Utilization of some forages as a protein source for growing goats by smallholder farmers

Nguyen Thi Hong Nhan

Agricultural Faculty,  Cantho University,Vietnam

Abstract

This study was aimed at evaluating the role of foliage from four leguminous trees (Sesbania grandiflora, Leucaena leucocephala, Hibiscus rosa-sinuensis and Ceiba pentadra) as a component of feeding systems for growing goats in the My Khanh village in the Mekong delta.

Leaves and thin stems, the parts of the foliage that are consumed by goats, were collected every afternoon from March through to June, 1998. The amount of fresh foliage collected per unit of time was significantly higher for Hibiscus rosa-sinuensis than for three other tree species (Sesbania grandiflora, Leucaena leucocephala  and Ceiba pentadra). The lowest harvest rate was for Sesbania grandiflora.

Two feeding trials were done with the leguminous tree foliage as the sole component of the diet or as supplements to the fresh husk obtained from maize ears harvested at the immature (baby corn) stage. Eight smallholder farm families participated in each trial. Two young goats were distributed to each family and were housed in separate pens in a simple shed with raised slatted floor. In the trial with the tree foliages as the sole diet, the highest liveweight gains were with Sesbania grandiflora (114 g/day) followed by Leucaena leucocephala (98 g/day), Ceiba petandra (94 g/day) and Hibiscus rosa-sinuensis (77 g/day). Feed intakes (fresh foliage) were in the range of 2.5-2.9 kg/goat/day. In the trial with husk from immature maize the treatments were the fresh husk as harvested,  or after ensiling,  and with supplements of either Sesbania grandiflora or Leucaena leucocephala providing half the offered dry matter together with fresh husk.  Best liveweight gain was with the supplement of Sesbania (112 g/day) followed by Leucaena (80 g/day). On the fresh husk as the only feed the growth rate was 50 g/day and was better than with the ensiled husk (32 g/day).

It is concluded that foliage from  Sesbania grandiflora has a high potential as a feed for growing goats, either as the sole component of the diet or as a supplement to the fresh husk from immature maize.

Key words: Goats, maize ear husk, Sesbania grandiflora, Leucaena leucocephala, Hibiscus rosa -sinensis, Ceiba pentadra, harvest rate, liveweight gain

Introduction

Goat raising is attractive to many farmers in Vietnam as there is a wide variety of feed resources that can be used.  This is because the natural diet of goats is the foliage of trees and shrubs and there are many species that goats will eat and which are present in home gardens, in hedge rows and on waste ground. Leguminous trees have advantages as they fix nitrogen and generally maintain their leaves even during the dry season. Data on the nutritive value for goats of the foliage from Sesbania grandiflora, Leucaena leucocephala, Ceiba pentadra and Hibiscus rosa-sinensis showed that all these species could be fed as the sole diet but that Sesbania grandiflora and Leucaena leucocephala supported higher dry matter intakes and had higher digestibilities of the nitrogenous fraction. An important feature of the use of tree foliages in "cut and carry" systems is the time taken to harvest them.  The labour required to do this is often ignored but,  in practice, it is an important factor for small scale farmers that have many activities to perform.

Another feed source that is becoming increasingly available in the Mekong delta is the "husk" and stover from immature maize harvested after 45-60 days. This is one of the on-farm residues from the production of "baby corn" which is canned and exported. After harvesting the young maize cobs, the maize husk and stover are still green and are a  potential feed resource for ruminants such as cattle, buffaloes and goats. The maize ear husks, in particular, are eaten readily by goats either in fresh form or after ensiling.  This feed resource is low in protein which creates an opportunity for it to be supplemented with the leaves from leguminous trees such as Sesbania grandiflora or Leucaena leucocephala.  A survey in My Khanh village in the Mekong Delta (Nguyen Thi Hong Nhan and Nguyen Trong Ngu 1997, unpublished data) showed that the fresh husk represented 67% of the total weight of the "ear" and that the potential yield could be as high as 3.5 tonnes/ha.

