is difficult to estimate available quantities. The economics of a centralized by-product processing plant attached to a slaughter house (slaughtering up to 1 250 sheep and goats, 33 cattle and 900 pigs/day for 250 days/year) were studied by Crawford (1973) who concluded that such a plant will generate a net profit, before taxes, of US $170 000 annually, if $0.01 per pound was paid for all the raw material collected.

INSTITUTIONS

According to the world directory of Institutions (FAO 1932a) and personal contacts, there are some 41 institutions engaged in research of by-product utilization in the region. The end products are animal feeds, fertilizers, chemicals, biogas, alcohol, yeast and paper (Table 4). The major technologies which have been used by the various institutions include mechanical treatment, chemical treatment, dehydration, ensiling, fermentation, composting, coagulation and filtration.

* Not found

** CR: crop residues Ag B: agro-industrial by-products AW: animal wasteOSC: olive seed cake DS: domestic sewage SHW: slaughter house wasteMW: municipal waste IF: industrial effluent SB: sugar industry by-products DB: dairy by-products

RESEARCH PRIORITIES

The FAO (1982b) inventory on by-products does not include data from many Middle East countries possibly because such data are not available. However, if we are interested in making the best possible use of them it is important to:

• Organize a survey of the type, quantity, seasonal availability, alternative uses and relative costs of by-products.

• Tabulate the feeding value of by-products based upon research studies with local animals at various production stages, and

• Assess the location of by-products versus that of livestock industries.

The existing livestock industries and other factors prevailing in some Middle East countries might justify importation of western technology and study of the commercial utilization of treated crop residues. On the other hand, simpler methods such as soaking and Torgrimsby's modification could be tried in developing countries (Jackson 1978). The latter, when mechanized, can also be used to meet the needs of farms in some rich Middle East countries (Jackson 1978).

Treatment of poor quality roughages with NaOH is currently too expensive and research should be concentrated on ammonification. Urea might be preferable to NH₃, especially for developing countries. The relatively long period of time (approximately 5 weeks) required for optimal treatment (Table 5) may be a disadvantage under certain conditions. The Flemstoff-Mad Amby (FMA) manufacturers in Denmark have developed an oven-like NH₃-straw processing plant, where treatment is completed within 14th at 95°C. Under high summer temperatures prevailing in Middle East countries the time required for treating straw following the stack method (Sundstol et al 1978) and the possibility of using greenhouses with plastic covering should be studied.

Means on the same line with different superscripts are significantly different

Processes for improving by-products must be practical and economical, and if possible, should use existing farm machinery and not require new and expensive machinery. Spraying urea solution on the straw at harvesting (using balers, flail type harvesters mounted with a sprayer) and subsequently stacking the bales in big stacks may be proved an efficient, economical and simple technique for treatment of crop residues. Treatment of crop residues with Ca(OH)₂ together with urea should receive further attention, as the first is available at a low price in the region, and the second adds nitrogen.

Feeding ammoniated straw to ruminants may result in relatively uniform NH₃ levels in the rumen. The effect of feeding such straw on rumen microbial protein synthesis should be examined.

Feeding treated straw in conjunction with concentrates results in lower digestibilities for treated straws. The digestibility of ammoniated straws with different proportions of concentrates and at different stages of production should be further investigated.

Dehydration of agro-industrial by-products results in a stable product which is flexible to use. On the other hand ensiling provides less flexibility, but requires less energy input thus its use should be further investigated, and efforts should be made to use facilities and equipment available in each country. Finally, before setting research priorities possible beneficiaries should be identified.

REFERENCES

Ben-Ghedalia, D. and Miron, J. 1981. Effect of sodium hydroxide, ozone and sulphur dioxide on the composition and in vitro digestibility of wheat straw. J. Sci. Fd and Agric. 32:224–228.

Ben-Ghedalia, D., Shefet, G. and Miron, J. 1980. Effect of ozone and ammonium hydroxide treatments on the composition and in vitro digestibility of cotton straw. J. Sci. Fd and Agric. 31: 1337–1342.

Crawford, L. 1978. By-product plan for processing slaughterhouse by-products. Technical Report prepared for the Government of Cyprus.

Economides, S. 1974. The effect of dried citrus pulp and grape marc on milk yield and milk composition of dairy cows. Tech. Paper No. 7. Agric. Res. Inst. Nicosia, Cyprus.

Economides, S., Hadjipanayiotou, M. and Georghiades, E. 1981. The nutritive value of straw, and barley and lucenna hay, and the nitrogen supplementation on the nutritive value of straw to sheep. Technical Buleltin 39. Agricultural Res. Institute. Nicosia, Cyprus.

FAO 1981a. FAO Production Yearbook. Vol. 35.

FAO 1981b. FAO Trade Yearbook. Vol. 35.

FAO 1982a. FAO Agric. Services Bulletin 21 (Rev. 2) Agricultural residues: World Directory of Institutions.

FAO 1982b. FAO Agric. Services Bulletin 47. Agricultural Residues: bibliography 1975–81 and quantitative survey.

Fontenot, J.P. 1981. Recycling of animal wastes by feeding. In: New Protein Foods, Vol. 4pp 277–304. Academic Press Inc.

Hadjipanayiotou, M. 1982a. Laboratory evaluation of ensiled poultry litter. Anim. Prod. 35:157–161.

Hadjipanayiotou, M. 1982b. The effect of ammoniation using urea on the intake and nutritive value of chopped barley straw. Grass and Forage Sci. 37: 89–93.

Hadjipanayiotou, M. 1983. Laboratory evaluation of urea-treated barley straw. J. Dairy Sci. 66 (suppl. 1).

Hadjipanayiotou, M. 1984a. Studies on the use of poultry litter as ruminant feed in Cyprus. Wld. Anim. Rev. (in press).

Hadjipanayiotou, M. 1984b. Effect of level and type of alkali on the digestibility in vitro of ensiled, chopped barley straw. Agric. Wastes (In press).

Hadjipanayiotou, M. and Louca, A. 1976. A note on the value of dried citrus pulp and grape marc as barley replacements in calf fattening diets. Anim. Prod. 23: 129–132.

Hadjipanayiotou, M., Louca, A. and Lawlor, M. J. 1975. A note on the straw intake of sheep given supplements of urea-molasses, soyabean meal, barley-urea or barley. Anim. Prod. 20:429–432.

Holzer, Z., Levy, D. and Folman, Y. 1980. Performance of fattening cattle and lactating beef cows on diets high in chemically treated wheat straw and poultry litter. Animal Fd. Sci. and Techn. 5: 299–307.

Jackson, M. G. 1978. Treating straw for animal feeding. Rome. FAO Animal Production and Health Paper No. 10.

