The hypothesis that was tested in this study was that sugar cane juice, mixed with boiled and macerated whole soya beans, and fed from a bottle fitted with a teat to simulate sucking, would be a suitable supplement for young kids reared by restricted suckling with partial milking of the dams. The experiment was done with 32 kids at the Research Centre and 30 kids on seven small scale family farms.

The cane juice and soya bean supplement increased daily liveweight gain by 55% on-station and 42% on-farm (from 34-35 g/day to 50-52 g/day). The soya beans represented 71% of the cost of the supplement and a cheaper alternative that can be produced easily on-farm is required to make the system attractive to farmers.

There is no tradition of production or consumption of fresh milk in Vietnam. The large ruminants are comprised of swamp buffaloes and the local "Vang" breed of cattle which are Bos taurus and similar to the "Chinese Yellow" breed. They are small and used for draught purposes and for meat. They are never milked. The goat population is also mainly of the meat type. They are small (about 20-30 kg mature weight) and as with the cattle are not used for milk production. In recent years attention has been focussed on the Bach Thao breed of goat which was developed originally during the Colonial period when "Alpine" and "Nubian" goats were introduced from France for crossing with the local breeds. The Bach Thea appears to have been selected from this crossbred population and is now a uniform and stable genotype of 35-45 kg mature liveweight, with "dual-purpose’ characteristics. It is usually black in colour with white markings along the back and on the head. It is found predominantly in the Ninh Thuan province in the Central Southern part of Vietnam.

The Bach Thao breed of goat was introduced to this Centre in 1992, when it was known as the Rabbit Research Centre. The name has since been changed to the "Goat and Rabbit Research Centre" to reflect the more diverse activities which the Centre presently undertakes.

The Bach Thao is now being promoted throughout Vietnam as a dual purpose breed that can give up to 1 litre of milk daily while raising the kids for meat or breeding according to a "restricted suckling" system of management (Dinh Van Binh and Preston 1995).

With the restricted suckling system there is need for extra feed supplementation of the kids to compensate for the milk taken for human consumption. In industrial countries, where there is usually a surplus of milk and milk products, such supplements are made from skimmed milk powder and vegetable oils which are reconstituted on the farm to simulate whole milk. This technology is not feasible in almost all developing countries where milk products are in deficit and have to be imported.

Sugar cane is grown commercially or at household levels in most tropical countries. The juice which is composed predominantly of sucrose with smaller quantities of reducing sugars, is easily expressed from the stalk using simple 2- and 3-roll mills and is frequently consumed as a drink or is made into "brown" sugar at household level. As sucrose can be digested by enzymes secreted into the small intestine, it can theoretically be utilized efficiently in ruminants by offering it from a bottle fitted with a teat, under conditions which favour efficient closing of the oesophageal groove, thus ensuring that the juice passes directly to the abomasum (rskov 1983). These conditions are induced by a state of psychological satisfaction as is the norm when the young ruminant sucks directly the milk from its mother. The "satisfaction"can also be simulated if the young ruminant is trained to associate the "drinking" with a feeling of excitement which stimulates the closing of the oesophageal groove. Sugar cane juice is very palatable and it has been observed (Dinh Van Binh, personal observations) that young goat kids become very excited and obviously "enjoy" sucking the juice through a teat attached to a bottle.

In contrast with lactase, needed for the digestion of lactose (milk sugar), little sucrase is secreted in the young ruminant but it appears to develop in the presence of the substrate. Young calves are know to secrete sucrase, the enzyme needed to digest the sucrose which is the predominant nutrient in sugar cane juice. But there appear to be no data on goats.

Sugar cane juice contains almost no protein (1% in the dry matter) and no lipids. Whole soya beans contain mainly protein and oil and would appear to be the most suitable supplement to complement the carbohydrate in sugar cane juice.

The hypotheses that were tested in this study were that:

• by introducing the sugar cane juice gradually to young goat kids, there would be opportunity for the sucrase enzyme to develop as a response to the presence of increasing quantities of the substrate (the sucrose).
• Whole soya beans, after toasting, grinding and mixing with the sugar cane juice would be used efficiently by young goat kids.

The experiment was carried out at the Goat and Rabbit Research Centre and on small scale farms where goats were raised commercially.

The Goat and Rabbit Centre is situated in Hatay province in North Vietnam. The mean ambient temperature is 23.3 ºC and the humidity 83%. Annual rainfall is over 1800 mm. There are two main seasons: the cool winter season and the hot summer with the rains concentrated in the summer.

The goat herd is composed primarily of the Bach Thao breed but recently there have been importations from India of Barbari, Jamnapari and Beetal breeds. Feeding is with a variety of local forage resources (guinea grass, elephant grass, Leucaena, jackfruit, Canada bean, mulberry) supplemented with concentrates. Milking is practised with the majority of the goats and is by hand once daily with restricted suckling after milking and suckling again in the afternoon (without milking).

Thirty two goat kids were allocated at six weeks of age to two treatments: the standard system used in the Centre (control) and the experimental treatment which received in addition sugar cane juice, mixed with boiled ground whole soya beans, fed by teat from a bottle. The experiment was done in three periods corresponding to blocks: there were 5 kids per treatment in block 1 (Februay to April 1995), 6 kids per treatment in block 2 (July to September 1995) and 5 kids per treatment in block 3 (from January to March 1996). The kids were kept in individual cages.

All the kids were suckled by their mothers for a 15 minute period following milking in the morning and again in the afternoon without milking. When milk consumption by suckling was very low it was supplemented with milk taken from a bottle and teat so as to provide about 100 ml of milk per day. The kids had free access to: a mixture of grasses (guinea grass and elephant grass) and tree leaves (Acacia mangium, Jackfruit, Trichantera gigantea, Flemengia congesta, Mulberry and Leucaena leucocephala, according to availability); and a molasses-urea block. A concentrate mixture was fed at 50-100 g/day.

