15 Feed and Industrial Uses for Cereals Introduction two categories: wheat, oats, rice and sorghum, of The worldwide usage of all the cereals, gathere which about 7% of the entire crop in each case ogether, as revealed in the FAO Food Balance used for industrial purposes, and barley, ch Sheets, is about 4% for seed, and the remainder maize and millet, of which nearly twice as mu almost equally shared between human food use (12-15%)is used industrially (49%)and animal feed plus 'processing and other (principally industrial) use(47%). The last cate- Raw materials used for feed and gory divides into about 37% for animal feed plus industrially 10%for industrial use. There is, however, con The raw materials used for these purposes fal siderable variation among the eight principal into three categories cereals, as shown in Table 15.1 1. The whole grain as harvested or perhaps with a minimum of World U 2. Certain components of the grain which pro- Cereals, 1984-86 average* vide the starting material for chemical process- Processing g These would include starch, for prod Food Feed and other Seed of ethanol, and pentosans, for manufacture of furfural 6.6 3. By-products of the milling process, which are not usually suitable for human food but which 5.378.3 33443.9 8.4 can be used for animal feed and for a wide 3.2 range of industrial uses, including fillers, adhe- 13.9 sives, abrasives. etc, besides the manufacture 11.8 2.7 of furfura Total 49.036.9 Source: FAo Food balance sheets 1984-86. Food and Animal feed Agriculture Organization, Rome, 1990 Apart from usage for human food, animal feed by far the largest use for cereals- both whole Thus, very little rice or millet is used for feed, grains and milling by-products hile over 70% of the entire crops of barley and Thus, in 1986/87, out of a total world produc- oats are so used, with the use of maize and tion of all cereals of 1, 830 million tonnes, 892 sorghum for animal feed not far behind million tonnes(48.7%)were used for animal feed For industrial use, the cereals seem to fall into (USDA, 1987b
15 Feed and Industrial Uses for Cereals Introduction two categories: wheat, oats, rice and sorghum, of which about 7% of the entire crop in each case is used for industrial purposes, and barley, rye, (12-15%) is used industrially. The wor1dwide usage Of all the cereds’ gathered Sheets, is about 4% for seed, and the remainder almost equally shared between human food use (49%) and animal feed plus ‘processing and other’ (principally industrial) use (47%). The last category divides into about 37% for animal feed plus siderable variation among the eight principal cereals, as shown in Table 15.1. together, as revea1ed in the FAo Food Ba1ance maize and millet, of which nearly twice as much Raw materials used for feed and industrially 10% for industrial use. There is, however, con- The raw materials used for these purposes fall into three categories: 1. The whole grain as harvested, or perhaps with a minimum of processing. 2. Certain components of the grain which provide the starting material for chemical processing. These would include starch, for production Cereal Food Feed and other Seed of ethanol, and pentosans, for manufacture of (Yo) (%) furfural. Wheat 66.5 20.2 6.7 6.6 3. By-products of the milling process, which are Barley 5.4 73.1 14.9 6.6 not usually suitable for human food, but which can be used for animal feed and for a wide Oats 5.3 78.3 7.3 9.1 33.4 43.9 14.3 8.4 range of industrial uses, including fillers, adhe- Rye Rice 88.0 1.8 7.0 3.2 Maize 20.7 63.9 13.9 1.5 sives, abrasives, etc., besides the manufacture of furfural. Sorghum 35.2 56.6 6.9 1.3 Millet 74.7 10.8 11.8 2.7 Total 49.0 36.9 9.8 4.3 Agriculture Organization, Rome, 1990. TABLE 15.1 World Usage of the Principal Cereals, 1984-86 average* Processing (Yo) (Oh) Animal feed Apart from usage for human food, animal feed is by far the largest use for cereals - both whole grains and milling by-products. Thus, in 1986/87, out of a total world production of all cereals of 1,830 million tonnes, 892 million tonnes (48.7%) were used for animal feed (USDA, 1987b). * Source: FA0 Food Balance Sheets 1984-86. Food and Thus, very little rice or millet is used for feed, while over 70% of the entire crops of barley and oats are so used, with the use of maize and sorghum for animal feed not far behind. For industrial use, the cereals seem to fall into 302
FEED AND INDUSTRIAL USES FOR CEREALS Maize is easily the most widely used cereal, kind of cereal involved and the proportion of that with about 282 million tonnes being used for cereal in the feed; also on the species of animal animal feed (annually) worldwide in 1984-1986, for which the feed is intended, particularly whether followed by barley(about 127 million tonnes)and for ruminants or for monogastric animals and wheat(about 103 million tonnes)(FAo, 1990). probably also on the stage in the animals life A large proportion of the cereal grains fed to cycle, e. g. thinking of poultry, whether for young animals passes through the hands of animal feed chicks, for broilers, or for laying hens processors’. By way of( xample, of the 5.2 million Some of the treatments applied by animal feed tonnes of wheat used for animal feed in the uk processors to cereal grain, and the resulting 1988/89, 2.87 million tonnes(55%)were used benefits are described below. y animal feed processors (a figure based on returns from compounders only, in Great Britain) Grinding H-GCA, 1990). The remainder, still a consider- able quantity, would presumably have been fed This is the commonest treatment, and relatively directly from the farm to the animals, not via inexpensive. Roller mills or hammer mills may be used but hammer mills are favoured because In the same year, 1988/89, 5.1 million tonnes by choice of a screen of suitable size, the hammer of wheat were used by four millers in the Uk mill can yield ground material of any particular which, besides yielding 3. 954 million tonnes of size from cracked grain to a fine powder. The flour, also produced 1. 132 million tonnes of objective of grinding is to improve the digestibility milling by-products- bran and middlings(fine Coarsely-ground grain is preferred for ruminants offal), most of which would have been used for more finely-ground grain for swine and poultry animal feed. Thus, the total quantity of wheat plus wheat milling by-products used for feeding Soaking animals in the Uk in 1988/89 must have been about 6. 3 million tonnes(NABIM, 1991) Grain may be soaked in water for 12-24 h A similar state of affairs probably exists for followed by rolling, for livestock feeding. The wheat in other countries, and also, to varying soaking softens the grain and causes it to swell extents, for other cereal grains worldwide thereby improving palatability. Processing cereals for animal feed Reconstitution The treatments applied to cereals by animal a process in which grain is moistened to 25- feed processors are both expensive and time- 30%m c and then stored in an oxygen-limiting consuming, and obviously would not be under- silo for 14-21 days. This process is successful taken unless such treatments offered considerable with maize and sorghum, and improves the feed dvantages over the feeding of untreated whole growth ratio for beef cattle grain, and were cost-effective. Both cold and hot dry and wet, mechanical and chemical methods of treatment may be used, with the objectives of Steam-rolling and steam-flaking mproving palatability, avoiding wastage, and Grain is treated with steam for 3-5 min(for encouraging consumption, thus leading to a greater steam-rolled) or for 15-30 min( for steam-iaked) fficiency of food usage and perhaps faster growth. and then rolled between a pair of smooth rollers Other objectives would be to improve digestibility These processes improve the physical texture and and/or nutritive value, to prevent spoilage, soften the grain. Steam-flaking makes thinner and to detoxify poisons and to inactivate anti- flakes than steam-rolling. The heat treatment may nutritional factors improve protein utilization by ruminants. In the The actual treatment used will depend on the steam-flaking process there will be some rupturing