Kiflewahid, B. 1983. An overview of research methods employed in the evaluation of by-products for use in animal feed. In by-product utilization for animal production (eds B. Kiflewahid, G. R. Potts and R.D. Drysdale) pp 93–115. IDRC Ottawa, CA.

Mavrogenis, A., Louca, A. and Lawlor, M. J. 1973. The use of grape pulp, grape seed meal and barley straw in lamb fattening diets. Tech. Bulletin 12. Agric. Res. Inst. Nicosia, Cyprus.

Naga, M.A. and El-Shazly, K. 1983. Use of by-products in systems in the Delta of Egypt. In By-product utilization for animal production (eds B. Kiflewahid, G.R. Potts and R.D. Drysdale) pp 9–15. IDRC, Ottawa CA.

Shah Iqual, S. and Muller, Z.O. 1983. Feeding animal wastes to ruminants. In: By-products utilization for animal production (eds B. Kiffewahid, G.R. Potts and R.M. Drysdale), IDRC, Ottawa, CA.

Sundstol F., Coxworth, E. and Mowat, D.N. 1978. Improving the nutritive value of straw and other low-quality roughages by treatment with ammonia. Wld. Anim. Rev. 26:13–21.

Tagari, H. 1977. The nutritive value of poultry by-products as ruminant feed, as affected by different disinfecting methods. Comprehensive report p 46. United States - Israel Binational Science Foundation.

POTENTIAL FOR THE BETTER UTILIZATION OF CROP RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS IN ANIMAL FEED IG IN THE INDIAN SUB-CONTINENT

M C N Jayasuriya

Animal Production and Health Section, IAEA, PO Box 100
A-1400 Vienna (Austria)

SUMMARY

Ruminants in the Indian Sub-continent are generally reared on poor quality herbage such as native grass, weeds and crop residues, because the available arable land is given high priority for cultivating cash crops to produce food for the ever-increasing human population. The prevailing economic conditions limit the importation of animal feedstuffs and ruminants in particular have to depend more and more on the vast quantities of crop residues and agro-industrial by-products available in this region.

Cereal straws are the predominant feed resource in the region, but their inherent nutrient deficiencies make them poor quality feeds. Despite the theoretical simplicity of supplementing straw with nitrogen, energy and minerals, to alleviate the nutrient deficiencies, feeding systems based on supplementation alone have not proven successful. Trials in Sri Lanka, India and Bangladesh have clearly demonstrated that ammoniation through the use of urea solution offers and excellent opportunity to increase animal production through the better utilization of crop residues. Apart from providing supplemental nitrogen, urea treatment increases the digestible energy intake by the animal.

Supplementation by way of small quantities of both soluble and rumen undergradable protein, improves the feeding value of the treated material. Simple methods acceptable to the small farmer are now available for treating cereal straws with urea solution.

The economics of straw treatment should not be viewed only in relation to production; treated straw has unlimited value as an “acceptable emergency feed” for sustaining animal production at times of feed scarcity.

INTRODUCTION

Ruminants in the majority of Asian countries are reared on poor quality herbage that can be harvested or grazed from uncultivable land, forest areas and water ways and stubble left over from the cultivation of crops, particularly cereal straws. Land suitable for arable farming is used for cash crops rather than for forage crops because of the high priority given to food production for human consumption. Since the availability of fodder from uncultivable lands and other areas is highly limited, crop residues and other by-products have become the mainstay for the nutrition of these animals.

The value of crop residues and agro-industrial by-products as animal feed becomes more important to the Indian sub-continent than to other regions because of the ‘dry spells’ regularly experienced by countries in this region. A dry season of 3–4 months with no green fodder for grazing is a common feature in this area. Cattle and buffaloes often lose condition and even succumb to death for lack of feed. There is, however, an abundant supply of crop residues, partiucularly cereal straw during this period because the dry season normally coincides with the harvesting time of cereal crops.

There is very little information on the actual availability and uses of crop residues and other agro-industrial by-products in the Asian region. A rough estimate of the availability of crop residues can be made using extraction rates (Table 1). Rice straw is the predominant fibrous residue, available in large quantities. It is also the major residue that is utilized to any reasonable extent in animal feeding. Statistics suggest that rice and wheat straws constitute over 50% of the total forage fed to cattle and buffaloes in India (Amble et al 1965). The utilization of rice straw as an animal feed is very variable in Sri Lanka; availability of green forage and other feed resources being the predominant factor governing this variation. In certain parts of the country, particularly in the Northern peninsula, almost all the harvested straw is used for animal feeding. While in the central hills straw is hardly used at all as a feed material. Using the average nutrient contents of some principal by-products, Mahadevan (1983) estimated that in quantitative terms, crop residues can supply a substantial part of the maintenance requirements of all ruminants in the Asian region. However, because of their low feeding value, they are not used in production rations to any significant extent.

Crop residues and many agro-industrial by-products have certain inherent disadvantages in that nutritionally, they have low digestibility and are deficient in nitrogen and in many mineral elements; they are physically resistant to comminution and may contain high amounts of indigestible lignin and silica. Low digestibility associated with low nitrogen content of the feed limits intake and animals on these diets alone are often in negative energy and nitrogen balance. It is therefore essential that these deficiencies are corrected when crop residues and agricultural by-products are used as feeds.

As pointed out by Greenhalgh (1980), despite the theoretical simplicity of supplementing straw with nitrogen and minerals, feeding systems based on straw supplemented with feed blocks or small amounts of concentrate have not proved quite satisfactory. The most recent innovation is the development of gelled molasses/nutrient blocks (with urea). These are now extensively studied by researchers in the Philippines through an FAO/UNDP project.

Apart from supplementation, many new techniques have been developed to increase the efficiency of utilization of crop residues and by-products of agriculture (Jackson 1977; Ibrahim 1981). Figure 1 summarizes the methods available for this purpose. Of the methods available for physical processing, grinding has given reasonable results when roughages are included in complete diets (Swan and Clark 1974) but it is uneconomic and impractical in situations in Asia. Furthermore, it has been suggested that grinding does not improve the ME value of the roughage to any significant extent (Greenhalgh 1980). Biological methods are still in the early stages of development and it may be some time before methods are devised for large-scale application. The most applicable way of improving the ME value of a roughage is by chemical treatment.

Figure 1: Methods of improving the nutritive value of fibrous residues (Source: Ibrahim 1981)

It has often been mentioned that processing is an ‘optional extra’ while the correction of nutrient deficiencies is ‘essential’ when considering poor quality roughages for animal feeding. However, often they become complementary as treatments which increase digestibility and intake may generate a need for additional nutrients to supply the requirements of the rumen microbes as well as the host animal.

