This study was conducted in the dry and rainy seasons in three ecologically different zones characterized by: acid soils, saline soils and hilly terrain. Rapid Rural Appraisal (RRA) and Participatory Rural Appraisal (PRA) methods were used to identify and collect data on the use of indigenous plants as feedstuffs. The general information was obtained from key informants at hamlet, village and district levels. All non-cultivated feed plants were identified botanically and information was obtained on the habitat of the plants, parts used, relative abundance, processing methods and seasonality. The qualitative information based on farmer knowledge illustrated the importance of understanding the role of the indigenous plants in animal diets.
Samples were collected based on farmers recommendations and field observations. The plants were grouped according to season, habitat (aquatic and terrestrial) and ecological zone and the DM, CP, CF, ash, Ca and P contents were determined.
Indigenous plants play an important role in livestock diets particularly in the remote areas of the Mekong delta. Local plants supply a large proportion of the protein, vitamins and minerals to the animal. In addition, some are also used as for medicinal purposes (Mwashayenyi 1994). The plants are adapted to the temperature, moisture and soil specific conditions and grow well on waterlogged soil, and some are fast growing and harvested all year around (Buathoki 1993). People living in the rural areas, especially the low income groups, rear livestock on diets based on high quantities of indigenous plants. They have an impressive knowledge of how to use plants for animal production. Indigenous knowledge is important for many kinds of development activities. Development projects may fail because they do not take into account local traditions and knowledge (Warren 1991).
Although non-cultivated plants are used commonly by farmers, little is known of the nutritive value of many species which are very abundant in the field and homestead areas. Especially interesting are the water plants, as they constitute an important source of protein and because they reproduce rapidly, and produce high yields of protein-rich plant biomass (Culley and Epps 1973).
The present study was conducted in order to assess farmers' knowledge and to determine the composition of non-cultivated plants used in animal feeding in the Mekong Delta.
In this study, Rapid Rural Appraisal (RRA) and Participatory Rural Appraisal (PRA) methods, as described by McCracken et al (1988), Chambers (1992a,b) and ILED (1994), were applied to learn about the farmers' knowledge on indigenous plants for animals feeding. The RRA and PRA methods emphasize group discussions and diagramming and pay especial attention to outsiders' behaviour, attitudes and interactions with local people (Mc Cracken et al 1988, Chambers 1992a, b).
In Soc Trang province, Thanh Tri district, the information and samples were collected in Long Hoa hamlet belonging to Tan Long village.
The third site was selected in Angiang province in the An Nong and An Cu villages. The population distribution of An Cu and An Nong village is scattered and consists of 80% ethnic people mainly Khmers (Annual statistics 1993).
Meetings were carried out with the local authorities and female and male groups. Some case studies were conducted in certain families with more knowledge of indigenous plants used for livestock. Walking around in the area was done with key informants to different sites to find and collect samples. The samples were collected and prepared before the meetings and used as a basis for group discussions on habitat, abundance, seasonality and plant use. Some prizes were given to children who collected the highest number of different species and to the person who knew most about the indigenous plants. The collection of this material has relied very much on the extensive knowledge regarding local feed resources among local people. To learn from the community, informal and participatory approaches were used as described in the methodology section. One very useful approach was the food or feed plants identification competition that was organized for children. The children were pupils in secondary and primary schools. The contest resulted in a large display of feed plants which later on could be used for discussions on habitat, uses and abundance. It indicated considerable knowledge of local feed resources among young children. The winner, who was a fourteen year old high school student, knew 43 plants.
In field sites, in the Saline area, a plant identification meeting was held with adults, key informants and children. Comparisons were made between adults and children and between groups. The adults identified the indigenous plants better than the children as knowledge is transferred from the old to the young generation. The men knew the plants and their uses better than the women as they spend more time in the fields than the women. They eat many different plants from the fields and observe which plants the ducks or buffaloes prefer. Some plants that could not be recognized by the farmers in the hamlets were taken to the pagoda for identifcation by healers with particular knowledge of plants. Most of those plants were used as medicinal plants. Uncommon plants were identified by local names and enclosed in plastic bags for later botanical analysis at the university. In the three areas, the total number of plants identified were 132 species used as feed for livestock.
