Energy is the most costly component of livestock rations and an assured supply is basic to sustained and economic animal production. An FAO study group on meat, representing 61 Member Nations, in 1972 predicted major increases in demand and extremely large deficits in supply of meat, especially beef, by 1980. Recent substantial increases in meat prices are partly a reflection of shortages of energy and protein feeds.
In tropical areas, sugarcane (Saccharum officinarum L.) produces more energy/area than any other crop. Exceptional yields of over 100 long tons1 of whole-plant sugarcane/acre/ year (250 metric tons/hectare/year) can be obtained, and high yields of 75 long tons are not uncommon (Warnaars, 1973). Yields vary greatly with moisture, fertility and so on. In Barbados, average yields of wholeplant sugarcane are about 39 long tons/acre.
W.J. Pigden is Research Coordinator (beef cattle), Canada Agriculture, Ottawa, and CIDA representative on Advisory Committee, Barbados Comfith Project.
1 1 long ton = 1.01605 metric tons.
The digestible energy in sugarcane is stored in the stalk, mainly as sugars. As the plant reaches maturity more and more of the reducing sugars are converted to sucrose. After maturity the sucrose content declines, with a corresponding increase in reducing sugars; this lowers its value for sugar production but not necessarily for animal feed.
The major barriers to the exploiting of this energy by animals appear to be the hard protective rind, which prevents animals from having ready access to the pith, and the traditional view that sugarcane as a source of human food is too expensive for animal feed.
The invention of the cane separation process by Miller and Tilby in the early 1960s (Dion, 1972) opened the way for major increases in animal production based on fractionation of sugarcane. A simple machine called a cane separator splits the cane and separates the soft sugarpith from the rind. The derinded material is called comfith (cf), a trade name for derinded sugarcane. It is a sweet, creamy white substance with the consistency of damp sawdust. The process was originally developed for use in sugarmills.
In 1969 Barbados requested assistance from Canada to evaluate and develop comfith as a feed. The Canadian International Development Agency sponsored the project and in 1970 awarded a contract to Canadian Cane Consultants to carry out the necessary research and development in Barbados in collaboration with the Ministry of Agriculture. The Canadian Cane Equipment Co., Edmonton, supplied the machines. Dr. E. Donefer of MacDonald College, P.Q., Canada, acted as nutritional consultant and Mr. L. James as the project nutritionist. The programme was evaluated at the end of three years (Pigden, 1972).
1. The cane separation process, showing the production of the various fractions from whole sugarcane.
Fractionation of sugarcane by the separation process
In normal sugar production practice, yields are given as tons of sugarcane stalk per acre without considering the cane tops (ct) which are discarded in the field. The tops are valuable for feeding ruminants and should be included to give yield figures for whole-plant sugarcane. Whole-plant sugarcane yields can be estimated by adding 30 percent to cane stalk yields (Warnaars, 1973). Thus, one acre of sugarcane yielding 30 long tons of sugarcane stalk will produce 39 long tons of whole-plant sugarcane, an average figure for Barbados.
Processing the cane stalks through the separator, as illustrated in Figure 1, produces two fractions, comfith and rind. The rind, which comprises 15 percent of the cane stalk, is discarded as a feedstuff but can be valuable for many purposes (heat, energy, pressed board, paper products, mulch, cattle bedding, etc.). A third fraction is produced by processing the cane tops through a chopper (Figure 1). The chopped cane tops are added to comfith to give a mixed cf+ct fraction suitable for ruminants. For nonruminants, however, cf only is a suitable feed.
Several models of cane separators are now manufactured by the Canadian Cane Equipment Co. The smallest is a hand-fed two-stage machine with a capacity of about half a ton an hour. The canes are first split and then passed through the derinder. An intermediate machine has a minimum capacity of 4 tons an hour. A large, completely automated unit is under development.
Physical, chemical and nutritional characteristics of sugarcane and its fractions
The cf fraction is the major energy source. It includes the sugar storage cells (pith) and the fibrovascular bundles, but no top or rind. It is highly palatable and low in dry matter (about 30 percent); 50–60 percent of the dry matter is in the form of extractable sugar, mainly sucrose. It is very low in crude protein (about 2 percent) and is comparable to barley in its digestible energy content (about 68 percent). Because of its high sugar content it ferments readily and produces an acid silage. Comfith can be dried and pelleted (James, 1973; Donefer, 1973).
