Saccharum officinarum

Bagasse

A distinction must be made between sugar-factory bagasse and the residual pressed cane stalk from small-scale panela production or cane fractionation for animal feed. The latter material has a much higher residual sugar content and hence feeding value for ruminants. 

FACTORY BAGASSE 

The fibre which leaves the last processing stage of the sugar mill contains roughly 50% moisture and 1.5-4% sucrose. It is passed through rotary sieves to remove fine particles (bagasse pith or bagacillo) which may be used as a filter aid later in the process. Much of the bagasse is then fed to the boiler furnaces where its heat of combustion provides the energy required for the operation of the factory. The surplus may be used in ancillary industries including the manufacture of compressed fibre board and paper. Many older boilers in sugar mills operate at less than 50% efficiency and there is scope for increasing the availability of bagasse for other uses besides fuel. 

Bagasse and bagasse pith are often used as fillers in compound diets and as carriers for molasses or molasses-urea mixture. Camola, one of the more common mixtures, consists of four parts bagasse pith and ten parts cane molasses. Molascuit contains more molasses than any other mixture. It is made by mixing pith with an excess of hot molasses, after which the mixture is centrifuged. The proportion of pith to molasses in molascuit is 1:6.25 by weight. 

The low digestibility, high lignin (>20%) and very low nitrogen content of raw bagasse limit is value to low level of inclusion in feeds. In order to overcome these limitations in nutritive value of bagasse and bagasse pith, various methods have been tried including: 

-	predigestion by chemical and physical methods, and
-	mixing readily available sources of carbohydrate (molasses)
	and nitrogen or protein

Chemical treatments include alkalis (sodium hydroxide) and ammonia (gas) or as urea. In order to convert urea to ammonia, a source of urease may be necessary for this more inert fibrous residue. The ground seed of jack-bean (Canavalia ensiformis) is being used commercially for this purpose in Colombia [Preston]. 

One method of treatment to increase digestibility which appears to have application on an industrial scale is the use of steam at high pressures. This is particularly appropriate at the sugar mill where there is usually surplus steam and the necessary technical knowledge and equipment are also available. 

Some of the original research on steam treatment of sugarcane bagasse was done in Mauritius (Wong et al., 1974, quoted in 576). Treatment of bagasse with high pressure steam (14 kg/cm ) for 5 minutes raised dry matter digestibilities from 28% to 60% (rumen nylon bag method, 48 hr incubation). Experiments in Colombia, using a diet of steam-treated bagasse, supplemented with 2-3 kg per 100 kg live weight of Gliricidia sepium foliage and 1-2 kg or ad libitum molasses/urea (10%) mixture, produced ADGs of 0.55-0.75 kg/day in Zebu steers [593]. There were no significant effects of the different levels of supplements. Ammoniation of the steam treated bagasse had a negative effect on ADG. 

Cuban sugar factories are set up to process bagasse pith for animal feed. A mixture of 60% bagasse pith, 34.6% final molasses, 2% urea, 0.2% salt and 3.2% water is made. The molasses-urea-bagasse pith must be fed within 36 hours. Now many plants are being converted to sodium hydroxide treatment of the pith which improves the digestibility and reduces the amount of molasses needed. 12 per cent NaOH solution is mixed for 5 minutes with the pith before adding molasses-urea (10%). The NaOH treatment is reported to improve digestibility from 20 to 50% [594]. The material is used as a roughage for milk production during the dry winter months when pastures are poor. 

RESIDUAL PRESSED CANE STALK 

This material (the product of on-farm or small factory cane fractionation) differs from factory bagasse because of the lower rate of extraction (50% v 70%) and therefore contains much higher levels of sugar. It is therefore a far more valuable feed for ruminants. It will normally be used fresh for feeding to draught animals, dual purpose/low yielding cows or finishing cattle. (Alternative options for using this material are for charcoal production and conversion to producer gas for fuel). 

A highly promising development is the use of the pressed cane stalk as a basal diet for small ruminants. If the freshly pressed stalk is offered to goats, they consume avidly the sugar-rich pith and discard the lignified rind. In studies in the Dominican Republic, goats on a mixed diet of pressed stalk and fresh Gliricidia sepium foliage selected and apparently preferred the pith to the green foliage [Mena, unpublished; quoted by Preston]. It should be fed in a way that permits selection, e.g. by giving 200% of the expected DM intake. 

Because of the low nitrogen content, it should be supplemented with molasses-urea, rice polishings, cottonseed cake, or some other bypass source, and green foliage such as legume tree foliage. 

					As % of dry matter
				DM	CP	CF	Ash	EE	NFE	Ca	P	Ref
Bagasse, Cuba				99.2	1.0	50.1	2.5	0.3	46.1			142
Bagasse pith, Cuba				87.8	1.7	45.1	2.5	1.5	49.2	0.39	0.04	"
Rumen DM degradability (in sacco): 48 hours
Raw bagasse (basal diet hay)									36.3			595
Raw bagasse (basal diet bagasse)									35.7			"
Raw bagasse (basal diet STB)									17.3			"
Steam-treated bagasse (STB) (basal diet hay) 69.0												"
STB (basal diet raw bagasse)									67.8			"
STB (basal diet STB)									47.9			"

References

142, 576, 591, 592, 593, 594, 595