Part III Other Symposium Papers (Contd.)

ECONOMIC ASPECTS

The final objective in ensuring expanded use of the AIBP and NCFR is high performance in animals and of a type that is demonstrated to be economical. With several crop residues, the importance of seeking an economic advantage has been emphasized (Giaever, 1984; Greehalgh, 1984). The total costs of the pretreatments need to be weighed against the beneficial effects, including the extent of the animal response. In simple terms, the significance of the economic aspect is illustrated in Table 12.

In order to illustrate this important point, three case studies are presented: two from Malaysia on the utilization of oil palm by-products and the other on rubber seed meal and one from Pakistan on poultry litter.

One study concerns in Malaysia utilization by buffaloes and cattle in an oil palm estate to seek effective utilization as well as control pollution. The animals were grazed as well as stall fed for three years. Table 13 summarizes the results. More recently, palm, kernel cake, another important by-product has been used 100 percent in feedlot for beef cattle and average dairy gain of 0.74 – 0.76 kg and a dressing percentage of 49.5 percent have been recorded in Sahiwal × Friesian cattle (Mustaffa Babjee, Hawari and Rosli, 1984).

Table 11. Lifetime Performance of Dairy Cattle Fed Leucaena Leaf Meal and Dried Poultry Litter in Rice Straw-Based Diets, Philippines

Source : Trung et al, 1987.

Note:     ^a Row means without a common superscript are statistically significance (P 0.05).

^b Based on current exchange rate (P1 = US$0.05).

Treatments     1 - 35% RS + 45% L and 20% concentrates.
2 - 35% RS + 30% L + 15% DPL and 20% concentrates.
3 - 35% RS + 22.5% L + 22.5% DPL and 20% concentrates.
4 - 35% RS + 65% concentrates.

Table 12. Illustration of Economic Benefits of Processing and/or Treatment of Residues and By-products

Source: Devendra, 1984.

The second Malaysian study concerns rubber seed meal. Provided the seeds can be collected, it is possible to process them into rubber seed meal, which as several studies have indicated can be utilized for feeding ruminants in particular.

Two experiments are cited, both involving rubber seed meal. In both examples, a 20 – 25 percent level of rubber seed meal partially replaced soybean meal for either broiler or egg production, and both diets were compared to control diets which did not have rubber seed meal. The control diets in both cases, as one will expect, were more expensive than those with rubber seed meal. The calculations in Table 14 demonstrate the reduced costs of feeding resulting from the use of rubber seed meal.

In the Pakistan study, poultry litter has been demonstrated to have distinct economic benefits when fed to ruminants. Table 15 presents data on the economic advantage of feeding the litter to lactating animals.

DELETERIOUS SUBSTANCES IN FEEDSTUFFS

Many AIBP and NCFR contain substances that are deleterious to animal health. Little is known about the effects of these to the animal body both in the short and long term. One is the presence of HCN or prussic acid in the “bitter” varieties of cassava leaves and stems and in rubber seeds. If these feedstuffs are used without treatment, death may occur in extreme cases. Fortunately, methods are now available to detoxify the HCN.

The second example concerns tannins which are widespread in such feedstuffs as sal seed cake, tamarind seed hulls and sorghum. Ruminants can tolerate a much higher concentration of tannins than rate or chicks. They can inhibit the activity of micro-organisms in the rumen and depress the digestion of protein and fiber (Mclend, 1974). On the other hand, tannins have been used to protect proteins from breakdown in the rumen (Driedger and Hartfield, 1977). With leucaena forage, there exists the toxic non-amino acid mimosine, which is degraded to another toxic compound, 3-hydroxy-4(1H)phyridone (DHP). The latt er is qoitrogenic. Other examples include the presence of theobromine caused by fermentation of cocoa pod husks and also a trypsin inhibitor in quar meal. Table 16 provides a summary of various types of toxic principals found in the main AIBP and NCFR. This list is not exhaustive but provides limited information on the approximate contents of the toxic principals. More information is required on the type and extent of these toxic principals and, especially their effects on animals.

STRATEGY FOR ACTION

Expanding the more intensive use of AIBP and NCFR calls for an urgent strategy that can specifically extend the use of the accumulated information on hand through more innovative feeding systems. The strategy is urgently required in view of the vast amount of available information and inadequate apparent application of what is already known.

Table 13. Economics of Utilizing Oil Palm By-Products by Baffaloes and Cattle in Malaysia (Dalzell, 1978)

Source : Dalzell, 1978.

1US$ = M$2.20

Assumptions:

1. The feed-lot is on an oil palm estate adjacent to the palm oil mill.
   Supplies of oil palm by-products are at no cost.
2. The palm oil mill has a capacity of 30 ts/hrs.
3. The feed-lot cattle numbers are sufficient for consumption of POME produced in the lowest production months, e.g., 2,000 tonnes of POME containing 90% moisture.
4. The POME could be processed to reduce the moisture content from 90 to 75% or lower.
5. The 2,260 cattle consume 11.8kg of POME with 75% moisture (2.95kg dry matter/head/day).
6. The cattle were purchased at 90kg live-weight and fed for 1 year giving a daily gain of 453g.

Table 14. Replacement of Soyabean Meal by Rubber Seed Meal in Poultry (Yeong, 1981)

Source : Yeong, 1981.

1US$ = M$2.20.

Table 15. Economic Advantage of Feeding Poultry Litter in Diets for Milk Production, Pakistan (Hasnain, 1983)

Source: Hasnin, 1983.

Note: ^a litre of milk costs 3.25 Rs.

Table 16. Examples of Toxic Substances in the More common Agro-Industrial By-Products and Non-Conventional Feed Resources

There are two aspects of this strategy. One is technical, involving the choice of technology and innovations. The second involves institutional requirements that can provide for the application of known technology.

Technical

A first essential in the technical side is to decide those feeds that are of primary and secondary importance. These are defined as follows:

Primary feedstuffs - Ingredients that form the main base in a feeding system. These constitute about 70 – 80 percent in the diet.

Secondary feedstuffs - Minor ingredients as supplements in the diet. These constitute up to 20 – 30 percent in the diet.

