4. THE ROLE OF TREES IN LAND USE

4.9 Trees and livestock including beekeeping

Trees can support livestock production in many ways. The main direct benefits of trees are as a source of:

• Primary feed where grass is scarce

• Supplementary feed where grass is of poor quality or when a protein supplement is required

• Shade

• Medicinal substances

• Materials for construction, e.g. materials for fencing and boma.

The presence of livestock is often a complicating factor for tree growing. Livestock browse on young tree seedlings and hamper regrowth, either planted or natural. In many areas, particularly in western Kenya, post-harvest grazing of fields is a common practice. After the harvest, the fields are often opened up for grazing on a communal basis, and cattle and goats are often free to feed on whatever they find at such times. Where such practices exist it is difficult to establish new trees in cropland.

Figure 4.20 Livestock may be a complicating factor in tree growing

Primary feed source

Fodder from trees normally constitutes a primary feed source for livestock in ASAL areas during the dry season. Then browse may constitute more than half of the diet. When livestock, browse on trees and shrubs it is often regarded as a sign of over-use of land. This is only partly true. In areas with long dry seasons, utilization of trees and shrubs for fodder is vital, but it is, of course, essential that the pressure on the vegetation does not exceed its long-term carrying capacity. Normally, livestock are more strongly dependent on tree fodder the drier the area concerned.

In high-potential areas grass is more important than trees as a fodder source. With increasing human population densities, however, land use shifts from a more labour-extensive type towards a higher input of labour per unit area of land. In situations where people utilize the land intensively, use of tree fodder in cut-and-carry systems becomes more frequent. With a growing human population in the highlands we may therefore expect to see intensified use of tree fodder in these areas.

Figure 4.21 A camel browsing on Acacia

A problem associated with the use of trees for fodder in high-potential areas is that there are few suitable species already growing in those areas. Among exotics, Leucaena leucocephala has become widespread, but it does well only up to 1,500-1,600 m and where soils are not too acidic. Sesbania sesban, Calliandra calothyrsus and Leucaena diversifolia are other fodder species suited to high-potential areas at slightly higher altitudes. Calliandra and L. diversifolia are, however, not yet very widespread. Grevillea was very important in Meru during the 1984 drought: it was largely due to Grevillea leaves that the livestock in the area survived. Even during normal years Grevillea is used as fodder in some areas, but it is a poor-quality fodder. Compared to some other high-potential areas of the world use of tree fodder in these areas in Kenya is not very highly developed.

Supplementary feed source

Ruminants need a good supply of protein to be able to digest carbohydrate effectively as they depend on micro-organisms for digestion of the carbohydrate. With a low protein intake these micro-organisms cannot reproduce. This explains why ruminants can "starve on a full stomach".

Green leaves principally contain carbohydrates, proteins and minerals. When grass dries out during the dry season the protein content falls rapidly and the result is that protein will be a limiting factor in carbohydrate digestion. Because of their deep roots, trees can remain green well into the dry season, and in addition the protein content of tree leaves is normally higher than that of grass. Therefore, tree leaves have an important role to play in livestock nutrition during the dry season.

Beside tree leaves, pods from trees, mainly those of Acacia, are also very important as a protein source for livestock. Gwynne (1969) found that during the dry season in Kenya seeds and pods of Acacia nilotica constitute up to 60% of dry weight fodder intake in cattle.

Trees and shrubs are becoming increasingly important as cheap supplementary feed in high-potential areas. Leaves from Leucaena and other leguminous shrubs are commonly used as supplementary feed in dairy production. Leucaena can, however, cause hair loss due to its high mimosine content. There are several ways of overcoming this problem, but the simplest way is to make sure that the proportion of Leucana in the fodder is kept relatively low. Pigs are the most sensitive animals in this respect, and they will only tolerate a level of Leucaena of up to 15% of the diet. For ruminants, Leucaena should not constitute more than 30% of the diet, unless the leaves are wilted in which case the ratio can be higher.

Daily use of fodder from leguminous shrubs (Leucaena spp., Calliandra, Sesbania spp., preferably in a mixture) will increase milk yields by 10-20% compared with a diet which is deficient in protein. If tree fodder is scarce, priority should be given to cows a month before and a month after calving, and as a dry-season reserve for all stock, particularly sheep and cattle. In meat production, the weight gain will be increased by two to four times with adequate supplementary feeding.

