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6.6.7 Rice by-products

Rice is by far the most important cereal crop in Asia and every year there are millions of tons of straw available after the crop has been harvested (Guzman, 1976). By-products which become available during processing of threshed rice include hulls, bran and polishings, in addition to the polished and broken rice. Rice mill meal is a mixture of these by-products (i.e. hulls, bran and polishings).

Rice straw has been a dominant item in the diet of village cattle and buffaloes for many years and is widely used as a supplement (e.g. Ocampo et al., 1990 reported that in Laguna, Philippines, 72% of dairy farmers were using rice straw). Gibson (1994) notes that in Laos villagers traditionally keep rice straw for dry season feeding. Also, in Vietnam rice straw is saved for use as a supplementary feed (see Figures 192 and 193). According to Ly et al. (1993) some 15 million tons of rice straw are produced annually in Vietnam.

However, it has low digestibility, is low in energy with a crude protein content of only 3–5 percent. Thus a diet of rice straw alone is not sufficient even to maintain the animals weight unless supplementary protein is provided (Devendra, 1982, Jackson, 1978). The nutritive value of rice straw is greatly influenced by the stage of harvesting; the protein content is higher if it is harvested when it still retains some of its green colour (O'Donovan, 1978). A major problem may be the conservation of excessive amounts of rice straw produced at harvest for later use.

Because of low digestibility and low intake of rice straw various physical, chemical and biological pre-treatments have been developed and various supplements used. (Doyle et al., 1986b; Trung, 1986). Economics determine the choice between these methods or combinations (Schiere and Ibrahim, 1988). The alkali spray treatment of straw has been shown to improve digestibility and intake (Jackson, 1977; Moran et al. 1982). The straw is sprayed or sprinkled with a dilute solution of NaOH at the rate of 1 litre kg-1 and the moist straw is immediately fed to animals. The optimum concentration of the NaOH solution is about 5 percent where straw is to be fed with limited supplements, however, where treated straw forms only about 50 percent of the diet, 7–8 percent is better (Jackson, 1978). According to Florido (1992) a very practical method of improving the utilization of rice straw is to soak it in water for two hours and drain before feeding This increases the digestibility of dry matter, crude protein and acid detergent fibre. In the Philippines, rice straw soaked for three days in an aqueous solution of CaO (3%) markedly increased the digestibility of the crude fibre and NFE (Guzman, 1976). Pacho and Perez (1976) compared lime-treated (2% CaO) rice straw and untreated straw at 60 percent of the total ration and demonstrated a 40 percent improvement in growth performance of Zebu bulls. Urea treated straw (see Figure 194) has also been used (Hossain and Rahman, 1981; Kumar et al., 1991; Perdok et al., 1982; Promma et al., 1985, 1993; Wanapat, 1985 and Wanapat et al., 1983b). According to Florido (1992) feeding heifers with urea treated rice straw was more economical than using urea-molasses sprayed straw.

Wanapat et al. (1983a) demonstrated that ensiling straw for 3–4 weeks with 5 percent urea and 0.2 percent salt increased its total digestible nutrients from 42 to 51 percent. Voluntary dry matter intake by growing steers increased by 39 percent while average weight gain was 0.430 kg head-1 day-1 compared with 0.134 kg head-1 day-1 for untreated rice straw.

The Straw Utilization Project in Sri Lanka (Schiere and Ibrahim, 1988) recommended treating 100 kg straw with 4 kg urea dissolved in 60–100 I water with about 7 days storage before feeding. Various models were used for calculating the economics of treatment and the need identified to consider also the interactions between treatment and supplementation.

Also in Sri Lanka the University of Ruhuna and the Coconut Research Institute have examined the effect of feeding heifers grazing natural herbage under coconuts with rice straw and rice straw plus supplements (Pathirana et al., 1992) Results after one year are shown in Table 135. Straw intake increased over time. Mean annual straw dry matter intake was 574 g head-1 day-1 on GS treatment compared to 1,171 g head-1 day-1 on GSS treatment with annual mean intakes of urea, molasses, rice polishings and mineral mixture at 29, 146, 125 and 15 g head-1 day-1 respectively. Supplementation not only increased the intake of straw but decreased the grazing pressure and resulted in heifers reaching a breedable stage much earlier. It is in the reproductive phase through early heat, early conception, earlier heavier and healthy calves, increased fertility, more calves per lifespan and more milk per lactation that the benefits begin to show.

Table 135. - Liveweight and liveweight gain data for heifers grazing natural herbage under coconuts1 and those fed rice straw and rice straw plus supplements (after Pathirana et al., 1992)

LW (kg head-1): Initial62.4  63.0  61.9  
65.5  78.2  100.5  
LW gain: kg head-1 yr-13.1a15.2b38.6c
kg ha-1 yr-1
g head-1 day-1

1 30 year old coconut plantation with palms spaced at 8.4 × 8.4 m (137 palms ha-1);
2 G = heifers grazed (at 6 ha-1) continuously on natural herbage.
   GS = as per G + unprocessed, unsupplemented rice straw ad. lib.
   GSS = as per GS plus supplements of urea, molasses, rice polishings and a vitamin mineral mixture

abc values within each row bearing different letters are significantly different (P = 0.01). Annual rainfall was 1,750–2,000 mm.

Figure 192

Figure 192. - Rice straw saved for cattle feed in Vietnam.

Figure 193

Figure 193. - A mixture of rice straw and fresh grass being fed to Yellow Vang cattle in Vietnam.