Tables 17 and 18 present a summary of the more important AIBP and NCFR which merit attention.

The nutritional and technical strategies have been enumerated previously (Devendra, 1986) but are reiterated below:

1. More intensive use of AIBP and NCFR especially in stall-feeding systems.
2. Increased use of dietary nitrogen sources.
3. Increase use of proteinaceous forages (e.g., cassava leaves, leucaena forage).
4. Strategic use of supplementary protein sources.
5. Use of urea-mollasses block licks.

Institutional

The institutional support for expanded and more intensive utilization of AIBP and NCFR is essential if the technical feasibility is going to be applied in small farm systems, which can, in turn, stimulate increased productivity from animals. There are two aspects to this: one concerns the priority for this work seen in the context of abundant quality produced, underutilization, reduced cost of production, reduced dependence on imports and foreign exchange savings, reduced pollution problems and further expansion in components of the animal industries. Unless high priority is given to this effort, the real benefits to the industries are unlikely to be realized.

Once the priority has been established, the next more pressing institutional task is the mode of its execution. This calls for the allocation of adequate resources (funds and manpower) and even more important, a strategy that can place much more emphasis on-farm research and development (Devendra, 1987). With respect to AIBP and NCFR inadequate OFAR represents an additional constraint to present underutilization and needs to be corrected in future efforts.

Table 17. Primary Agro-Industrial By-Products and Non-Conventional Feedstuffs in Asia

Table 18. Secondary Agro-Industrial By-Products and Non-Conventional Feedstuffs, Asia

The figure below demonstrates this point with specific reference to rice straw involving station-level research, OFAR and development (Devendra, 1987). In this context, it is worth reiterating two main conclusion on the review of rice straw as a feed for ruminants (Doyle, Devendra and Peace, 1986).

Two major criticisms can be made of the research conducted on rice straw utilization hitherto. Firstly, most feeding trials that address treatment effects and production response, have not involved cost: benefit evaluations. Far too often, significant responses have attracted more attention than they deserve, and may in fact have been misleading as the cost of inputs has been excessive. This situation needs to be corrected and it is imperative that the final step in the analysis is an economic assessment of the treatments under consideration. Until convincing evidence is produced to support the value of an improved rice straw-based feeding system, the current situation of using straw will continue. Evaluations also need to bear in mind that improvements in crop yield or in animal production obtained on research stations are seldom achieved when such changes are implemented at the farm level.

Secondly, there is a great need for improved evaluation of new technologies through on-farm testing and demonstrations. On-farm trials are probably the only accurate assessment of whether new technology packages are acceptable both economically and socially to the farmers as they take into account all of the interacting components unique to small farm systems. They are a means of identifying and addressing the constraints to adoption of new feeding systems, and in many instances in Asia, the importance of such trials far out-weighs the need for further documentation of the effects of supplements or pretreatments.

Potential Possibilities

It is appropriate to identify potential examples of AIBP and NCFR which merit particular focus, and which can through interventions, make a significant contribution to improved performance and productivity from the animal resources. Table 19 presents a list of some examples of primary feeds appropriate to individual species, by location. Both ruminants and non-ruminants are identified. In the former case, mainly meat animals, including the use of the swamp buffaloes for draught and meat production, are the species of choice.

Irrespective of the choice of feed and location, for successful application, acceptable feeding systems are those that are simple, practical, within the limits of farmers' capacity and resources availability, convincing and consistently reproducible. The approach at the farm level is to seek optimum rather than maximum performance. Moderate to low levels of animal performance may be biologically inefficient, but could be more economically viable than high levels of performance, especially within the limitations of small farm systems. It is equally essential that in order to ensure both success and the impact of new technology, that OFAR involves the participation of farmers.

- INCREASED PER ANIMAL PRODUCTION

- EFFICIENT UTILIZATION

- REDUCED POLLUTION

- INCREASED FARM INCOME

A Strategy for Station Level Research, On-Farm Animal Research and Development Exemplified by the Utilization of Rice Straw in Asia

Table 19. Examples of Primary Feeds for Intensive Utilization, by Location

CONCLUSIONS

Expanding the use of agro-industrial by-products and non-conventional feed resources in Asia is one of urgency. The urgency relates to continuing low animal performance, inadequate utilization of the available feed ingredients and poor efficiency of existing animal production systems. The strategy to correct this situation calls for more innovative technical application of the information on hand, backed by strong institutional support that can focus more particularly on the primary AIBP and NCFR. In this context, the following factors merit attention:

1. Critical need for priorities in feed resource use with reference to species, type of feed(s), location and economic benefits;
2. On-farm testing far outweighs the need for more basic information on nutritive value of feeds;
3. More innovative systems of feeding value;
4. Strong institutional and resource support required; and
5. Issues of policy.

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3. IMPROVING THE UTILIZATION OF CONVENTIONAL ANIMAL FEEDSTUFFS

A. Miyazaki*

INTRODUCTION

The earth on which we live is large indeed. Its environmental condition varies from place to place. Farm animals and poultry are kept under variable conditions, eating a variety of feedstuffs. Thus, feeding materials in the world are so variable that it is not easy to define precisely what conventional feed resources are vis-a-vis non-conventional ones. During some of the author's field trips in Asia, he found water buffaloes eating banana wastes in the Philippines and swine eating water hyacinth in South China. Filipinos and Chinese take it for granted that these materials are popular regional feedstuffs since they have long been used as feed. But broadly speaking, banana wastes and water hyacinth are not familiar feedstuffs in the world.

The title of the present paper which was given by the APO organizing committee, is “Improving Utilization of Conventional Animal Feedstuffs”. It is in sharp contrast to that of Devendra's which is “Expanding Use of By-product and Non-conventional Feed Resources”. However, there is actually no distinct borderline between conventional feed resources and non-conventional ones. According to Devendra, non-conventional feed resources refer to all those feeds that have not been traditionally used in animal feeding and/or are not normally used in commercially produced rations for livestock. He also remarked that the non-conventional feed resources embrace a wide diversity of feeds that are typical of, and abundant in, the region. Consequently, it is better for us to classify banana wastes and water hyacinth as non-conventional feed resources.