CHEMICAL TREATMENT OF RESIDUES AND BY-PRODUCTS

The chemical treatment of roughages preceded mechanical treatment, with the work of German pioneers such as Beckmann (1921) and Kellner (1926). Since 1964, there has been a widespread renewal of interest in chemical treatment, particularly in the developing countries, which have the highest potential for crop residues as ruminant feed.

A review of literature published so far, leads to the following general observations:

• In a majority of experiments, both in vitro and in vivo, sodium hydroxide has been used as the chemical reagent for treatment.

• There is no doubt as to the effect of sodium hydroxide on digestibility and intake of a roughage. In general, digestibility increases between 10–20% units can be expected with intake increases of 30–50%.

• Because of increase in digestibility and intake, the intake of ME is considerably increased leading to improved production. Various levels of body weight increases have been recorded depending upon the level of inclusion of the roughage in the diet. For example, Pirie and Greenhalgh (1978) reported 0.7–1.2 kg of gain in beef cattle fed diets containing 60% treated straw. Similarly, Jayasuriya et al (1982a) showed that milk yields of Friesian cows can be increased by 26% by feeding a diet containing 65% treated rice straw.

• The achievements in (2) and (3) above are diminished by some drawbacks such as high price of sodium hydroxide, the corrosive nature of the chemical and the necessity for protective equipment and trained personnel for application. This has made sodium hydroxide treatment unfavourable amongst the Asian farmer.

• Ammonia is an alternative to sodium hydroxide for treatment of crop residues (Jackson 1977; Sundstol et al 1978). It has been adopted in many European countries because (a) it does not leave residual alkali like sodium hydroxide and (b) it also increases the nitrogen content of the material. The standard method of ammonia treatment is not feasible under small farm situations in Asian countries because of the high cost of liquid or gaseous ammonia, lack of storage and transport facilities and lack of trained personnel to carry out treatment.

• One of the most promising methods of ammoniation is to use fertilizer grade urea as a solution (4–5% w/w) and preserve the sprayed material under air tight conditions for 3–4 weeks. The method developed by Jackson in India and tested and modified by animal nutritionists in this region (Saadullah et al 1981; Jayasuriya and Perera 1982) has clearly demonstrated that this treatment increases digestibility and intake of the residue leading to increased animal production. On-farms trials in Indai (Agarwal and Verma 1988), Sri Lanka (Perdok et al 1982; Jayasuriya 1982) and Bangladesh (Saadullah et al 1982) have shown that urea-ammonia treated straw offers a great promise for the future of animal production in the Indian sub-continent. These studies have also stressed the necessity for a simple and economic treatment system for the village farmer.

RESOURCES REQUIRED FOR STRAW TREATEMENT AND THEIR AVAILABILITY AT VILLAGE LEVEL

Ammoniation using a 4% solution of urea (40 g urea dissolved in one litre of water per kg of straw) is a simple process that can be carried out at the village level. The appropriate quantity of urea dissolved in water is sprinkled on the straw either using a garden watering can or a tin can with many holes in it. Application need not be uniform as the ammonia formed on hydrolysis will penetrate into the moisture in the straw. The sprayed material is then stacked. An air tight cover is preferable to prevent the less of gaseous ammonia, but is not essential. However, the feeding value of the treated material will vary according to the type of cover used and the choice of treatment method (see discussion later). As one can see, the method does not require special equipment or trained personnel to implement it.

A careful examination of the method of treatment suggests the necessity of scales to weight straw and urea and means of measuring the required quantity of water and of spreading it as evently as possible. Under practical conditions a farmer can be trained to bundle straw in approximately 10 kg lots. He can be taught to measure urea in approximate quantities using a pre-calibrated container. The same principle can be applied to measure water. Therefore, in practice, what is required from the point of view of equipment is only a bucket which is normally available in any household.

Our experience as well as that in India (Agarawal and Vermas 1983) and Bangladesh (Dolberg et al 1981) clearly shows that the technology is acceptable to the farmer. However, simpler and more economic methods of treatment must be made available to him if wide scale adoption is to be ensured.

TREATMENT SYSTEMS FOR THE FARMER

The ‘open stuck’ method seems to be the most popular method of treatment in India while in Bangladesh straw is often treated in bamboo baskets covered with banana leaves or in pits dug in the ground. In Sri Lanka we have developed and tested three treatment systems, each having its own advantages and disadvantages.

Closed system:

A pit 165 cm × 165 cm × 75 cm (length × width × depth respectively), partly buried in the ground, is built with bricks and cement. It is divided into four equal compartments by cross walls and the inside of each compartment is lined and smoothed with cement (Figure 2a). Straw treatment is carried out inside these compartments, each of which can hold approximately 60–70 kg of untreated straw, which is sufficient to feed 2–3 adult cattle (300 kg live weight) for 3 days. Straw is treated for 9 days according to a schedule (Table 2a) at 3 day intervals. As seen in the schedule, compartment 1 should be empty on the 13th day for the scheduled fifth treatment and this procedure should ensure a steady supply of treated straw. If the farmer considers the above programme cumbersome, he may have a two compartment pit of the proportionate size. Here he will treat every 8th day and feed the treated straw for an average of seven days starting from the 4th day after treatment (Table 2b).

After treatment each compartment is covered with a polythene sheet and air tightness is ensured by having sand bags kept on the shallow grooves on the pit wall (Figures 2b).

Initially, straw was treated for 3–4 weeks, but laboratory investigations suggested very little benefit by extending the treatment period beyond 10 days. This was also found to be convenient from the point of view of the farmer.

Open system:

The open system does not require a pit but a roof cover made of straw or cadjan is recommended. The required quantity of straw is sprinkled with the urea solution and the treated straw is stacked into a heap under the shed. A somewhat similar schedule to the one used for the closed system can be adopted but it is recommended that the treatment duration be less than 10 days as otherwise moulds tend to exceed the tolerable levels. Feeding of treated straw can begin by the 7th day after treatment so that feeding of that particular heap is complete in 10 days.

Figure 2a: A four compartment pit made of brick and cement. (165 cm × 165 cm × 75 cm)

Figure 2b: Cross section A-A showing the shallow groove on the pit walls

Figure 3 A General view of the semi-open bamboo shed

Semi-Open system:

A shed having a roof cover is divided into four compartments of appropriate size according to requirements using either bamboo sticks or any other suitable material as shown in Figure 3. Straw is treated in batches inside each compartment according to a schedule similar to the one used for the open system (Table 2) and stacked into heaps. At the end of treatment both the sides and the top of the compartment can be covered either by jute hessian or used urea bags. Even green material such as banana leaves and coconut fronds spread over the heaps can help in minimizing losses of moisture due to evaporation. The treatment period should not exceed 10 days as moulds tend to develop and make the material unpalatable.

