Supplementing rice by-products with foliage of Trichanthera gigantea in diets of growing and lactating pigs and fattening ducks

Nguyen Thi Hong Nhan and Nguyen Van Hon

Department of Animal Husbandry, College of Agriculture, Cantho University, Vietnam

Abstract

The growing and utilization of Trichanthera gigantea by farmers in the Mekong delta has increased rapidly since the introduction of the tree in 1991.  From the three stem cuttings imported in 1991 it is estimated that the trees are now grown and used by more than 1,000 farmers in South Vietnam.  

Experiments were carried out with lactating sows, growing-fattening pigs and fattening ducks to evaluate the use of the fresh leaves of Trichanthera gigantea  as a supplement to traditional diets based on rice bran and broken rice. The experiments with pigs were done in the homesteads of collaborating farmers who already were growing and using Trichanthera gigantea as feed. The experiment with ducks was done on a private farm close to Cantho University. 

Average intakes of fresh leaves were:  4.2 and  3.6 kg for lactating sows (Large White *  Baxuyen [local]) and fattening pigs (same type of crossbred) equivalent to 130 and  112 g/crude protein/head/day, respectively.  Performance (litter size and weights for the sows and growth rate of fattening pigs) was the same on diets with and Trichanthera gigantea. Pigs offered Trichanthera gigantea leaves ate less concentrates than the controls and feed costs were significantly lower.

For the experiment with Muscovy ducks (age range 30 to 90 days) , fish meal or soya bean were omitted from the concentrate (the control diet contained 10% of each)  when T gigantea . leaves were fed.  Average intakes of leaves were 61 g/day  for ducks fed the diet without fish meal  and 66 g/day when the soya bean meal was omitted. Concentrate intakes were similar on all diets as was growth rate.  Feed costs were lower for both diets containing Trichanthera gigantea. The skin and fat of the carcasses of ducks fed Trichanthera gigantea leaves were more pigmented (yellow rather than white) a characteristic appreciated by local consumers.

Comparing results with reports from the Cauca Valley in Colombia, from where the Trichanthera gigantea originated, it appears that nutritive value was higher for the Trichanthera gigantea grown in the Mekong delta.  It is suggested that the ecosystem in the delta (1,200 to 2,000mm rainfall and high humidity) was more favourable for rapid growth of the Trichanthera gigantea (resulting in higher nutritive value) than the ecosystem in Colombia (less than 1,000 mm rainfall and lower humidity).

Key words: Trichanthera gigantea, lactating pigs, growing pigs, fattening ducks, nutritive value

Introduction

The multi-purpose tree Trichanthera gigantea was introduced as stem cuttings to Vietnam from Colombia in 1991 as a potential source of feed for livestock. The growing and utilization of Trichanthera gigantea by farmers in the Mekong delta has developed rapidly since that time.  A television programme showing the farmers growing and using Trichanthera gigantea led to requests for seed material from more than 200 farmers and representatives of Government extension services (Nguyen Thi Hong Nhan, unpublished data).  It is estimated that more than 1000 farmers have introduced the tree into their home gardens and are using it to feed all classes of livestock, and that the impact of the technology is increasing.

Early work was concerned with methods of establishment of the cuttings. Mature brown stems had higher germination rates than immature green stems; there were no advantages from initial planting in plastic bags in the nursery compared with direct planting in the field (Nguyen Thi Hong Nhan 1998). An important advantage in biomass production was noted when the Trichanthera gigantea was grown under partial shade provided by banana trees (Nguyen Thi Hong Nhan et al 1997). The application of this latter observation under farm conditions, with shade provided by bananas and jackfruit (Artocarpus heterophyllus) trees, showed a doubling of biomass production when Trichanthera gigantea was grown in the shade as opposed to full sunlight (Nguyen Thi Hong Nhan 1998). This farm trial attracted the attention of many farmers in the area who quickly observed the ease of establishing the tree and the fact that the leaves were readily consumed by pigs, ducks, chickens and goats (Nguyen Thi Hong Nhan, unpublished observations).

The following experiments were set up to document the effects of using the fresh leaves of Trichanthera gigantea to supplement rice bran and broken rice which are local feed resources used traditionally by farmers in the Mekong delta for their pigs and poultry.

Location

The study was done in the Mekong delta in SE Vietnam. As the name indicates the area is close to sea level and is intersected by many rivers and canals. The average rainfall is between 1,200 and 2,000 mm, the average temperature 30 ºC and the humidity in the range of 80 to 90%. Acid-sulphate soils (pH 4.3-4.7; organic matter 1.6 to 2.6%) predominate in the area.

Experiments were carried out with:

• Lactating sows 
• Growing-fattening pigs
• Fattening ducks

The experiments with pigs were done in the homesteads of collaborating farmers in a village some 10 km from Cantho, who already were growing and using Trichanthera gigantea as feed. The experiment with ducks was done on a private farm close to Cantho University.