2. L. James (left), project nutritionist, and Dr. E. Donefer (right), technical consultant, showing freshly separated comfith and rind strips.
Although cf is fed without cane tops to nonruminants, the tops are normally combined with cf for ruminants in the same ratio as produced in whole sugarcane. The cf+ct mixture is higher in cellulose, somewhat lower in sugar and contains one third more crude protein (about 3 percent). The digestible energy content of cf+ct for ruminants is similar to that of cf. Ensiling produces an acid silage as for cf.
Rations based on cf or cf+ct must be supplemented with protein, minerals and vitamins. Because of the high soluble carbohydrate fraction of cf or cf+ct, urea can be included in supplements at high levels (60–80 percent of nitrogen requirements) for ruminants.
The rind fraction is high in lignin, cellulose and waxes, and would be expected to have a low feeding value similar to that of bagasse. In a fully integrated cow/calf operation the rind could be steamed after the method of Bender et al. (1970) to increase its digestibility and feeding value for cows. Direct experimental data are lacking on the feeding value of treated or untreated rind.
Comfith and comfith plus cane tops in animal rations
Because cf would normally be fed mixed with ct, the following data on feeding sugarcane fractions to ruminants are confined almost entirely to the use of cf+ct. Similarly, for nonruminants, data on the feeding of cf alone are given. All the animal trials referred to were carried out in Barbados.
Beef cattle and sheep
Friesian male calves and Barbados Blackbelly sheep were employed as test animals. The cattle, ranging from 225 lb (100 kg) to about 750 lb (340 kg) liveweight, were started on fresh cf-ct rations and fed for periods which varied from 45 to 250 days. The rations were fortified with protein, mineral and vitamin (PMV) supplement and urea to levels adequate for good feedlot performance. About 60 percent of the nitrogen was fed as urea. The remainder came from cf+ct and common oilseed meals or fish meal. Average daily gain for animals on cf+ct based rations was 2 lb (0.9 kg) (James, 1973: Donefer, 1973). Supplementing cf+ct with other energy sources, such as maize and molasses, increased average daily gain by as much as one third.
Meat quality was found to be excellent, and able to compete with high quality North American beef in the Barbados tourist trade.
3. Sugarcane in Guadeloupe, showing its enormous potential to capture and store solar energy as carbohydrates.
In the sheep trials, cf+ct rations resulted in up to 0.25 lb (0.11 kg) average daily gain and were shown to be satisfactory for fattening lambs. Ensiled cf+ct rations were less satisfactory than those based on fresh cf+ct. Silage dry-matter intakes and the growth rates of cattle and sheep were much lower than on fresh cf+ct. Methods of improving silage intakes have been investigated with some success (James. 1973).
Rapeseed meal was found to be a very satisfactory protein supplement for feeding with cf+ct.
Feeding trials in which cf+ct replaced 50 percent or more of the forage and concentrate in lactating dairy cow rations indicated that cf+ct rations can maintain milk production, normal milk composition and body condition (James, 1973). Considering all the current relevant information on ruminants, cf+ct is likely to be a satisfactory feedstuff for lactating cows and growing heifers.
4. Holstein-Friesian bulls eating a comfith and cane tops mixture with protein-mineral-vitamin supplements, and gaining 0.9 kg a day.
For fattening pigs, up to about 50 percent of concentrates can be replaced by fresh cf during the finishing period while maintaining growth rates of 1 lb/day (0.5 kg/day) or slightly more. The young pig is unable to utilize cf efficiently (James, 1973).
The effect on reproduction of feeding cf is not known, but it seems probable that fairly high levels could be utilized.
No problems in the use of cf in fresh or dried forms in swine rations have arisen other than the finding that high levels restrict feed intake. Meat quality was highly satisfactory from pigs fed cf rations.
The limited work done with poultry indicates that cf can be of some use for broilers and roasters, but may have a much larger place in rations for egg production where relatively higher levels of fibre can be tolerated. More work is needed before definite conclusions can be drawn (James, 1973).
Unique features of sugarcane and its fractions for feeding livestock
Self-storage and conservation in the field
Whereas cane for sugar production must be harvested within a limited period, as sucrose content peaks with maturity, cane for animal feed can be left standing in the field until needed (Warnaars, 1973). This selfstorage feature allows the production and maintenance of a uniform supply of energy without the problems of variable supply associated with conventional crop production in wet and dry seasons. It also eliminates costly conservation and storage requirements; in Canada, for example, storage capacity for about six months' supply of animal feeds is needed for the nongrowing season. Animal and feed management systems are greatly simplified by the self-storage feature of sugarcane.
