Study on processing, storing and using sugar cane
leaves as ruminant feed

 

  Bui Van Chinh, Le Viet Ly, Nguyen Huu Tao, 
Nguyen Van Hai  and Tran Bich Ngoc

National Institute of Animal Husbandry, Hanoi 

                 

Abstract

Sugarcane leaves (SCL) were ensiled after adding 3% of “C” molasses (DM basis), sun-dried or treated with urea (4% DM basis). The apparent digestibility of the organic matter (in vivo) was 49.3% for dry SCL, 53.1% for urea-treated SCL and 55.9% for ensiled SCL, respectively. Feed intakes (kg DM/100kg liveweight) by mature local cattle were 1.59 for dry SCL, 1.76  for  urea-treated SCL and 1.98 for ensiled SCL. Ten crossbred heifers (Hereford x Local) (mean liveweight 160 kg) were allocated to:  ensiled SCL and control (hay), both fed ad libitum together with daily quantities of 0.37 kg rice bran, 2.4 kg cassava residues and 2 kg elephant grass. The experiment lasted 60 days. The daily weight gains were 590 g for SCL and  560 g for the control. The respective data for feed conversion (kg DM/kg liveweight gain) were 8.34 for SCL and 9.3 for the control.  Processing costs of the sugar cane leaves were lowest for ensiling.

Key words: sugar cane leaves, ensiling, cattle, growth, conversion

 

Introduction

Sugar cane (Saccharum officinarum) is one of the  tropical crops which has the highest biomass production (Brown et al 1987;  Alexander 1988;  Gohl 1993). The by-products when this crop is harvested and processed are the ‘tops’ (includes the growing point and the leaves) and molasses, all of which can be considered as important feed resources for ruminants in the tropics (Preston and Leng 1991; Golh 1993; Le Viet Ly et al 1998).  Much research has been done on the feeding value of sugar cane stalk, tops and molasses as ruminant feed (Preston 1988) but there are no reports on the feeding value of the leaves. 

 

In Vietnam, sugar cane is harvested mainly in the dry season which is a period of the year when there is a lack of the roughage for ruminants. According to statistical data in Vietnam, the cultivated area of sugar cane is over 250,000 ha. An increasing proportion of the sugar cane is now processed in modern factories, which means in practice that the entire plot of cane for any one farmer may be harvested in the space of one or two days. This makes it difficult to use the tops and leaves as feed unless some form of conservation is practiced.  As a result much of the tops are wasted on the field and burned so the ash can be used as fertilizer. According to Gohl (1993), the fresh sugar cane leaves account for 10-12% of the total sugar cane biomass. Thus in Vietnam, it is estimated that the total amount of this by-product is annually about 1.5 million tonnes. The sugar cane leaves have a high crude fibre content (40-42% of  dry matter), but are also rich is soluble carbohydrates. Therefore they are a potential feed resource for ruminants in the dry season. An advantage of  integrating ruminant production with sugar cane growing is the opportunity to recycle organic fertilizer (manure) to the soil and thus improve its fertility.

 

The following experiment was designed to compare different ways of conserving the fresh leaves of sugar cane.

 

Materials and methods

Ensiling of sugarcane leaves with “C” molasses

Sugar cane leaves were separated from the growing point and chopped into small pieces (3-4 cm) and mixed with “C” molasses at rates of: 1, 2, 3 and  8% (DM basis). The mixtures were ensiled in plastic bags (capacity ---? Litres) and opened after 30, 45 and60 days for determination of pH, acetic acid, lactic acid and butyric acid. 

Urea-treatment of  sugar cane leaves

Sun-dried sugar cane leaves (DM 75%) were chopped into small pieces and treated with urea at concentrations of 1, 2, 3, 5% (DM basis)

Rumen digestibility

The in sacco method (Ørskov et al 1980) was used to measure the rumen degradability of the ensiled and urea-treated leaves. Three local cattle (liveweight 200-215 kg) fitted with rumen cannulas were used for the incubations. They were fed on native grass ad libitum.

Study on apparent digestibility (in vivo)

Three mature local cattle (liveweight 200-220 kg) were fed dry sugar cane leaves (control), urea-treated cane leaves (4% urea) and ensiled sugar leaves with 3% molasses (on DM basis).  The design was a 3*3 Latin square arrangement with three feeds and three periods each of 10 days. Total collection of faeces was made on the last 7 days in each period.