Experiment 1: Trichanthera gigantea for lactating sows

Materials and methods

The experiment was started in October 1997 and finished in June 1998.The treatment comparisons were between the control diet based on rice bran and broken rice, and the same diet supplemented with fresh leaves of Trichanthera gigantea. Twelve farmers participated in the experiment. In two households there were 2 pigs on each treatment while in the remaining ten households there was one animal on each treatment. The pigs were crosses of Large White with the local "Baxuyen" and had farrowed for the first time at the time of starting the experiment. During gestation all the pigs had received the control diet without Trichanthera gigantea. The composition of the control diet (% air-dry) was: rice bran 45, broken rice 45, "local" fish meal from the market (35-40% protein) 10%. It was offered ad libitum in three feeds daily.  Foliage of Trichanthera gigantea (leaves and green stems) was harvested daily from trees in the home garden established one year previously and subjected to regular (every 2 months) harvesting. It was offered ad libitum in 3-4 feeds throughout the day, fresh foliage being harvested on each occasion. Samples of Trichanthera gigantea foliage and the concentrate mixture were taken at the beginning and end of the trial for analysis. The samples of Trichanthera gigantea were immediately oven-dried (105 ºC) for 24 hours and stored until blended for analysis for nitrogen (AOAC 1985). The samples of concentrate were also blended for analysis of nitrogen. Analytical data are in Table 1.

Table 1: Content of dry matter and protein (N*6.25) in fresh samples of Trichanthera gigantea and the concentrate
	Dry matter, %	N*6.25 in DM, %
Trichanthera gigantea foliage	14.7	20.8
Trichanthera gigantea leaves	16.4	21.7
Trichanthera gigantea stem (green)	11.5	16.4
Concentrate	89.0	12.2

Records were taken of numbers and weights of piglets at birth and at weaning (56 days). Amounts of feed offered were recorded daily.

Results and discussion

The fresh leaves were eaten avidly by the sows with average intakes of 4.22 kg/day providing 0.62 kg of dry matter and 0.130 kg/day of crude protein. There were no differences in size and weight of the litters at birth and at weaning between sows fed the control diet or the diet with supplementary Trichanthera gigantea leaves (Table 2). However, the sows offered Trichanthera gigantea consumed less (P=0.02) concentrate than control sows. As a result the feed cost was less (P=0.02) for the sows eating Trichanthera gigantea.  Protein intakes were similar on both diets. Trichanthera gigantea contributed 24% of the protein in the experimental treatment.

Table  2 :  Mean values for performance of litters of pigs from sows  fed concentrates (rice bran and broken rice) with or without Trichanthera gigantea
	Control	Trichanthera gigantea	SEM	Probability
At birth
Number	11.7	11.5	0.497	0.82
Litter wt, kg	15.8	15.0	1.18	0.65
Piglet, kg	1.37	1.30	0.111	0.65
At weaning
Number	11.2	10.5	0.373	0.24
Litter wt, kg	150	136	13.3	0.47
Piglet, kg	13.3	13.0	1.13	0.85
Weight gain, kg/day	0.22	0.22	0.019	0.85
Feed intake, kg/day
Trichanthera gigantea, fresh             "                 "       , (dry)	0	4.22 (0.62)
Concentrate	4.46	3.47	0.24	0.02
CP from conc.	0.54	0.42	0.029	0.02
CP from TG	0	0.13
CP total	0.54	0.55	0.029	0.001
Feed costs, VND
Feed	8480	6590	455	0.02
Per piglet	3964	3482	417	0.43

There appear to be no reports in the literature on the feeding of leaves of Trichanthera gigantea to lactating sows.  Sarria (1994) fed fresh leaves of Trichanthera gigantea together with soya bean meal (or cooked soya bean seeds) to sows during gestation receiving sugar cane juice as the energy source. There were no differences in litter size or weight between the control sows (receiving only soya bean as protein source) and those supplemented with Trichanthera gigantea.  The Trichanthera gigantea was fed ad libitum while the soya bean was restricted so that total protein intake was about 150 g/day.  Under these conditions the sows ate from 1.3 to 1.5 kg daily of Trichanthera gigantea leaves, which represented about 30% of the total protein intake.  In the present experiment with lactating sows the intakes of Trichanthera gigantea were much higher (average of 4.22 kg/day) but the proportion of diet protein in the form of Trichanthera gigantea was a little less (about 24%).  From the farmer standpoint, the important result was the reduction in feed cost as the sows offered Trichanthera gigantea leaves ate less concentrate (P=0.02).  No costs were ascribed  to the growing and harvesting of Trichanthera gigantea as this required only (under-utilized) family labour.  The perennial growth habit of the Trichanthera gigantea avoids the need for replanting and being a tree it can be considered as having a favourable effect on the environment. 

