J. Audru
Agrostologist, Institut d`Elevage et de Medecine Vétérinaire des Pays Tropicaux
Maisons-Alfort
2. The palatable trees and shrubs
4. Utilization prospects for browse species in the livestock sector
5. Are research and experiments on browse plants necessary in the Guinean zone?
The Guinean zone is characterized by a hot, humid climate and thick rain forest. The areas which can be utilized or traversed by livestock and small ruminants are either of anthropic origin, i.e. a substitution facies of the forest after clearance or maintained by burning, or else of edaphic origin, consisting of savanna enclaves on lithosols or poor substrates such as ferrugineous sands or hydromorphic surface soils.
There are nevertheless two sectors which, for different reasons, stand out because they do not present the same conditions for introducing livestock production and, in the future, developing livestock production, whatever kind of production system and species is selected (cattle, sheep or goats). These sectors are as follows:
a) from north to south the value of browse plants diminishes and the closer one moves towards the Guinean sector the more the animals refuse foliage;
b) the value of browse is particularly pronounced in the case of zebus. Some interest is also shown by humpless breeds, but these are generally less willing to consume the leaves of trees. Humpless cattle are more numerous in this area. This difference in taste between humped and humpless breeds remains at the level of observation since it has never been studied. In sheep and goats many suffrutescent and subligneous species are still consumed in this zone, especially the secondary species, which may be anthropic in origin, found around the outskirts of villages. However, no systematic study has been undertaken, as far as the present author is aware.
Studies and surveys are very scarce for the Guinean zone, except for the work of J. Piot in the Adamawa (Cameroon) on cattle. Furthermore, those available take the form of scattered notes and observations, since the subject has never been a priority and in fact ligneous species are considered as invaders on grassland and treated as such.
a) Highly palatable species
In the Adamawa (Cameroon), for zebus:
Cussonia barteri, Seamann, Araliaceae, leaves
Daniellia oliveri Hutch. et Dalz., Caesalpiniaceae, young leaves
Ficus thonningii Blume, Moraceae, leaves
Gardenia ternifolia, Schum. et Thonn., Rubiaceae, dry or green leaves
Phyllanthus muellerianus, Exell., Euphorbiaceae, leaves
Piliostigma thonningii, (Schum.) M. Readh., Papilionaceae, leaves and pods
In Ivory Coast, for humpless breeds:
Parinari curatellifolia Planch. ex Benth.Rosaceae, leaves and fruit
to which should be added Daniellia oliveri as cited above.
b) Palatable species
In the Adamowa (Cameroon), for zebus:
Bridelia ferruginea, Benth., Euphorbiaceae, leaves
Bridelia ndelensis Beille, Euphorbiaceae, leaves
Bridelia cf. speciosa Müll. Arg., Euphorbiaceae, leaves
Canthium venosum Hiern., Rubiaceae, leaves
Carissa edulis Vahl., Apocynaceae, leaves and young branches
Erythrina sigmoidea Hua, Papilionaceae, leaves and young flowers
Ficus glumosa Del, Moraceae, leaves
Hymenocardia acida Tul., Euphobiaceae, leaves
Lannea schimperi Engl. Anarcadiaceae, leaves and young flowers
Lophira lanceolata Van Tieg. Ochnaceae, young leaves
Mussaenda arcuata Lam. ex Poir., Rubiaceae, young leaves and flowers
Pittosporum vidiorum Sims, Pittosporaceae, leaves
Tricalysia okelensis Hiern, Rubiaceae, leaves
Vitex doniana Sweet, Verbenaceae, young leaves
Vitex madiensis Oliv., Verbenaceae, young leaves
In Ivory Coast, for humpless breeds:
Lophira lanceolata, as quoted above, young leaves
Trema guineensis (Schum. et Thonn. Ficalho, Ulmaceae, leaves
c) Unpalatable species
These species should be mentioned, but their browse value is minimal since they belong to a category in which the whole plant may be consumed, but always in very small quantities.