Apart from these three treatment systems, straw can also be sprayed or sprinkled with a urea solution and fed immediately without having to preserve it. This is supplementation rather than treatment but it is possible under farm conditions.

A COMPARISON OF THE TREATMENT SYSTEMS

A summary of advantages and disadvantages of the different treatment systems as compared to feeding untreated or supplemented straw is given in Table 3. It is quite clear that in all aspects the semi-open system is intermediary to the other treatment systems. The closed system is the most expensive as it requires initial capital investment. But it gives the best quality treated material with possibilities of higher animal production. The cement pit could also have other uses. It could be used as storage space for grain or water when straw treatment is not possible for various reasons. It could also serve as a silage pit for conserving pasture during the lush season.

Table 3 A summary of advantages and disadvantages of the different treatment systems using urea as a source of ammonia (US untreated straw: SS straw supplemented with 4% urea a rayed on the straw: TS_o straw treated by the open system: TS_so straw treated by the semi-open system: T_c1 straw treated by the closed system)

In addition to ad libitum straw all animals received 1 kg fresh grass, 0.5 kg rice bran and 60 g mineral mixture daily.

(Source: Straw Utilization Project, Sri Lanka-unpublished)

Animals in both experiments received ad libitum straw, 1 kg fresh grass, 1.5 kg rice bran and 250 g mineral mixture daily. In addition, animals in Experiment 2 received 3 kg/d of fresh Glyricidia leaves.

(Source: Straw Utilization Project - Sri Lanka)

Table 4 gives some of our unpublished data on comparisons between the different treatment systems.

As mentioned earlier, the increase in digestibility and intake of a by-product due to treatment generates the need for extra nutrients for both rumen microbes and the host animal. This leads to the necessity of supplementing the treated material for increased animal performance.

SUPPLEMENTATION OF CROP RESIDUES AND OTHER BY-PRODUCTS

Apart from alleviating nutritional deficiencies, an ideal supplement should also maintain or increase intake of the basal dietary material. The supplement should increase the efficiency of utilization of nutrients leading to increased animal production. It is not always that a feed added to a basal diet acts as a true supplement. Instead of truly supplementing the nutrients in the basal diet, the added feed may substitute part of the nutrient supply. The nutritional principles underlying the use of non-protein nitrogen (NPN) and rumen undegraded dietary protein (UDP) have been extensively discussed. It appears that in general while NPN supplies dietary requirements, UDP increases the amino acid supply to the animal, providing for increased production. Tree fodder legumes such as Glyricidia maculata and Leucaena leucocephala have been found to be highly suitable as supplements for treated straw diets. They contain a relatively high content of UDP compared to common protein supplements such as coconut oil meal (Jayasuriya et al 1982b), which presumably supplies the extra amino acid requirement of the animal. Rice bran, one of the under-utilized by-products abundant in Asia, has been shown to be highly beneficial when added to straw based diets.

From the foregoing discussion it is evident that urea-ammonia treatment offers an excellent opportunity to increase animal production through crop residues and by-products of agricultural in the Indian sub-contient. It is a method highly suitable for the small farmer as it does not involve high technology and sophisticated machinery. Suitable supplementation with energy and protein should enhance its utilization for production purposes. The recent trend appears to be the supplementation by way of ‘catlytic’ quantities of both soluble and rumen non-degradable energy and protein. The soluble component is expected to stimulate the activity of rumen microbes enabling them to cope with the increased intake of the roughage. The rumen non-degradable component will then provide the extra energy and protein needed for growth and production.

Any new feeding system must be economically viable to be acceptable to the farmer. There is very little information on the economic feasibility of feeding urea treated straw to cattle and buffaloes. The cost of preparing treated straw can be easily calculated but response to treatment has not been established in actual monetary terms. One must realise that treated straw is not a substitute for good quality fodder. It is an emergency feed for periods of fodder shortage. Sustaining animal production during such periods and preventing death due to starvation has unlimited economic advantages. Straw treatment must be considered in this perspective.

RESEARCH PRIORITIES FOR THE REGION

Availability and current utilization of by-products (Survey information)

There is no doubt that crop residues, particularly cereal straws, are the major source of feed for cattle and buffalo in the Indian sub-continent. However, the picture is not sufficiently clear particularly in relation to the type and quantity of by-products fed and the seasonality of feeding. Ad hoc surveys have often pointed out the wide variation that exists in by-product utilization between and within countries. Information is urgently required not only on the total availability of different by-products in each country but also on their availability in relation to the needs in different parts of the country.

Better utilization of crop residues (basic research)

Plenty of information is now available on the benefits of urea-ammonia treatment. Investigation should continue on the use of other chemicals such as calcium hydroxide for possible use in the future. The use of urea-molasses-mineral blocks with untreated residues in practical feeding systems should be throughly investigated, and if proved satisfactory,could be one of the simplest ways of increasing utilization of crop residues in the region. Special mention must be made of the necessity for further research in biological upgrading using fungi and extra cellular enzymes. The rapid development of genetic engineering will probably allow the manufacture of ligninases in the future. If economic, this could have major application for improving the nutritive value of crop residues.

Supplementation of residue-based diets (long-term applied research)

Although some information is now forthcoming on the influence of supplementation of straw-based diets on voluntary feed intake, digestibility and production (milk, meat and draught power) more information is still required, particularly for by-products other than cereal straws. Sugar cane bagasse, cane tops, corn stover and corn cobs are some of the major by-products that need immediate evaluation.

Supplementation should be by way of small quantities of green forage, tree fodder legumes (Glyricidia maculata, Leucaena leucocephala), industrial by-products (tea waste, oil seed meals), non-protein nitrogen (poultry litter) and minerals. The effect of different levels of supplements on intake and digestibility of the basal roughage and on production parameters need monitoring. Nutritional studies should be accompanied by economic evaluation, particularly in relation to the small farmer and low levels of productivity.

Effect on reproductive performance (long-term applied research)

Studies on the effect of plane of nutrition, using residue-based feeding systems, on reproductive performance and disease resistance need investigation. Improved nutrition will generally improve the reproductive performance of the animal. This may particularly be true with the water buffalo.

Systems for small farmers (applied research)

Incorporation of straw and other crop residues in feeding systems suitable for the small farmer in the region needs further study. Investigations should be directed towards establishing maximum levels of inclusion of basal roughage for optimizing production.

Buffalo and cattle (basic studies)

It is frequently claimed that the buffalo has a greater capacity to consume and digest low quality roughages compared with cattle. They are also credited with being more able to utilize non-protein nitrogen than cattle. However, the experimental evidence is not clear and there is need for more carefully conducted research. Similarities between species will allow extrapolation of nutritional information gained with cattle to buffalo and vice versa. Given the importance of the buffalo in this region, if they are shown to be better able to utilize fibrous residues than cattle, the evidence will promote the development of farming systems using by-products and the buffalo.