FEED AND INDUSTRIAL USES FOR CEREALS 303 Maize is easily the most widely used cereal, kind of cereal involved and the proportion of that with about 282 million tonnes being used for cereal in the feed; also on the species of animal animal feed (annually) worldwide in 1984-1986, for which the feed is intended, particularly whether followed by barley (about 127 million tonnes) and for ruminants or for monogastric animals and wheat (about 103 million tonnes) (FAO, 1990). probably also on the stage in the animal’s life A large proportion of the cereal grains fed to cycle, e.g. thinking of poultry, whether for young animals passes through the hands of ‘animal feed chicks, for broilers, or for laying hens. processors’. By way of example, of the 5.2 million Some of the treatments applied by animal feed tonnes of wheat used for animal feed in the UK processors to cereal grain, and the resulting in 1988/89, 2.87 million tonnes (55%) were used benefits are described below. by animal feed processors (a figure based on returns from compounders only, in Great Britain) Grinding (H-GCA, 1990). The remainder, still a considerable quantity, would presumably have been fed This is the commonest treatment, and relatively directly from the farm to the animals, not via inexpensive. Roller mills or hammer mills may processors. be used, but hammer mills are favoured because, In the same year, 1988/89, 5.1 million tonnes by choice of a screen of suitable size, the hammer of wheat were used by flour millers in the UK mill can yield ground material of any particular which, besides yielding 3.954 million tonnes of size from cracked grain to a fine powder. The flour, also produced 1.132 million tonnes of objective of grinding is to improve the digestibility. milling by-products - bran and middlings (fine Coarsely-ground grain is preferred for ruminants; offal), most of which would have been used for more finely-ground grain for swine and poultry. animal feed. Thus, the total quantity of wheat plus wheat milling by-products used for feeding Soaking animals in the UK in 1988/89 must have been about 6.3 million tonnes (NABIM, 1991). Grain may be soaked in water for 12-24 h, A similar state of affairs probably exists for followed by rolling, for livestock feeding. The wheat in other countries, and also, to varying soaking softens the grain and causes it to swell, extents, for other cereal grains worldwide. thereby improving palatability. Processing cereals for animal feed Reconstitution The treatments applied to cereals by animal A process in which grain is moistened to 25- feed processors are both expensive and time- 30% m.c. and then stored in an oxygen-limiting consuming, and obviously would not be under- silo for 14-21 days. This process is successful taken unless such treatments offered considerable with maize and sorghum, and improves the feed/ advantages over the feeding of untreated whole growth ratio for beef cattle. grain, and were cost-effective. Both cold and hot, dry and wet, mechanical and chemical methods Steam-rolling and steam-f,aking of treatment may be used, with the objectives of improving palatability, avoiding wastage, and Grain is treated with steam for 3-5 min (for encouraging consumption, thus leading to a greater steam-rolled) or for 15-30 min (for steam-flaked) efficiency of food usage and perhaps faster growth. and then rolled between a pair of smooth rollers. Other objectives would be to improve digestibility These processes improve the physical texture and and/or nutritive value, to prevent spoilage, soften the grain. Steam-flaking makes thinner and to detoxify poisons and to inactivate anti- flakes than steam-rolling. The heat treatment may nutritional factors. improve protein utilization by ruminants. In the The actual treatment used will depend on the steam-flaking process there will be some rupturing
Y OF CEREALS of the starch granules, and partial gelatinization beef cattle, maize is generally fed with another of the starch, resulting in more efficient use of cereal: the greatest benefit comes from combining the feed by slowly digested grains (maize, sorghum) with rapidly digested grains(wheat, barley, high Pelleting moisture maize). A combination of 67% of wheat through a die to make pellets -a form whi q plus 33% of dry-rolled maize gave a 6% comple- Steamed grain is ground and the mass is forced mentary effect as compared with feeding 100% all domestic animals seem to prefer to meal. 75% of high-moisture maize plus 25% of dry- However, pelleted cereals are not recommended rolled grain sorghum or dry maize gained more for ruminants because a decrease in food intake rapidly and used the feed more efficiently than ay ensue. On the other hand, pelleting leads to those fed either grain alone (Sindt et al., 1987) increased consumption by swine and poultry, For cows, a typical diet would contain 41% of possibly because pelleting masks the flavour of high-moisture maize(along with alfalfa and soya- unpalatable ingredients in the diet. Pelleting also bean meal, etc. )(Schingoethe, 1991). grinding improves the utilization of amino acids by swine. cracking or rolling the grains, or steam-flaking The heat used in pelleting may be effective in may improve the digestibility. A calf-grower feed inactivating heat-labile toxins might contain 65% of maize, sorghum or barley, plus 10%of rolled oats and 20% of soyabean meal Popping and micronizing (Morrill, 1991) Typical feeds for early-weaned lambs would In grain that has been popped and then rolled, include 67% of ground shelled maize plus rupture of the endosperm improves utilization of 10% of cottonseed hulls, or 74% of ground ear the starch in the digestive tract. micronizing is a maize plus soyabean meal and supplements ( ely similar process to popping, but uses infrared 1991) radiation for heating the grain For pigs of all ages, maize might provide 85% of the grain in the rations. Use of high-lysine Treatment of high-moisture grain soyabean meal needed The feed grains must be Grain harvested at a relatively high moisture ground, e. g. through a hammer mill with /168 content, e.g. 20-35% m.c., can be chemically in. screen. Finely-ground maize is used more treated to prevent the development of moulds efficiently than coarsely-ground, but very fine during storage, to produce excellent feed grinding, making a dusty meal, is to be avoided Recommended treatment of high-moisture grain The proportion of ground maize in the feed for is with acids, used at a rate of 1.0-1.5%. Such swine at various stages of growth could be 80% acids could be propionic alone, or with acetic or for pregnant sows and gilts, 76% for lactation formic acids. Maize and barley, thus treated, can diets for sows and gilts, 63-71% for young pigs be fed to swine, maize and sorghum to beef cattle 78% for growing pigs, and 84% for finishing pigs (Church, 1991) For feeding poultry, maize, sorghum, wheat Feeding maize to animals and barley are the most important cereals and should be ground and perhaps pelleted Maize(corr n)provided 85% of the cereals fed Pelleting prevents the sorting out of constituents to broilers in the U.S.A. in 1984, with sorghum of the diet, and is recommended for chicks providing 11% and wheat 4%(USDA, 1987a). In and broilers. Pelleting minimizes wastage and 1986, the cereals contributing to the feed for improves palatability. Maize could provide 57% livestock in the U.S. A. were: maize 75%, sorghum of the feed for broiler starters, 62% for broiler 9%, oats 6%, barley 4%, wheat plus rye 6%. For finishers, 45% for chickS, 57% for growers (7-12
304 TECHNOLOGY OF CEREALS of the starch granules, and partial gelatinization of the starch, resulting in more efficient use of the feed by ruminants. Pelleting Steamed grain is ground and the mass is forced through a die to make pellets - a form which all domestic animals seem to prefer to meal. However, pelleted cereals are not recommended for ruminants because a decrease in food intake may ensue. On the other hand, pelleting leads to increased consumption by swine and poultry, possibly because pelleting masks the flavour of unpalatable ingredients in the diet. Pelleting also improves the utilization of amino acids by swine. The heat used in pelleting may be effective in inactivating heat-labile toxins. Popping and micronizing rupture of the endosperm improves utilization of the starch in the digestive tract. Micronizing is a similar process to popping, but uses infrared radiation for heating the grain. Treatment of high-moisture grain Grain harvested at a relatively high moisture content, e.g. 20-35% m.c., can be chemically treated to prevent the development of moulds during storage, to produce excellent feed. Recommended treatment of high-moisture grain is with acids, used at a rate of 1.0-1.5%. Such acids could be propionic alone, or with acetic or formic acids. Maize and barley, thus treated, can be fed to swine, maize and sorghum to beef cattle (Church, 1991). (Cromwell, 1991). Feeding maize to animals Maize (corn) provided 85% of the cereals fed to broilers in the U.S.A. in 1984, with sorghum providing 11% and wheat 4% (USDA, 1987a). In 1986, the cereals contributing to the feed for livestock in the U.S.A. were: maize 75%, sorghum 9%, oats 6%, barley 4%, wheat plus rye 6%. For beef cattle, maize is generally fed with another cereal: the greatest benefit comes from combining slowly digested grains (maize, sorghum) with rapidly digested grains (wheat, barley, highmoisture maize). A combination of 67% of wheat plus 33% of dry-rolled maize gave a 6% complementary effect as compared with feeding 100°/~ dry-rolled maize (Kreikmeier, 1987). Cattle fed 75% of high-moisture maize plus 25% of dryrolled grain sorghum or dry maize gained more rapidly and used the feed more efficiently than those fed either grain alone (Sindt et al., 1987). For cows, a typical diet would contain 41% of high-moisture maize (along with alfalfa and soyabean meal, etc.) (Schingoethe, 1991). Grinding, cracking or rolling the grains, or steam-flaking, may improve the digestibility. A calf-grower feed might contain 65% of maize, sorghum or barley, plus 10% of rolled oats and 20% of soyabean meal (Morrill, 1991). Typical feeds for early-weaned lambs would In grain that has been popped and then rolled, include 67% of ground shelled maize plus 10% of cottonseed hulls, or 74% of ground ear maize plus soyabean meal and supplements (Ely, 1991). For pigs of all ages, maize might provide 85% of the grain in the rations. Use of high-lysine maize would allow a reduction in the amount of soyabean meal needed. The feed grains must be ground, e.g. through a hammer mill with %ti% in. screen. Finely-ground maize is used more efficiently than coarsely-ground, but very fine grinding, making a dusty meal, is to be avoided. The proportion of ground maize in the feed for swine at various stages of growth could be 80% for pregnant sows and gilts, 76% for lactation diets for sows and gilts, 63-71% for young pigs, 78% for growing pigs, and 84% for finishing pigs For feeding poultry, maize, sorghum, wheat and barley are the most important cereals and should be ground and perhaps pelleted. Pelleting prevents the sorting out of constituents of the diet, and is recommended for chicks and broilers. Pelleting minimizes wastage and improves palatability. Maize could provide 57% of the feed for broiler starters, 62% for broiler finishers, 45% for chicks, 57% for growers (7-12