Figure 194

Figure 194. - Urea treated rice straw for stall fed cattle, Vietnam.

Liyanage and Pathirana (1992) noted that cattle grazing only natural herbage produced 0.8 l milk head-1 day-1 compared with 3.0 l milk head-1 day-1 produced by those grazing natural herbage and fed supplemented rice straw. Pathirana et al. (1993) reported on experimental results after five years.

Noting that attempts to introduce improved, well managed pastures and cattle (high input systems) under coconuts had made little progress, it was stressed that this experiment was an attempt to study the long-term effects of low inputs, simulating field conditions, involving indigenous cattle, natural herbage and straw as it is; the resources commonly available to small dairy farmers, as a first step towards increased productivity. Reproduction and lactation data are presented in Tables 136 and 137. What is of considerable economic consequence for the farmer is the amount of milk collected up to a given point in time. Thus in Table 137 the effect of nutrition on the overall total number of days in milk and the total milk yield in each treatment group up to the end of May 1993 is impressive (total milk yield 803 compared to 7, 164 kg!).

Pathirana et al. (1993) also noted that compared with an indigenous herd on improved pasture at a low stocking rate fed 1.2 kg of concentrates head-1 day-1 which gave an average daily milk yield of 1.9 kg and a yield of 438 kg lactation-1 (Mahadevan, 1953), the GSS animals on natural herbage at a high stocking rate fed approximately half that quantity of concentrates demonstrated the significant contribution of supplemented rice straw for production.

Legume forages have been used as protein supplements with rice straw; Devendra (1983), Moog (1981), Sevilla and Perez (1976) demonstrated good performance with ipil-ipil (L. leucocephala) (see Tables 132–133).

Table 136. - Reproduction data of animals without straw (G), with straw (GS), with straw and supplement (GSS)

Treatment GroupAge at first oestrus (mo)Age at first conception (mo)Age at first calving (mo)
 No. calves bornWt. of calves at birth (kg)LW at first oestrus (kg)
G13412.710.0–14.6    99a75–141
GSS9716 13.89.0–21.2133b102–150  
 LW at first conception (kg)Calving interval (months)
G  125*105–160--

abc Means bearing different superscripts are significantly different (P < 0.01). Data for means without superscripts were not statistically analyzed due to insufficient data, particularly in G group.
* n = 5
** n = 7

Natural and Perez (1975) used copra meal and liquid molasses-urea supplementation of rice straw (see Table 138) and Trung et al. (1989a) concluded that feeding of urea treated straw was more economical than urea-molasses sprayed straw. Perdok and Leng (1990) used supplements of cotton seed meal with a basal diet of untreated or ammoniated rice straw with all animals receiving rice polishings and with continuous access to molasses /urea block-licks containing 15% urea. The heifers fed ammoniated straw grew 267 g head-1 day-1 faster and consumed 11% more straw than the heifers on untreated straw. In Brazil Veitia et al., (1971) fed two year old Zebu bulls rice straw at the rate of 1 percent of body weight, ad libitum molasses (with 3% urea), bone meal, salt and 1 kg of a high protein concentrate. The bulls gained 0.91 kg head-1 day-1. Chadhokar (1983a) compared liveweight gains of crossbred heifers on diets of paddy straw, Gliricidia, rice polish and fresh grass plus poonac (see Table 139). O'Donovan and Chen (1972) fed growing heifers with rations in which chopped rice straw comprised 25 and 35 percent of the total mixture, the remainder consisting of cane molasses, sweet potato chips, soybean meal and urea. Daily liveweight gains ranged from 460 g to 820 g, the former reflecting low soybean content in the ration and the depressing effect of 45 percent cane molasses. Satisfactory gains were obtained when all feed ingredients, except soybean meal, were home grown and about two thirds of the entire ration consisted of rice straw and molasses (O'Donovan, 1978). Devendra (1983) demonstrated the advantage of feeding chopped instead of long straw and the effect of substituting variable levels of rice straw with cassava leaves, leucaena leaves, stems, pods and Gliricidia leaves. In Philippines Marbella et al. (1981) demonstrated the potential of rice straw and ipil-ipil (leucaena) for beef production.

Table 137. - Lactation data of animals without straw (G), with straw (GS), with straw and supplements (GSS)1

Treatment Group No. days in milkMilk yield lactation-1 (kg head-1)
1st lactation2nd lactation1st lactation2nd lactation
 Average milk yield (kg head-1 day-1)Overall total lactation data+
1st lactation2nd lactationTotal no. days in milkTotal milk yield
Overall avg milk yield
(kg head-1 day-1)
G*1.431.01–1.63--   567   8031.42

1 Not analyzed statistically due to insufficient data, particularly from G group. Animals were milked as long as possible.
* Data from only two completed lactations; two more lactations continuing on the date of computation (31 May 1993).
** Data from only 5 completed lactations; 4 more lactations continuing.
*** Data from all 9 completed first lactations. data from only two completed second lactations included; five more second lactations continuing.
+ Data from all completed as well as from all continuing lactations for all animals in each treatment group.

The use of rice straw as ruminant feed has been the subject of a number of workshops and several proceedings have been published; for example Ibrahim and Schiere (1986). Also refer to Doyle et al. (1986) for a review of key aspects.