Experiment 2: Trichanthera gigantea for growing-fattening pigs

Materials and methods

The experiment was started in January 1998 and finished in October 1998. Eighteen farmers participated in the experiment each with 2 pigs. Nine farmers fed only the control  (traditional)  diet of broken rice and rice bran. Nine other farmers fed the fresh leaves of Trichanthera gigantea as a supplement to the traditional diet.  Both the traditional diet and the Trichanthera gigantea leaves were fed ad libitum. The pigs were crosses of Large White with the local "Baxuyen" and had been purchased from neighbouring farmers soon after weaning (about 60 days of age and with about 15 kg initial weight).  The composition of the control diet (% air-dry) was: rice bran 50, broken rice 50.  Harvesting of the Trichanthera gigantea was as described in Experiment 1.  The pigs were weighed at 30 day intervals under the supervision of the researcher. Feeds offered were recorded daily by the farmers.  Samples of Trichanthera gigantea foliage and the concentrate mixture were taken at the beginning and end of the trial for analysis using the methods described in Experiment 1. 

Results and discussion

As in Experiment 1, intakes of  Trichanthera gigantea leaves were high (3.63 kg/day) supplying 112 g daily of crude protein (Table 3). There were no differences in growth rate between the control (traditional diet) and the diet supplemented with fresh leaves of Trichanthera gigantea (P=0..21).  As in Experiment 1, the pigs offered the leaves of Trichanthera gigantea ate less (P=0.001) concentrate and their feed costs were therefore lower (by 20%; P=0.002). The Trichanthera gigantea leaves provided 31% of the dietary protein.

Table 3 : Performance of growing-fattening pigs fed rice bran and broken  rice alone (control) or with ad libitum fresh leaves of Trichanthera gigantea
	Control	Trichanthera gigantea	SEM	Probability
Liveweight, kg
Initial	15.1	15.0	0.743
Final	84.9	81.0	2.271	0.21
Daily gain	0.436	0.413	0.012	0.21
Intake, kg/d
Concentrate	3.330	2.450	0.085	0.001
Trichanthera gigantea	0.000	3.630
Total DM	3.000	2.740	0.073	0.02
Dry matter conversion	6.88	6.75	0.299	0.76
Protein in DM, %	11.6	13.4	0.061	0.001
Feed cost, VND/d	4825	3564	124	0.001
Piglet gain, VND/kg	11088	8766	449	0.002

In earlier work in Colombia with fattening pigs fed sugar cane juice (Sarria et al 1992), the leaves of Trichanthera gigantea were sun dried and mixed with soya bean meal (first 10 weeks) or fed fresh (last 6 weeks) to provide 5, 15 or 25% of the dietary protein.  Intakes of the fresh leaf reached a maximum average of 0.78 kg/day.  However, growth rate and feed conversion deteriorated significantly with increasing level of Trichanthera gigantea.  In the present experiment, intakes of fresh leaves averaged 3.6 kg/day and there were no differences in performance between control and supplemented pigs, but feed costs were substantially lower.  

Experiment 3: Trichanthera gigantea for growing-fattening ducks

Materials and methods

This experiment was carried out in a private farm close to the University.  The treatments (three) were the traditional "balanced" diet for fattening ducks containing fish meal and soya bean meal (control), or the same diet without fish meal or without soya bean meal (Table 4) but with free choice feeding of fresh leaves of Trichanthera gigantea. Muscovy ducks (n = 126) were used over the age period 30 days to 90 days. There were 7 males and 7 females in each group and 3 replications of each treatment / group.  Two males and two females were slaughtered from each treatment /  group at the end of the trial.  The leaves of Trichanthera gigantea were harvested from trees established 12 months earlier on the farm. Harvesting procedures of the Trichanthera gigantea were similar to those described in Experiment 1. 

Table 4: Composition of the concentrate component of the experimental diets (TG-FM with Trichanthera gigantea ad libitum and fish meal) (TG-SBM with Trichanthera gigantea ad libitum and soya bean meal)
	Control	TG-FM	TG-SBM
Broken rice	39.5	44.5	44.5
Rice bran	40	45	45
Fish meal	10	10	0
Soya bean meal	10	0	10
Bone meal	0.5	0.5	0.5
As % of DM
N*6.25	18.3	16.1	14.1
ME (kcal/kg)	2,684	2,608	2,655
Cost/kg feed	2147	1889	1689

Results and discussion

The ducks consumed readily the leaves of the Trichanthera gigantea with average intakes in the range of 67 to 70 g/day (Table 5) supplying from 13 to 14% of the total dietary crude protein. In contrast with the findings with the pigs, the intake of concentrate was not reduced (P=0.60).  Growth rate was the same on all the diets; however, the use of  Trichanthera gigantea leaves to eliminate the costly fish meal or soya bean meal from the diet, led to a reduction in feed costs  (P=0.014). There were no apparent differences in carcass quality except that the skin and the fat were much more pigmented (yellow rather than white) in the carcasses of the ducks fed Trichanthera gigantea.  This feature of duck carcasses is preferred by local consumers. These results are similar to those reported by Nguyen Thi Hong Nhan et al (1997) where fattening ducks ate 70-80 g fresh Trichanthera gigantea leaves daily as partial replacement of fish meal or soya bean meal in a basal diet of broken rice and rice bran and where growth and carcass traits were the same as on the control diet.