Among indigenous trees, Ficus sycomorus and Kigelia africana have been reported as being used for supplementary feed.

Figure 4.22 Supplementary feeding of green leaves during the dry season

Shade

Trees in pastures will provide shade, and under the crown of a tree livestock can enjoy lower temperatures which will contribute to higher milk production. If there is no shade in hot lowland areas heat stress may occur. Young or newborn animals are more vulnerable since their ability to regulate their body temperature is less developed. Heat stress results in an increased loss of water through sweating and loss of appetite which, in turn, will result in lower animal productivity. Some important factors that influence temperature regimes in hot climates are wind, humidity and direct solar radiation.

Figure 4.23 Boran bull under Acacia shade at midday

Veterinary medicine

Traditional use of trees and herbs for extraction of drugs for disease control may be very important, particularly in remote areas where veterinary services are not well developed. Numerous different species are used for such purposes, and there are potential pharmacological substances yet to be identified, purified and evaluated, some of which may already have been in local use for many years.

Materials for construction

Livestock owners need wood for construction of various structures in animal husbandry. Fences are perhaps the most obvious of these. Fences often play a key role in land use. Without fencing it is difficult to control the movement of cattle and trees and shrubs play a role either as live fences or when cut to provide dead fencing material. Live fencing is important both in high potential and ASAL areas, whereas the use of dry thorny branches is more common in ASAL areas. In high-potential areas "dead" fences are more often constructed using fence posts and wire. In both cases products from trees are, of course, essential.

There are also other well-known uses for construction materials from trees in connection with livestock production.

Trees and beekeeping

The two main products from beekeeping, honey and beeswax, are valuable commodities that can contribute both to subsistence and income generation. In addition to this direct output, improved pollination by honeybees means better harvest of nearby crops. Bees feed on the pollen and nectar in flowers. This resource is not utilized by any other livestock, and thus bees do not interfere with other components in the land-use system. Beekeeping does not occupy any valuable land, and furthermore it is a flexible enterprise in terms of the labour requirement. Bees do not require daily attention and the work can be done when the beekeeper has time to spare. In other words, there are many good grounds for keeping bees.

Honey can be both a food, a medicine, or a cash crop, or it can be used for brewing. As a sweetener honey is more nutritious than sugar, and it adds diversity to the diet. The market for honey is good in most areas, and honey has a great potential as an export commodity. The three countries that export most honey in the world (Mexico, China and Argentina) are all in the developing world, and in those countries a large beekeeping industry has developed. African countries have an untapped potential in this respect considering the widespread knowledge of this age-old practice that exists on the continent.

Beeswax has many uses too. The most well-known one is for the manufacture of candles. Beeswax does not deteriorate with age and thus can be stored, and there is a good market for export.

World honey production is near one million tonnes, but still more important is the role bees play in the pollination of over 100 cultivated crops. Bees pollinate crops such as avocado, oil-seed crops, coffee, legumes, mango, pawpaw, and sunflower. It has been reported that four well-managed beehives per hectare in a field of sunflowers increase the yield Of sunflower seeds by 15-20% (Pawlick, 1989).

Figure 4.24 Traditional beekeeping

Kenya's production potential is estimated at 80,000-100,000 tons of honey and 8,000-10,000 tons of beeswax annually, whereas the actual production in 1987 was 34,000 tons of honey and 3,600 tons of beeswax. It is estimated that the number of traditional hives is around 2 million, and that there are some 50,000 modern top-bar hives.

Trees are important for beekeeping both as a source of nectar, to provide wood for hives and as a good habitat for bee colonies. Hence tree growing and beekeeping are strongly associated. The most important zone for further development of beekeeping in Kenya is the semi-arid zone. The high species diversity in this zone makes it the area with the highest beekeeping potential in the country. Most efforts to develop commercial beekeeping are made in that zone as other agricultural enterprises are not favoured by the climatic conditions. Honey is already a major source of income in such areas (Kagio and Muriithi, 1989).

Contact your local beekeeping officer or livestock officer for more information on improved hives, etc.