In seeking an optimum use of local resources for the development of ruminant production in the region, this study was aimed at investigating the feed value of some native tree fodders found in the Mekong Delta of Vietnam. The hypotheses to be investigated were:

• The husk from immature maize cobs (baby corn), when supplemented with foliage from fodder trees, would be a suitable diet for growing goats.
• There would be important differences in the harvest rate (defined as the the weight of fresh foliage collected per unit of time) between different fodder trees.

Selection of sample sites

My Khanh village in the Mekong Delta was chosen as the location for the study as a large area (100ha) is regularly planted with maize for production of immature cobs for industrial processing. Furthermore, there are tree foliages available in the village and some initial information was available concerning their nutritive value (Nguyen Thi Hong Nhan 1998).

Methodology

The project began in March 1997 as a cooperative study between Cantho University, the local village organizations and a Women’s savings group. Visits were made to the village and public meetings and discussions were held so as to identify local problems. This approach to defining a research project is based on the concept of Participatory Rural Appraisal (PRA) (McCracken et al 1988; Chambers 1992a,b) a methodology which is currently very popular in Vietnam. The aim is to  empower local communities through an information gathering and reflective process.

Data collection

Keeping farmers involved and interested in the study is essential   (Dolberg 1995). Experimental data were collected by frequent visits to the project site.

Harvesting rate of legume foliage

Measurements were made over a period of three months, from March to May 1998, of the quantities and the time taken to harvest the foliage of four leguminous trees:  Leucaena leucocephala, Sesbania grandiflora , Ceiba pentadra and Hibiscus rosa-sinensis. March to May is the transition period in South Vietnam when the climate changes from the dry to the wet season. The sites for collecting the leaves were in the village. The time taken to harvest a given amount of green biomass (the leaves attached to the fine stems) was recorded. Usually the leaves were collected in the afternoon for feeding the following morning.

On-farm measurement of goat performance

Thirty-two weaned goats were distributed to 16 poor farm households in My Khanh village with 1 male and 1 female for each household. Two groups of households were selected according to availability of: (Group 1)  fodder trees (Leucaena leucocephala, Sesbania grandiflora ,Ceiba pentadra and Hibiscus rosa-sinensis); and (Group 2) an area of 1,000 m² planted with maize. The farmers were shown how to prepare a simple pen with a slatted floor to confine the goats and how to ensile the maize ear husk (Group 2).  The goats were confined throughout the 24 hours and had free access to the different feeds and to water. Before starting the experiment, the goats were vaccinated against food and mouth disease and also dewormed.

Experimental design and data collection

Group 1

The foliages from Leucaena leucocephala, Sesbania grandiflora, Ceiba pentadra and Hibiscus rosa-sinensis were given as the sole diet to each of two goats (housed separately) in each of two households (total of 8 households and 16 goats). In each case the foliage consisted of the leaves attached to the fine stems, the coarse branches having been removed. Feed and water were always available.

Group 2

Arrangements were similar to those in Group 1, except that the diets consisted of fresh or ensiled immature maize husks or fresh husks supplemented with either Leucaena leucocephala or Sesbania grandiflora. The farmers participating in the two latter treatments were advised to follow  a scale of feeding which provided approximately equal parts (on dry matter basis) of ensiled maize husks and tree foliage.

Measurements

The goats were weighed every month at the same time of day on each occasion. A spring balance was used which was hung from a tree or suspended from a metal tripod. The amounts of feeds offered and refused were recorded daily by members of the farm household. This information was revised on the weekly visit of the researcher. All the data were coded and stored in a spreadsheet in a portable notebook computer, for subsequent statistical analysis using the general linear model software of Minitab (release 10.2, 1994). When differences in treatment means were significant at the probability level of P<0.05 the means were compared using the Tukey  test (Minitab, release 10.2, 1994).. Data for each group of farmers were analyzed independently.