In this presentation, the feedstuffs which are abundantly used in developed places in the world are regarded as conventional feed resources. This includes green fodders, hay, silage, straws, cereal grains, oil cakes, brans, some industrial by-products, animal products and so on which are very familiar and important feedstuffs in many countries. Also, they are listed on the standard tables of feed composition in leading countries. In the process, efforts will be done to minimize overlapping with Devendra's presentation, since the FAO publication of his paper on “Non-conventional Feed Resources in Asia and the Pacific” has already been released.

^* Laboratory of Animal Nutrition, Department of Animal Science, College of Agriculture, Kyoto University, Kyoto, Japan.

CLASSIFICATION OF CONVENTIONAL FEED RESOURCES

In general, feedstuffs have long been classified into the following categories: 1) forages, 2) concentrates, 3) supplements and 4) additives. But there are always some feedstuffs that do not fit into any one category or meet the criteria of more than one class. Therefore, a system of classifying and naming feeds in a detailed and systematic manner was developed in many countries to provide a means of describing feeds accurately and in detail. By establishing a uniform nomenclature, all farmers and feed manufacturers should be able to understand what others are talking about. This classification also intends to facilitate computer formulation of rations in the developed countries and to provide an international classification and listing of feedstuffs since the interrelationships among counties in the world are getting closer.

The classification of feedstuffs in the U.S.A. and Canada, for example, is as follows:

NRC Classification of Feedstuffs

1. Dry roughages and forages
   Hay: Legume, non-legume
   Straw
   Fodder
   Stover
   Other feed with greater than 18 percent fiber:
   Hulls and shells
2. Pasture, range plants and green forages
3. Silages
   Corn, legume, grass
4. Energy feeds
   Cereal grain, mill by-products, fruits
   Nuts and roots
5. Protein supplements
   animal, marine, avian and plant
6. Mineral supplements
7. Vitamin supplements
8. Nonnutritive additives
   Antibiotics, coloring materials, flavours, hormones and medicants.

Forages listed in the first three categories are variable in quality since there are so many environmental factors affecting the nutritive value of the plants used in the form of green, dry and fermented roughages.

On the other hand, feedstuffs listed in categories 4 and 5 are not so variable in quality though the nutritive value of grains and oil cakes of different origin differs.

Supplements under categories 6, 7 and 8 are relatively purified or specialized materials which are mixed in different ways with the feedstuffs in categories 1 to 5.

MATURITY - MAJOR FACTOR AFFECTING FEEDING VALUE OF FORAGES

In order to utilize forages as efficiently as possible, it is important to understand the factors affecting forage quality.

Environmental factors usually have a profound effect on forage quality. Knowledge of these is vital for management and proper manipulation of plant maturity, fertilization and plant species in order to obtain optimum quality forage. The effect of climate such as temperature, light and moisture on plant growth will be excluded in this paper. Even as these factors are very important, they are uncontrollable in many places in the world.

The predominant factor influencing digestibility of forages is the stage of maturity when cut. Most forages, irrespective of plant species, decline in nutritive quality with age.

Feeding value of grass and legume decreases linearly as the plant grows after late vegetative stage. The decline is remarkable in net energy content for production in each plant which suggests the importance of the cutting stage of forages for animal production.

It has also been shown by Reid et al and Mellin et al that the dry matter digestibility for ruminants of first-cut forage in New York state and of timothy hay in Main could be estimated by the following regression equation: percentage of digestible dry matter = 85 - .48X, where X is days after April 30 in New York state and days after May 15 in Maine. First-cut forages taken during the spring and early summer when the effects of warming season and maturity positively interact show steep declines in digestibility. The major reason for this relationship is that as plants mature, the amount of holocellulose (all cellulose), lignin and crude fiber increases in a nearly linear fashion up to the time of seed set. Protein content of the plants usually decreases in a similar manner as the stage of maturity progresses. A few exceptions occur, such as in the corn plant where the formation of grain rich in readily available carbohydrate offsets the lignification of the stalk and leaves. Accordingly, it has recently become popular in many advanced operations to use whole crop corn silage which contains fodder and grain. In general, however, it cannot be too strongly emphasize that regardless of species, forages should be cut well before maturity.

In fact, heat-dried hay of late cutting with small loss of nutrient during hay making is, to our astonishment, inferior to weathered, field-cured hay. Weathering is well-known to have serious effect on nutritive value of hay.

Not only the nutritive value of forages but also the intake by animals will decrease when the cutting date retards after maturation of the plant. Due to the decreases in intake as well as those in the content of total digestible nutrients, hay of late cutting produces bad result in dairy cattle.

FORAGE PREPARATION AND PROCESSING

Forages are used in the form of green, dry and fermented feeds. Feeding value of forages is remarkably influenced by the conditions to which they are subjected until the animals actually eat them, even if the plants were cut at the appropriate stage of growth. Silage and hay of the same origin and given properly in the form of green and dry feeds are known to have almost equal feeding value for growing steers.

On the other hand, intake of dry matter decreases when the forages are processed into silages. As a result, daily gain is very low when the ration consists of silage only. But the situation is improved by increasing the ratio of hay from 0 percent to more than 20 percent in silage-based ration.

Many methods for roughage preparation and processing have been proposed and used for quite a long time now. But processing green forages and silages is not so popular as processing hay. Therefore, only the effect of processing hay is discussed in this paper. Hay is frequently baled or cubed. Baling and cubing make transportation easy and makes mechanical handling possible. The cube is believed to produce more rapid gain due to a greater feed intake resulting from coarsely grinding of forages.

Feeding hay in different forms (i.e., long, chopped, ground and pelleted) affects the performance of animals. The most classic processing method for hay is chopping. But the recent advance in processing roughages has made grinding and pelleting relatively popular. Though there are so many reports discussing the effect of processing, any one method cannot be considered superior to others due to the variety of feeding systems applied and type of roughages used.

