Whole sugarcane may be used as green forage and can provide a valuable dry season fodder. It is preferably established in a compact area (approximately 1 ha per 30 head of mature cattle) and fed off each year; the entire stand being replaced every seven to ten years. It can be used for fattening cattle and as the basal forage for dual purpose and low-yielding dairy cows (less than 10 litres/cow/day).
It is better chopped for feeding, using slowly revolving chaff cutters, high speed disintegrators with knoves and beaters or using a forage harvester. There is little effect of processing method on nutritive value. [Preston] As soon as the cane is chopped, the sugars begin to ferment into alcohol and organic acids, which tend to have a negative effect on animal performance. Thus it is important that the chopped cane be consumed by animals with a minimum delay.
In a 1983 survey of the Campinas county of Sao Paulo State in Brazil, 70% of the farms had sugarcane as green stock [Caielli]. It covered 1.3 ha of an average area of 123 ha. The amount given per animal per day averaged 14 kg (9.9-17.6 kg) and was fed with protein supplements such as cottonseed meal or soyabean meal, or sometimes supplemented with urea or rice polishings.
Feeding trials have also been conducted in India with crossbred cows producing 10-12 kg per day [Rangnekar], with an average intake of sugarcane of 20.5 kg per day. It was found that, by harvesting cane at shorter intervals of 6 months, a more leafy material and fairly high yields (c. 200 t/ha) could be obtained.
High and low fibre varieties showed no difference in animal performance [Pate]. In feedlot trials, live weight gain and animal performance declined when chopped sugarcane comprised greater than 20-30% of DM, where the remainder of the diet was ground corn, cottonseed meal and minerals.
(Attempts were made in the early 1970's to derind sugarcane, using the fibrous material for paper or board manufacture and the residual pith for animal feed. This system has been abandoned as not commercially viable because of the high investment and operating costs of the equipment. For ruminants, whole chopped sugarcane has proved to have almost the same potential as the pith and the technology required is much simpler and cheaper).
Correct supplementation is the key to animal productivity on sugarcane. The principles are well established and based on:
- satisfying the needs of rumen microbes for fermentable nitrogen (ammonia), trace nutrients (peptides, amino acids, minerals and vitamins) and the physical attributes of an efficient rumen ecosystem (small quantities of readily fermentable fibre).
- sources of protein, glucose precursors and long chain fatty acids able to bypass (or escape) the rumen fermentation so that the available nutrients are balanced according to the needs of production.
- feeds and/or chemical substances capable of manipulating rumen fermentation so as to:
- increase propionate relative to other VFAs
- eliminate (or reduce) protozoa in the rumen
Optimum levels of rumen ammonia appear to be provided by the equivalent of 30 g urea per kg sugarcane DM. [Preston]. Trace nutrients for the rumen microbes and the physical attributes of a good rumen ecosystem are conferred by highly digestible green forages such as sweet potato tops and foliages from legume trees such as Leucaena at rates of about 600 g DM / 100kg LW.
Rice polishings have proved to be the best sources of by-pass nutrients because of their richness in essential amino acids, starch and lipids. The most economic rate is 500-1000 g per day. However, other supplements have given good results (e.g. cottonseed cake, maize/fishmeal concentrates). An important point is that these various types of supplements which act in the rumen or as bypass nutrients interact so that neither urea nor rice polishings was effective when given alone, yet they had a dramatic effect on animal performance when given together.