Judging from the research priorities for the region it is evident that rigorous research has to be done without delay. However, lack of qualified scientific personnel and facilities for research and extension are two of the major constraints that appear to limit research and development in this region. Poor remuneration and other hardships have driven many qualified personnel away from their homeland looking for greener pastures in the developed world. Training junior scientists through short-term, intensive training courses could be one way of overcoming the present shortage of personnel. A more permanent solution to the problem would be to persuade respective governments to provide better facilities and incentives to their scientific personnel involved in research and development.

Acknowledgements

The unpublished data reported in this paper is from research conducted in Sri Lanka under the sponsorship of Straw Utilization Project, funded by the Netherlands Government. I am very thankful to Mr J.B. Schiere of the straw Utilization Project for his invaluable help.

REFERENCES

Agarwal, I.S. and Verma, M.L. 1983. Experiences in on-farm research and application of by-product use for animal feeding in Asia. In: By-products Utilization for Animal Production. Proc. Workshop on Applied Research, Nairobi, Kenya, 26–30 September 1982. pp. 140–147.

Amble, V.N. Murthy, V.V.R., Sathe, K.V. and Goel, B.B.P.S. 1965. Milk Production in Bovines in India and their feed availability. Indian J. Vet. Sci. Animal Husb., 35: 221–228.

Beckmann, E. 1921. Conversion of grain straw and lupins into feeds of high nutrient value. Festscher. Kaiser Wilhelm Ges. Ford. Wiss. Zehnjahrigen Jubilaum, pp. 18–26.

Dolberg, F. Saddullah, M. and Haque, R. 1981. Straw treatment in a village in Noakhali district, Bangladesh. Proc. Seminar on Maximum Livestock Production from Minimum Land. Mymensingh, Bangladesh, 2–5 Feb. 1981.

Greengalgh, J.F.D. 1980. Use of straw and cellulosic wastes and methods of improving their value. In: By-products and Wastes in Animal Feeding (Ed. E.R. Orskov). Occasional Publication No. 3, British Society of Animal Production, pp. 25–31.

Ibrahim, M.N.M. 1981. Physical, chemical, physico-chemical and biological treatments of crop residues. An overview. In: The Utilization of Fibrous Agricultural Residues (Ed.G.R. Pearce) Australian Development Assistance Bureau Research for Development Seminar three (1983). Government Publishing Service, Canberra. Australia.

Jayasuriya, M.C.N. and Perera, H.G.D. 1982. Urea-ammonia treatment of rice straw to improve its nutritive value for ruminants. Agric. Wastes 4: 143– 150.

Jayasuriya, M.C.N. Perdok, H.B., Ross-Parker, H.M. and van Houtert, M.F.J. 1982a. Effect of alkali-treated rice straw supplemented with spent tea leaf and thyroprotein on milk yield, milk composition and certain physiological parameters of dairy cows. Anim. Feed Sci. Technol. 7: 201– 216.

Jayasuriya, M.C.N., Wijeyatunge, C. and Perera. H.G.D. 1982b. Rumen and post-rumen fermentation of spent tea leaf protein and other protein sources studied by the nylon bag method. Anim. Feed Sci. Technol. 7:221– 224.

Jayasuriya, M.C.N. 1982. Production responses from diets containing rice straw ensiled with urea. In: The Utilization of Fibrous Agricultural Residues as Animal Feeds. (Ed. P.T. Doyle). School of Agriculture and Forestry, University of Melbourne, Australia, pp. 102–113.

Jackson, M.G. 1977. The alkali treatment of straws. Anim. Feed Sci. Technol. 2: 105–130.

Kellner, O. 1926. (The Scientific Feeding of Farm Animals) (translated by W. Goodwin). 2nd end. Duckworth, London.

Mahadevan, P. 1983. A review of the current status and problems of swamp buffalo production. In. Current Development and Problems in Swamp Buffalo Production. (Ed. H. Shimizu). Proc. Preconference Symposium of the 5th World Conference on Animal Production. Tusukuba, Japan, 198, pp. 3–17.

Perdok, H.B., Thamodevam, M., Blom, J.J., Van den Born, H. and van Valuw, G. 1982. Practical experience with urea ensiled straw in Sri Lanka. In: Maximum Livestock Production from Minimum Land. Joydevpur, Bangladesh, February 15–18 1982.

Pirie, R. and Greenhalgh, J.F.D. 1978. Alkali treatment of straw for ruminants. I. Utilization of complete diets containing straw by beef cattle. Anim. Feed Sci. Technol. 3:143–154.

Swan, H. and Clarke, V.J. 1974. The use of processed straw in rations for ruminants. Proc. Univ. Nottingham Nutr. Conf. Feed Manufacturers, 8:205– 233.

Saadullah, M. Haque, M. and Dolberg, F. 1981. Effectiveness of ammonification through urea in improving the feeding value of rice straw in ruminants. Trop. Anim. Prod. 6: 30–36.

Saadullah, M, Haque, M. and Dolberg, F. 1982. Treated and untreated rice straw to growing cattle Trop. Anim. Prod. 7: 187–190.

Sundstol, F., Coxworth, E. and Mowat, D. N. 1978. Improving the nutritive value of straw and other low quality roughages by treatment with ammonia. World Anim. Review 26: 13–21.

POTENTIAL FOR THE BETTER UTILIZATION OF RESIDUES AND AGRO-INDUSTRIAL BY-PRODUCTS BY MONOGASTRIC ANIMALS IN CENTRAL AMERICA

Manuel Cuca

Colegio de Postgraduados
Institución de Ensénanza e Investgación en
Ciencias Agricolas
Chapingo, Mexico

SUMMARY

Most of the tropical and Sub-tropical countries have shortage of protein and energy sources like soybean meal and maize. Therefore, it is very important to use other locally grown materials of lower cost. Ingredients that can be used in poultry and swine diets in Mexico and Central America are sorghum, rice polishings, cassava leaf meals, banana and molasses. Alternative systems include encouragement to back yard type of swine and poultry keeping.

An inventory should be made of all the resources available in each area. Research is needed in order to determine the biological value of some unconventional ingredients. The results must be organized and the information made available to the producers who are in a position to use these ingredients. It is recommended that each country should establish an office that can make decisions and co-ordinate all the research on crop residues and by-products.

INTRODUCTION

In 1974 Cuca and Avila reported on some new sources of protein and energy available for poultry in Latin American. Since that time new ingredients have been studied and research has been conducted in order to improve the nutritive value of these feeds. This presentation will mention some results of research done in Mexico and Central America, including Cuba, and also give some ideas about the problems and possible solutions for better use of industrial by-products and crop residues.