In one experiment it was shown that grinding and/or pelleting improved the intake of mixed hay by the animals, though digestibilities of organic matter, crude protein and crude fiber decreased. Lowered digestibilities are brought by the faster driving of hay in the digestive tract due to the decreased particle size by grinding. Pelleting roughages usually reduces digestibility of the roughage since the feed intake is usually higher on the pelleted roughages. Even though there is a depressed digestibility of digestible energy due to pelleting, the utilization of the net energy may be improved to a point where the net energy per unit of weight may actually be higher than that of the unprocessed roughages. When the quality of hay is low, improvement of intake is remarkable by grinding and pelleting. For example, voluntary intake of aftermath hay was reported to be 1.10 multiples of maintenance in chopped form while it was 2.09 in ground and pelleted form.

Aftermath hay is not palatable and voluntary intake is restricted by its low quality. Thus the effects of pelleting roughage are greatest with low quality roughages and as the forage quality improves, benefits are reduced. There is another benefit of pelleting in practical feeding and management, i.e., pelleting roughage can be transported more economically over longer distances than long hay which is so bulky.

When roughage is the sole feed, grinding will reduce waste and refusal of the unpalatable portions. In fact, feed wastage was 2.4 percent for ground hay while it was 16.2 percent for hay fed in the long form. Feed refusal was minimum with pelleted form in which hay was ground and reformed as pellet. But with fattening rations containing low levels of roughages, the usual recommendation is that the roughage should not be finely ground. With modern beef finishing rations containing as little as 10 percent roughage, it is extremely difficult to determine if roughage processing has an effect on feed intake.

CHEMICAL TREATMENT TO IMPROVE FEEDING VALUE OF ROUGHAGES

Among the conventional feed resources, cereal crop residues such as straws and stovers are the most attractive feedstuffs because of their abundant supply.

Much more attention hereafter will be focused on these resources as less dependence on cereal grains in the diet and increased livestock production are expected in the future. At least one kg of cereal crop residue is produced in the field for each kg of grain produced. It usually contains enough lignin to be characterized as low quality roughage and cannot be used extensively in animal feeding when medium or high productivity is required. It is also characterized by low crude protein in dry matter, low digestibility and low voluntary intake.

Minerals and vitamins are necessary for minimum utilization of cereal crop residues. Supplements alone do not overcome problems of low intake and low metabolizable energy content. Processing may be undertaken to improve the feeding value of these low quality feedstuffs. Chemical treatment is one of the promising methods to improve feeding value of straws and stovers.

Chemical treatment was based on delignification process developed for the manufacture of paper from lignocellulosic materials such as wood and straws. Kellner and Kohler in 1900 prepared “fodder cellulose” by boiling rye straw under pressure in a solution containing sodium hydroxide and several other alkali salts. The effectiveness of their treatment was indicated by digestibilities of 88 percent and 90 percent, respectively, for organic matter and crude fiber, compared with the original materials whose digestibility would have been less than 50 percent. The results demonstrated that delignification procedures could be used to convert low-quality forages to feedstuffs of relatively high energy availability.

In 1921, Beckmann described a process that came to be widely used for upgrading the feeding value of straw. It received reputation not only in countries with a chronic fodder shortage but also in Europe during the war-years when animal feeds were in short supply. The method involves soaking chopped or loosely baled straw in cold 1.0 – 1.5 percent NaOH solution at a ratio of 8 parts solution to 1 part straw for 4 – 24 hours period at atmosphere temperature and draining away the liquor and then extensively washing to remove residual alkali before feeding. The resultant “straw pulp” was fed in a wet condition. The method has the advantages of being simple, relatively non-hazardous to operators and effective. However, there are also disadvantages such as high usage of labour, water and alkali and a short preservation period of less than one week.

Many investigators have tried to overcome these disadvantages. In the European countries, methods of alkali treatment for straws were improved and applied industrially and commercially since the 1970s.

Heat and pressure were employed to produce dry pelleted product by using complex machinery. In this system, the disadvantages of the old soaking method is avoided by adopting the semi-dry process for NaOH treatment. Industrial processing, however, suffers the drawback of expensive plant and machinery and inevitably high cost of transport compared with processing in straw-producing farms for local use.

On the other hand, on-farm processing usually involves a less complex range of machinery with no pelleting and with less emphases on producing a dry product. Theoretically, on-farm treatment can be carried out with the aid of a watering can or bottle and a pitchfork. However, NaOH is a dangerous reagent and mixing it with straw by hand is not recommended. On-farm processing is not yet widely practiced because suitable methods are still under development. The hazards of on-farm processing will be reduced with lower concentrations of solution although preparation will still present dangers.

In European countries where farm size is considerably large, machines have been developed for on-farm use in which bales are shredded, sprayed with NaOH and passed through a chamber in which the alkali is mixed with the straw. The treated straw is then put into a heap in which heat develops and increases the action of the alkali.

Not only straws but also almost all of the low quality grass hay could be improved by NaOH treatment. Mwakatundu and Owen showed in 1974 a linear relationship between response to NaOH treatment (6g NaOH per 100g hay organic matter) and digestibility in vitro of untreated hay organic matter. The equation was Y = 53.78 – 0.621X ± 0.043 (r = 0.984), where Y is response of NaOH treatment and X is organic matter digestibility in vitro of untreated hay. Many investigators suggested that the most effective amount of NaOH for this treatment is 4 percent. By this treatment, the digestibility in barley straw increased from 55 percent to 66 percent in dry matter, 70 percent to 100 percent in hemicellulose and 66 percent to 79 percent in cellulose. Similar result was reported on tropical grass hay. Digestibilities of dry matter and fiber increased from 44.9 percent and 58.8 percent to 58.3 percent and 69.6 percent after 4 percent NaOH treatment, resulting in a remarkable improvement of gross energy digestibility from 49.6 percent to 62.1 percent. In this experiment, dry matter intake was increased by the treatment.

Although NaOH has been by far the most common chemical used to treat lignified feedstuffs, many studies have been conducted to determine the applicability of other chemicals. Since 1959, a number of chemical reagents other than NaOH have been investigated to determine the effects on lignin degradation to improve feeding value. These include chlorine dioxide, lime solution, calcium hydroxide, sodium peroxide, calcium hypochlorite, sodium sulfite, sodium sulfide, sodium carbonate, hydrogen peroxide, bleaching powder and so on. The conclusion was that NaOH was the most effective reagent.