Results and discussion

Effect of season and source of foliage on rate of harvesting

Figure 1: Time taken to harvest the foliage (leaves and fine stems) of four fodder trees (Leucaena leucocephala, Sesbania grandiflora , Ceiba pentadra and Hibiscus rosa-sinensis) in My Khanh village

The mean values for the harvest rate (weight of green biomass harvested per minute) of the four fodder trees, during each of  three months, are shown in Figure 1. There were significant differences among the different trees (P=0.001) and between different months. The interaction between month and species of tree was also significant (P=0.001). In the South of Vietnam, it starts raining at the beginning of May. At this time the trees, after the long dry season, recover and grow rapidly with abundant foliage. This appears to be the reason why the average harvest rate was higher in May than in the earlier months of April or March. Harvest rate increased from March through to May for all the trees with the exception of Hibiscus rosa-sinensis which had the highest rate in April. Hibiscus is known for its tolerance to dry conditions and therefore was least responsive to the onset of the rains in May. It was almost twice as fast to harvest foliage from Hibiscus as from the other trees as the leaves are densely packed in the foliage. In contrast, it took significantly longer to harvest a given amount of foliage from  Sesbania grandiflora than from the other trees (P=0.001), perhaps reflecting the fact that Sesbania grandiflora grows relatively high, making it more difficult to harvest.

The time taken to cut and collect feed by hand is an important factor in "cut and carry" systems for livestock managed in confinement, as is the case in most situations in Vietnam. This characteristic of a feed is rarely reported but is said to be the reason in Colombia for using Leucaena leucocephala in a grazing system and Gliricidia sepium for "cutting and carrying" as practical observations showed that the harvest rate (kg foliage/unit time) was much higher for Gliricidia than for Leucaena (Preston T R 1997, personal communication).

Tree foliage as the sole diet

Composition of the foliage

Data on the composition of the foliage from the different trees (Table 1) are taken from the nutrition study (Nguyen Thi Hong Nhan 1998) which was done simultaneously.

Table 1. Mean values for chemical composition (% dry matter) of leaves and fine stems of the tree foliages (values are as % of dry matter, except for dry matter which is % of fresh biomass)
	DM	N*6.25	Crude fibre	Ether extract	Ash
Sesbania grandiflora	27.86	21.37	13.62	7.4	8.52
Leucaena leucocephala	26.24	20.47	17.05	7.1	6.73
Hibiscus rosa -sinensis	19.97	13.82	14.59	7.32	11.64
Ceiba pentadra	21.24	14.29	116.38	3.74	8.48

The important differences are in dry matter and crude protein content where Sesbania and Leucaena have much higher values than Hibiscus and Ceiba.

Feed intake

According to practical conditions, the treatments were not always followed strictly, and the farmers sometimes offered other kinds of feed.  However, the overall trends (Table 2) are similar to those observed in the nutrition study (Nguyen Thi Hong Nhan 1998).

Table 2: Mean values for intake of tree foliages and change in liveweight (g/day) of the goats.
	Sesbania	Leucaena	Ceiba	Hibiscus	SE	Prob.
Fresh foliage	2870	2640	2810	2490	120	0.15
Dry matter	800a	693ac	596bc	498b	27.9	0.001
Crude protein	171a	142b	84.8c	68.9c	5.2	0.001
Liveweight gain	114a	98b	94b	77c	2.7	0.001
abcd Means within rows with different superscripts differ significantly at the probability level shown

Intake of the fresh foliages was high on all treatments but because of higher dry matter content in the Sesbania and Leucaena, dry matter intakes were highest on these foliages. In general, the goats responded well to all the feeds, although they took longer to adapt to the Hibiscus foliage. The mucilaginous substance present in the leaves of Hibiscus might have been a factor limiting intake. Sesbania and Leucaena traditionally proved their high palatability with the highest growth rate (P=0.001) being observed on Sesbania, followed by Leucaena, Ceiba and Hibiscus. However, for all the foliages the growth rates were at an acceptable level. High values for growth rate of 5-6 month old goats fed on Sesbania grandiflora (100 ± 34 g/day) were reported by Nguyen Thi Thuy (1996).