In Adamawa (Cameroon), for zebus:
Acacia sieberiana var. villosa A. Chev., Mimosaceae, mainly leaves
Albizia coriaria Welw. ex Oliv., Mimosaceae, mainly leaves
Albizia zygia J.F. Macbr. Mimosaceae, mainly leaves
Ficus ovata Vahl., Moraceae, mainly leaves
Mussaenda erythrophylla Schum et Thorn., Rubiaceae, mainly leaves
Psorospermum febrifugum Spach, Hyperieaceae, mainly leaves
Psorospermum glberimum Hochr. Hyperiaeceae, mainly leaves
Ternninalia macroptera Guill. et Perr., Combretaceae, mainly leaves
Veronia amygdalina Del., Compositae, mainly leaves
In Ivory Coast, with humpless breeds:
No proper observations have been made on the subject.
Albizia lebbeck, Mimosaceae, leaves
Cassia siamea Lam., Caesalpinaceae, leaves
Gossypium spp., Malvaceae, leaves
Lawsonia inermis L. Lythraceae, leaves and young branches
Mangifera indica L. Anacardiaceae, leaves and fruit
Manihot spp., Euphorbiaceae, leaves and roots
Moringa oleifera Lam. Moringaceae, leaves
Morus spp., Moraceae, leaves
This is not an exhaustive list and gives only the species most frequently cultivated or farmed.
Research and experiments are few and far between in the Guinean zone, except for the regional study by J. Piot in the Adamawa. Although the results of the analyses are extrapolated from European norms, it is important to emphasize the remarkably high crude protein content in relation to other available feeds, especially grasses, during the dry season. Most palatable species have a content which is rarely lower than 10%, whereas standing grass crops during the same period are below 5%. This is extremely important, since it enables the introduction and propagation of species considered to be of browse value for extensive animal production purposes to be envisaged.
In order not to have to extrapolate the results, experiments were mounted on similar types of pasture in natural savanna, as follows: a) over a given area the ligneous vegetation is entirely preserved, while b) over an identical area it is destroyed. Two herds as similar as possible utilize these two types of pasture and the results are obtained by using a cattle weigher
This method implies identical utilization methods and the rationalized utilization of browse plants so that they are within reach of the animals. The results will highlight the real importance of browse during the dry season and possibly during the rainy season as well.
As regards browse production on natural savanna, whatever figures are obtained can have only an indicative value since the variables are so many: density, height, phenology, etc. Here again the results will only have a value if the experiment is carried out on combined grass and ligneous crops. By working on given areas and discovering the respective production of each component in the combination it will be possible to evaluate the contribution made by the browse species, as against that of the control grass.
To sum up, browse is important in the forest zone and especially in the forest fringe area, but it still remains to make the phenological stage preferred by the animals coincide with the troughs in the protein content of grassland.
In the forest fringe and forest zones the development of animal production and especially cattle production has never depended on the existence of savanna, in contrast to what is generally believed, so that savanna should only be considered as a makeshift solution during the first years in which animal production is started up.
Except in the case of a few favourable sites where animal production can take place at low cost, it is no use entertaining fond hopes, and in the majority of cases land will have to be rapidly reclaimed and controlled. Land reclamation and control require investment. Should investments be channelled towards maintaining a proper sylvopastoral balance or should they necessarily be devoted towards land clearance before establishing forage crops?
Any mechanical intervention in the Guinean zone is expensive, with costs which are out of all proportion to the financial means available to the livestock producer. Land clearance, even when partial to improve the forage potential, cannot therefore be considered without subsidies.
In any case, at present subsidies can only be considered on condition that the forage systems advocated are technically simple and durable: simple in that the techniques employed require no material investment and management and utilization require only the minimum of discipline and maintenance; durable in that these systems will have to be efficient for ten years or so, a reasonable period in which the producer will be able to acquire some expertise in livestock management.
Browse trees and shrubs can contribute, just as grass can, to the partial solution of animal feed problems in the Guinean zone, and the extent to which they do so will depend on the importance attributed to them. The forage systems described below take into account: a) the arable value of the land; b) the human environment; c) the species raised.