Furthermore, NaOH treatment is superior because no toxic effect has been reported on animals. In the dry treatment system, although residual NaOH is not washed from the straw before feeding, apparent physiological ill effects have not been found. The only observation is an increased water consumption when the treated straw is given. Therefore, the obvious practical disadvantage for housed animals would be increased bedding requirement due to the increased excretion. In addition to those points, short reaction periods are highly evaluated in this treatment.

There are now two attractive alkali reagents: ammonia and calcium hydroxide. Ammonia increases both the digestibility and the nitrogen content of low quality forages. Calcium hydroxide is relatively cheap and less dangerous to handle than NaOH, and is known to be more suitable for use on farm. So much attention has been paid by many investigators to these two reagents though data on calcium hydroxide are limited.

Ammonia has the advantage over NaOH in improving the crude protein analysis of straw as well as its digestibility. Therefore, interest has shifted in many countries during the past few years to ammonia as a chemical for treating straw. Ammonia treatment usually involves treating straw with ammonia at 3.5 percent. The effectiveness drops off rapidly if less than 3 percent is used. Three methods are now in use: i) injection of anhydrous ammonia into stacks covered with plastic sheets; ii) injection of aqueous ammonia (usually a solution of 28 – 35 percent of ammonia in water) into stacks covered with plastic sheets; and iii) injection of anhydrous ammonia into sealed metal containers or ovens on which heat is applied. The speed of reaction of ammonia with straw is greatly affected by the temperature. When the temperature is less than 5°C, a period of more than 8 weeks is required for treatment. At 15 – 30°C, it takes 1 – 4 weeks and at over 90°C, it takes less than 24 hours for optimum treatment.

Increases in crude protein content by treatment with anhydrous ammonia were from 3.5 percent to 8.4 percent in barley straw and from 4.0 percent to 8.0 percent in wheat straw. Digestibilities of wheat straw increased from 45.5 percent to 53.3 percent in dry matter and from 51.4 percent to 63.9 percent in crude fiber by 3.5 percent ammonia treatment. Intake of straw also increased from 39.1g/BW.75 kg to 46.5g. Improvement in intake of tall fescue hay was more remarkable in cattle than in sheep after ammonia treatment.

Usually the effect of alkali treatment on feeding value of straw was large when the content of straw increased in the diet. For example, net energy content for production of rice straw was 0.22 kcal/g, 0.49 and 0.51 for intact, 4 percent NaOH and 5 percent ammonia treated straw in 72 percent rice straw (high roughage) diet. On the other hand, net energy content was 0.70, 0.78 and 0.80 respectively in 36 percent rice straw (high concentrate) diet.

The treatment of straw with alkali, namely, NaOH and ammonia, is a well-established technique to improve its nutritive value. But the higher prices of NaOH and ammonia have frequently discouraged their utilization in many developing countries. In some countries, there is a method of using urea or urea-containing materials such as urine as a substitute for ammonia. When urea is added to straw packed in plastic sacks, urea gradually breaks down to ammonia. As a result, increased digestibility in vitro and in vivo and higher intake were observed in the ruminant animals eating urea-treated straw. Addition of urease reduced the treatment time required to achieve a given level of digestibility. Urea-treatment is now considered to be an attractive method of processing straw since the cost of urea is relatively low and handling urea on farm is very easy and not dangerous.

Both the factory and on-farm treatments have been given an extensive trial in the United Kingdom over the past five years. As a rule of thumb it may be said that a good sample of treated straw can be valued at 60 percent of the price of barley. If barley can be purchased on the farm at 100 pounds/mt, or can be provided on the farm at a similar figure, treated straw can be worth 60 pounds/mt. The cost of treating straw with alkali varies greatly according to the throughput of the machines but, with the alkali costing about 14 pounds, the whole treatment is unlikely to cost less than 30 pounds/mt. With dry straw costing 20 pounds/mt, the treated product will cost 50 pounds/mt. For some farms, this may be an economical price for a reliable roughage.

A few years ago, the cost of treatment with ammonia in the United Kingdom was about 6,700 yen/mt of straw, made up of about 4,800 yen for the ammonia and about 1,900 yen for the plastic sheet. The cost of plastic cover can be reduced by building larger stacks or utilizing old silos, etc., where only a top sheet may be required.

PHYSICAL TREATMENT TO IMPROVE FEEDING VALUE OF FORAGES

Experiments on physical treatment of forages except chopping, grinding and pelleting to improve feeding value are considerably small in number. But other methods have been investigated in many countries. Garrett, W.N. et al reported that steam treatment of rice straw under the pressure of 28 kg/cm² for 20 and 90 sec. did not have any preferable effect on digestibilities of organic matter, nitrogen and cellulose. The result shows that digestible energy of the treated straw is slightly lower than the intact one. But steam processing of rice straw with alkali was effective in increasing the digestibilities of organic matter and cellulose, resulting in a slight increase in digestible energy content. The improvement would be brought by alkali treatment during steaming of the rice straw.

Recently, a new processing method by explosion was introduced to improve feeding value of low quality materials rich in lignocellulosic materials. In this process, chopped straw or other materials such as hulls and woods were steamed at the pressure of 20 – 30 kg/cm² for 1 – 8 min. and were exploded by releasing them momentarily from the pressure. During the processing, the lignin and carbohydrate bond are cleaved, which seems to result in an increase of digestibility of lignocellulosic materials. Apparent organic matter digestibility of rice straw was improved from 42.7 percent to 51.9 percent by exploding straw for 2 min. under the pressure of 22.5 kg/cm². An increase of organic matter digestibility mainly contributed to the improvement of cellulose digestibility from 50.1 percent to 74.3 percent. Digestible and metabolizable energy then are elevated from 1.67 to 2.16 and from 1.31 to 1.75 kcal/g dry matter, respectively.

Also, Gamma and electron irradiation is reported to increase digestibility of dry matter in vitro. But it is uneconomical at present.

