Sugar cane tops as a feed for goats; Effect of harvest season

Nguyen Thi Mui, T R Preston* and Dinh Van Binh

Goat and Rabbit Research Centre, Son Tay, Hatay, Vietnam
* University of Tropical Agriculture, Finca Ecologica, Thu Duc, Ho Chi Minh City, Vietnam

 Abstract

Two feeding trials were done to compare sugar cane tops with guinea grass as the main forage source for weaned goats in both the wet (July-December 1995) and dry seasons (January-May 1996). There were six groups (wet season) and five groups (dry season), each of 2 goats, on each forage source. The rest of the diet consisted of leaves of Trichanthera gigantea and Acacia mangium (wet season) or of Jack fruit (dry season). In both seasons there were additional supplements of a molasses/urea block and concentrate. For the wet season the trial began 25 July 1995 and ended December 1995; for the dry season the trial began in January 1996 and ended in May 1996.

 There was no significant difference in liveweight gain in the wet season between goats fed sugar cane tops and guinea grass. In the dry season, the growth was significantly higher for goats fed the sugar cane tops . Data for feed conversion showed a similar pattern with significant improvements in goats fed sugar cane tops compared with guinea grass in the dry season. Growth rates on sugar cane tops were 49% higher in the dry than in the wet season. The improvement for guinea grass in the dry season compared with the wet season was 25%. Feed conversion was better in the dry than in the wet season for sugar cane tops but the opposite was the case for the guinea grass.

Key words: Sugar cane tops, goat, guinea grass, growth, season

Introduction

Sugar cane top is a major by-product of the sugar industry which is often left in the field unutilized after harvest. The sugar cane top consists of 3 distinct parts: the green leaves (blades), the leaf sheath bundle and a variable amount of immature cane. The yield of tops varies considerably with variety, age at harvest, growing conditions and management practices. It accounts for 16-18% of the total biomass production, or about 28% of the weight of the stalk (Nguyen Thi Mui et al 1996a). Based on data for production of sugar cane (stalks)(Official Statistics 1994), it is estimated that there are some 1.7 to 2 million tonnes of sugar cane tops produced annually in Vietnam.

 In hilly land area, livestock depend heavily on sugar cane tops, especially in the winter season when the productivity of other species of grasses is lowest. Thus farmers are well acquainted with the use of sugar cane tops in the winter season but there is little experience of using this resource in the wet season. Preliminary data from our Centre indicated that sugar cane tops were better than Guinea grass as the roughage source for milking goats (Dinh Van Binh et al 1996).

 The following study was carried out to obtain more information on the relative feeding value for goats of sugar cane tops harvested during the wet and dry seasons.

 Materials and methods

The study was carried out at the Goat and Rabbit Research Centre in two seasons with 44 weaned goats. In the wet season, 24 goats (initial weight around 11.5 kg) were allocated to two treatments: CTL fed Guinea grass and SCT fed sugar cane tops. There were six groups each of 2 goats on each treatment. For the wet season the trial began 25 July 1995 and ended December 1995; for the dry season the trial began in January 1996 and ended in May 1996.

Sugar cane tops were collected each day from sugar cane harvested throughout the year (see Nguyen Thi Mui et al 1996b). The leaves were chopped by hand into 15-20 cm pieces; the growing point was split into two parts. Guinea grass was cut and collected daily from perennial plots and was fed long without chopping. Both roughages were offered 3 times per day at levels of about 150% of recorded intake. High protein foliage (Trichanthera gigantea and Acacia mangium) was fed in the wet season and Jackfruit leaves (Artocarpus heterophyllus) in the dry season. They were supplied 2 times per day plus supplementation with a multi-nutritional block and rice bran given once per day in the morning.

 Measurement were made daily of feed intake. The goats were weighed every fortnight and the study was ended when the goats had reached the stage when they could be sold for breeding.

Results and discussion

The composition of the feeds is shown in Table 1. Both sugar cane tops and guinea grass had a higher dry matter content in the dry than in the wet season. The tree foliages had a higher crude protein content and much less fibre than guinea grass. Sugar cane tops also had less fibre than guinea grass in both wet and dry seasons.

Table 1: Composition of diets (both crude protein CP and crude fibre CF are as % of DM)
	Wet season			Dry season
	DM	CP	CF	DM	CP	CF
Sugar cane tops	18	5	33.1	21	4.1	35.6
Guinea grass	17	12	37.6	19	12.5	38.8
T. Gigantea	13	15.2	16.8	nd	nd	nd
A. Mangium	30	17	nd	nd	nd	nd
Jackfruit leaves	nd	nd	nd	33	18	nd
MUB	65	28	65	28	nd	16.5
Concentrate	90	14	8	90	14	7.6

Growth rates and feed intakes of the goats in the wet and dry seasons are shown in Table 2. There was no significant difference in liveweight gain in the wet season between goats fed sugar cane tops and guinea grass (P=0.31). In the dry season, however, the results were in favour of the sugar cane tops (P=0.05). Data for feed conversion showed a similar pattern with significant improvements for goats fed sugar cane tops compared with guinea grass in the dry season (P=0.03).

Growth rates on sugar cane tops were 49% higher in the dry than in the wet season. The improvement for guinea grass in the dry season compared with the wet season was 25%. Feed conversion was better in the dry than in the wet season for sugar cane tops but the opposite was the case for the guinea grass.

Table 2: Mean values for live weight gain, feed intake and conversion for weaned goats fed sugar cane tops or guinea grass as the main forage source in wet and dry seasons
	Wet season			Dry season
	SCT	Guinea	SE/P	SCT	Guinea	SE/P
No of goats	12	12		10	10
Duration, days	93	93		96	96
Live weight, kg
Initial	11.5	11.7		12	12.6
Final	15.8	15.8		18.1
Daily gain, g	46.6	46.5	±0.6/0.31	69.9	58.0	±0.5/0.05
Feed intake, kg/day
SCT	1.22	0		0.75	0
Guinea grass	0	1.86		0	1.1
Total DM	0.47	0.53	±0.56/0.01	0.55	0.63	±0.41/0.01
N*6.25, g/day	54	77	±0.9/0.01	53.2	76.4	±0.6/0.01
Conversion*	12.8	14.7	±2.1/0.51	8.1	18.4	±0.8/0.02
* Feed dry matter/weight gain

Conclusion

It is concluded that:

• Sugar cane tops can replace guinea grass as the main forage source for growing goats
• Goats fed sugar cane tops in the wet season have the same weight gain and feed conversion as those fed guinea grass.
• In the dry season both weight gain and feed conversion are better for goats fed cane tops than for those fed guinea grass.

Acknowledgements

This study was supported financially by the International Foundation for Science through a grant to the senior author ((B/2291-1).

References

Dinh Van Binh and T R Preston 1995 Guinea grass or sugar cane tops supplemented with concentrates or Acacia mangium, molasses-urea blocks and rice bran for dual purpose goats. Livestock Research for Rural Development. Volume 7, Number 3:1-4

Nguyen Thi Mui, Preston T R, Dinh van Binh, Le Viet Ly and Ohlsson I 1996a Effect of management practices on yield and quality of sugar cane and on soil fertility. Livestock Research for Rural Development. Volume 8, Number 3:51-60

Nguyen Thi Mui, T R Preston, Dinh van Binh, Le Viet Ly and Ngo Tien Dzung 1996b Effect of planting season and type of fertilizer on biomass yield and quality of sugar cane. Livestock Research for Rural Development. Volume 8, Number 1:13-18

Official Statistics 1994 Ministry of Agriculture and Food Industry, Hanoi, Vietnam

Received 7 January 1997