G.S. Byenkya
Animal Health Research Centre
P.O. Box 24, Entebbe, Uganda
Introduction
Location of pasture research in Uganda
Historical highlights of pasture research prior to 1960
Evaluation studies of pasture species
Recommended pasture species
Discussion and conclusion
Acknowledgements
References
Abstract
Forage germplasm introduction and evaluation work in Uganda has been reviewed. Many species have been evaluated by different workers in different parts of the country. This has been in terms of their establishment, persistence and production characteristics, fertilization and yields, defoliation, chemical composition and nutritive values, animal productivity and their seeding abilities. From these studies, the Ministry of Agriculture has demarcated Uganda into six zones with recommendations of various pasture species for each zone. Most of the grass species evaluated and recommended are indegenous to Uganda, while nearly all the legume species are exotic. Availability of planting seed has been observed as the major hindrance to pasture development programmes in the country.
Uganda is one of the East African countries crossed by the Equator, and lying between latitude 4°12'N and 1°29'5 and longitude 29°34'E and 35°E. It is bordered by the Sudan in the north, Kenya in the east, Tanzania and Rwanda in the south and Zaire in the west. It covers a total area of 235,886 sq. km.
The climate is good, with a mean annual rainfall varying from 510 mm in the North-Eastern parts of Karamoja to 2160 mm or more in the Sesse Islands in Lake Victoria. The rainfall is bimodal with the first peak being in March-May (first rains) and the second in September-November (second rains) with dry periods in between the peaks. Further north the two seasons tend to coalesce into one rainy season of about five months centred around July and one long dry hot season. A mean monthly maximum temperature exceeding 37.8° C has been recorded in some parts of the country with a seasonal variation barely above 6°C. A figure of 10°C for mean monthly minimum temperatures has also been obtained with a seasonal variation of just about 3°C.
Generally most soils are able to support some form of agriculture. Those soils with high productivity include:
1. those associated with volcanic activities,2. those clays formed from parent material derived partly or wholly from basic amphibolite rocks,
3. those deep, red or brown, loam or clay loam, pediment soils,
4. deep sedimentary soils.
The above four groups are well represented all over the country and have been cultivated extensively. There are also those soils with low to nil productivity, which are shallow or very sandy or sometimes with a lot of gravel. This group also includes those montane soils on the slopes of mountains. These are mostly in the north with localised patches and pockets in the rest of the country.
Vegetation varies from rain forests to savanna and grassland with a small patch of bushland and thicket in the extreme northeastern part of the country in Karamoja.
Agriculture is the backbone of Uganda's economy, engaging the majority of the population and currently accounting for about 95% of all foreign exchange earnings. Crop husbandry plays the leading role in the overall farming system and is poorly integrated with animal husbandry. Livestock are an important factor in the ordinary life of the majority of Ugandans. Their values to the owners range from wholly economical to social/prestigious uses in marriages and other cultural ceremonies and as security against shortcomings. The productivity of these herds is, however, very low. The livestock population density is greatest in the northern and northeastern parts of the country. These areas also tend to have low rainfall and can be classified as natural grasslands or rangelands. According to the 1979 statistics of the Ministry of Animal Industry and Fisheries, Uganda had 5,053,510 cattle, 2,453,528 goats and 962,315 sheep.
A number of institutions are involved in pasture research in Uganda. These stem from two different parent ministries, namely the Ministry of Agriculture and the Ministry of Animal Industry and Fisheries (Veterinary Department). Although pasture work can be traced way back to the turn of this century, it was not until 1920 that a proper experimental station was established.
Currently three research institutions are engaged in pasture research in the country in addition to the Faculty of Agriculture of Makerere University. These are:
1. Serere Research Station - established in 1920 in the East to carry out experimental work in the so-called "short-grass areas" i.e. in the eastern and northern parts of the country. This belongs to the Department of Agriculture and carries out research on crops including pastures and some animal work.2. Kawanda Research Station - about 50 km north of Kampala was established in 1937 in the "tall or elephant grass areas". It belongs to the Department of Agriculture and it is the seat of crop research in the country but with some animal production work going on.
3. Animal Health Research Centre (AHRC) - situated south of Kampala belongs to the Department of Veterinary Services and Animal Industry. It carries out research and diagnostic services in both animal health and production.
There are, however, some smaller agricultural research stations and agricultural colleges which at some stage have been involved in pasture work. These include Namulonge Research Station, Bukalasa Agricultural College and Arapai Agricultural College, all three belonging to the Ministry of Agriculture. Because of the many institutions involved, which belong to different parent ministries, there arises the problem of coordination of research efforts to avoid duplication. Although Uganda's third Five-Year Development Plan 1971/72-1975/76 stated that "In order to avoid duplication and to effect a better integration of efforts, in future all Government research on livestock and pasture will be sponsored and administered by the Ministry of Animal Industry," this has not fully been implemented.