FEED AND INDUSTRIAL USES FOR CEREALS 305 weeks)and developers(13-18 weeks),48% for preferred to one in which ground maize is the laying hens(Nakaue and Arscott, 1991) sole cereal because it results in better plumage For horses 25-39% of the feed could less feather-picking, and less cannibalism. On the cracked maize, along with 45-30% of rolled and other hand the corncob plus maize feed gives a 7-10% of wheat bran(Ott, 1991) reduced egg production and less body-weight By-products of the milling of maize are also gain(Clark and Lathrop, 1953) used for animal feeding. A product known as hominy feed comprises the entire by-product streams from the dry milling of maize. It is a Barley for animal feed relatively inexpensive high-fibre, high-calorie Apart from its use in malting, brewing and material which is high in carotenoids (yellow distilling(c f. Ch. 9), the next most important pigments desirable for chicken feed) and vitamins use for barley is as food for animals, particularly A and D. Hominy feed is an excellent source pigs, in the form of barley meal of energy for both ruminants and monogastric As whole barley contains about 34% of crude animals, in this respect being equal or superior fibre, and is relatively indigestible, the preferred to whole maize. Hominy feed competes with type of barley for animal feeding is one with a other maize by-products-corn gluten feed and low husk content. Low protein barleys are favoured spent brewers' grains as an animal feed. for malting and brewing, but barley of high Hominy feed may partially replace grain in diets protein content is more desirable for animal feed for horses, provided the feed is pelleted(Ott The total digestible nutrients in barley are 991). Gluten feed is recovered from the steeping given as 79%. Digestible coefficients for consti water in which maize is steeped as a stage in w tuents of ground barley are 76% for protein, 80% milling(q v ) After the separation of the germ, for fat, 92% for carbohydrate and 56%for fibre in the wet-milling of maize, and extraction of the(Morrison, 1947) oil, the residue- germ cake-is used for cattle The feeding value of barley is said to be equal feed to that of maize for ruminants(Hockett, 1991) and 85-90% of that of maize for swine( cromwell 1991). For swine, barley can replace all the maize in the feed; indeed barley is preferred to maize The maize cob(corn cob in the U.S. A. is the for certain animals, e. g. pigs. The feeding value central rachis of the female inflorescence of the of barley fo is improved by grinding plant to which the grains are attached, and which pelleting, cubing, rolling or micronizing(Hockett remains as agricultural waste after threshing. As 1991). It is also used extensively in compound about 180 kg of cobs(d b ) are obtained from feeds each tonne of maize shelled, the annual produc For poultry, a feed containing barley and tion of cobs in the U.S. A alone is of the order improved egg production and feed efficiency as of 30 million tonnes compared with either cereal fed alone lorenz Cobs consist principally of cellulose 35%, pen- and Kulp, 1991 tosans 40% and lignin 15%. Agricultural uses for Swine fed barley grew faster and had a more maize cobs, listed by Clark and Lathrop(1953), efficient feed/gain ratio if the barley was pelleted include litter for poultry and other animals; than if fed as meal. Feed for pregnant sows and mulch and soil conditioner; animal and poultry gilts can contain up to 85% of ground barley, up feeds. The feeding value of corncobs is about 62% to 65% for lactating sows, 80% for growing pigs of that of grains. Up to 67% of ground corncobs, and 86% for finishing pigs( Cromwell, 1991) ith 14%of ground shelled maize and some The barley is normally fed either crushed or soyabean meal and molasses-urea provided a as a coarse meal, thereby avoiding wastage that suitable feed for cattle. For poultry, a feed could result from the passage of undigested grains containing corncob meal plus ground maize is through the alimentary tract. The widespread use
FEED AND INDUSTRIAL USES FOR CEREALS 305 weeks) and developers (13-18 weeks), 48% for preferred to one in which ground maize is the laying hens (Nakaue and Arscott, 1991). sole cereal because it results in better plumage, For horses, 25-39% of the feed could be less feather-picking, and less cannibalism. On the cracked maize, along with 45-30% of rolled and other hand, the corncob plus maize feed gives a 7-10% of wheat bran (Ott, 1991). reduced egg production and less body-weight By-products of the milling of maize are also gain (Clark and Lathrop, 1953). used for animal feeding. A product known as hominy feed comprises the entire by-product Barley for animal feed streams from the dry milling of maize. It is a relatively inexpensive high-fibre, high-calorie Apart from its use in malting, brewing and material which is high in carotenoids (yellow distilling (c.f. Ch. 9), the next most important pigments desirable for chicken feed) and vitamins use for barley is as food for animals, particularly A and D. Hominy feed is an excellent source pigs, in the form of barley meal. of energy for both ruminants and monogastric As whole barley contains about 34% of crude animals, in this respect being equal or superior fibre, and is relatively indigestible, the preferred to whole maize. Hominy feed competes with type of barley for animal feeding is one with a other maize by-products - corn gluten feed and low husk content. Low protein barleys are favoured spent brewers’ grains - as an animal feed. for malting and brewing, but barley of high Hominy feed may partially replace grain in diets protein content is more desirable for animal feed. for horses, provided the feed is pelleted (Ott, The total digestible nutrients in barley are 1991). Gluten feed is recovered from the steeping given as 79%. Digestible coefficients for constiwater in which maize is steeped as a stage in wet- tuents of ground barley are 76% for protein, 80% milling (q.v.). After the separation of the germ, for fat, 92% for carbohydrate and 56% for fibre in the wet-milling of maize, and extraction of the (Morrison, 1947). oil, the residue - germ cake - is used for cattle The feeding value of barley is said to be equal feed. to that of maize for ruminants (Hockett, 1991) and 85-90% of that of maize for swine (Cromwell, 1991). For swine, barley can replace all the maize in the feed; indeed, barley is preferred to maize Maize cobs The maize cob (corn cob in the U.S.A.) is the for certain animals, e.g. pigs. The feeding value central rachis of the female inflorescence of the of barley for pigs is improved by grinding, plant to which the grains are attached, and which pelleting, cubing, rolling or micronizing (Hockett, remains as agricultural waste after threshing. As 1991). It is also used extensively in compound about 180 kg of cobs (d.b.) are obtained from feeds. each tonne of maize shelled, the annual produc- For poultry, a feed containing barley and maize tion of cobs in the U.S.A. alone is of the order improved egg production and feed efficiency as of 30 million tomes. compared with either cereal fed alone (Lorenz Cobs consist principally of cellulose 35%, pen- and Kulp, 1991). tosans 40% and lignin 15%. Agricultural uses for Swine fed barley grew faster and had a more maize cobs, listed by Clark and Lathrop (1953), efficient feed/gain ratio if the barley was pelleted include litter for poultry and other animals; than if fed as meal. Feed for pregnant sows and mulch and soil conditioner; animal and poultry gilts can contain up to 85% of ground barley, up feeds. The feeding value of corncobs is about 62% to 65% for lactating sows, 80% for growing pigs of that of grains. Up to 67% of ground corncobs, and 86% for finishing pigs (Cromwell, 1991). with 14% of ground shelled maize and some The barley is normally fed either crushed or soyabean meal and molasses-urea provided a as a coarse meal, thereby avoiding wastage that suitable feed for cattle. For poultry, a feed could result from the passage of undigested grains containing corncob meal plus ground maize is through the alimentary tract. The widespread use