Rice bran is also widely used as a livestock feed; in Cameroon it is used to replace a large part of the maize in beef-fattening diets (Dia Ndumbe, 1982). Moran (1983, 1983a) used rice bran as a supplement to elephant grass for cattle and buffalo in Indonesia and Till et al. (1991) reported good responses in terms of liveweight gains from weaner heifers fed on a grass-legume pasture in South Sulawesi, Indonesia and supplemented with rice bran and molasses/urea. Guzman (1976) indicated that while rice bran was a very useful supplementary feed for cattle, it deteriorates quite rapidly during storage. As a roughage source only small levels of rice husk of around 5 percent (or less) should be included in the total diet of cattle. Tillman et al. (1969) demonstrated, in practical feeding trials, that 3 percent rice husks gave the best dressing percentage in bullocks. White et al. (1971) showed that a major advantage of rice husk (at only 5%) is that it is a suitable carrier for high levels of dietary molasses (in this case about 83%).

Table 138. - Feedlot growth performance of bulls as affected by copra meal and liquid molasses-urea supplementation of rice straw (Perez, 1976)

No. of bulls6666
Initial weight (kg)148.0155.2154.4148.8
Final weight (kg)184.2200.5220.5180.9
Av. daily gain (kg)0.29ab+0.36b0.52c0.25a
Daily feed intake (kg)    
Total feed
Feed efficiency kg kg-1 gain13.93a12.81a10.55a20.33b

+ Means in a row without a common letter are significantly different (P < 0.05).
I - 70% Napier grass + Centrosema, 30% copra meal, 1% salt-bone meal
II - 70% rice straw, 30% copra meal, 1% salt-bone meal + 250 g ipil-ipil leaf meal head-1 day-1.
III - 50% rice straw, 25% copra meal, 25% molasses-urea, 1% salt-bone meal + 250 g ipil-ipil leaf meal head-1 day-1.
IV - 50% rice straw, 50% molasses-urea, 1% salt-bone meal plus 250 g ipil-ipil leaf meal head-1 day-1.

Table 139. - Effect of alternative feeds on growth of crossbred heifers over 322 days
(Chadhokar, 1983a)

TreatmentsMean daily feed intake DM kg animal-1Average weight gains kg animal-1
InitialFinalIncreaseDaily gains
1.Fresh grass + poonac (2 kg)5.31332691360.42
2.Paddy straw 50% + Gliricidia 50% + rice polish 0.95 and 1.43 kg4.91282431150.36
3.Paddy straw 50% + Gliricidia 50% + rice polish 1.43 and 1.90 kg5.11322551230.38
4.Paddy straw 50% + Gliricidia 50% + rice polish 0.95 and 2.38 kg5.01322571250.39

For the first 112 days wet paddy straw was fed in treatment 4.
Animals were fed at a low level of rice polish for the first 112 days and then at a higher level until completion.

Sanchez (1991) reported on the effects of feed supplementation in North Sumatra, where sheep grazed native forages (mainly Paspalum conjugatum, Ottochloa nodosa, Cyrtococcum oxyphylum, Pueraria phaseoloides, Centrosema pubescens and Mikania cordata) under 18 year old rubber at an initial stocking rate of 6.7 ewes ha-1 from 0800 to 1600 hours and then returned to traditional wooden barns with elevated slat floors where supplementary feeding took place. Over three years (Sumatran Thin Tailed) ewes received one of four levels of energy supplementation (0,0.6, 1.0 or 1.4% of body weight) daily provided by concentrates made from a mixture of rice bran, cassava meal, molasses, fish meal, urea and limestone (Reese, 1988). Overall productivity of the ewes head-1 and weight-1 improved (see Table 140) although Sanchez notes that the particular ingredients used made the economics questionable.

Table 140. - Productivity of Sumatran Thin Tailed ewes with increasing levels of feed supplementation. (After Reese, 1988)

Feed level
(% BW)
Litter sizeLamb weight per lambing
Lambing interval
Yearly lamb weight (kg)
per eweper kg ewe
0  1.32a11.1ab219a19.0a0.92ab

Values within columns with different superscripts are significantly different (p <0.05).

Supplementation also increased average daily gains of lambs by 27 to 65% (with an average of 40%).

6.6.8 Sugar cane

Sugar cane is an important commercial crop in many tropical countries with various residues and by-products available for livestock feeding. For a detailed review of sugar cane as animal feed and experience in various countries see FAO (1988a). Bibliographies on the use of sugar cane in animal feeding are also available (FAO, 1988b, 1988c).

Sugar cane tops - large quantities are available during harvesting. They average about 30 percent of dry matter and contain 2–3.5 percent crude protein. Daily intake of chopped tops varies from about 25–35 kg (Perez and Hsu, 1973). When balanced for protein, sugar cane tops provide for maintenance and give a daily gain of about 0.2 kg in cattle (Guzman, 1976). A diet of chopped sugar cane leaves containing 5–6 percent crude protein was sufficient to meet the maintenance requirements of dairy cattle and to provide for the production of about 2 kg of milk per cow (O'Donovan, 1970). In Mauritius it was reported that for an adult cow of 400 kg liveweight an intake of approximately 45 kg of fresh cane tops per day was sufficient only for maintenance and production of about 3 litres of milk (Sansoucy, 1971). Attempts at ensiling and subsequent feeding in the Philippines showed that silage made from sugar cane tops was an unsatisfactory ration when fed on its own (Guzman, 1976). The best alternative was to supplement the silage with a natural source of protein (copra meal) and molasses-urea (see Table 141). Naseeven (1988) reported on various methods of improving the feeding value of sugarcane tops in Mauritius including supplementation with cotton seed meal, rice polishings, copra cake, fish meal, rice bran, molasses/urea and brewers grains. With cotton seed cake and fresh tops milk yields were increased from around 5 l to 12.5 l.