Cut sugarcane can be stored for about a week without serious deterioration in quality.
The high yields of cf+ct/acre permit the development of large animal production units on small areas.
Efficient use of nonprotein nitrogen (urea)
Because most of the supplemental protein can be replaced by cheaper urea, cf+ct is particularly suited to beef, dairy and sheep production. The high soluble carbohydrate content of cf+ct virtually eliminates the toxicity risk of urea.
cf and cf+ct are easily ensiled
Although growth rates of cattle on ensiled cf and cf+ct have been relatively low, these feeds are simple and inexpensive to store for emergency use. Methods of stimulating silage intakes will undoubtedly be found.
Apparent lack of digestive problems
Throughout the feeding trials no bloat, acetonemia, acidosis, molasses toxicity or other digestive disorders were noted.
cf and cf+ct are low in protein, vitamin and mineral content, hence correct supplementation is essential for their efficient use as feeds.
Estimated costs of beef production from fractionated sugarcane
In estimating costs the following assumptions have been made:
Overall feed conversion of beef rations in the Barbados trials was about 10 lb total dry ration per lb of liveweight gain. The ration was approximately 80 percent cf+ct and 20 percent PMV supplement. For commercial production it is estimated that this ratio could be changed to 85 percent cf+ct and 15 percent PMV supplement. This can be achieved by increasing the urea in the supplement and reducing the fairly generous supplement safety factor incorporated into the experimental rations.
Based on 8.5 lb cf+ct/lb liveweight gain, 23 184 lb dry matter will give 2 728 lb of beef per acre. The PMV supplement requirements then become 2 728 × 1.5 = 4 092 lb.
Costs can be calculated as follows (in Canadian dollars):
|1.||Cost of 39 long tons of whole-plant sugarcane (based on $9.00/ ton for 30 tons stalk)||$270.00|
|2.||Processing costs at $0.001/lb for 77 280 lb fresh cf+ct (including overhead and operating costs)||77.00|
|3.||Cost of 4 092 lb PMV supplement at 7 cents/ lb||286.00|
|Total feed costs for producing 2 728 lb beef||$633.00|
Feed costs per lb of beef produced are therefore $633.00 ÷ 2 728 = 23.3 cents (current feed costs per lb of beef produced in Canada range from 35 to 40 cents).
Thus, in conclusion, it may be stated that feed costs for beef production on cf+ct are much lower than costs in North America. However, the proportionate cost of the PMV supplement is very high, partly because cf+ct requires substantial supplementation and also because costs are based on manufactured supplements. In many instances much of the supplementation could be provided more cheaply by local feedstuffs. For example, good quality alfalfa would provide most of the essential supplements.
Table 1. Yields per acre of sugarcane and its separated fractions1
|Cane fraction||Fresh||Yield per acre|
|Whole sugarcane||39.0||87 360||-|
|Carte stalk||30.0||67 200||-|
|Cane tops (ct)||9.0||20 160||-|
|Comfith (cf)||25.5||57 120||17 136|
|Cane rind||4.5||10 080||-|
|Comfith + cane tops (cf+ct)||34.5||77 280||23 184|
1 Based on a 30 long ton/acre yield of sugarcane stalk.
2 Based on 30 percent dry-matter content for cf and cf+ct.
Bender, F., Heaney, D.P. & Bowden, A. 1970. Forest Products Journal, 20(4): 36–41.
Dion, H.G. 1972. Animal protein no longer a “wasteful luxury.” Cooperation Canada, Sept./Oct. Ottawa, Canada. Information Division, Canadian International Development Agency.
Donefer, E. 1973. Comfith as an animal feed. Document, CIDA Seminar on Sugarcane as a Livestock Feed, Barbados, 30–31 January 1973.
James, L.A. 1973. Comfith in rations for livestock. Document, CIDA Seminar on Sugarcane as a Livestock Feed, Barbados.
Pigden, W.J. 1972. Evaluation of comfith as a commercial livestock feed in the Caribbean. Report prepared for the Caribbean Development Bank, Bridgetown, Barbados, and released for distribution to the CIDA Seminar on Sugarcane as a Livestock Feed, Barbados.
Warnaars, B.C. 1973. Growing of sugarcane as an animal feed. Document, CIDA Seminar on Sugarcane as a Livestock Feed, Barbados.