 

Voluntary intake of ensiled and fresh sugar cane leaves for growing cattle

Four crossbred weaned calves (Hereford´Local) with body weight of 130 kg were allocated to two treatments:

·        ES: Ensiled sugar cane leaves

·        FS: Fresh sugar cane leaves

The sugar cane leaves were fed ad libitum and supplemented with 0.5 kg/day rice bran and 2 kg/day green grass. The experimental period was 24 days after which the treatments were reversed for a further 24 days.

 

Ensiled sugar cane leaves on cattle  performance

Ten crossbred heifers (Hereford´Local) were allocated to two treatments:

• ES: Ensiled sugar cane leaves
• Hay: Control fed grass hay

Animal on both treatments also received daily 0.37 kg rice bran, 2 kg Elephant grass and 2.4 kg cassava root waste. The experiment was carried out for 60 days. The animals were weighed every month and feed consumption recorded daily.

 

Results and discussion

Conserving sugarcane leaves by ensiling

 

Levels of molasses of 3% (DM basis) or more all produced silage of with acceptable pH and smell which was retained at least for 60 days (Table 1). The good silage quality with 3% or more of molasses was confirmed by the data for lactic and butyric acid concentrations (Table 2).

 

 

Rumen degradability of dry matter, organic matter and crude fibre was increased by ensiling the leaves with 3% or more of molasses.

 

Conserving sugar cane leaves by drying and urea treatment

 

 

After two weeks of treatment,. the leaves reacted with 1 or 2% urea were infected by moulds.  The most appropriate level on the basis of the rumen degradability data were 4 and 5% urea (DM basis) (Table 4)

Digestibility (in vivo) of processed sugarcane leaves

 

Although sugarcane leaves have a high fibre content (40-42%) the crude protein of 7.6-8.2% and NFE of 39.2-41.5% indicate that this byproduct is a potential feed resource for ruminants.

Dry matter intake, expressed as percentage of liveweight, and apparent digestibility coefficients were higher on the ensiled sugar cane leaves than on the dry leaves, with intermediate values for the leaves treated with urea (Table 6). Intake of the dry sugar cane leaves decreased with time (to 1 kg DM/100 kg LW) while the intake of the ensiled leaves increased, reaching a value exceeding 2 kg DM/100 kg LW (Figure 1).

Figure 1: Trends in voluntary intake by cattle of dry sugar
cane leaves and leaves ensiled with 3% molasses

 

Effect of ensiled sugar cane leaves on performance of heifers

A basal diet of ensiled sugar cane leaves, supplemented with small quantities of rice bran, cassava root residues and grass supported significantly better growth rates and feed conversion, than when hay was the basal roughage source (Table 7). Feed costs for the diet with ensiled cane leaves were only some 60% of those on the hay diet.

 

 

The cost of processing the sugar cane leaves was estimated to be 480, 520 and 370 VND/kg dry matter for drying, urea treatment and ensiling with molasses, respectively. By comparison the opportunity cost of rice straw was VND 600/kg.  Better animal performance and lower processing costs combine to make ensiling the preferred method of conserving the sugar cane leaves.

 

Conclusion

• Ensiling of sugar cane leaves with 3% of “C” molasses gave a feed with good keeping quality and was cheaper than drying or treatment with urea.
• Apparent digestibility of organic matter and fibre, and intake of dry matter, were significantly higher for ensiled compared with dry sugar cane leaves
• Crossbred local cattle fed ensiled sugar cane leaves supplemented with small amounts of rice bran, cassava waste and grass had daily weight gain of 590 g/day

Acknowledgements

We would like to thank SAREC who financially supported this study

 

References

Alexander A G 1988 Sugarcane; a source of biomass. Animal Production and Health Paper, FAO. Number: 72: 46-60.

 

Brown W F, Philips J D and Jones D B 1987  Ammonification or cane molasses supplementation of low quality forages.  Journal of Animal Science 64: 1205-1214

Gohl  1993  Tropical feeds.  Hanoi Agricultural Publishing house,  Page: 418-434

Le Viet Ly, Bui Van Chinh and Nguyen H Tao 1998 The study on using sugar cane by-products as ruminant feed. Information of Science and Technologies on Animal Production. Hanoi. No-4 . Pages: 1-6

Ørskov E R,  Hovell DeB F D and Mould F 1980. The use of the nylon bag technique for the evaluation of feedstuffs.  Tropical Animal Production. . Volume 5, Number 3: 195-213

 

Preston T R 1988 Sugar cane as animal feed; an overview.  Animal Production and Health Paper, FAO. Number: 72: 61-71.

Preston T R and Leng R A 1991 Matching ruminant production systems with available resources in the tropics and sub-tropics. Pp: 165-185. Agricultural Publishing House, Hanoi (in Vietnamese)

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