Table 141. - Feedlot performance of bulls on sugar cane silage and various supplements
(Guzman, 1976)

Average daily feed intake (DM kg)+4.735.045.07
Average daily weight gain (kg head-1)+0.250.410.39
Average feed efficiency kg feed kg-1 liveweight gain+19.6   12.6   13.0  

I - ad lib. feeding of silage alone.
II - Silage and molasses - urea (3% urea) at 60% and 40% respectively of total air dry ration.
III - Silage, molasses and copra meal at 60%, 20% and 20%.
IV - Silage, molasses - urea, copra meal at 60%, 20% and 20%.
+ Treatment discontinued after 9 weeks as animals suffered excessive weight losses.

Bagasse - is the residue of sugar cane after juice extraction. Although much is used as a fuel in sugar factories, it has been used for feeding livestock in many countries (Abdalla et al., 1990; Beames, 1961; Horchstrasser et al., 1977; Inkerman et al., 1988; Kirk et al., 1962 and Martin et al., 1976). Bagasse is a low - quality feed, mainly because of its high percentage of lignocellulose, however when mixed with protein and an energy source such as cane molasses, moderate levels of bagasse can promote satisfactory liveweight gains. Levels higher than 30 percent tend to depress rate of gain (O'Donovan, 1978). Stuart (1988) evaluated the effect of NaOH and NH3 treatments on sugar cane residues. Pigden and Bender (1978) suggest both alkali and steam treatments to increase bagasse digestibility while Hassoun et al. (1990), Khan et al. (1992) and Ortega et al. (1991) showed that urea treatment improved nutritive value. In Colombia de la Cruz (1990) concluded that steam - treated bagasse can be used successfully in the fattening of cattle and Rangnekar et al. (1986) in India used steam treated bagasse as dairy cattle feed. In Puerto Rico, Randel et al., (1972) demonstrated that Holstein and Brown Swiss cows had a daily milk production of 12.5 kg cow-1 where raw bagasse comprised 40 percent of the ration (plus 27% cane molasses, 18.45% shelled corn, 10% tuna fish meal, 2.5% urea and 2.05% other ingredients). Alkali treated bagasse (2% NaOH for 24 hours) increased daily milk production to 17.2 kg. Kirk et al. (1962) concluded that balanced diets for cattle containing 20 to 30 percent bagasse levels produced rapid weight and economic gains. O'Donovan (1978) suggested that where less than maximum gains are required, by - product mixtures containing bagasse are useful in maintaining stock or promoting a low rate of gain among beef animals during the dry season. Figures 195, 196 and 197 illustrate the production of bagasse (and raw sugar) by a small mobile cane crusher in Vietnam.

Molasses - is a valuable source of energy (FAO, 1975). For an overview of the use of molasses see Preston (1988) and FAO (1988a). Elias (1988) described the commercial feeding of molasses to ruminants in Cuba. Initially, levels of only 5–10 percent were used in the feed compounding industry in industrialized countries which imported it as an ingredient in mixed feeds (Preston, 1982a). It has long been known that the inclusion of a small percentage of molasses reduces dustiness in mixed meal and pelleted rations (Preston, 1972b; Preston and Willis, 1974), improves the palatability of the diet and is particularly valuable when incorporated with coarse unpalatable roughages, but it was not until the late 1960's that the first successful use of high levels of molasses in cattle fattening rations was reported from Cuba (Preston et al., 1967). Growth rates exceeding 0.8 kg day-1 were obtained in crossbred Zebu bulls given rations in which almost 80 percent of the dietary energy was derived from molasses. By restricting forage intake to only 1.5 percent of the animal's liveweight (on a fresh weight basis) as opposed to providing forage ad libitum it was found that the daily intake of molasses was increased by some 50 percent and overall animal performance was significantly improved. This led to the development of large scale commercial feeding systems for cattle in both conventional feed lots (see Tables 142–143) and semi-confinement (see Table 144). Continuing research has resulted in technical and economic improvements such as the use of high quality forages such as Leucaena, cassava and sweet potato leaves to supply both protein and roughage (see Table 145) and the supplementation of poor quality roughages with poultry litter (Ffoulkes and Preston, 1978a; Hulman et al., 1978; Meyreles and Preston, 1982; Preston, 1982a). De la Hunte (1981) reported on successful systems of intensive beef production in Zimbabwe, based on sugar cane by-products, chiefly molasses. ‘Dry’ molasses feeds have been produced commercially in South Africa and the United States, but have not been widely used because of handling problems and cost (Preston and Willis, 1974). In Mauritius, Sansoucy (1971) produced a concentrate for dairy cattle based on 72 percent molasses, 13 percent bagasse, 8 percent ground nut cake, 3 percent urea and 4 percent minerals in which 90 percent of the ingredients were local raw materials. Not only was the expensive maize ingredient replaced but the resulting concentrate, in spite of the high molasses content, was produced in the form of an easily handled flour.

Figure 195

Figure 195. - Sugarcane crushing using a small mobile unit, Vietnam.

Figure 196

Figure 196. - Bagasse after the juice has been extracted.

Figure 197

Figure 197. - Bagasse (and raw sugar).