Most tropical countries have a shortage of conventional protein and energy sources, like soybean meal and corn. Therefore, it is very important to use other materials locally grown at lower prices. The following discussion analyses some alternative sources of energy and protein available in Mexico and Central America.

SOURCES OF ENERGY

Corn and sorghum, and sometimes wheat and barley, are the main sources of energy for the swine and poultry industry. But, as mentioned before, these ingredients are not available in sufficient quantities because they are used mainly for human consumption directly and indirectly, and, most of the time, they have to be imported.

Sorghum

In general, the results reported in the literature have indicated that sorghum can replace all the corn in the diet, although feed conversion tends to be poorer. In Mexico there are different hybrids, some being bird resistant and some not; the difference is in the tannin content.

Equirate (1976) found a negative correlation between tannin content and metabolizable energy, that is, as the tannin increases the energy decreases (Table 1). In broilers, tannins have a toxic effect not only in low (12%) protein diets, but in diets with a normal protein (20%), the only difference is in feed conversaion (Suarez 1977). Results reported by Pro (1983) indicated that high tannin diets negatively affect feed conversion in broilers, laying hens and swine. Results reported by Sosa et al (1982) showed that the cellular content decreases as the amount of tannin increases. Thus, the lower metabolizable energy content may be the result of the decreased concentration of starch and soluble carbohydrates which are the main components of the cellular content and contribute most of the energy.

* Equiarte (1976)

a, b. Values in the same column with different superscripts differ(p<.05)

Rice and rice polishings

In many countries, as indicated by Pino (1962), rice is a very important, ingredient in the formulation of diets. One of its by-products is rice polishing, which represents about 10% after the rice is dehulled and polished for human consumption. This ingredient is a very good source of energy (15% fat) for poultry and swine; also it has about 12% protein.

Table 2 shows the compositions of rice polishing, corn and sorghum. It can be seen that rice polishing has higher protein and fat content, and protein quality comparable to corn and sorghum. According to Arteaga and Cuca (1974), rice polishing can substitute up to 40% of the corn in a broiler diet (0–8 weeks), but higher levels depress growth and cause diarrhoea. A study with Leghorn-type hens (Arteaga and Avila 1975) showed that rice polishing can be used up to 10% of the diet without adverse effects and no differences were observed in egg weight and feed conversion, but higher levels decreased egg production (Table 3).

* Cuca et al (1980)

* Arteaga and Avila (1975)

a,b. Values with different superscripts in the same columnare different (P<0.05)

Kratzer and Payne (1977) indicated that heat can improve the nutritive value of rice polishing and also decrease the activity of a trypsin inhibitor. Also they observed an increase in body weight in broilers although only a small fraction of the trypsin inhibitor was destroyed. In order to determine the metabolizable energy (ME) of raw and autoclaved (1.05 kg/cm² for 30 min) rice polishing from two different places (Veracruz and Morelos) in Mexico, an experiment was conducted using broilers from 14 to 28 days of age (Bezares et al 1979a). The ME values (Kcal/kg) for raw rice polishing were 2940 (Veracruz) and 3100 (Morelos), and for the autoclaved 3460 (Veracruz) and 3310 (Morelos). These results show that heat treatment increased the nutritive value of rice polishing for chicks.

* Bezares et al (1979)

Bezares et al (1979a) fed different levels (0, 15, 30 and 45%) of raw and autoclaved rice polishing to broilers (7 to 35 days of age) and observed an increase in body weight with autoclaved rice polishings; however, as level increased the gain was less (Table 4). In another experiment, using chickens from 7 to 14 days of age, Bezares et al (1979b) showed that when autoclaved (1.05 kg/cm² at 0, 90 and 180 minutes) rice polishing was used as the only source of protein (11.7%), body weight was almost doubled with the 90 minutes autoclaved rice polishing. Further increase of autoclaving time decreased body weight. These results indicated 90 minutes autoclaving to be best time and that some growth inhibitors are destroyed.

Recently Din et al (1979) found that diets with rice bran (40%) caused a high egg production. Also, these investigators reported that using 75% rice bran decreased egg production, but when this rice bran was autoclaved a significant increase in egg production was obtained. In one experiment with broilers, Manjarrez et al (1973) used 0, 50 or 100% of cassava meal-rice polishing instead of corn. The results indicated no significant differences among treatments in body weight, but feed conversion was worse.

In similar studies with laying hens, no differences were observed in egg production, egg weight and feed conversion. However, it was mentioned that the use of this combination instead of corn in diets for poultry will be limited because of the price and availability of these ingredients.

Manjarrez et al (1973) conducted an experiment to study the nutritive value of a cassava meal-rice polishing combination as a substitute (0, 50 and 100%) for corn in pig diets. The experiment was divided in two parts according to the animal's live weight: the first part from 20 to 60 kg and the second from 60 kg to market weight. In the first period, the level of cassava meal-rice polishing caused no differences in animal performance. For the second part, the 50% substitution gave the best results while the 100% level depressed both growth and feed conversion (Table 5).

* Manjarrez et al 1973

POTENTIAL OF SUGAR CANE FOR NON RUMINANTS IN CENTRAL AMERICA AND THE CARIBBEAN

Data on the annual production of sugar and molasses in Central America are in Table 6. The high yield of soluble carbohydrates in sugar cane that can be utilized for non ruminant animals, makes this plant one of the most economical sources of energy for poultry and swine. In the Central America and Caribbean area, there are appreciable quantities of sugar by-products, specially molasses and raw sugar, that can be used in high amounts for the preparation of poultry and swine feed.

* FAO (1974) Volume 28

** Assuming 30 kg of molasses for each 100 kg of sugar.

Poultry

The reason why molasses is not used in diets for chickens is that it produces soft faeces causing problems in the litter; otherwise it could be used up to certain levels without detrimental effects. Studies conducted by Rosenberg (1956) indicated that cane molasses can be used at up to 36% of the diet. Growth rates were similar, but feed efficiency was poorer in molasses fed chicks. It was observed that the faecal moisture content increased as the molasses content increased.

In Cuba, Perez and Preston (1970) studied the use of high levels of molasses in broilers fed liquid diets and two types of molasses (A: molasses as such; and B: molasses without extraction of sugar). They found that chickens fed molasses B had higher final body weight than the ones with molasses A (1549 vs 1106 g at 63 days of age). Zavala et al (1969) reported that growing chicks fed molasses (up to 20%) containing diets, had gains similar to chicks fed rations without molasses.