TECHNOLOGY OF CEREALS of barley by pig feeders is related to its effect on to animals, viz. not via a feed processor, could the body fat, which becomes firm and white if include parcels that did not meet these standards the ration contains a large amount of barley meal and also wheat that was unfit for milling 1953) When wheat was fed to cattle, the efficiency of chiproly'(i. e. hi-pro-ly) barley is a mutant two- feed usage was greater for dry-rolled wheat than row barley from Ethiopia containing the 'lys,' for wholewheat. Dry milling increased grain gene, which confers high lysine content(cf. p. digestibility from 63 to 88%. Further processing, 71). Hiproly barley contains 20-30% more lysine e.g. steam-flaking or extruding, gave no further than is found in normal barley High-lysine barley improvement(Church, 1991). For beef cattle has been shown to improve the growth rate of wheat is best used in combination with other feed pigs(Hockett, 1991). A recent high-lysine barley grains, e.g. maize or grain sorghum. a blend of mutant originating in Denmark is Riso 1508, with 67% wheat plus 33% dry-milled maize improved 50% more lysine than in Hiproly barley. Risg feed efficiency as compared with either wheat or 1508 is intended to provide a feedstuff with an maize alone (Ward and Klopfenstein, 1991) improved amino acid balance for the pig and dairy When fed to finishing lambs for market, wheat industries, one objective being to avoid the neces- had 105% of the feeding value of shelled maize sity of feeding fishmeal, which gives a taint to when the wheat comprised up to 50% of the total he product grain(Ely, 1991).For By-products from the dry milling of barley to food, but is often too expensive. Wheat is similar make pearl barley are used for animal feed, to maize on an energy basis, but has a higher con particularly for ruminants and horses, as con- tent of protein, lysine, and available phosphorus, tituents of compound feeds. brewers'grains and and wheat can replace all or part of the maize in distillers'dried grains are by-products from the the diet for pigs. Non-millable wheat, damaged brewing and distilling industries that can be moderately by insects, disease, or containing incorporated in feeds for ruminants; they are too garlic, can be fed to swine( Cromwell, 1991) fibrous for pigs and poultry For feeding poultry, wheat should be ground and preferably pelleted, to avoid sorting out of Wheat for animal feeding feed constituents by the birds. For poultry, the feed efficiency of wheat is 93-95% of that of maize The animal-feed use of wheat 1980-1984, (Nakaue and Arscott 1991) world-wide, averaged 19.8 million tonnes per Wheat milling by-products- bran and midd- annum. In the U.S. A. alone in 1988/89, 270 lings provide palatable food for animals. million bu(about 7. 35 million tonnes)were used Wheat middlings can replace grain in the feed for livestock feed. The use of wheat for animal provided the diets are pelleted -otherwise they feed is influenced by price, location and nutrient are too dusty. The energy of wheat middlings value(Mattern, 1991) utilized better by ruminants than by monogastric The importance of wheat as an animal feedstuff animals. Cows fed rations containing 60% of is further illustrated by the establishment, by the concentrate did well if 40% of the concentrate Home-Grown Cereals Authority, in the U. K, of was wheat middlings; sv% of the maize in the quality specifications for 'standard feed wheat,, middlings replaced up in association with the National Farmers'Union rations. Middlings are also fed to poultry. Wheat and the U. K. Agricultural Supply Trade Associa- bran is the favoured feedstuff for horses and for tion,in 1978, and subsequently updated. These all ruminants( Church, 1991) quality specifications, which apply to grain destined for the feed compounder, mention moisture con- tent(max. 16%)and content of impurities Oats for feeding animals ergot, max0.05%; other cereals 5%; non-grain The usage of oats for livestock feeding in the impurities 3%(H-GCA, 1990). Wheat fed directly U.S.A. in 1986 was 9.6 million tonnes, exceeding
306 TECHNOLOGY OF CEREALS of barley by pig feeders is related to its effect on the body fat, which becomes firm and white if the ration contains a large amount of barley meal (Watson, 1953). ‘Hiproly’ (i.e. hi-pro-ly) barley is a mutant tworow barley from Ethiopia containing the ‘Zys’ gene, which confers high lysine content (cf. p. 71). Hiproly barley contains 2630% more lysine than is found in normal barley. High-lysine barley has been shown to improve the growth rate of pigs (Hockett, 1991). A recent high-lysine barley mutant originating in Denmark is Riso 1508, with 50% more lysine than in Hiproly barley. Riso 1508 is intended to provide a feedstuff with an improved amino acid balance for the pig and dairy industries, one objective being to avoid the necessity of feeding fishmeal, which gives a taint to the product. By-products from the dry milling of barley to make pearl barley are used for animal feed, particularly for ruminants and horses, as constituents of compound feeds. Brewers’ grains and distillers’ dried grains are by-products from the brewing and distilling industries that can be incorporated in feeds for ruminants; they are too fibrous for pigs and poultry. Wheat for animal feeding world-wide, averaged 19.8 million tonnes per annum. In the U.S.A. alone, in 1988/89, 270 million bu (about 7.35 million tonnes) were used for livestock feed. The use of wheat for animal feed is influenced by price, location and nutrient value (Mattern, 1991). The importance of wheat as an animal feedstuff is further illustrated by the establishment, by the Home-Grown Cereals Authority, in the U.K., of quality specifications for ‘standard feed wheat’, in association with the National Farmers’ Union and the U.K. Agricultural Supply Trade Association, in 1978, and subsequently updated. These quality specifications, which apply to pain destined for the feed compounder, mention moisture content (max. 16%) and content of impurities - ergot, max. 0.05%; other cereals 5%; non-grain impurities 3% (H-GCA, 1990). Wheat fed directly to animals, viz. not via a feed processor, could include parcels that did not meet these standards and also wheat that was unfit for milling. When wheat was fed to cattle, the efficiency of feed usage was greater for dry-rolled wheat than for wholewheat. Dry milling increased grain digestibility from 63 to 88%. Further processing, e.g. steam-flaking or extruding, gave no further improvement (Church, 1991). For beef cattle, wheat is best used in combination with other feed grains, e.g. maize or grain sorghum. A blend of 67% wheat plus 33% dry-milled maize improved feed efficiency as compared with either wheat or maize alone (Ward and Klopfenstein, 1991). When fed to finishing lambs for market, wheat had 105% of the feeding value of shelled maize when the wheat comprised up to 50% of the total grain (Ely, 1991). For pigs, wheat is an excellent food, but is often too expensive. Wheat is similar to maize on an energy basis, but has a higher content of protein, lysine, and available phosphorus, and wheat can replace all or part of the maize in the diet for pigs. Non-millable wheat, damaged moderately by insects, disease, or containing garlic, can be fed to swine (Cromwell, 1991). For feeding poultry, wheat should be ground, and preferably pelleted, to avoid sorting out of feed constituents by the birds. For poultry, the feed efficiency of wheat is 93-95% of that of maize Wheat milling by-products - bran and middlings - provide palatable food for animals. Wheat middlings can replace grain in the feed, provided the diets are pelleted - otherwise they are too dusty. The energy of wheat middlings is utilized better by ruminants than by monogastric animals. Cows fed rations containing 60% of concentrate did well if 40% of the concentrate was wheat middlings; swine did well when wheat middlings replaced up to 30% of the maize in the rations. Middlings are also fed to poultry. Wheat bran is the favoured feedstuff for horses and for all ruminants (Church, 1991). Oats for feeding animals The usage of oats for livestock feeding in the U.S.A. in 1986 was 9.6 million tonnes, exceeding The animal-feed use of wheat 1980-1984, (Nakaue and Arscott, 1991)
FEED AND INDUSTRIAL USES FOR CEREALS the feed usage of barley(7.0 million tonnes)in advantage for weanlings and yearlings(Ott, 1973) that year (USDA, 1987), although worldwide Oats that are musty should not be used(Ott he usage of oats for animal feed, at 38.3 million 1991). tonnes per annum, was less than one-third of the The by-products of the dry milling of oats- amount of barley so used worldwide, viz. 126.8 oat dust, meal seeds, oat feed meal -are of million tonnes, in 1984-1986(FAO, 1990). reasonably good feeding value. Oat feed meal Oats have a unique nutritional value, particularly oat mill feed in the U.s.A. is a feed of low for animals which require feed having a relatively nutritive value suitable for ruminants, used to high level of good quality protein, but with lower dilute the energy content of maize and other energy content. The level of protein in oat groats grains is higher than that in other cereals; moreover, the Feed oats -the lights, doubles and thin oats quality of oat protein, particularly the amino acid removed during the cleaning of oats -are almost balance, surpasses that of the protein of other equally nutritious to normal oats, and are used ereals, as shown by feeding tests(Webster, 1986; for livestock feeding(Webster, 1986) McMullen, 1991). he good value of high-protein oats has been hown in diets for swine and poultry, although Sorghum for animal feed he nutritive value for these non-ruminants can Sorghum is a major ingredient in the feed for be further improved by supplementation of the swine, poultry and cattle, particularly in the oats with lysine and methionine(Webster, 1986). Western hemisphere. From the worldwide pro- For feeding to animals, oats are first ground duction of sorghum of 66 million tonnes in 1984- or rolled Rolled oats can provide 10% of the feed 1986, 56.6%(37. 