Group interviews were focussed on the uses of plants. In the Mekong delta. Wild plants have always been commonly used for many purposes including food, feed, fertilizer, medicine, fibre and Mulching.
Not only the terrestrial plants but also the aquatic weeds are important in the rural areas by providing food for humans. The foliage of some water plant species are eaten raw in salads or cooked as a vegetable. The rhizomes of Eleocharis dulcis are eaten commonly by farmers in the Saline area. When the plant density becomes too high, farmers often transplant them to empty land near the house.
Women in Phuong Binh and Long Hoa would say “Plants for livestock are free, if not we would be lost”. Many plants are used as livestock feed for pigs, ducks, buffaloes and chickens. Duck production is a tradition, especially in the acid Plain of Reeds and in the Saline area. When raising ducks in the fields with acid soils, the farmers observe the feathers of the ducks. If they become reddish-yellow in colour in combination with a depressed growth or egg production, the farmers consider the ducks to be contaminated by the acidic water. Then, it is necessary to detoxify the ducks in order for them to recover productivity. Ducks are given sodium bicarbonate and also some plants with a laxative function. Some acidic laxatives from plants such as mung bean seeds boiled with sugar or water spinach, Ceratopteris thalictroides or extract from Cassia alata are used in the drinking water for the ducks.
Sometimes, farmers use Phragmites karka tops, Morinda citrifolia and Jussiaea erecta boiled slowly and given to the ducks in the morning when they are thirsty.
Aquatic plants have the advantage of extremely high growth rate (Penfound and Early 1984, cited by Joce 1990). Most aquatic plants, including water hyacinth and Hydrilla, have high nutritive values similar to high quality forage (Easely and Shirley 1974). However, ash contents are very high, between 33–42%. This was mentioned by Ravindran and Blair (1992), who stated that a common characteristic of water plants is high water and ash content.
Lemna spp are used very commonly as fish and animal feeds in traditional practices. Lemna is low in fibre (12.1% in DM) but high in protein (33.4% in DM). However, dry matter is very low (3.8%) and ash content (24.5% in DM) high, probably as a result of a low level of nutrients in the water. Water spinach is planted commonly and is a favoured vegetable for human consumption. It is also commonly used for traditional feeding of pigs, ducks, chickens and fish.
Commelina and Ludwigia species are also used commonly as food, feed and medicinal herbs. They are liked by pigs and ducks. The crude protein content is between 16–23% in dry matter. Hydrophyla erecta and H. salicifolia are very palatable for pigs, but they only grow in the wet season. Farmers usually give them to pigs as green forage and especially as the main feed in the period of feed scarcity.
Many other species that were found that are interesting for animal feeding because of their palatability. Alternanthera sessilis, Ludwigia adscendens, L. octovalvis, Commelina spp, especially, A. repens are very common in pig feeding. They can be used as fresh forage or cooked. They withstand some drought and also grazing. In the wet season, the crude protein content of A. repens is high (22.6%), but the fibre content is also rather high.
Farmer knowledge on the use of non-cultivated plants for livestock is very extensive and many plants are used in the Mekong delta for many purposes. The knowledge is transferred from the old to the young generation. The wild plants are very abundant and available all year around, especially in the acid sulphate soil area. Water plants are used commonly in the community not only for animals but also for human consumption. Many of the non-cultivated plants are very high in protein content and have potential as feeds for animals. Using the aquatic plants for animal feeding may be a weed control solution in the intensive rice production areas not only in Vietnam but in other tropical countries.
The use of non-cultivated plants for pigs and poultry is traditional, however, information on nutritive value, anti-nutritional factors and optimal levels to use in animals diets is still limited in the region.
Biobaku W O and Ekpenyong T E 1991 Effect of feeding graded levels of water lettuce and water hyacinth on growth of rabbits. Journal of Applied Rabbit Research 14:2, 98–100.
Flora Maleasia 1950–1995 Edited by Van Steenis and De Wild. Published by Kluwer Academic Published the Netherlands.
McCracken J, Pretty J and Conway G 1988. An introduction to rapid rural appraisal for agricultural development. Sustainable Agriculture Programme. International Institute for Environment and Development. London, England.