Molasses in laying hens

Cano et al (1965) indicated that a 10% molasses diet resulted in a similar but cheaper egg production compared to a commercial diet. Zavala et al (1969) gave molasses (0, 5, 15 and 20%) to laying hens, and observed no difference in egg production and egg weight, although birds on the molasses diets had lower body weight than those on the control diet. Soldevila and Rojas (1976) conducted three experiments with laying hens and they used up to 20% molasses. The results were similar on all treatments, perhaps because the diet had similar protein and energy content. There were no problems with wet faeces since the birds were in cages.

Swine

According to De Alba (1968), molasses has a nutritive value equivalent to 70–80% of corn. At the present time in Mexico, a tonne of corn costs US$118 and the cost of a tonne of molasses is US$25 and, for this reason, molasses is a cheaper source of energy compared with cereal grains. When using molasses, it is important to consider its low protein content, high ash content and absence of fat. Inclusion of high levels of molasses in swine, as in poultry has been limited due to the following factors. First of all, more than 30% of molasses produces laxative effects in all types of swine, mainly in baby and growing pigs (Blanco et al 1964). Secondly, as the level of molasses increases in the diet there is less energy, which may cause lower body weight gains. With 15 to 20% molasses, gain is not affected although feed efficiency can be slightly poorer.

According to Buitrago et al (1977), levels of up to 30% molasses gave gains similar to the control diet (corn-soybean meal). However, a higher feed consumption and poorer feed efficiency were observed in the molasses treatments. Apparently, an economical advantage can be achieved with levels of molasses from 20 to 30% in a 13% protein diet.

Gestating and lactating sows can tolerate high levels of molasses (30%) without adverse reproductive effects. In some experiments, cereals have been completely substituted by molasses with good results.

In order to eliminate the laxative effect and increase the energy in diets with high levels of molasses, several substances have been tested. Brooks and Iwanaga (1967) used 13% bagasse and, to increase energy content, they added fat. They reported that the laxative effect was eliminated and pig performance improved.

Another problem associated with the use of high levels of molasses in swine diets is the difficulty in mixing, coupled with storage and handling problems.

Banana

In the tropical part of Central America, Caribbean and Mexico, there are several ingredients not completely used for human consumption, that can be utilized in swine diets. One of these is the banana (Musa sapientum) which has a great potential for feeding pigs. Data from Costa Rica indicate that only 68% of the banana production goes to the market, the remainder may be used in the farm for human consumption and animal nutrition.

Ripened fresh banana, adequately supplemented with protein, vitamin and minerals, may be used for growing and finishing pigs, also in gestation but not during lactation, because sows cannot eat enough banana to satisfy their energy requirements. Results reported by Clavijo and Maner (1975) pointed out the benefits of using ripe banana, fresh green banana and green cooked bananas (Table 7).

** 30% protein containing fish meal, cotton seed meal, corn, vitamins,minerals and antibiotics.

The astringent flavor and low palatability limit ingestion and it is important not to give green or fresh banana when maximum feed consumption is necessary. Also it is very difficult to dry the ripe banana. The meal is prepared from green banana. This meal can be used up to 75% in pig diets. However, it is important to mention that during growing and finishing periods, for each increase in the amount of banana meal in the diet there is a lineal decrease in body weight gain and feed efficiency. This is because the metabolizable energy is lower in banana meal than in corn. When banana meal is used up to 50% in diets for gestating and lactating sows, the results are similar to diets with cereals.

Cassava (Manihot esculenta Cranz = M utilizima pohl.)

This is one of the most productive root crops in tropical areas in terms of dry matter yield per hectare. The ease of propagation and the economy of production make cassava an inexpensive and valuable source of carbohydrate. Table 8 shows the chemical composition of eight Central American cassava varieties.

* Barrios and Bresani (1967) (cited by Montilla 1980)

The initial experiments in which cassava meal was used in broiler diets indicated poor chick performance, probably because the diets were not adequate in all nutrients. Recently Montilla et al (1970) used up to 30% cassava meal in broiler diets without adverse effects. Armas and Chicco (1973) and Montilla et al (1975) reported similar results. However, Maner and Santos (1971) reported that cassava meal used at 45% of the diet (corn-soybean meal, sesame meal and fish meal) in substitution of corn, and fed to broiler chicks during 4 weeks, depressed significantly chick growth. Enriquez and Ross (1972) reported no adverse effects when using 50% cassava meal diets supplemented with 0.15 to 0.20% methionine. Santana (1979) found no response to methionine addition to high cassava meal (40%) diets for broilers.

When used in diets for laying hens, cassava meal can substitute all the cereal of the diet without adverse effects on egg production and feed efficiency (Montilla et al 1973; Portal et al 1977). However, Pereira da Silva and Tardin (1971) reported a significant decrease in egg weight with 100% substitution (52 vs 56 g), and the birds lost weight as the level of cassava meal increased.

Reports from CIAT, in Colombia, indicate the problems, levels and recommendations about the use of cassava meal in pigs. In Mexico, Santana (1979) used high levels of cassava (64, 69 and 71%) in pigs (25 kg to 80 kg liveweight) and found no difference in gain and feed conversion, although a significant difference was noted in feed consumption (Table 9).

* Santana (1979)ab Values in the same line with different superscript, differ(P< .05)

SOURCES OF PROTEIN

Leaf meal from cassava

The cassava leaves are rich in protein. The proximal composition is: 77.0% moisture, 8.2% protein, 3.3% soluble carbohydrates, 1.2% fat and 7.2% crude fibre. According to Rogers and Milner (1963), the amount of protein (dry basis) from several Brazilian varieties ranges from 17.8 to 34.8%, while varieties from Jamaica go from 18.5 to 32.4%. Eight samples of leaves and stems analyzed in Venezuela (Montilla 1980) gave an average of 22.6% crude protein. It is important to mention that when cassava leaves are sun cured or dehydrated, all the HCN is liberated and no toxic effects are found when consumed by animals.

Ross and Enriquez (1969) used up to 20% cassava leaf meal in chicken (Leghorn) diets and found a decrease in gain and feed efficiency when the diet had more than 5% cassava leaf meal. However, when methionine (0.5 to 0.20%) and corn oil (3%) were added, the results were similar to the control diet. Mendes et al (1973) found no significant differences in body weight and feed efficiency when 3, 6 and 9% leaf meal were added to diets for broilers. Montilla et al (1979) reported that although there is a deleterious effect in gain and feed efficiency with the addition of 16% leaf meal cut at 90 day intervals, the results are similar to those obtained with commercial feed and costs are not different. These workers reported that with this amount of cassava leaf meal, it is possible to save up to 22.6% of protein oil meal per kilogram of chick produced. They also pointed out the importance of pelleting the diets in which cassava leaf is used. Portal et al (1977) showed that cassava leaf meal has some yellow pigments that gave a good egg yolk pigmentation and that can substitute for all the alfalfa in laying hen diets. Also they indicated that when cassava leaf meal is used up to 10%, no difference was observed in egg production, feed efficiency and egg weight.