BIOLOGICAL TREATMENT TO IMPROVE FEEDING VALUE OF FORAGES

Growing fungi on straw and then feeding the mixture of fungi and straw to animals is a classic method of biological improvement. This method was once adopted in the European continent and the mixture was called “mycofutter”. But the quality of the product was so variable and unpredictable that it was not widely taken up on farm.

A more promising method is to attack the straw with fungi which break down the lignocellulose complex through their enzymic activity and thus render the cellulose fraction of the straw more available to microbial action. Such fungi occur in nature and have been shown to work well. Basidiomycetes are, for example, the primary decomposer of plant debris in natural environment. One group of Basidiomycetes especially causes white rot contributing to lignin decomposition. This fungus is expected to convert low quality materials such as straw and wood, rich in lignin into edible form.

To cultivate these fungi efficiently, it is necessary to sterilize the substrate such as straw before cultivation. If not, harmful microflora will grow on it and residual substrate after cultivation cannot be used as animal feed. This type of sterilization is actually impossible to carry out economically on the farm.

However, since naturally white-rotted wood called “Palo Podrido” has been used as a kind of forage in the southern part of Chile, biological upgrading of straw or low quality materials is recently expected in many countries. Researchers in West Germany studied to find fungi capable of quick straw colonization, high lignin decomposition and production of useful nutrients with minimal substrate and energy loss due to metabolic respiration. The result showed that in vitro digestibility of dry matter increased from 40.0 percent in the intact wheat straw to 55.1 – 68.6 percent after 79 days of fermentation by Stropharia rugosoannulate and to 60.4 – 71.6 percent after 120 days. Pleurotus sp. also improved in vitro digestibility of straw but to a relatively smaller extent than the former fungus.

In some countries, there are moves to utilize the residual substrate after cultivation of edible mushroom as feed for ruminants. In Japan, for example, in addition to traditional bed log culture, industrial mushroom production using artificial substrate has been developed. This substrate consists of soft or hard wood sawdust with different amounts of rice bran and some other supplements. In this system, a large amount of residual substrate remains after harvesting edible fungi. It means that the process of mushroom production in this manner can potentially be utilized for feed production from lignocellulosic materials.

It was reported that in vitro dry matter digestibility of residual substrate of Nameko mushroom (Pholiota nameko) was improved from 10 percent in the original substrate to more than 40 percent. On the other hand, no improvement was observed in the residual substrate of winter mushroom (Flammurina velutipes) and oyster mushroom (Pleurotus ostreatus).

There is some likelihood of a commercial system for enzymic improvement of straw becoming available. The use of laboratory produced enzymes in place of the fungi may enable the process to be speeded up and made more efficient. When cellulolytic enzyme, namely, cellulase, which can digest cellulose was sprayed directly on rice hull base diet, the digestibility of dry matter increased from 54.4 percent to 63.5 percent and that of energy also increased from 52.8 percent to 61.7 percent.

One experiment showed that hemicellulose addition to NaOH treated rice straw caused an improvement of digestibility of dry matter from 52.3 percent for NaOH treated straw to 58.6 percent. Digestibility of dry matter in the intact rice straw in this experiment was only 44.1 percent. Therefore, enzymic treatment seems to have additional good effect to NaOH treatment on straw. Treatment with microorganisms show potential but it requires much further research and development for practical use on farm.

PROCESSING OF CEREAL GRAINS

The level of cereal grains needed as feed ingredients for animals depends largely upon the rate production desired. When the rate of production is low, roughages may be used as a sole ingredient. In this case, no grain is required for feeding animals. Mature beef cow and growing feeder cattle, for example, need no grain when they are fed abundantly with roughages of good quality. When high rate of production is desired, however, the energy intake of the diet must be increased by adding grain or other high energy supplements. Finishing beef cattle in feedlot and lactating cows in dairy operation require much grains for keeping a high level of production.

Usually, gross energy of feed is divided into maintenance energy and production energy, the latter being the energy used for gain, milk production and the like. The more the amount of production energy ingested, the more production will be expected. It is, therefore, very important for high production to ingest as much production energy as possible. Grain rich in starch, a readily available carbohydrate, is very attractive feed resource in animal feeding. But since grains are more important as food for human consumption, feeding grains to animals and poultry are apt to be restricted in many places.

In some developed countries where the level of living is considerably high and supplies of grains are large, high grain feeding systems have developed. Abundant supplies of grains are induced by a high level of domestic production or high national income to enable the import of grains as feed. The reason why grains are popularly used as feed in some countries is that the energy input become lower for producing grains by the improvement of cultivating and harvesting methods. It is also known that metabolizable energy yield per ha is greater in grain production than in forage production.

Moreover, it was reported by Blaxter that fat synthesis in ruminants on good hay was 780 kcal per kg of feed as compared with 1950 kcal of fat synthesized per kg of corn grain. Consequently, grains become the desirable energy source for animals of high productivity. In the U.S.A., steer fattening rations may contain as much as 85 percent grains and the grains may supply up to 90 percent of the usable energy of the ration.

Fossil fuel is necessary for grain production in large-scale operations. Its value relative to the price of feeds will be expected to increase in the future. Thus, it is important that energy must be used efficiently. Consequently, greater emphasis is being placed on processing methods for grains which improve feeding value but require less energy.

Prior to 1960, little attention was given to the method of grain processing. Only a few processing methods such as grinding, cracking and steam rolling were adopted by feedlot operators in the U.S.A. Among them, steam rolling was believed to reduce the dustiness of grain preparation and kill the viable weed seed. This processing is applied not to improve feeding value of grains but to improve the handling manner. Riggs stated in his report in 1958 that rolling or crashing had little advantage over grinding. On the other hand, cooking prior to feeding had been very popular in Japan. Farmers believe that cooking improved not only feeding value but also palatability of concentrate ration, especially when fed cattle sometimes refused ingesting feed at a latter period of fattening because of continuous over-eating. Even in that case, when the concentrate ration was cooked just before feeding, the amount of intake increased temporarily and the animals recovered from lack of appetite. At that time, wood chops collected easily from small mountains around their residences were used as fuel. It means that the cost of fuel was believed to be free. But the village conditions changed and farmers began to buy expensive has as substitute for cheap wood chops for daily use. As a result, the cooking of feed became unpopular in this country since 1955.