The other main use of molasses has been as a supplement to poor quality cattle feed. Often sprayed or poured over feeds to increase palatability it is also used as a carrier for NPN. Mott et al. (1970) reported that feeding 2 kg of molasses-urea supplement per day increased liveweight gain of Zebu steers grazing Guinea grass pasture. Other responses to NPN carried in molasses are reported below (see section 6.6.10). In Vietnam, Ly et al. (1993) demonstrated that molasses-urea blocks, as supplements for cattle fed rice straw and maize stover, increased milk yield by 10.5%.

Table 142. - Recommended procedures for feedlot fattening of cattle on molasses-based diets (Preston, 1978)

Weeks of fatteningDaily allowance(kg)
Fresh forageFish mealMolasses/urea1Minerals2
Firstad lib.0.5ad libad lib
Second150.5ad libad lib
Third100.5ad libad lib
Fourth100.5ad libad lib
Fifth to Eighth100.4ad libad lib
Ninth onward100.3ad libad lib

1 Contains (%): 2.5 urea, 0.5 common salt, 1.5 water, 95.5 final (blackstrap) molasses (first dissolve the urea and salt in the water at 50°C prior to adding this to the molasses).
2 Contains (%): 50 dicalcium phosphate (or bone meal), 50 common salt (add 0.1% cobalt sulphate if soil is deficient in this element).

Table 143. - Effect of change from traditional forage/concentrates (1969) to high molasses ration (1970) in a commercial feedlot in Cuba (Preston, 1982a; Munoz et al., 1970)

Total liveweight gained in feedlot
(kg day-1)
Liveweight gain kg day-1 per:  
        0.43   0.88
Unit feed dry matter
          0.065       0.093
Deaths (%)      0.1   1.0
Emergency slaughter (%)      0.4   3.0

Table 144. - Input-output data for 3500 crossbred Zebu bulls in 11 commercial units in Cuba (Preston, 1982a)

Liveweight gain (kg day-1)1.04   0.740.83
Conversion rate*2   
5.9  14.79.1  
fish meal
0.32   0.540.45
Deaths (%)--   1.330.44
Emergency slaughter (%)--   1.330.38

*1 Animals were confined for 18 hours daily where they had free access to the molasses/urea and 400 kg day-1 of a fish meal supplement. Forage was provided by restricted grazing (6 hrs. day-1) mainly on Pangola or Guinea grass pastures (Morciego et al., 1970).

*2 Amount of molasses/urea or fish meal required per kg of liveweight gain.

Table 145. - Substitution of Ischaemum aristatum and ground nut cake by Leucaena forage in molasses1 based diets for growing bulls in Mauritius (Preston, 1982a; Hulman et al., 1978)

(% liveweight day-1)
Ground nut cake (g day-1) plus l. aristatum
Liveweight gain
(kg day-1)
       0.79      0.74      0.85   0.60   0.74
Feed conversion3    9.2   12.2    9.710.510.4
Molasses as % of diet79686273   53  

1 Molasses contained 3% urea and all animals received a mineral mixture ad lib. (50% Sodium chloride and 50% Dicalcium Phosphate).

2 Fresh Leucaena used at 2%, 3.5% and 5% of liveweight daily.

3 Feed dry matter per unit liveweight gain.

Derinded cane - is the process where a separator splits the cane and removes the soft pith (or comfith) from the rind (Dion, 1973) with the main objective of using the rind component as raw material for high quality compressed boards and the pith for conventional sugar production, alcohol fermentation and as an energy feed for livestock (Preston, 1982a). Trials have shown high performance rates from cattle fed the pith (or derinded cane) suitably supplemented with chopped cane tops, urea and a true protein source (Donefer, 1973; Pigden, 1972, 1978). The major drawback has been the relative cost and the sophistication of the compressed board manufacturing process. Additionally various feeding trials have shown that derinded cane showed no significant difference in animal performance from chopped whole cane (see Figure 198), moreover the technology of chopping whole cane is simpler and cheaper (Preston, 1976b; Preston et al., 1976).

Chopped whole cane - the major cost of using the whole cane (tops, stalk and trash) for feeding cattle is not in the growing but in the harvesting, transporting and processing operations. Hand harvesting only appears to be economically feasible on small family farms of 2–3 ha; larger units would need to be mechanized (Preston and Leng, 1978b). In practice, the use of the whole sugar cane has proved useful as a dry season feed where the main aim is maintenance.

In the absence of supplementation, whole sugar cane (and derinded cane) is only a maintenance feed. Supplementation of chopped whole cane with urea and minerals will support some gain (0.1–0.2 kg day-1) but growth rates of the order of 0.9–1.0 kg day-1 are only possible when some good quality forage and a source of by-pass nutrients are given in addition to the urea and minerals (Preston, 1982a). Preston and Leng (1978b) recommend supplement levels for either chopped whole cane or derinded cane plus tops (at 70:30 ratio) to be:

Figure 198

Figure 198. - Effect on liveweight gain of level of rice polishings given as supplement to a basal diet of chopped whole or derinded sugar cane (Preston and Leng, 1978a).

Highly digestible forages used include sweet potato foliage (Meyreles et al., 1979), cassava foliage (Meyreles et al., 1977) and Leucaena leaf (Alvarez and Preston, 1976). Examples of supplements found to give good results are given in Table 146. Wadsworth (1990) demonstrated that the feeding of whole fresh chopped sugar cane ad libitum with approximately 1 percent fresh weight addition of urea and 0.5 kg rice polishings heifer-1 day-1 to confined animals (compared with rotational grazing of Hypharrenia rufa pastures) resulted in faster liveweight gains and a reduction in age at first service from 38 to 26 months. Using a herd production model increased production and net income which were shown to be 12.7 kg liveweight LSU-1 yr-1 and US$ 8.85 LSU-1 yr-1 respectively.