3 million tonnes)were used for for calves(along with 65% of maize, sorghum or animal feed. In the same period, the U. S A alone barley)(Klopfenstein et al. 1991), and is a good produced 14.9 million tonnes, of which 14 starter feed for pigs, although too expensive for million tonnes went for animal feed (FAO, 1990) other pigs. ground oats can provide 25% of the For feeding to animals, the sorghum is hammer feed for pregnant sows, 20% for lactating sows, mill ground and then generally steam- faked 10% for young pigs, 15% for growing and finishing using high moisture steam for 5-15 min to raise pigs( with maize, wheat or barley supplying most the moisture content to 18-20%, followed by of the remainder of the feed)(Cromwell, 1991). rolling to make thin flakes(Rooney and serna- For feeding to pigs, the oats should be ground Saldivar, 1991). Steam-flaking improves the feed through a hammer mill, using a h2 in. screen. efficiency of sorghu Pelleting of the ground oats gives faster growt For swine, low-tannin types of sorghum have than unpelleted meal for swine Cromwell, 1991). a nutritive value equal to that of maize but he feeding value for swine, relative to maize brown, high-tannin types, grown for their resis is 100% for oat groats, and 80% for whole oats. tance to attack by birds and their decreased For poultry, oats have 93% of the value of maize liability to weathering and fungal infestation, for broilers, 89% for layers( Cromwell, 1991; have a reduced nutritive value( cromwell, 1991) Nakaue and Arscott, 1991). Sorghum provided 11% of all the cereal grain For feeding to finishing lambs for the market, fed to broilers in the U.S.A. in 1984, and 9% of oats have 80% of the feeding value of maize(ely, all the cereal grain fed to livestock in the U.s.a 1991) in1986(USDA,1987a3c) istorically, oats are regarded as the ideal feed As compared with dry-rolled sorghum, recon- for horses, and in North America this view still stituted sorghum(moistened to 25-30%mc and btains. For young or poor- toothed horses, the then stored for 14-21 days in a silo in a low oxygen whole oats are best rolled or crushed. As com- atmosphere before feeding) produced a better pared with whole oats, crushed oats gave a 5% daily weight gain in feed-lot cattle, and also feeding advantage for working horses, and a 21% produced a considerable improvement in feed/
FEED AND INDUSTRIAL USES FOR CEREALS 307 advantage for weanlings and yearlings (Ott, 1973). Oats that are musty should not be used (Ott, 1991). The by-products of the dry milling of oats - oat dust, meal seeds, oat feed meal - are of reasonably good feeding value. Oat feed meal (= oat mill feed in the U.S.A.) is a feed of low nutritive value suitable for ruminants, used to dilute the energy content of maize and other grains. Feed oats - the lights, doubles and thin oats removed during the cleaning of oats - are almost equally nutritious to normal oats, and are used for livestock feeding (Webster, 1986). Sorghum for animal feed Sorghum is a major ingredient in the feed for swine, poultry and cattle, particularly in the Western hemisphere. From the worldwide production of sorghum of 66 million tonnes in 1984- 1986, 56.6% (37.3 million tonnes) were used for animal feed. In the same period, the U.S.A. alone produced 14.9 million tonnes, of which 14.8 million tonnes went for animal feed (FAO, 1990). For feeding to animals, the sorghum is hammermill ground and then generally steam-flaked, using high moisture steam for 5-15 min to raise the moisture content to 18-20%, followed by rolling to make thin flakes (Rooney and SernaSaldivar, 1991). Steam-flaking improves the feed efficiency of sorghum. For swine, low-tannin types of sorghum have a nutritive value equal to that of maize, but brown, high-tannin types, grown for their resistance to attack by birds, and their decreased liability to weathering and fungal infestation, have a reduced nutritive value (Cromwell, 1991). Sorghum provided 11% of all the cereal grain fed to broilers in the U.S.A. in 1984, and 9% of all the cereal grain fed to livestock in the U.S.A. As compared with dry-rolled sorghum, reconstituted sorghum (moistened to 25-30% m.c. and then stored for 14-21 days in a silo in a low oxygen atmosphere before feeding) produced a better daily weight gain in feed-lot cattle, and also produced a considerable improvement in feed the feed usage of barley (7.0 million tonnes) in that year (USDA, 1987b), although worldwide the usage of oats for animal feed, at 38.3 million tonnes per annum, was less than one-third of the amount of barley so used worldwide, viz. 126.8 million tonnes, in 1984-1986 (FAO, 1990). Oatshaveauniquenutritionalvalue,particularly for animals which require feed having a relatively high level of good quality protein, but with lower energy content. The level of protein in oat groats is higher than that in other cereals; moreover, the quality of oat protein, particularly the amino acid balance, surpasses that of the protein of other cereals, as shown by feeding tests (Webster, 1986; McMullen, 1991). The good value of high-protein oats has been shown in diets for swine and poultry, although the nutritive value for these non-ruminants can be further improved by supplementation of the oats with lysine and methionine (Webster, 1986). For feeding to animals, oats are first ground or rolled. Rolled oats can provide 10% of the feed for calves (along with 65% of maize, sorghum or barley) (Klopfenstein et al., 1991), and is a good starter feed for pigs, although too expensive for other pigs. Ground oats can provide 25% of the feed for pregnant sows, 20% for lactating sows, 10% for young pigs, 15% for growing and finishing pigs (with maize, wheat or barley supplying most of the remainder of the feed) (Cromwell, 1991). For feeding to pigs, the oats should be ground through a hammer mill, using a '/z in. screen. Pelleting of the ground oats gives faster growth than unpelleted meal for swine (Cromwell, 1991). The feeding value for swine, relative to maize, is 100% for oat groats, and 80% for whole oats. For poultry, oats have 93% of the value of maize for broilers, 89% for layers (Cromwell, 1991; Nakaue and Arscott, 1991). For feeding to finishing lambs for the market, oats have 80% of the feeding value of maize (Ely, 1991). in 1986 (USDA, 1987a,c). Historically, oats are regarded as the ideal feed for horses, and in North America this view still obtains. For young or poor-toothed horses, the whole oats are best rolled or crushed. As compared with whole oats, crushed oats gave a 5% feeding advantage for working horses, and a 2 1%
308 gain ratio (Stock et al. 1985). When fed to swine, Rice in feed for animals reconstituted sorghum gave a slight improvement only in the case of high-tannin sorghum A total of 6.5 million tonnes of rice was used 3 For beef cattle, grain sorghum has 85-95% of annually, worldwide, in the period 1984-86 for feeding value of maize. The sorgh hum animal feeding, nearly all(6.0 million tonnes) digested slowly in the and has a relatively being used in Asia( China 3.2 Mt; Thailand 0.7 Mt)(FAO,1990) lower total tract digestibility(Klopfenstein et aL., For feeding swine, rice if pelleted can replace 1991 50% of the maize in the feed or 35%if fed Ground sorghum can provide up to 80% of feed for pregnant sows, 76% for lactating sows, meal For young pigs, the feed could contain 20% 71% for young pigs, 78% for growing pigs, and of rice bran, if pelleted(Sharp, 1991).The 84 for finishing pigs( Cromwell, 1991). Fc feeding value of pelleted, broken rice for swine poultry, suggested rations include 18% of sorghum is 96% of that of ( Cromwell, 1991) Considerable use for animal feeding is made of layer-breeders(ed as all-mash in a warm climate) a mixture of rice bran and rice polishing.rds for chick starters, 13% for growers(7-12 weeks) well with wheat. It contributes a useful amount of biotin, pantothenic acid, niacin, vitamin E and Rye in animal feed linoleic acid to mixed feeds, thereby reducing the requirement for supplementation with vitamin/ Of the annual total world usage of rye for minerals premix. The contribution of linoleic acid animal feed, of 14.5 million tonnes, in the period in rice pollards is of particular value in rations the USSR, the USSR using 39.3%, Poland 30.3% for laying hens, where it has a beneficial effect and Germany(FRD plus gDR)15.2%. Usage in on egg size(Australian Technical Millers, 1980) For growing pigs, up to 30% of rice pollard can the whole of north and central America was only be fed in balanced rations without adverse effects 3. 4% of the total Rye is used in areas where it is cheaper than on growth rate or carcase quality (Roese, 1978) (the residue left after oil barley, but, although rye is high in energy, extraction from rice bran)has an increased content growth of animals on rye is slower than on other of protein and a good amino acid profile for mono- cereals, possibly because its unpa intake. Rye contains a high level of pectin(a gastric animals, also good protein and phosphorus carbohydrate), which reduces its feeding value. contents for ruminants. However, it is not a good Thus, rye is compounded with other cereals for Source of fatty acids animal feed. Rye also contains a resorcinol Rice mill feed is a mixture of rice pollards and 5-alkyl-resorcinol-which was once thought to ground rice hulls used for animal feed. In 1986 be toxic to animals. Attempts are being made to 0.72 million tonnes of rice mill feed were used breed lines of rye with lower levels of resorcinol. for animal feed in the U.S. A. ( USDA, 1987c) Horses feed on rye grain show no ill effects Ground rice hulls are a highly fibrous, lot from possible toxic constituents(Antoni, 1960), energy foodstuff, suitable for diluting the energy and rye can be successfully fed to swine and level in rations for cattle, sheep, goats, pigs and cattle when it contributes up to 50%in a mixed poultry (Australian Technical Millers, 1980).The total digestible nutrients(at 14%m c )in rice K'i The presence of ergot in rye is a risk if the rye hull are 15% for cattle and 25%for sheep(Juliano fed to swine, as the ergot can cause abortion 1985) in sows, and reduce the performance of growing Rice hulls contain 9-20% of lignin, thereby pigs(Drews and Seibel, 1976; Cromwell, 1991; limiting their use for animal feed. Various de- Lorenz, 1991). lignification processes have been suggested, e.g