Apart from the edaphic savanna, which has no arable value, the vegetation is a forest climax. Whenever utilization and management methods are used on savanna in a forest fringe or forest zone, bush encroachment and reforestation are inevitable. If the soils have an arable value and land reclamation takes places via bush clearance, two alternatives are available: forage crops may be included in a rotation; or forage crops may be cultivated outside the rotation system.
Where forage crops are included in a crop rotation system, whatever system is adopted the cultivated fallow has a twofold purpose: to provide green manure and feed resource. The cropping period should be 1 year, and two cycles are possible owing to the favourable climate. The first cycle might consist of maize while the second cycle would be an annual pulse sown as a catch-crop. Either one of the crops may be used while green, since cultivated fallow is primarily an agricultural operation. In this case the forage crop can be considered as no more than a balance feed whatever the livestock production conditions, and the producer should have other feed sources at his disposal. These might consist of forage crops based on perennial grasses or shrub crops either by themselves or in combination. Where forage crops are cultivated outside the crop rotation, the forage system used may be based on cropping one or two grass species and some browse and fruit species. The grasses provide the feed base while browse species contribute all or part of the protein balance.
Before going into details it is important to understand that this system can only be envisaged because two well tried and tested grasses are available. The grasses cultivated are Brachiaria ruziziensis and Panicum maximum and its ORSTOM K 187B, G 23 and T 58 clones in particular. These have been developed at Adiopodoumé and tested by the CRZ at Minankro-Bouaké. These plants are ecologically very flexible and well adapted to the Guinean environment. They can be utilized directly by grazing or via a cut-and-carry system while green, or for making silage. The method advocated is alternating grazing with cutting and carrying.
Brachiaria ruziziensis is established for 3 to 5 years or more. During the first 3 to 5 years the areas planted are treated as for a forage crop. Extracts are offset by fertilization. After 3 or 5 years the areas may be regarded as improved pasture. Fertilization need be used only as a spur to development, and nitrogen only is used.
An area planted with Panicum maximum may similarly be considered as a forage crop for the first 1 to 5 years and treated as such. From year 5 onwards it may be managed as an improved pasture until the 10th year, and treated the same as Brachiaria. In Nigeria 15-year-old areas still support 2 LU/ha during the rainy season in areas with 1000 mm.
Panicum maximum, especially, is a grass suitable for extension, for the following reasons: a) it adapts very well to dry-land cropping; b) it manages well with moderate fertilization; c) it can be maintained by burning off; d) it is resistant to competition, especially from ligneous plants; e) it is highly resistant to temporary overstocking; f) mechanical methods can be used for planting, on account of its perenniality.
This is almost the only forage system in which it is possible to establish almost permanent animal production using: a) detailed survey methods to establish parks and plots; b) contour management; c) shrub strip cropping without risk of scattering or competitions; d) management of included non-arable areas such as rocky outcrops, scree and faults.
The ligneous species to be used are browse or fruit species. For enclosing parks and plots providing shade for resting areas and constructing hedges, the following should mainly be used: Moraceae: Morus spp.: mulberry trees, especially Morus alba L. Mimosaceae: Prosopis chilensis (Mol.) Stuntz (syn. P. juliflora Sw. DC) Mimosaceae: Pithecellobium saman (Jacq.) Benth. (Mimosa saman Jacq.) syn.: Enterolobium saman (Jacq.) Prain, Albizia flavovirens Hoyle; common names: "arbre à miel" or "arbre à confiture". The first of these species is cultivated for its leaves while the two others are grown for fruit.
Secondly, the following may be used: Moraceae Ficus gnaphalocarpa (Miq.) Stued. ex A. Rich. (leaves and fruit), Moraceae Ficus capensis Thunb. (leaves), Moraceae Ficus glumosa Del. (leaves), Moraceae Ficus thonningii Blume (leaves), Moraceae Ficus vallis-choudae Del. (fruit). For cover crops or in strips, or for non-arable areas: Mimosaceae: Leucaena leucocephala (Lam.) de Wit. (syn.: L. glauca, L. Benth); also named Lamtoro (Madagascar), pois lolo (Mauritius). The leaves, fruit and young pods are palatable.