Table 5: Performance of growing-fattening Muscovy ducks fed balanced concentrates or with the fish meal (FM) or soya bean meal (SBM) replaced by fresh leaves of Trichanthera gigantea (TG)
	FM + SBM	FM + TG	SBM+TG	SEM	Probability
LWt gain, g/d	22.4	23.8	24.2	3.1	0.91
Feed intake, g/d
Concentrate	72.5	69.8	67.2	3.6	0.6
Trichanthera gigantea	0	60.7	65.7
Crude protein intake,g/d
Concentrate	13.2	13.1	12
T gigantea	0	1.9	2
Total	13.2	15.0	14
Feed cost, VND	9339	7915	6807	411	0.014
Weight at slaughter,g
Liveweight	2727	2632	2527	60.1	0.14
Carcass weight	1867	1700	1725	78.3	0.31

Conclusions

The use of fresh leaves of Trichanthera gigantea as a supplement to traditional diets for lactating and growing-fattening pigs, or as replacement for fish meal or soya bean meal for fattening ducks, resulted in substantial saving in feed cost with no loss in performance.  This is in contrast with results reported from Colombia where growing pig performance was reduced when Trichanthera gigantea leaves were fed as partial replacement for soya bean meal (Sarria et al 1992). 

The genetic makeup of the Trichanthera gigantea used in Vietnam was similar to that used by Sarria et al (1992) since it was derived from the same original plant material.  There are, however, marked difference in the ecosystems between the two locations. In Colombia the Trichanthera gigantea was growing in the floor of the Cauca Valley at an elevation of 1,000 msl, at a latitude at a similar distance from the equator but with marked differences in annual precipitation (<1000mm in Colombia compared with 1,200 to 2,000 mm in the Mekong Delta).  The average year-round ambient temperate and humidity in the Mekong delta are also higher than in the Cauca Valley in Colombia.  Rosales (1998) has drawn attention to the importance of the ecosystem in which the Trichanthera gigantea is grown and effects on it's nutritive value.  It is possible that the apparent differences in nutritive value between Trichanthera gigantea grown in the Mekong delta compared with the Cauca Valley in Colombia can be explained on this basis.  

Acknowledgements

This research was supported by the International Foundation for Science through Grant No: B/2231-2 to the senior author.

References

AOAC 1985 Official methods of analysis. Association of Official Analytical Chemists.12th edition. Washington, DC.

Nguyen Thi Hong Nhan 1998 Agronomic and nutritional studies on Trichanthera gigantea. MSc Thesis, Cantho University, Vietnam

Sarria P, Villavicencio E and  Orejuela  L E 1991 Utilización de follaje de Nacedero (Trichanthera gigantea) en la alimentación de cerdos de engorde.  Livestock Research for Rural Development. Volume 3, Number 2: http://www.cipav.org.co/lrrd/lrrd3/2/cipav1.htm. 

Sarria Patricia 1994 Efecto del nacedero (Trichanthera gigantea) como reemplazo parcial de la soya en cerdas en gestación y lactancia recibiendo una dieta básica de jugo de caña. Livestock Research for Rural Development. Volume 6, Number 1: http://www.cipav.org.co/lrrd/lrrd6/1/sarria1.htm 

Nguyen Thi Hong Nhan, Nguyen Van Hon, Vo Van Son, Preston T R  and Dolberg Frands 1996 Effect of shade on biomass production and composition of the forage tree Trichanthera gigantea. Livestock Research for Rural Development. Volume 8, Number 2: http://www.cipav.org.co/lrrd/lrrd8/2/nhan.htm.  

Nguyen Thi Hong Nhan, Preston T R  and  Dolberg Frands  1997 Use of Trichantera gigantea leaf meal and fresh leaves as livestock feed. Livestock Research for Rural Development. Volume 9, Number 1: http://www.cipav.org.co/lrrd/lrrd9/1/nhan91.htm.  

Rosales Mauricio 1997 Trichanthera gigantea (Humboldt & Bonpland.) Nees: A review. Livestock Research for Rural Development. Volume 9, Number 4: http://www.cipav.org.co/lrrd/lrrd9/4/mauro942.htm.

Received  11 June 1999

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