308 TECHNOLOGY OF CEREALS gain ratio (Stock et al., 1985). When fed to swine, reconstituted sorghum gave a slight improvement only in the case of high-tannin sorghum. For beef cattle, grain sorghum has 85-95% of digested slowly in the rumen and has a relatively lower total tract digestibility (Klopfenstein et al. , 1991). Ground sorghum can provide up to 80% Of the 71% for young pigs, 78% for growing pigs, and poultry, suggested rations include 18% of sorghum 14% for developers (13-18 weeks), and 20% for layer-breeders (fed as all-mash in a warm climate) (Nakaue and Arscott, 1991). Rye in animal feed Of the annua1 tota1 wor1d usage Of rye for animal feed, of 14.5 million tonnes, in the period 1984-1986, nearly 94% was used in Europe and and Germany (FRD plus GDR) 15.2%. Usage in the who1e Of north and centra1 America was Only 3.4% of the total. Rye is used in areas where it is cheaper than Rice in feed for animals A total of 6.5 million tonneS of rice was used annually, worldwide, in the period 1984-86 for animal feeding, nearly all (6.0 million tonnes) Mt) (FAO, 1990). For feeding swine, rice if pelleted can replace 50% of the maize in the feed, or 35% if fed as meal. For young pigs, the feed could contain 20% feeding value of pelleted, broken rice for swine Considerable use for animal feeding is made of a mixture of rice bran and rice polishings - is a high energy, high protein foodstuff comparing well with wheat. It contributes a useful amount of biotin, pantothenic acid, niacin, vitamin E and linoleic acid to mixed feeds, thereby reducing the requirement for supplementation with vitamin/ minerals premix. The contribution of linoleic acid in rice pollards is of particular value in rations for laying hens, where it has a beneficial effect For growing pigs, up to 30% of rice pollard can be fed in balanced rations without adverse effects on growth rate or carcase quality (Roese, 1978). Extracted rice bran (the residue left after oil the feeding va1ue Of maize* The sorghum is being used in Asia (China 3.2 Mt; Thailand 0.7 feed for pregnant sows, 76% for lactating sowsJ of rice bran, if pelleted (Sharp, 1991). The 84% for finishing Pigs (Cromwell, 1991)' For is 96% of that of maize (Gromwell, 1991). for chick starters, 13" for growers (7-12 weeks)J the by-products of rice milling. Rice pollards - the USSR, the USSR using 39.3%, "land 30*3% On egg size (Australian Technical Millers, 1980). bar1ey, but, a1though rye is high in energy7 growth Of anima1s On rye is 'lower than On Other cereals, possibly because its unpdatabiliq restricts intake* Rye contins a high level Of pectin (a exuaction from rice bran) has an increased content of protein and a good amino acid profile for monogastric animals, also good protein and phosphorus COntentS for ruminants. However, it is not a good carbohydrate), which reduces its feeding value. Thus, rye is compounded with other cereals for animal feed. Rye also contains a resorcinol - 5-alkyl-resorcinol - which was once thought to be toxic to animals. Attempts are being made to breed lines of rye with lower levels of resorcinol. Horses feed on rye grain show no ill effects SOurce of fatty acids. Rice mill feed is a mixture of rice pollards and ground rice hulls used for animal feed. In 1986, 0.72 million tonnes of rice mill feed were used for animal feed in the U.S.A. (USDA, 1987~). Ground rice hulls are a highly fibrous, low from possible toxic constituents (Antoni, 1960), and rye can be successfully fed to swine and energy foodstuff, suitable for diluting the energY level in rations for cattle, sheep, goats, Pigs and cattie when it contributes up to 50% in a mixed feed. The presence of ergot in rye is a risk if the rye is fed to swine, as the ergot can cause abortion in sows, and reduce the performance of growing pigs (Drews and Seibel, 1976; Cromwell, 1991; Lorenz, 1991). poultry (Australian Technical Millers, 1980). The total digestible nutrients (at 14% m.c.) in rice hull are 15% for cattle and 25% for sheep (Juliano, 1985). Rice hulls contain 9-20% of lignin, thereby limiting their use for animal feed. Various delignification processes have been suggested, e.g
FEED AND INDUSTRIAL USES FOR CEREALS 30 treatment with alkali or with acid(see Juliano maize for swine, but became equal to maize when 1985, Ch. 19 for details). Treatment with 12% supplemented with lysine caustic soda also reduced the high silica content Pearl millet(rolled) provided excellent protein of rice hulls, while treatment of the hulls with for beef cattle, and steers gained as well on rolled anhydrous ammonia plus monocalcium phosphate pearl millet as on sorghum( Serna-Saldivar et al, at elevated temperature and pressure increased 1991) the crude protein equivalent, broke down the harsh silica surface, and softened the hulls, thus providing an acceptable feedstuff for cattle and Production of ethanol from cereals sheep uliano, 1985) Ethanol(ethyl alcohol) is produced by the An even more successful treatment of rice hulls enzymic action of yeast on sugars, which are was incubation with Bacillus spp for several days: themselves produced by the hydrolysis of starch is treatment reduced the lignin and crude fibre In as much as all cereals contain a large proportion contents to a greater degree than soaking in of starch, it should be possible to obtain ethanol caustic soda uliano, 1985) from any cereal. This happens when cereal grai are malted and then brewed to make beer, which The millets for animal feeding is an aqueous solution of alcohol. The production of ethanol can be regarded as a modification of Of the 3. 1 million tonnes of millet used world- the brewing process, in which starch separated wide annually for animal feed in 1984-1986, 1. 3 from the grains is the starting material, and pure million tonnes were used in the former Soviet ethanol, rather than an aqueous solution, is the nion, 1. 1 Mt in Asia (including 0.7 Mt in final product. China), and 0.5 Mt in Africa(including 0. 3 Mt The principal reasons for making ethanol from in egypt)(FAO, 1990). There was no recorded cereals are that ethanol can be used as a partial use of millet for animal feed in the U. s A. during replacement of gasoline as a fuel for internal this period although it is reported that proso combustion engines and that the process is a millet(Panicum miliaceum)is grown in the U.S.A. useful way of dealing with surplus grain whenever for birdseed(Serna-Saldivar et aL., 1991) it arises. Interest in the process increases when .. Feeding trials have shown that millets have fuel shortages occur and/or when prices of feed tritive values comparable to, or better than, grain are depressed those of the other major cereals: proso millet has Thus, a wheat surplus in Sweden in 1984 was 89 of the value of maize for feeding swine, and dealt with by establishing a plant that separated can replace 100% of the maize in rations for swine the starch from a residue to be used for animal (Cromwell, 1991). Animals fed millet perform feed. About half of the starch(the best quality) better than those fed sorghum; they produce was to be used by the paper industry, the better growth because the millet has a higher remainder for production of ethanol. The addi- calorific content and better quality protein( Serna- tion of 4% of ethanol to gasoline does not lead to Saldivar et al. 1991). starting problems or to an increase in fuel con Poultry produced better gains when fed millet sumption and, in fact, increases the octane number than when fed sorghum or wheat; the efficiency (Wadmark, 1988 of feed conversion was better for chicks fed pearl The possible yield of etha millet(Pennisetum americanum)than on wheat, to the type of cereal used 430 It from rice, 340- maize or sorghum; proso millet was equivalent 360 1t from wheat, 240-250 It from barley and to sorghum or maize in respect of egg production oats(Dale, 1991) and weight, and efficiency of feed use The process of manufacture of ethanol from For swine, finger millet(Eleusine coracana)was cereals starts by grinding the grain and ther as good as maize for pig finishing diets; proso cooking it with water and acid or alkali Amylase millet had a slightly lower feed efficiency than enzyme is added to the cooled mash to promote