The situation has changed. An international revival of processing grains has occurred after 1960. One of the changes adopted in the U.S.A. in processing is the increased use of sorghum grains, which is smaller in size than corn grain and is easy to escape from the digestive tract without being utilized efficiently, in animal feeds. Before then, corn was the most popular feed grain. Since corn is now believed to be only one feed grain that can be fed satisfactorily in whole form to cattle, there was no need to process corn for animals. But the other feed grains such as sorghum grain, barley, rye and oat need to be processed by some methods.

The increasing amount of cereal grains being fed to animals has stimulated the development of various techniques for processing cereals in order to increase the efficiency of utilization of dietary constituents, improve the palatability of high cereal diets and, consequently, improve animal performance.

The purpose of processing grains is summarized as follows: first, processing increases efficiency of feed utilization by improving palatability and digestibility. The increase in surface area by processing makes feed more easy to be attacked by bacteria and/or enzymes. In addition, processing alters the molecular structure of grains to enhance digestion.

Methods for processing cereal grains are many and varied, but these are classified into two basic types: hot processing in which heat is either applied or created during the treatment process and cold process. Each of these two broad categories can be sub-divided into wet or dry processes. In the former, water is either added to the grains or the grain is harvested and stored with a high moisture content.

COLD PROCESSING OF GRAINS TO IMPROVE FEEDING VALUE

Grinding is a process to reduce the particle size of grains by impact, shearing or attrition. Grinding is usually accomplished with a hammer mill. A hammer mill grinds grains by beating them until they are fine enough to pass through a screen. The size of screen will determine the degree of fineness desired. It is important to know what degree of fineness is appropriate for feeding each kind of animals.

In general, finer grind is more subject to wind loss, tends to ball-up in digestive tract, does not feed down properly in a self-feeder, and tends to have a faster rate of passage through the digestive tract. Also, finer grind may not only result in cattle going off feed (refused palatability), but also cause digestive disturbances such as ruminal parakeratosis in feedlot cattle. Therefore, it is recommended to grind grains into optimum particle size for each animal.

Take grinding grains for beef cattle, for example. It is essential to break the sorghum grain before feeding because of its hard seed coat. On the other hand, grinding corn differs from that of sorghum and the effect of grinding on the improvement of feeding value depends upon the roughage/concentrate ratio of the diet. Corn should be coarsely ground if it is fed with dry roughage in the ration of more than 15–20 percent. When corn grain is contained in a diet at 45 percent, digestibility of dry matter of the diet increases from 60.8 percent in unprocessed whole corn to 67.1 percent in ground corn. In this experiment, increases in digestibilities of cell walls and ether extract are remarkably large.

In the case of corn fed with silage wherein palatability is not a problem, a medium-fine grinding is preferred. Processing corn loses its advantage when it is fed with a limited intake of roughages of less than 15–20 percent in the diet. In fact, it is reported that whole dry corn fed to cattle with limited roughage produces equal or superior gain, comparing with processed corn with limited roughage.

Dry rolling or cracking involves changing the shape and/or size of grain particles by passing grain between a closely fitted set of rollers. Crimping is accomplished in a manner similar to rolling except that instead of rollers with smooth surfaces, rollers with corrugated surfaces are used. The end result is much the same.

Soaking is considered to be practical when grain is very hard and not mechanically processed before feeding. When milo was soaked for 16 hours in water and then cut in the decorticator into six to ten pieces, TDN content increased to 78.3 percent from 72.1 percent in dry rolled condition. Soaking will be a useful method in improving feeding value of small grain on small farms.

The reconstituting process involves the addition of water to dry grain to raise the moisture to 25 to 30 percent (higher for milo than corn) followed by storage in whole form in an oxygen limiting silo for at least 14 to 21 days prior to feeding. This processing may improve the digestibility of dry matter from 64.4 percent in dry whole milo to 83.1 percent. A similar result was observed when early harvested moist milo of 23–32 percent moisture was given to cattle. In this experiment, feed conversion improved from 5.37 of dry milo to 4.20 of moist milo. But digestibility of dry matter in reconstituted corn was almost equal to that in dry whole corn. These results show that a proper method should be applied for processing each kind of grain. However, the daily gain of cattle ingesting reconstituted corn was somewhat superior to those eating dry whole corn, which was the result of greater intake of reconstituted grain.

Germinating the seed was once considered efficient in processing grains. Sprouted grain is the growing of plants with their roots immersed in aqueous mineral nutrient salts, instead of in soil. This means that sprouted grain for feed is produced with water and chemicals, without dirt. It may provide the grass juice factor for dairy cattle when pasture is not available. But germinating grain is not now considered to be of practical value, since the cost of sprouted grain is over four times as high as that of the original one.

HOT PROCESSING OF GRAINS TO IMPROVE FEEDING VALUE

Prior to the development of the new grain processing systems in the 1960s, only grinding and pelleting of the concentrate portion of beef cattle rations received considerable attention. Pelleting grains and other concentrates or roughages is accomplished through agglomerating ground materials by compacting and forcing them through die openings. Some combination of heat, moisture, and pressure is usually, but not always, needed in the process. Pellets can be made in different diameters, lengths and hardness. Pelleting returns the feed to a free-flowing form, facilitating the mechanization of handling and also its use in a self-feeder. Moreover, pelleting reduces storage space of feed.

Pelleting grain or hay is considered to have the advantage of reducing dustiness and increasing palatability and thus makes for greater consumption. Of course, the loss of fine particle ingredients of feeds is reduced during transport. It reduces selective eating and feed wastage. In cattle feeding, the advantage of pelleting is dependent largely upon the roughage/concentrates ratio of the diet. Under condition of high roughage diet, pelleting increases feed consumption and improves feed efficiency. Thus, increased gain is expected. On the contrary, when the cattle ingest high concentrate diet, pelleting reduces feed consumption and feed efficiency does not improve. Therefore, gain is apt to be reduced. Even when the percentage of corn in the diet is less than 70 percent and the rest is roughage, intake and gain are not improved by pelleting if roughage is ground.

