The purpose of the present study was to evaluate the use of leaves from the Jack fruit tree (Artocarpus heterophyllus), banana plants (Musa spp), Acacia mangium and Trichantera gigantea trees as supplements to a basal diet of rice straw and sugarcane tops, feed resources which are widely available in North Vietnam especially in the winter season. The leaves were fed to lactating goats which were allocated to the treatments from the 4th to the 12th week of lactation. From kidding until the end of the 4th week the goats were fed a standard diet of Guinea grass (Panicum maximum) supplemented with 500 g/head/day of a 15% protein concentrate. During the first two weeks the kids were always with the mother. At the start of the 3rd week the kids were separated and the does were milked once daily (07.00hr); the kids were allowed to suck for 30 minutes after milking in the morning and again in the afternoon (16.00hr) without prior milking of the dam. During the 4th week the yield was measured by weighing the milk produced at milking and by estimating the milk consumed by the kids by weighing them before and after suckling. The yield in the 4th week was used as covariate to adjust the yield during the experiment.

The highest milk yields were obtained from goats fed leaves from Jack fruit (765 ml/day) and Acacia mangium (736 ml/day) which did not differ significantly from each other. Both were superior to bananas (676 ml/day) while the Trichantera gigantea was the worst (571 ml/day). The does gained weight on the Jack fruit treatment (1.85 kg from 7 to 12 weeks) but lost weight (-1.24 to -2.2 kg) on the other treatments. The growth rates of the kids were lowest on Acacia mangium (14g/day) and ranged from 48 to 60 g/day on the other treatments.

It is concluded that a diet of sugar cane tops, molasses-urea block and leaves from the Jack fruit tree, with small amounts of rice bran (200 g/day) can be recommended as a basal diet for lactating goats and growing kids, especially during the dry winter season when grasses are in short supply.

The conventional feeding system for dairy goats in Vietnam is based on the use of grasses, natural and improved, supplemented with concentrates. In the North of Vietnam the dry winter season is difficult for forage production, as the natural pastures become dry and the improved grasses cannot grow. It is also important to find an alternative for the concentrates as these are becoming increasingly scarce and expensive because of competition from poultry and pigs. In view of this situation, research at this Centre is directed towards the development of alternative feeding systems which make use of local resources that are available the year round.

In contrast with grasses, sugar cane gives highest biomass yield and best quality (percent sugars in the juice) when harvested during the dry winter season. The multi-purpose tree Acacia mangium also grows better than other trees such as Leucaena leucocephala at this time. The leaves of Acacia mangium are of low degradability in the rumen of cattle (Bui Xuan An et al 1992). Despite this apparent limitation, it was found in an earlier study at this Centre (Dinh van Binh and Preston 1995) that sugarcane tops supplemented with a molasses-urea block, rice bran and foliage from Acacia mangium could replace the conventional diet of Guinea grass and concentrates with improvements in milk yield and growth of the kids.

Other sources of leaves which are available in the winter season are the Jack fruit tree (Artocarpus heterophyllus), banana plants (Musa spp) and Trichantera gigantea, a multi-purpose tree recently introduced from the coffee-growing areas of Colombia.

The purpose of the present study was to evaluate the use of leaves from the above trees as supplements to a basal diet of rice straw and sugarcane tops, feed resources which are widely available in Vietnam especially in the winter season.

The four treatments were the leaves of:

• Acacia mangium (AM)
• Bananas (BAN)
• Jack fruit (JF)
• Trichantera gigantea (TG)

Table 1: Content of dry matter in fresh samples and of protein(N*6.25) in the dry matter
	Dry matter	N*6.25
A mangium	31.7	17
Banana	22.5	13.8
Jack fruit	26.9	18.1
T gigantea	19.0	12.5
SC tops	21	4.5
MUB	74.5	31.6
Rice bran	87.6	13
Guinea grass	19.9	13
Concentrate	90.3	15
Rice straw	39	22.1

They were fed to lactating goats (n=20) of the Bach Thao, Barbari, Jamnapari and Beetal breeds (the last three recently imported from India).The goats were allocated to the treatments when they reached the end of the 4th week of lactation and continued on the experimental diets until the end of the 12th week of lactation.

From kidding until the end of the 4th week the goats were fed the control diet of Guinea grass (Panicum maximum) supplemented with 500 g/head/day of a 15% protein concentrate. During the first two weeks the kids were always with the mother. At the start of the 3rd week the kids were separated and the does were milked once daily (07.00hr); the kids were allowed to suck for 30 minutes after milking in the morning and again in the afternoon (16.00hr) without prior milking of the dam. During the 4th week the yield was measured by weighing the milk produced at milking and by estimating the milk consumed by the kids by weighing them before and after suckling. The yield in the 4th week was used as covariate to adjust the yield during the experiment.

From the beginning of the 5th week the experimental diet was introduced gradually replacing the standard diet over a period of 3 days.