Youssef (1987) reported on three experiments carried out in Trinidad to study the utilization of whole sugar cane by cattle and sheep.

In Trinidad and Tobago three “sugar cane villages” have been set up where the approach to animal feeding is now based on the integral use of sugar cane for monogastric and polygastric feeding (FAO, 1992e). The feeding system for large and small ruminants is based on:

35–40% whole chopped sugar cane
15–20% C molasses
15% wheat middlings
10–15% corn
5–10% poultry offal and/or litter
leucaena leaves, salt and differing amounts of minerals.

Sheep raised in a dry lot reach 35 kg liveweight in 5½–6 months. For the beef herd, average daily gain head-1 is 0.8 kg producing a liveweight of 330–340 kg at 15 months of age.

Table 146. - Supplements found to give good results in diets of sugar cane/urea (Preston and Leng, 1978b)

CategoryMilking cowSuckling calf1)Steer/heifer
Mean liveweight kg2)450110300
Rate of supplementation kg day-1   
A.Protein/cereal meal3)  2.0  0.251.2
B.(Leucaena forage11.01.56.0
 (Banana fruit13.02.07.0

1) For early weaned calves, quantities should be tripled.
2) Pro rata for different liveweights within each category of stock.
3) e.g. rice polishings or whole cotton seed or combinations of 25% fish meal (for soybean/rapeseed meal/cotton seed meal) and 75% maize meal.

Sugar cane juice - Preston (1982a) concludes that future developments with sugar cane should be based on simple methods of separating the juice from the fibre. Sugar cane juice following alkali treatment to enhance its digestibility has supported performance rates equal to, or exceeding, those obtained on cereal grain rations (see Tables 147–148). The fibrous fraction, including any residual sugar, can be converted into charcoal, producer gas or an energy feed for draught animals (Preston, 1982a). Use of sugarcane juice as animal feed has been reviewed by Mena (1988).

In the Philippines, pigs fed an average 0.5 kg day-1 of a restricted protein supplement and sugarcane syrup have shown an average daily gain of 0.45 kg, their initial and final liveweight being 12 and 70 kg, respectively. By using sugarcane juice as a source of energy for their pigs instead of sending the cane for milling, farmers have increased their net incomes from sugarcane by 25 to 30% (FAO, 1992e).

Table 147. - A comparison of cattle performance on sugar cane juice/urea and molasses/urea basal diets1) with and without a by-pass concentrate supplement of sunflower cake (Sanchez and Preston, 1980)

ParameterWithout sunflower cake+ sunflower cake
(1 kg day-1)
Molasses/ureaSugar cane
Liveweight gain kg day-1   0.250.80   0.551.32
Feed conversion2)21.57.4211.86.44

1) Molasses or juice, supplemented with urea was fed ad libitum and all animals received fresh forage (African star grass) at the restricted rate of 3% of liveweight daily. Trial period: 84 days. Initial weight of cattle: 260–280 kg.
2) DM feed per unit liveweight gain.

Table 148. - A comparison of Zebu bull performance on a basal diet of ad libitum sugar cane juice supplemented with Leucaena1) with and without a fish meal supplement (Preston, 1982a)

Parameter Fish supplement (400 g day-1)
Liveweight gain (kg day-1)1.020.85
Feed conversion2)5.7  5.8  

1) Fresh forage at 2% of liveweight.
2) DM feed per unit liveweight gain

6.6.9 Sweet potato (Ipomea batatas)

Residues of rejected roots and foliage (see Figure 199) can be used as supplementary feeds for cattle (Backer et al., 1980; FAO, 1992c: Ruiz et al., 1980, 1981). A study in Costa Rica demonstrated good liveweight gains with various combinations of roots and foliage (see Table 149) with highest liveweight gains being achieved where the ratio of forage to tubers was 50:50. Although it would not be economical to feed large quantities of good quality sweet potatoes to cattle, in the study reported by Backer et al. (1980) and Anon. (1980c) the residues from one hectare were enough to feed 5.5 young bulls weighing 200 kg for a 100 day period, with a weight gain of 710 g day-1, and so provide extra profit. Backer et al. (1980) concluded that the use of forage and waste tubers of sweet potato as livestock feed is economically attractive for small producers. Sweet potato haulms were fed to dairy cows with good results by O'Donovan (1970). In Cuba, Dominguez (1992) suggested that sweet potato tuber and vines could replace maize in pig diets.

Figure 199

Figure 199. - Sweet potato foliage after tuber harvest on the 2.0 ha model form, Zanzibar, Tanzania. Foliage was used for feed in the 5 cow unit (see Chapter 9, Section 9.5.11).

Table 149. - Weight gains of young bulls fed different combinations of sweet potato roots and foliage (Anon., 1980c; Backer et al. 1980)

Ration (% dry base)+Consumption
Kg DM 100-1 kg liveweight
Weight Gain
kg animal-1 day-1

+ The rations were given equal protein content (11% of raw protein) by the addition of urea.