To sum up, a livestock producer in the Guinean zone should start off by fattening from grass in order to pay off, as far as possible, the planting and maintenance of forage crops and browse plants. He should introduce a breeding herd after 3 or 5 years, by which time the areas under forage crops may be considered as improved pasture. He may continue fattening on new areas, including renewed former pasture, according to the importance which he attaches to animal production.
Areas in which the land has no arable value are usually savanna which has been invaded by bush to a greater or lesser degree, and where the perennial grass stratum has almost disappeared or consists largely of annuals1. The grass/ligneous plant balance has been upset and any attempt to resow with grass is expensive and risky.
1 Annual grasses in the Guinean zone are almost always of little interest or of only very short-term value. They are mostly unpalatable, especially to cattle.
The only possible and long lasting improvement is to upgrade the fruit and browse potential using the species mentioned above, especially Leucaena leucocephala and its varieties. The dissemination and invasion capacities of the species tested, and there are certainly alternatives to Leucaena, are two valuable assets to be sought after in this particular case. It should be possible to achieve a kind of "forage forest", suitable for use in a semi-intensive system.
In sociological terms, whatever the ethnic group or area concerned, there are always two development alternatives with regards to the intensification of forage cropping since there are always two kinds of animal producers. These are:
a) those who practise animal production or possess animals and who make use of the grass which the Good Lord provides without any idea of respecting an ecological balance, either because they are ignorant of it, or else because they wish to be ignorant of it, or consider their animals at the same level as poultry as regards providing them with food. This is a production system based on ancestral tradition and habits, carried out by men who, in order to remain free, reject development outright and even now often possess no intellectual equipment other than their religious education. Paradoxically it is this type of livestock production which, even now, still provides most of the meat supply.b) those who wish to enter animal production with the backup of loans and private funds; these people have no technical knowledge of animal production and especially of animal feeds, and fortunately they possess no bad habits or prejudices either.
For extensive animal production purposes, whether the zone is agricultural or not and whether the soils are suitable for cropping or not, once the grass-ligneous plant balance has been disrupted, although the zone still remains suitable for pastoral production, is it better to regenerate the grassland or to put the emphasis on the ligneous cover using browse or fruit species?
Grassland regeneration requires at least partial bush clearance, the introduction of competitive browse species able to disseminate and resist mismanagement, prohibited grazing, rotation, and all the other methods which add up to correct grazing management. Regeneration according to a grid system (2000 m2 per ha) costs, depending on the density of forage plants, between 50 and 80% of the cost price of establishing a hectare of forage crops (excluding bush clearance). What is more, nature assists in the dissemination of the forage species introduced. Fertilization is avoided for economic reasons and the aim is to reach an annual carrying capacity of 250 kg. However, it is an illusion to think that the forage growth will do any better than the spontaneous grass which has disappeared, without fertilization and management.
All this is complex, expensive, and not a lasting solution; furthermore it is inapplicable under extensive production conditions especially amongst people who do not feel it to be any concern of theirs.
The Guinean savanna is suitable for forestry, and bush control by burning, although free of charge, often becomes ineffective after only a few years, even if denuding and erosion of the areas used does not occur, with consequences with which we are all too familiar. Given this state of affairs, solutions have be found which will allow an appreciable improvement in animal feeds at the same time as involving a larger number of animals, whatever the amount of interest aroused.
At the moment planting fruit or browse species is the only possible solution, for a number of reasons: a) once established the species introduced will survive whatever the type of management and the risk of burning; b) a roughshod rotation system can be implemented, because browse improvement is thought to be less valuable than an improvement in the forage grass; c) this work may be regarded as a kind of land reclamation, in which case financing problems are avoided.
Later on, once the producers have reached a more intensive production stage, it will in any case be necessary to clear the bush and manage cultivable areas, using contour farming, subsoiling, levelling work and so on, as would have had to be done for natural bush clearance. Increasing the density of the ligneous stratum therefore presents no problem. At that stage further investment will have to be envisaged, but it is to be hoped that this would be definitive. The browse species to use are the same as given above, although further species should be identified and tested.
Although simple this method does require some semblance of rationalized utilization of palatable ligneous species. Piot defined this kind of rationalization as having three aspects: a) elimination of unpalatable species; b) pruning of young palatable species to allow animals to utilize them better; c) cutting and distribution of those plant parts out of reach of the animals. It is to be hoped that livestock producers would understand the sound basis of these methods.