The 5th and 6th week were considered as the "changeover" period and from 7 to12 weeks as "experimental" for evaluation of the diets.

The feeding levels during the experimental period were:

Tree leaves at 4% of liveweight (fresh weight)(eg: 2 kg leaves for a goat weighing 50kg); rice straw treated with urea (4 kg urea and 50kg water for 100 kg straw) ad libitum; sugar cane tops (5% of live weight); MUB ad libitum; rice bran (250 g/day/doe).

The liveweight of the does was recorded at the beginning of the experiment (day 43 from parturition) and at intervals of 10 days subsequently. Kids were weighed every 7 days. Feed offered and refused was measured daily. Samples of offered feeds were analysed for dry matter and nitrogen. Milk consumed by the kids was determined by weighing them before and after suckling.

Average milk yields during the "standard" period (week 4 used as covariate) and the experimental weeks 7 though 12 are presented in Figure 1 and in Table 2 together with the mean yield for weeks 7 through 12. The experimental data are "adjusted" yields after correction by covariance for yield in the standard period. Best results were with leaves from the Jack fruit tree and from Acacia mangium which did not differ significantly from each other. Both were superior to bananas while the Trichantera gigantea was the worst.

Table 2: Mean values for "adjusted*" total daily milk yield from week 7 to week 12 of lactation of goats fed leaves from Jackfruit, A mangium, bananas and Trichanthera gigantea as supplements to sugar cane tops and rice straw
Week	JF	AM	BAN	TG	SE/Prob
	------------g/head/day-------
4*	1275	1134	1170	1230	±26/0.001
7	848	806	760	613	±47/0.003
8	764	731	674	575	±36/0.002
9	779	748	618	555	±32/0.001
10	748	736	625	600	±27/0.001
11	857	778	754	571	±23/0.001
12	596	617	627	512	±21/0.001
Mean (7-12)	765	736	676	571	±25/0.001

* Used as covariate to adjust milk yields in weeks 7 through 12

The changes in weight of the does and the kids from week 7 to week 10 when they received the experimental diets are shown in Table 3. The weight changes of the does were mostly in line with results for milk yield, with the does fed Jack fruit leaves gaining 1.85 kg while those on the other treatments all lost weight the differences between the Jack fruit and the rest being significant (P=0.01). All the kids gained in weight with those on the Jack fruit, Acacia mangium and Trichantera gigantea showing normal growth (48-60 g/day) while those fed banana leaves had significantly lower growth rates (14 g/day).

Table 3: Changes in liveweight of does and kids fed sugar cane tops and rice straw supplemented with leaves of Jack fruit, Acacia mangium, banana and Trichanthera gigantea
	JF	AM	BAN	TG	SE/Prob
Does
Liveweight, kg
Initial	37.1	33.6	30.3	28.5	±3.0
Final	38.3	32.3	28.4	27.8	±2.7
Gain, kg*	1.85	-1.11	-2.20	-1.24	±0.70/0.01
Kids
Initial	8.36	9.01	7.08	8.24	±0.27
Final	12.2	11.3	10.8	11.1	±0.26
Gain, g/d*	48	14	58	60	±5.3/0.001

*adjusted by covariance for initial weight

The good results with Jack fruit leaves as the supplement are confirmed by the study of Keir et al (19Jack), also carried out at our Centre. The average growth rate of kids fed only foliage from Jack fruit plus molasses-urea blocks was 67 g/day, while kids fed foliage from Trichantera gigantea lost weight. Preliminary observations at the University of Agriculture and Forestry, in South Vietnam, of lactating goats fed only leaves from Jack fruit trees were that they had high voluntary intakes and that milk yield was sustained at pre-experimental levels (Rodriguez Lylian, 1996, personal communication)

Mean values for the intake of dietary constituents are shown inTable 4. Highest intakes of fresh leaves was for the Jack fruit treatment (1,640g/d), followed by bananas (1,100), then Trichantera gigantea 998) with lowest intake on the Acacia mangium (710). The goats ate very little of the urea-treated rice straw with highest intake (78g/d) on the TG treatment and lowest (25g/d) on BAN. Intake of sugar cane tops was similar on all treatments (1,100 to 1,450g/d). Most MUB was consumed by goats on the JF treatment (213g/d) and least on TG (120g/d). Intake of rice bran varied very little (217 to 237g/d).

• Leaves of the Jack fruit tree appear to be of superior nutritive value to all other leaves tested as a supplement to a low-protein, carbohydrate-rich diet as provided by sugar cane tops, rice straw and molasses-urea block. The leaves from Trichantera gigantea supported the poorest performance.
• A diet of sugar cane tops, molasses-urea block and leaves from the Jack fruit tree can be recommended as a basal diet for lactating goats and growing kids, especially during the dry winter season when grasses are in short supply.

This study was partially financed by the International Foundation or Science through a grant to Nguyen Thi Duyen (B/2357-1).

Received 10 September 1996