6.6.10 Urea (non protein nitrogen or NPN)

Many pastures, especially during the dry season, have a very low digestible protein and total digestible nutrient level, a high fibre content and low palatability (Alexander, 1978; O'Donovan, 1978; Topps, 1972). Without protein supplements intake is low. Urea is the most commonly and widely used NPN supplement because it is relatively cheap (however, it is toxic if ingested rapidly by the animal in more than very small amounts). The principles of the use of non-protein nitrogen and by-pass proteins in the ruminant diet have been presented by Kempton et al. (1978) and Lossli and McDonald (1968). Kellaway and Leibholz (1983) reporting on the effects of nitrogen supplements on the intake and utilization of low quality forages concluded that dietary requirements for rumen-degradable nitrogen can be supplied entirely as NPN. However, supplements of NPN and proteins are equally effective in stimulating forage intake provided that intake of NPN is not too infrequent.

Reid (1953) reviewed the use of urea in cattle feeding and concluded that it could satisfactorily replace up to 25 percent of the total dietary nitrogen. A more recent review was carried out by Leng et al. (1977) and Butterworth (1985) presents details of studies conducted in different areas of the tropics. When O'Donovan et al. (1972) compared urea with soybean meal in concentrates for milking cows under zero-grazing conditions with urea supplying about 50 percent of total dietary nitrogen, 8 percent less milk was produced. Preston and Willis (1974) suggest that the maximum proportion of nitrogen that can be furnished by urea is about 30 percent. In many cases the decision to use NPN (particularly for feedlot operators) is an economic one, i.e. a cheap source of nitrogen may be preferable to expensive (often imported) protein for feeding rations.

Various studies have investigated the most appropriate level of daily supplementation with urea. According to Butterworth (1985) the most comprehensive experiment was carried out by Grant (1979) who indicated that the most efficient response was to 20 g head-1 day-1.

According to Guzman (1976) urea is usually fed on the basis of 1 percent of the total air dry matter or 2–3 percent of the concentrate mixture. In most cases it is designed to provide up to 30 percent of the total dietary nitrogen requirement. These levels may be raised provided that a palatable feed such as molasses is fed, with a high content of soluble carbohydrates. 1 kg of urea added to a ration is equivalent to 2.5 kg of crude protein, but it has no energy value. If urea is fed to excess it will prove toxic to cattle as can happen where lumpy urea is mixed with the ration or where the ration is carelessly mixed. Urea should be ground as finely as possible.

Alexander (1978) has reviewed the various methods of feeding NPN supplements:

Raleigh and Wallace (1963) obtained good growth responses in cattle when they supplemented mature meadow grass hay (5.5% protein level) with 1.6% urea. Alexander (1978) reported on a number of experiments where improved growth rates resulted from the use of urea. O'Donovan et al. (1972) compared milk yields with soybean meal and urea in concentrates for milking cows under zero-grazing conditions. Anon. (1983a) reported on a modified urea-molasses block used with tethered animals in India and Garg and Gupta (1993) used urea molasses mineral block licks as a supplement to a wheat straw-concentrate diet. A group of Jersey bulls fed straw plus concentrate plus urea-molasses blocks gained weight three times as rapidly as a group fed only straw plus concentrate, in addition, feed costs per each kilo gained were reduced by two thirds, from 9.3 to 3.7 rupees. In rice straw-molasses diets containing urea, it has been shown, for example, that for 20, 40 and 60 percent levels of rice straw inclusion, voluntary feed intake can be increased by between 41.3 – 47.5, 36.6 – 48.8 and 24.3 – 29.3 percent respectively (see Table 150). Rekib et al. (1970) reported on growth rates of cattle fed urea-supplemented and unsupplemented rice straw; research findings from Bangladesh (Saadullah et al., 1981 a-b) and South-East Asia (Jayasuriya, 1982; Wanapat et al., 1982) indicate that the nutritive value of rice straw is improved by more than 50 percent when ensiled, sprayed or stacked with urea.

The use of multinutrient blocks as a strategic supplement for ruminants (providing both fermentable nitrogen and by-pass nutrients) has been reviewed by Alam and Ghosh (1993), Combellas (1991), Habib et al (1991), Hendratno et al (1991), Leng et al (1991), Saadullah (1991), Sansoucy (1995) and Sansoucy et al (1988). Increasingly the cold process of manufacture is used at farm level, new binders such as clay have been used with low molasses content and blocks have also been used as carriers for anthelmintic medicines for control of internal parasites (Sansoucy, 1995).

6.6.11 Various oil cakes and meals as protein sources

There are a large number of by-products from tree crops which have a potential as animal feeds and especially as protein supplements (FAO, 1992b):

Castor (Ricinus communis) - a by-product meal is obtained from the oil extraction process, however, due to the presence of a toxic substance ricinoleic acid and allergens, castor seed has a limited use as a feed ingredient, although detoxification is possible by heat treatment (Hutagalung, 1981). The use of castor seed meal has been restricted to 5 percent in the total ration of ruminants (Robb et al., 1974).

Table 150. - Effect of urea inclusion on intake of rice straw (Devendra, 1979)

20% rice straw40% rice straw60% rice straw
DM intake (g day-1)341.8504.0483.0328.7499.2489.1302.4428.8376.0
Urea intake (g)-1.24.9-9.212.2-6.19.4
% increase in rice straw intake-47.541.3-48.836.6-29.324.3

Guar (Cyamopsis tetragondoba) - in spite of the presence of a residual gum and a trypsin inhibitor, guar meal has been used in balanced diets to produce liveweight gains of > 0.5 kg day-1 in growing calves (Sagar and Pradhan, 1975).

Kapok (Ceiba pentandra) - with cattle, supplementation of 40 percent kapok seed meal to a concentrate mixture produced satisfactory performance; beyond this level toxicity has been reported (Sahai and Kehar, 1968).