Roasting is a process in which air-dry grain is heated in a roaster to about 150°C, producing a puffed and slightly carmelized appearing product. Partial starch gelatinization occurs during the heating. But the experiment on cattle showed that roasting corn did not improve intake and daily gain, but slightly improved feed conversion.

Micronizing is a process in which air-dry grain is heated to between 90 and 150°C by exposure to microwaves from an infrared generator. The grain is then dropped into special rollers which have spiral grooves. Internal moisture in the grain volatilizes, causing expansion and gelatinization. Digestibilities of dry matter, crude protein and starch are not affected by micronizing of wheat grain.

But the effect of this processing appeared in a different way The experiment of micronizing milo showed that, although daily gain of the cattle was almost equal, feed conversion improved very much from 7.42 in dry rolling to 6.75 in micronizing. Composition of VFA in rumen fluid changed when micronized milo was given. It is characterized by a remarkable decrease of acetic acid and remarkable increase of propionic acid, and thus the acetate to propionate ratio decrease from 1.57 to 1.03 by feeding micronized grain.

Popping is a process in which air-dry grain is exposed to very high temperature for a short time - perhaps for 15 to 30 seconds at 370 to 430°C. Heat causes moisture in grain to steam, which gelatinizes and expands the starch granules. Popped grain is very bulky, so it is usually rolled before feeding. The effect of popping is remarkable in improving feed conversion. When milo was popped are rolled, feed conversion decreased to 5.50 from 6.90 of dry rolled milo feeding. Ruminal acetate decreased and propionate increased remarkably, thus resulting in the decrease in acetate to propionate ratio to 0.88 from 1.80.

There is another method of dry heating which is extruding. In this process, heat and pressure are applied to air-dry grain as it is pushed by a tapered spiral screw through an orifice, producing a ribbon-like product which breaks into thin flakes.

Steam rolling is a process in which air-dry grain is exposed to steam for a short time (1 to 8 min.) and then rolled. Therefore, this process is wet heating. Less starch alteration occurs than in steam flaking, so feeding value is not materially improved over dry rolling.

Steam flaking is a process in which air-grain is exposed to steam for a long time (15 to 30 min.), then rolled to produce a very thin flake. Flaking gelatinizes some of the starch granules, rendering them more digestible. Steam flaked corn is more digestible in dry matter, crude protein and ether extract than cracked corn. One experiment showed that TDN of the steam flaked milo was 88.3 percent in dry matter while it was 79.9 percent in dry rolled milo. A comparative study showed that steam processing and reconstitution are superior methods to grinding.

In pressure flaking, air-dry grain is steamed under pressure at 3.5 kg/cm² for 1 to 2 min., cooled down to about 90°C and finally dried to 20 percent moisture before being rolled to thin flakes. Though this processing is more expensive than steam flaking, its effect on improving feeding value is rather small. Therefore, pressure flaking is not profitable in many cases.

In the exploding process, air-dry grain is placed in high tensile strength containers and subjected to steam under pressure at about 17 kg/cm². In about 20 sec., the pressure is released and the grain escapes as expanded balls with hulls removed. It is now considered not to be economical since the improvement is not so large enough to balance the cost of processing.

Alkali treatment of grain is not popular because the crude fiber content of grains is usually very low. But one experiment showed that NaOH treatment was effective in increasing the dry matter digestibility of corn. Ruminal fiber digestion increased remarkably in the treated corn. The result suggests that utilization of grain high in fiber such as barley and oat could be improved by alkali treatment.

FEED ADDITIVES TO IMPROVE FEEDING VALUE OF FEED

There are some feed additives which improve feed efficiency indirectly by stimulating the growth of the animals. Others directly improve the efficiency of feed utilization. The most popular additives are hormone or hormone-like compounds and antibiotics.

Until 1979, a hormone-like compound, diethylstilbestrol (DES) was approved as an oral additive or a subcutaneous implant for feedlot cattle in U.S.A. It was quite effective in stimulating decomposition of nitrogen resulting in more rapid gain, improved feed efficiency and less fat deposition in animals fed to the same weight. Daily gain of steer increased 4 to 37 percent averaging 17 percent and feed conversion was improved 4 to 24 percent averaging 12 percent by the continuous administration of 10–20 mg DES per day. But it has been withdrawn by the FDA, in fear of potential possibility of bad effects on human health. Hormones and hormone-like compounds are now used in many countries and are available in improving the utilization of the conventional feed resources.

Melengestrol acetate improves feed efficiency (6–10 percent) by stimulating growth of feedlot heifer (7–11 percent). Ralgro is claimed to improve gain (10–12 percent) and improve feed efficiency (7–10 percent) in beef cattle. Synovex is known to increase gain (10–15 percent) and improve feed efficiency (8–12 percent) in beef cattle.

Antibiotics are fed in order to reduce the incidence of subclinical levels of bacterial infections of the digestive and respiratory tracts, and thus are often credited with improving the rate of gain and feed efficiency. Many kinds of antibiotics are used for this purpose and are very effective. Recently, monensin, one of the antibiotics, was known to have a remarkable effect on feed utilization in cattle. According to Goodrich, R.D. et al, cattle fed monensin-containing diets gained 1.6 percent faster, consumed 6.4 percent less feed and required 7.5 percent less feed per gain than cattle fed control diets. The improvement seems to have resulted from modification of acid production in the rumen (dominant production of propionate), modified feed intake (decreased intake), change in gas production (decreased production of methane) and so on. Many new feed additives are expected to influence the utilization of conventional feed resources in the future.

As already mentioned, the feeding value of forages and grain may be improved by preparation and processing. Feed additives also play an important role in improving feeding value. These improvements, however, are better achieved in the developed countries where machines can be used for proper processing, fossil fuel energy is available, and farm size is large enough to enjoy a big advantage resulting from small individual improvement through new processing. In many areas in Asia, however, farming size is not so large that the preparation and processing developed in the advanced countries cannot be adopted in the same manner. It is important for the feed scientists in Asia to translate those methods into more available form to enable everyone to enjoy the fruits of new knowledge on improving the nutritive value of conventional feed resources.

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