The sugar cane juice was prepared daily using a buffalo-drawn 2-roll crusher. Extraction rate averaged 50% (kg of juice from 100 kg stalks) and the ?Brix (dissolved solids) of the juice varied from 18 to 19%. Whole soya beans were boiled with the sugar cane juice for 30 minutes in proportions of 25 kg air dry beans (85% dry matter) and 75 kg juice (19% dry matter) and after slight cooling were homogenized in a hand-driven stone grinder used traditionally for preparation of soya cake. The resulting mixture was fed at room temperature from a "baby’s" feeding bottle fitted with a teat.

At the beginning of the trial (6 weeks of age) the quantities offered were 30-50 ml divided in two feeds daily, given about one hour after suckling. Every 3 days the quantities were increased by 50 ml/day until a maximum of 200 ml was reached; from 14 to 20 weeks the quantities were increased again to a maximum of 300-500 ml daily according to the ability of the kid to digest the supplement. For example, when liquid faeces (diarrhoea) were seen the quantities of juice/soya bean were reduced until normal faeces were again observed.

The liveweights of the kids were recorded every 10 days. Feed intakes were measured daily by subtracting residues from the amounts offered. Samples of feeds were taken at intervals for determination of moisture and nitrogen using standard methods.

The same treatments as in the on-station trial were applied on each of seven small scale farms that were producing goats commercially. The procedures and measurements were the same except that choice of the basal diet varied according to the resources available on each farm. The numbers on each treatment ranged from 2 to 3 on each of the farms with a total of 30 animals in the trial. Most of the farmers prepared the sugar cane juice and soya bean mixtures on their farms but occasionally it was provided by the Centre.

Mean values for initial and final liveweights and daily growth rates (calculated by linear regression of weight against time on the trial) for the on-station trial are presented in Table 1. Feed intakes are presented in the same table.

Table 1: Mean values for growth and feed intake of goat kids given sugar cane juice and boiled soya beans (SCJ) by simulated suckling (bottle with teat)(100 day trial)
	Cont.	SCJ	SE/Prob
Liveweight, kg
Initial	6.5	6.5	±0/56/0.97
Final	9.6	11.5	±0.51/0.01
Daily LW gain, g/d	33.7	52.2	±2.9/0.001
Milk (fresh basis), g/day
From mother	21.7	8.6	±3.8/0.023
From bottle	78.8	85.4	±4.9/0.36
Total milk	101	93.9	±2.8/0.11
SC juice, g/day	0.00	280
Soya bean, g/day	0.00	60
Feed DM intake, g/day
Grass	28.9	29.8	±3.4/0.85
Foliage	68.9	61.2	±11/0.61
MUB	33.3	31.9	±1.5/0.27
Concentrates	13.6	19.4	±1.1/0.001
Total dry matter	153	224	±12/0.001
Conversion of DM	4.89	4.71	±0.35/0.72

The kids fed sugar cane juice and boiled soya beans grew almost twice as fast as those on the control diet. They consumed more total dry matter mainly due to the additional nutrients in the sugar cane juice and the soya beans. Digestive upsets were not a problem with the kids during the experimental period and the few cases of mild diarrhoea were easily controlled by reducing the amount of cane juice and soya beans that were offered.

The data obtained on the seven farms are summarized in Table 2. The growth rates on both the control and sugar cane juice treatments were similar to those on-station and were significantly higher (by 42%) for the goats that were supplemented with the mixture of sugar cane juice and soya beans.

Table 2: Growth and feed intake of goat kids given sugar cane juice and boiled soya beans by simulated suckling (bottle with teat) (mean values for 7 farms)
	Control	SCJ	SE/Prob
Liveweight, g
Initial	8.05	8.13	±0.88/NS
Final	16.4	19.3	±0.51/0.02
Daily gain	35.1	49.7	±3.5/0.01

The significant increase in growth rate due to supplementation with sugar cane juice and soya beans (55% on-station and 42% on-farm), together with the absence of digestive upsets, indicates that both the sucrose in the cane juice and the protein and oil in the soya beans were utilized efficiently.

It was calculated that the cost of the mixture of soya beans and sugar cane juice was VND 1,150/litre of which VND 1,100 (61%) corresponded to the soya beans. Thus 341 g of the mixture fed daily would cost VND 392 which would be covered easily by the value of the additional 18.5 g daily gain which was VND 648 (VND 35,000/kg liveweight). However, the labour cost would be a factor on-station but perhaps not so on-farm. The need obviously is to find a cheaper alternative protein source to replace the soya beans.

• Young goat kids between the ages of 6 and 20 weeks utilized efficiently a mixture of sugar cane juice (75%) and boiled soya beans (25% of air-dry beans) fed by teat from a bottle in quantities increasing from 50 ml/day to a maximum of 500 ml/day at 20 weeks.
• The cane juice and soya bean supplement increased daily liveweight gain by 55% on-station and 42% on-farm (from 34-35 g/day to 50-52 g/day)
• The soya beans represented 61% of the cost of the supplement and a cheaper alternative that can be produced easily on-farm is required to make the system attractive to farmers.

The study was financed partially by the International Foundation for Science through a grant to the senior author (B/2357-1).

rskov E R 1983 The oesophageal groove reflex and its practical implications in the nutrition of young ruminants.In: Maximum Livestock Production from Minimum Land (editors: C H Davis, T R Preston, M Haque and M Saadullah) Bangladesh Agricultural University, Mymensingh pp47-53

(Received 1 September 1996)