For newcomers to animal production the forage system based on Brachiaria ruziziensis or even better on Panicum maximum with fruit and browse plants can currently be used by people with no experience of animal production It should be recalled that for a breeding herd of 100 head of 80 LU the areas necessary are: a) on natural pasture at a rate of 5 ha/LU, 400 ha; b) on Brachiaria ruziziensis, after 3 years, 80 ha; c) on Panicum maximum, after 5 years, 40 ha. These figures are average but they clearly show that it is easier to find a few dozen ha than 400 or 500 ha in a zone essentially characterized by forest. The cost of bush clearance and infrastructure also remains fairly low.
To put it briefly, Panicum maximum is a grass which can be extended with little or no risk of failure, a very important aspect. Planting browse and fruit plants should at least in part offset any possible nitrogen deficiency without hindering general farm management methods. Models on a real life scale should be mounted, but it is very important to provide permanent and efficient follow-up.
The systems described above primarily concern cattle. For sheep and goats the alternatives have not been studied. Of course it is well known that sheep and goats enjoy shrubs much more than cattle, a significant fact in the Guinean zone. The species consumed are many but no study has specified their exact number and seasonal importance in feed. As a result the browse species known to be applicable for cattle are used on sheep raising farms and fattening projects currently being started, as is now occurring in Ivory Coast.
The utilization and management of the browse species normally cultivated is still posing problems with cattle. These problems are magnified in the case of small ruminants, since they have different browsing methods; they uproot plants and trample on them, carrying capacity and regrowth period vary, and at identical establishment costs the long-term survival of crops is hazardous. Moreover, it cannot be known whether the feed or rather the feed composition, is really suitable for this kind of animal. There is no doubt at all that research will be necessary on the local species habitually browsed, especially amongst suffrutescent or subligneous species, such as the Sida genus and some Cassia varieties.
Natural grazing land in the forest and fringe forest zones plays, with few exceptions, only a supporting role while livestock production is being started, and it must be borne in mind that investment should aim not to maintain it but rather to replace it. Flourishing savanna does not necessarily mean good grazing (derived savanna), nor does pseudo-prairie (edaphic savanna), merely because the animals can be maintained there throughout the year. Livestock development is therefore linked with the intensification of forage production.
As regards cattle raising, in a pure grassland system, which is the simplest kind, there is no grassland legume which can really give satisfactory results. On the other hand grasses such as Brachiaria ruziziensis, and more especially some clones and hybrids of Panicum maximum, are especially adapted to this kind of utilization. All the same, in-depth tests remain to establish certain parameters, for example the carrying capacity and durability of the crop with moderate fertilization. In this case it will be necessary to balance the feed ration with nitrogen, so that the solution doubtless lies in shrub and fruit browse species.
Still with regard to cattle raising, the poorer areas can be improved using fruit and browse shrubs, since any work on reconstituting the grass stratum would also be costly and yield highly chancy and transitory results. This principle also applies to the southern Sahelian and Sudanian zones for areas which still have a pastural suitability.
As regards sheep raising it is not certain that a diet based on forage crops, using the species with which we are familiar, best answers the needs of this animal, when it is understood that feeding behaviour varies very considerably. It may be possible to raise sheep using a dry grass such as Cenchrus or Chloris and a crop combination of suffrutescent species and shrubs. Again, the most palatable browse species will have to be discovered on a regional basis, while the palatability of introduced species with an alleged forage value will have to be tested.
Finally it should be recalled that in the Guinean zone the establishment of any crop presupposes bush clearance. This can be subsidised only on condition that the forage systems proposed as a subsequent solution are durable and simple. Ligneous and subligneous forage fruit species can contribute substantially to the development of animal husbandry in the humid zone. Besides the species cited above, some of which are described in the appendix, others should also be researched in the tropics, especially Albizzia, Dalbergia, Grewia and some Cassia spp. Research and experimentation are thus by no means without value in a zone which is reputed to be evergreen.
Drawings of some fruit and forage species
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