Feather meal

Hydrolyzed feather meal is high in protein (80–85%) and its price is lower as compared with other sources of protein. Its content of methionine, lysine, histidine and tryptophan are low, which limits the amount of this protein to be used in diets for laying hens (Avila et al 1974).

Blood meal

This is another product of high protein content (80%) and although deficient in isoleucine, it is very rich in lysine. But its use is limited by its low digestibility and, since it is a fine powder, the diets stick in the chickens' beaks. Also the quality of blood meal is not very reliable, mainly in tropical countries, due to very poor industrial processing. Its use is limited to 3 to 4% in poultry and swine diets.

Dehydrated poultry manure

Dehydrated poultry manure (DPM) can be used in isocaloric diets up to 20%. Couch (1974) indicated that the true protein in DPM is 10% and small amounts of aminoacids are present. The Ca and P content is high. The amount of metabolizable energy varies from 720 to 1350 Kcal/Kg; consequently its use in diets for chickens is limited. Experiments conducted by Bezares and Avila (1974) indicated that DPM can be used up to 5%, without fat supplementation, or up to 20% with energy supplementation. In diets for laying hens Bezares and Avila (1976) reported that DPM can be used up to 15% insted of sorghum. Cuca (1975) found that DPM can be used up to 5 to 10% in diets for laying hens without affecting egg production or egg weight. In general, when DPM is used there is an increase in feed consumption in order to compensate for its low energy value.

Rossainz et al (1976) indicated that DPM can be incinerated in order to concentrate the Ca and P. These minerals are highly available for poultry. This incinerated product contained similar amounts of Ca and P, as in bone meal and Rock Phosphate.

Fly larvae (Musca domestica L.)

Pro (1983, unpublished data) conducted several experiments to study the nutritive value of fly larvae for poultry. In the first experiment he used different levels of fly larvae meal (FLM), which substituted 0, 25, 50, 75 and 100% of the soybean protein in a diet for broilers from one day up to five weeks of age. The results (Table 10) indicate that FLM, at the levels studied, gave similar results in body weight gain, although a significant difference in feed conversion was observed when FLM supplied 75 or 100% of the protein in the ration.

Pro (1983)

Because the procedure utilized to obtain the FLM is difficult and time consuming, a second experiment was designed to evaluate the performance of broilers fed fresh fly larvae (FFL) as the only source of food, compared to fresh fly larvae supplemented with sorghum, vitamins and minerals, and a control diet (sorghum-soybean meal). The results (Table 11) indicate that the birds fed nothing but FFL had significantly lower weight gains and feed consumption than those fed the fly larvae supplemented with sorghum, vitamins and minerals or the control diet. Although there were no differences in feed conversion due to treatments, the birds fed FFL as the only source of food tended to utilize it less efficiently.

* Larvae with 10% moisture Pro (1983)

** (P < 0.01)

A third experiment was conducted with broilers to simulate back yard production conditions. The larvae were given together with pig manure spread on the floor. The experiment started at 19 days of age when the chicks were able to be on their own and pick the larvae from the floor. In addition, the birds had access to a mixture of sorghum, vitamins and minerals and, in some treatments, antibiotics and coccidiostats. The results, after 44 days of feeding (Table 12), showed a significant difference in weight gains between the birds fed the control diet and those that received the rations that included fly larvae. However, no differences were observed between the larvae treatments.

* The consumption of larvae was not taken into account: Pro (1983)

CONCLUSIONS

In most tropical countries, there are two types of poultry and swine production systems. The most important one is the industrial, because of the number of animals and amount of money invested. This industry normally uses the same ingredients that are common all over the world, like corn and soybean meal. Only recently, and because corn is used for human consumption, sorghum has been utilized successfully in Mexico and some other countries. Likewise, with the idea to substitute soybean meal, other by-products have been utilized such as sesame meal, cottonseed meal, safflower meal, etc. In tropical countries, locally grown and less expensive ingredients have been used in order to avoid imports. Even though there are some alternative feed ingredients that can be incorporated into animal diets, at the present time they are not being used because either the nutritive value is not completely known, the amounts available are not sufficient, or they present problems in handling and are difficult to obtain (like molasses). Some products, like bananas, are difficult to obtain in large quantities in areas where the swine industry is located.

The second poultry and swine production system is the back-yard type, which is very important from the social point of view but, in terms of numbers and level of production, it is considered to be a very small family operation, comprising 2–5 pigs and 20–30 birds, which are sold for hard cash in case of necessity. Under these conditions, the animals are fed whatever is available (some grain or bananas), but not a balanced feed.

It would be highly recommended, in some countries, to make an inventory of the feed resources and then start a program to evaluate them from the nutritional and availability standpoints. The inventory would be useful for knowing all possible sources and amounts available; and to determine their possible use on an industrial scale. After these studies, the next step would be to establish lines of research, starting with proximal analyses, to determine the content of crude protein, fat, fiber, ash, etc. Also, it would be necessary to know possible combinations with other ingredients and the nutritional optima. The amino acid content and metabolizable energy could be determined; and, finally, some economic studies would have to be conducted to ascertain if the proposed use is economically feasible.

In the banana-growing areas, and near the processing plants, it would be possible to feed swine with this product since the transport of the feed would be minimal and it would be available in some months only.

Furthermore, it is well known that there are some ingredients, such as blood meal, that can be used but due to poor processing and lack of quality controls, they are not utilized in industrial operations. Sometimes the processing equipment is not available, or there is a lack of qualified personnel to run the plants, and, therefore, the quality of the final product is very poor, as in the case of tankage, meat meal, bone meal and, in some instances, fish meal. It is necessary to organize the results of all this research and make the information available to the producers that are in a position to use these ingredients.

Finally, but not less importantly, it is recommended that in each country an office should be established that can make decisions and coordinate all the research. Possibly, these offices could be regional centers such as INCAP (Institute of Nutrition of Central America and Panama, Guatemala), ILCA (International Livestock Centre for Africa, Ethiopia), CATIE (Tropical Agricultural Research and Training Centre, Turrialba) and others, which would give advice through the national associations affiliated to the Latin American Association for Animal Production (ALPA).

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Armas, A.E., and C.F. Chicco. 1973. Evaluacion de la harina de yuca en raciones para pollos de engorde. ALPA. IV Reunion. Memorias: NR-7.

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Arteaga, F.C. and M. Cuca G. 1974. Utilizacion del pulido de arroz en la alimentacion del pollo de engorda. Tec. Pec. Mex. 26: 24–27.

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