FEED AND INDUSTRIAL USES FOR CEREALS 309 maize for swine, but became equal to maize when supplemented with lysine. Pearl millet (rolled) provided excellent protein for beef cattle, and steers gained as well on rolled pearl millet as on sorghum (Serna-Saldivar et al, 1991). treatment with alkali or with acid (see Juliano 1985, Ch. 19 for details). Treatment with 12% caustic soda also reduced the high silica content of rice hulls, while treatment of the hulls with anhydrous ammonia plus monocalcium phosphate at elevated temperature and pressure increased the crude protein equivalent, broke down the harsh silica surface, and softened the hulls, thus providing an acceptable feedstuff for cattle and sheep (Juliano, 1985). An even more successful treatment of rice hulls was incubation with Bacillus spp. for several days: this treatment reduced the lignin and crude fibre contents to a greater degree than soaking in caustic soda (Juliano, 1985). The millets for animal feeding Of the 3.1 million tonnes of millet used worldwide annually for animal feed in 1984-1986, 1.3 million tonnes were used in the former Soviet Union, 1.1 Mt in Asia (including 0.7 Mt in China), and 0.5 Mt in Africa (including 0.3 Mt in Egypt) (FAO, 1990). There was no recorded use of millet for animal feed in the U.S.A. during this period, although it is reported that proso millet (Panicum miliaceum) is grown in the U. S.A. for birdseed (Serna-Saldivar et al., 1991). Feeding trials have shown that millets have nutritive values comparable to, or better than, those of the other major cereals: proso millet has 89% of the value of maize for feeding swine, and can replace 100% of the maize in rations for swine (Cromwell, 1991). Animals fed millet perform better than those fed sorghum; they produce better growth because the millet has a higher calorific content and better quality protein (SernaSaldivar et al., 1991). Poultry produced better gains when fed millet than when fed sorghum or wheat; the efficiency of feed conversion was better for chicks fed pearl millet (Pennisetum amem'canum) than on wheat, maize or sorghum; proso millet was equivalent to sorghum or maize in respect of egg production and weight, and efficiency of feed use. For swine, finger millet (Eleusine coracana) was as good as maize for pig finishing diets; proso millet had a slightly lower feed efficiency than Production of ethanol from cereals Ethanol (ethyl alcohol) is produced by the enzymic action of yeast on sugars, which are themselves produced by the hydrolysis of starch. In as much as all cereals contain a large proportion of starch, it should be possible to obtain ethanol from any cereal. This happens when cereal grains are malted and then brewed to make beer, which is an aqueous solution of alcohol. The production of ethanol can be regarded as a modification of the brewing process, in which starch separated from the grains is the starting material, and pure ethanol, rather than an aqueous solution, is the final product. The principal reasons for making ethanol from cereals are that ethanol can be used as a partial replacement of gasoline as a fuel for internal combustion engines and that the process is a useful way of dealing with surplus grain whenever it arises. Interest in the process increases when fuel shortages occur and/or when prices of feed grain are depressed. Thus, a wheat surplus in Sweden in 1984 was dealt with by establishing a plant that separated the starch from a residue to be used for animal feed. About half of the starch (the best quality) was to be used by the paper industry, the remainder for production of ethanol. The addition of 4% of ethanol to gasoline does not lead to starting problems or to an increase in fuel consumption and, in fact, increases the octane number (Wadmark, 1988). The possible yield of ethanol varies according to the type of cereal used: 430 l/t from rice, 340- 360 l/t from wheat, 240-250 Ut from barley and oats (Dale, 1991). The process of manufacture of ethanol from cereals starts by grinding the grain and then cooking it with water and acid or alkali. Amylase enzyme is added to the cooled mash to promote
310 TECHNOLOGY OF CEREALS the hydrolysis of starch to glucose, and the mash liquefying enzyme is needed for the subsequent is then fermented with yeast, releasing carbon saccharification with glucoamylase. Ethanol yields dioxide gas, and producing alcohol. The wort is from wet-extruded and from steam-cooked grain treated with steam in a beer still, and the alcohol were almost equal, but the extrusion method uses is finally separated in a rectification column, less energy. Roller-milled whole barley, wheat or yielding 95% ethanol and leaving a protein- oats can be used in this process, with or without enriched residue, suitable for animal feeding the addition of thermostable alpha-amylase, which (Dale,1991) appears to have little effect during extrusion As a motor fuel, ethanol has various advantages cooking The fermentation stage is carried out over gasoline: it has a very high octane number; using either yeast( Saccharomyces cerevisiae) or the it increases engine power; it burns more cleanly, bacterium Zymomonas mobilis, the latter produc producing less carbon monoxide and oxides of ing an increased initial rate of fermentation(Linko nitrogen. On the other hand, there may be 1989a, b) difficulties in starting the engine on ethanol alone and accordingly a blend of ethanol with gasoline Furfural production from cereals Other uses for ethanol made from cereals. Corncobs the hulls of oats and rice, and besides motor fuel, include use as a solvent in fibrous parts of other cereals are rich in pentosans antifreeze and as the raw material for the manu- condensation products of pentose sugars, whicl facture of various chemicals, e.g. acetaldehyde, are associated with cellulose as constituents of ethyl acetate, acetic acid glycols(Dale, 1991). cell walls, particularly of woody tissues The carbon dioxide evolved during the fermen Thus, the pentosan content of oat hulls is given tation stage finds uses in oil fields, for recovery as 29%, along with 29% of cellulose and 16% of of additional oil, in the manufacture of methanol, lignin(McMullen, 1991). Pentosans are the start as a refrigerant and in carbonated beverages ing material for the manufacture of furfural,a (Dale,1991) chemical with many uses. Indeed, commercial A process for the continuous production of utilization of oat hulls and other pentosan- rich ethanol from cereals, involving screening, filter- cereal materials lies in the manufacture of furfural ing, saccharification, fermentation and distillation (MacArthur-Grant, 1986) tages,has recently been patented(Technipetrol Furfural was first produced commercially in SPA, 1989), while a dual-purpose flour mill has 1922. By 1975, oat hulls were providing about been described in which the four is air-classified 22% of the annual demand for furfural in the to produce a high protein fraction(particle size: U.S.A. but thereafter the demand for furfural 2-5 um) and a residual protein-depleted fraction and other furan chemicals far outstripped the for use as the starting material for production of supply of oat hulls, and increasing use was then Corncobs can be used for the production of hulls, corncobs, bagasse(Shukla, 1975. 2.rice ethanol (Bonnet and willm, 1989) made of other sources of pentosans, vi ethanol, and also of furfural (vide infra). By Plants for the commercial production of furfural treating the cobs with dilute sulphuric acid, 80% from agricultural residues have been established of the pentosans in the cobs are converted to in the U.S. A. The plant at Cedar Rapids, lowa pentoses, from which furfural is obtained, while uses oat hulls and corncobs; the one at Memphis the residual cellulose can be hydrolyzed to glucose tn uses rice hulls, corncobs and cottonseed in 65% yield(Clark and Lathrop, 1953) hulls; while the plant at Omaha, NB uses corn- Extrusion cooking has been suggested as a cobs only( Clark and Lathrop, 1953) method for pretreating grain to be used for the The commercial process for manufacturing production of ethanol. The thermomechanical furfural involves the boiling of the pentosan effects of extrusion cooking produce gelatinize- containing material with strong acid(sulphuric tion and liquefaction of the starch so that no or hydrochloric) and steam for 7-9 h at 70 psi
310 TECHNOLOGY OF CEREALS the hydrolysis of starch to glucose, and the mash is then fermented with yeast, releasing carbon dioxide gas, and producing alcohol. The wort is treated with steam in a beer still, and the alcohol is finally separated in a rectification column, yielding 95% ethanol and leaving a proteinenriched residue, suitable for animal feeding (Dale, 1991). As a motor fuel, ethanol has various advantages over gasoline: it has a very high octane number; it increases engine power; it burns more cleanly, producing less carbon monoxide and oxides of nitrogen. On the other hand, there may be 1989a,b). difficulties in starting the engine on ethanol alone, and accordingly a blend of ethanol with gasoline is generally used. Other uses for ethanol made from cereals, besides motor fuel, include use as a solvent in antifreeze and as the raw material for the manufacture of various chemicals, e.g. acetaldehyde, ethyl acetate, acetic acid, glycols (Dale, 1991). The carbon dioxide evolved during the fermentation stage finds uses in oil fields, for recovery of additional oil, in the manufacture of methanol, as a refrigerant and in carbonated beverages (Dale, 1991). A process for the continuous production of ethanol from cereals, involving screening, filtering, saccharification, fermentation and distillation stages, has recently been patented (Technipetrol SPA, 1989), while a dual-purpose flour mill has been described in which the flour is air-classified to produce a high protein fraction (particle size: 2-5 pm) and a residual protein-depleted fraction for use as the starting material for production of ethanol (Bonnet and Willm, 1989). Corncobs can be used for the production of ethanol, and also of furfural (vide infra). By treating the cobs with dilute sulphuric acid, 80% of the pentosans in the cobs are converted to pentoses, from which furfural is obtained, while the residual cellulose can be hydrolyzed to glucose in 65% yield (Clark and Lathrop, 1953). Extrusion cooking has been suggested as a method for pretreating grain to be used for the production of ethanol. The thermomechanical effects of extrusion cooking produce gelatinization and liquefaction of the starch so that no liquefying enzyme is needed for the subsequent saccharification with glucoamylase. Ethanol