Mahua (Madhuca indica) - although mahua cake contains saponins which are not palatable, Ranjhan (1978) indicated that processes have been developed whereby mahua cake could constitute 50 percent of the concentrate mixture for crossbred calves.

Mango (Mangifera indica) - mango seed kernel has been used at a 20 percent level in concentrate diets for calves (Patel et al., 1971) and up to 40 percent level for working bullocks (Patel et al., 1972).

Neem (Azadirachta indica) - a rather unpalatable cake with a bitter taste and unpleasant smell (Hutagalung, 1981). However, it has been used in concentrate mixtures for dairy cattle in times of drought at inclusion rates up to 10 percent in India (Patil et al., 1975). According to Nath et al. (1983) water washing of neem seed kernel cake (and sun drying) increased its palatability and gave similar calf growth rates to a standard concentrate mixture. Reddy et al. (1993) indicated that water washed neem seed cake can replace concentrate mixtures up to 30 percent without any deleterious effect on the performance of crossbred dairy cows. Shukla and Desai (1988) noted that neem leaves are widely used as a dry season cattle feed in India and parts of Asia.

Pineapple (Ananas comosus) - pelleted pineapple bran incorporated into copra cake or palm kernel cake was used in Malaysia to fatten beef cattle (Mohd. Idris, 1981). The copra cake ration with 55% pineapple bran gave the best daily gains and feed efficiency.

Rubber (Hevea brasiliensis) - rubber seed meal with 25 percent crude protein has the major limitation of the presence of hydrocyanic acid, which can be reduced by heat treatment and storage (Devendra, 1981). In Kerala, India, feeding of the meal at 20 percent level has been found suitable for calves and lactating cows (Anon., 1976b) and Rajan et al. (1990) used rubber seed cake at 20 percent level (for 200 days) for fattening goats for meat without adverse effect.

Sal (Shorea robusta) - the sal tree is grown extensively in India as a source of timber and various experiments have been conducted on the utilization of sal seed cake by livestock. Although it has a high content of tannin, results from feeding cattle sal seed meal as part of a concentrate mixture showed that supplementation up to 30 percent did not adversely affect performance, but feed intake was depressed when fed alone or with molasses (Sonwane and Mudgal, 1974). Kurar and Mudgal (1972) reported that up to 30 percent sal seed meal and 2 percent biuret in the diet gave optimum growth and utilization in growing heifers. Shukla and Talapada (1973) concluded that up to 40 percent sal seed meal was optimum with hay and Napier grass in the diet of bullocks.

Tamarind (Tamarindus indicus) - by-products include kernels (15% crude protein) and hulls (9% protein). According to Hutagalung (1981), the kernels can substitute nearly all the maize component of concentrate mixtures for cattle, whereas the hulls can only replace maize up to 10 percent in the mixture (Reddy et al., 1977).

Tobacco (Nicotiana tabaccum) - Ranjhan (1978) indicates that tobacco seed oil cake can be incorporated into concentrate mixtures for dairy cows up to about 25 percent of the ration.

Although this chapter has reviewed possible supplementary feed sources and given examples of their use, it will be shown in Chapter 9 that their use by smallholders is usually in more complex combinations, with the small farmer using whatever resources are available at different times of the year. Thus in Luzon, Philippines, a study by Nagpala and Moog (1979) and Moog and Nagpala (1979) illustrates how livestock raised under coconuts are fed with indigenous plants growing in the plantations and supplemented with crop by-products. Cogon (Imperata cylindrica), Kulape (Paspalum conjugatum) and gabutin (Cyrtococcum acoresscens) were among the main feed items for cattle comprising 12– 20 percent of the feeds given especially during the months from June to December. More often these feeds were supplemented with utaw-utawan (Glycine sp.). Fresh corn stalks and corn stover constituted 52.7 percent of the ration during July to October. Acacia pods (Samanea saman), Kulotang bilog (Triumfetta semitriloka) and bagin-tubig, were also fed to fatteners. Centrosema pubescens was fed throughout the year (Argonosa, 1991).

Livestock raised under coconuts utilize forage from legume trees, leaves from madre de cacao (Glyricidia sepium), acacia pods (Samanea saman), stalk of coconut fronds and banana leaves as feed (Nagpala and Moog, 1979). Also Leucaena leaves and twigs are chopped and fed with rice bran water. Moog and Nagpala (1979) noted that a farmer raising crops on one ha. would have sufficient farm feed resources and herbage production year round to raise two heads of cattle. In the smallholder dairy development project of the Philippine Dairy Corporation (PDC) in the coconut growing provinces of Southern Luzon, farmers usually tether their animals in the coconut plantation during the day. Although in some cases no feed supplements are provided usually before or after tethering, the farmers provide the animals with crop by-products (such as corn stover, pineapple leaves, rice straw or banana peelings) or a concentrate made from copra meal, salt and rice bran (Arganosa et al., 1988). Trung et al. (1985) showed that dried poultry manure can be a good supplement to rice straw for dairy cattle from yearling to the end of the first lactation. Usually it comprised about 23 percent of the total ration. Sabutan et al. (1986) experimented with 98 percent molasses plus 2 percent urea for animals grazing under coconuts.

In Costa Rica (Van der Grinten et al., 1992), a survey of dairy farmers revealed that supplements used included molasses (58% of farms), brewer's grains (26%), banana peelings (11%), plantain pseudo stalk (5%) and king grass (42%).

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