Feed dry matter intake and liveweight gain were highly correlated with intake of crude protein (Figures 2 and 3). Liveweight gain and dry matter intake were also highly correlated (Figure 4). The data in Figures 2, 3 and 4 indicate the sequence of events that,  according to Preston and Leng (1987), usually determines ruminant animal performance on tropical feed resources. Dry matter intake is determined by the balance of essential nutrients especially the protein: energy  ratio. In turn, the dry matter intake is what determines performance parameters such as rate of liveweight gain.

Figure 2: Relationship between intake of crude protein and intake of dry matter (n=16)

Figure 3: Relationship between intake of crude protein and daily liveweight gain  (n=16)

Figure 4: Relationship between dry matter intake and liveweight gain (n=16)

Tree foliages as supplements to ensiled maize husks

Composition

Data on the chemical analysis of the maize ear husk before and after ensiling are presented in Table 3.

Table 3. Chemical composition of maize ear husk before and after ensiling (as % dry matter, except for dry matter which is as % fresh material)
	Dry matter	N*6.25	Crude fibre	Ether extract	Ash
Maize ear husk	15.1	12.3	22.6	5.38	3.67
Ensiled maize ear husk	15.9	11.9	21.7	6.33	5.34

The relatively high content of crude protein in the maize ear husk and moderate level of crude fibre indicates that this crop residue is nutritionally superior to most tropical grasses.

The tree foliage had a significant effect on feed dry matter intake which was increased by more than 50% (Table 4).

Table 4. Feed intake (g/day) and liveweight change (g/day)  in goats fed maize ear husk, fresh or ensiled and with or without supplementary tree foliage
	Maize ear husk	Ensiled maize husk	Maize husk + Leucaena	Maize husk + Sesbania	SE	Prob.
Dry matter	423a	321b	646c	610c	18.9	0.001
Crude protein	51.8 a	38.1a	132b	128b	3.4	0.001
Liveweight change	50.7ab	32.5b	80.4ac	112c	7.5	0.001
abcd Means within rows with different superscripts differ significantly at the probability level shown

The higher intake was reflected in superior liveweight gains with best results being obtained for supplementation with Sesbania. Goats fed with this supplement gained at twice the rate of those receiving only the fresh or ensiled ear maize. Goats fed the ensiled ear maize husk ate less dry matter than those fed the fresh maize husk and tended to have lower rates of liveweight gain.

The outstanding results from this study relate to the use of foliage of Sesbania grandiflora as a feed resource. The liveweight gain of goats fed this foliage as a supplement to fresh maize ear husks, or as the sole component of the diet, exceeded 100 g/day which is surprisingly high for goats fed only on forages.

The results from using immature green maize ear husk as the basal diet of goats are encouraging, especially when this feed is supplemented with foliage of Sesbania grandiflora or Leucaena leucocephala. The use of ensiled maize ear husk may require longer periods of adaptation as this is a novel feed for goats.

The harvest rate (amount of foliage collected per unit of time) was highest for Hibiscus rosa-sinensis and lowest for Sesbania grandiflora.

Acknowledgments

This study was carried out at My Khanh village in Cantho province, and was made possible through the financial support of the Danish Embassy in Hanoi, the University of Tropical Agriculture (UTA) and FAO through the courtesy of Dr Steve Reynolds. It was submitted to the University of Tropical Agriculture in November 1998 in partial requirements for the MSc degree (http://www.hcm.fpt.vn/inet/~utaf

I gratefully appreciate the help of the People's Committee of the village for facilitating my communication with the farmers.

Dr T R Preston, Frands Dolberg, Dr E R Ærskov and Dr H M  Shelton showed great interest in the research and advised me on the execution of the project and the analysis of the data.

I would like to thank also my colleagues in the Department of Animal Husbandry in Cantho University and Lylian Rodriguez of UTA for sharing their experiences with me.

Received 10 December 1998

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