yields from wet-extruded and from steam-cooked grain were almost equal, but the extrusion method uses less energy. Roller-milled whole barley, wheat or oats can be used in this process, with or without the addition of thermostable alpha-amylase, which appears to have little effect during extrusion cooking. The fermentation stage is carried out using either yeast (Saccharomyces cmevisiae) or the bacterium Zymomonas mobilis, the latter producing an increased initial rate of fermentation (Linko, Furfural production from cereals Corncobs, the hulls of oats and rice, and the fibrous parts of other cereals are rich in pentosans, condensation products of pentose sugars, which are associated with cellulose as constituents of cell walls, particularly of woody tissues. Thus, the pentosan content of oat hulls is given as 29%, along with 29% of cellulose and 16% of lignin (McMullen, 1991). Pentosans are the starting material for the manufacture of furfural, a chemical with many uses. Indeed, commercial utilization of oat hulls and other pentosan-rich cereal materials lies in the manufacture of furfural (MacArthur-Grant, 1986). Furfural was first produced commercially in 1922. By 1975, oat hulls were providing about 22% of the annual demand for furfural in the U.S.A., but thereafter the demand for furfural and other furan chemicals far outstripped the supply of oat hulls, and increasing use was then made of other sources of pentosans, viz. rice hulls, corncobs, bagasse (Shukla, 1975). Plants for the commercial production of furfural from agricultural residues have been established in the U.S.A. The plant at Cedar Rapids, Iowa, uses oat hulls and corncobs; the one at Memphis, TN uses rice hulls, corncobs and cottonseed hulls; while the plant at Omaha, NB uses corncobs only (Clark and Lathrop, 1953). The commercial process for manufacturing furfural involves the boiling of the pentosancontaining material with strong acid (sulphuric or hydrochloric) and steam for 7-9 h at 70 psi
FEED AND INDUSTRIAL USES FOR CEREALS (C5H80an+ nH2o i nC5 HoOs tanks; production of tetrahydrofurfuryl alcohol, a Pentose for dy C-CHO polytetramethylene ether glycol fo thermoplastics; manufacture of D-xylose, phenolic Cs HIo05 CaH3O'CHO 3H20 Furfura↓ resin glues and adhesives; production of anti- skid tread composition; filter aid in breweries FIG. 15. 1 Chemical reactions in the production of furfural (MacArthur-Grant, 1986) pressure. Previous grinding of the hulls is not Other industrial uses for cereals required. A sequence of reactions takes place. The There are many other industrial uses, besides pentosans are dissociated from the cellulose; then the production of ethanol and furfural, for cereal the pentosans are hydrolyzed to pentose sugars, grains, their milled products, and the by-products and finally the pentose sugars undergo cyclo- of milling. Use of cereals in malting, brewing and hydration to form furfural, a heterocyclic adehyde, distilling have been discussed in Ch. 9. Other which is removed continuously by steam distillation industrial uses are dependent on either the chemical (see Fig. 15. 1)(Dunlop, 1973; Johnson, 1991). characteristics or the physical properties of the The theoretical yield of furfural from pentose raw material. They make use of cereals or cereal 64%(plus 36% of water), so the theoretical products as absorbents abrasives, adhesives, yield of furfural from oat hulls containing 29% binders and fillers, carriers, and for such purposes of pentosans would be 22%, although a yield of as filter aids, litter for animals, fertilizers, floor only about 13% is achieved in practice The yield sweepings, fuel, soil conditioners, oil well drilling from corncobs is similar while that from aid. They are also used in the paper and mineral hulls is somewhat lower, at 12% theoretical processing industries in practice uliano, 1985; Pomeranz, 1987) A large proportion of the cost of the process is Wheat accoun ted for by the need to raise high pres ure Industrial uses for the milling products of steam: for every 1 lb of furfural produced, 15- wheat have been listed by Pomeranz(1987).Both 26 lb of high pressure steam at 188 C are required Furfural finds uses as a selective solvent for wheat four and wheat starch are used in paper for refining animal and vegetable oils in the facture of paper, boards, plywood, etc. Starch is manufacture of margarine. It is also used for th purification of butadiene, which is needed for the Gluten separated from wheat flour finds uses manufacture of synthetic rubber. in paper manufacture, as an adhesive, and as the One of the most important uses for furfural, starting material for the preparation of sodium owever, is in the manufacture of nylon. Nylon, glutamate and glutamic acid Wheat germ is used in the production of antibio. was first produced in 1927 by the firm e. l. du tics, pharmaceuticals and skin conditioners,while Pont de Nemours and Co., and was introduced wheat bran may be used as a carrier of enzymes, ntibiotics and vitamins(Pomeranz, 1987) to the industry in 1939. Polyamides,are formed Starch is also used to make rigid urethane foam by the condensation of a diamide and dibasic acid, for insulation and paints, in plastics and to nylon are hexamethylene diamine and adipicacid. process crude latex in the manufacture of rubber The value of furfural arises from the fact that is an important source of hexamethylene diamine. Rye Other uses for furfural include: production of The gums, both soluble and insoluble, make formaldehyde furfural resins for making pipes and rye a good substitute for other gums in wet-end
FEED AND INDUSTRIAL USES FOR CEREALS 31 1 HC - CH tanks; production of tetrahydrofurfural alcohol, a II II solvent for dyes, paints, etc.; production of "c\ /C-CHo polytetramethylene ether glycol for making thermoplastics; manufacture of D-xylose, phenolic C5HIoO5 = C,H,O'CHO t 3H20 Furfural resin glues and adhesives; production of antiPentose Fur f ura I skid tread composition; filter aid in breweries (MacArthur-Grant, 1986). (C5H804), + nHpO = nC5Hlo05 Pen toson Pentose 0 FIG. 15.1 Chemical reactions in the production of furfural from pentosans. Other industrial uses for cereals pressure. Previous grinding of the hulls is not required. A sequence of reactions takes place. The There are many other industrial uses, besides pentosans are dissociated from the cellulose; then the production of ethanol and furfural, for cereal the pentosans are hydrolyzed to pentose sugars, grains, their milled products, and the by-products and finally the pentose sugars undergo cyclo- of milling. Use of cereals in malting, brewing and hydration to form furfural, a heterocyclic adehyde, distilling have been discussed in Ch. 9. Other which is removed continuously by steam distillation industrial uses are dependent on either the chemical (see Fig. 15.1) (Dunlop, 1973; Johnson, 1991). characteristics or the physical properties of the The theoretical yield of furfural from pentose raw material. They make use of cereals or cereal is 64% (plus 36% of water), so the theoretical products as absorbents, abrasives, adhesives, yield of furfural from oat hulls containing 29% binders and fillers, carriers, and for such purposes of pentosans would be 22%, although a yield of as filter aids, litter for animals, fertilizers, flooronly about 13% is achieved in practice. The yield sweepings, fuel, soil conditioners, oil well drilling from corncobs is similar, while that from rice aid. They are also used in the paper and mineral hulls is somewhat lower, at 12% theoretical, 5% processing industries. in practice (Juliano, 1985; Pomeranz, 1987). A large proportion of the cost of the process is Wheat Industrial uses for the milling products of accounted for by the need to raise high pressure wheat have been listed by Pomeranz (1987). Both steam: for every 1 lb of furfural produced, 15- Furfural finds uses as a selective solvent for sizing and coating, and as adhesives in the manu- refining lubricating oils and petroleum spirit, and facture of paper, boards, plywood, etc. Starch is for refining animal and vegetable oils in the also used for finishing textiles. Gluten separated from wheat flour finds uses manufacture of margarine. It is also used for the purification of butadiene, which is needed for the in paper manufacture, as an adhesive, and as the starting material for the preparation of sodium manufacture of synthetic rubber. One of the most important uses for furfural, glutamate and glutamic acid. however, is in the manufacture of nylon. Nylon, Wheat germ is used in the production of antibio- 26 lb Of high pressure stearn at 1880c are required' wheat flour and wheat starch are used in paper a spthetic fibre, defined chemical1y as a &amide, was first produced in 1927 by the firm E' I' du tics, ph-aceuticals and sb conditioners, while wheat bran may be used as a carfier of enzymes, antibiotics and vitamins (Pomeranz, 1987). Starch is also used to make rigid urethane foam for insulation and paints, in plastics and to process crude latex in the manufacture of rubber. Pont de Nemours and Co., and was introduced to the industry in 1939. 'Polyamides' are formed by the condensation of a diamide and dibasic acid, and those moSt Often wed in the manufacture Of nylon are hexamethylene diamine and adipic acid. The value of furfural arises from the fact that it is an important source of hexamethylene diamine. Other uses for furfural include: production of formaldehyde furfural resins for making pipes and Rye The gums, both soluble and insoluble, make rye a good substitute for other gums in wet-end