A brief chronological listing of the highlights of pasture research findings in Uganda up to 1960 has been given by Henderlong (1973) as follows:
|
1906 |
Introduction of legume species primarily for vegetative cover and soil conservation. |
|
1925 |
A collection of pasture grasses started by Maitland near Kampala. |
|
1930 |
Selected species from the 1925 planting were established in larger plots at Bukalasa for general observations on grazing and feeding. |
|
1931 |
Grass collections were started at Ngetta and later at Serere. |
|
1932 |
Continuous cultivation of arable crops even with green manures was shown at Serere to result in decreased crop yields when compared to crop yields under shifting cultivation. |
|
1933 |
All governmental farms in Uganda changed their crop rotations to include a two- to four-year planted grass rest (fey) phase. This policy gave the first real impetus to research investigations with the local grasses. |
|
1945 |
Stylosanthes gracilis was introduced in Uganda from Australia by Thomas (1966) and planted at Kawanda and later at Serere. |
|
1948 |
Chloris gayana was recommended as the best overall grass species for the grazed temporary ley throughout most of Uganda. In some areas, elephant grass (Pennisetum purpureum) was also commonly used for the temporary ley phase, but it proved difficult to eradicate from cropland. It required vegetative planting, and it was better adapted as a fodder crop than for direct grazing. |
|
1954 |
Detailed systematic work on grass and grass-legume mixtures was initiated at Serere by Horrell (1958). |
|
1956-1958 |
Introduction of legume species for the "forest area" was initiated at Kawanda in addition to the earlier grass museum and introductions at Kawanda by Thomas (1966). These initial studies included over 100 different grass species, of both temperate and tropical origins, and approximately 60 different tropical and temperate legumes. |
Much of the earlier detailed investigative work was done mainly on grasses. Various texts were published on these grasses. Initially they were investigated for the rest period after arable cropping, and their importance as a source of grazing or fodder was then subsidiary. The effects of the animals on soil fertility were unclear until it was later shown that grazing did not reduce yields of subsequent crops (Kerrham, 1947).
The introduction of exotic animals after 1960 was an impetus to extensive grassland improvement. Evaluation of both indigenous and exotic pasture species was initiated as a result of this development. These have, over the years been evaluated in terms of management studies on establishment, persistence and production fertilization and yields and defoliation. Evaluation further concerned itself with chemical composition and nutritive values, animal productivity and seed production.
Establishment, Persistence and Production
Horrell (1958, 1963) gives an account of a wide range of grasses and legumes studied at Serere in nursery plots to determine their suitability for leys in eastern and northern Uganda. He pays special attention to persistence, production, habit, seeding ability and to a lesser extent palatability. The origins of the species in question are also given. From such studies, he was able to recommend the following species for use in eastern and northern Uganda.
|
Grasses: |
|
|
Chloris gayana |
for leys |
|
Cenchrus ciliaris |
for leys |
|
Cynodon plectostachyus |
for leys |
|
Hyparrhenia rufa |
for leys |
|
Pennisetum purpureum |
for dry season supplementary grazing |
|
Setaria spp. |
for dry season supplementary grazing |
|
Paspalum notatum |
for lawns |
|
Cynodon dactylon |
for lawns |
Legumes: The most successfully adapted legumes under these conditions included:
Stylosanthes gracilis, Calopogonium orthocarpum, Centrosema pubescent, Desmodium spp., Pueraria phaseoloides, Glycine javanica (now Neonotonia wightii).
All of the above except Neonotonia wightii were exotic to Uganda. The study demonstrated the ability of a number of tropical legumes to grow vigorously and reproduce in this environment. A good growth of Stylosanthes gracilis with a crude protein content of up to 24% has been achieved at Animal Health Research Centre (AHRC Entebbe, unpublished data). Chloris gayana has also been successfully established under a silage crop cover of sorghum at Entebbe while Melinis minutiflora was unable to establish (Harker, 1954). Pennisetum clandestinum was found to grow well in pot experiments at AHRC, Entebbe (unpublished). Other pasture species have been tried in different environments in Uganda, but the reports are difficult to come by.
Fertilization and yields
The use of fertilizers was considered important in pasture work in Uganda. Nitrogen fertilization was established to be essential for good production of pure grass swards or leys (Horrell and Bredon, 1963; Horrell and Tiley, 1970; Olsen, 1972). It was found that production of grass species falls sharply in the second and third years from planting but that yields could be maintained at a steady level by application of N or by the inclusion of a successful legume such as Desmodium intortum.
Phosphorus or superphosphate was proved valuable for the establishment of legumes (Stobbs, 1969a; Olsen and Moe, 1971). They reported that liming was useful for the persistence of lucerne and its modulation but showed no general effects on the establishment, persistence, production or modulation of either Desmodium or Stylosanthes.
Responses of Hyparrhenia rufa, Panicum maximum, Stylosanthes guianensis, Centrosema pubescens and Macroptilium atropurpureum to phosphorus, sulphur and potassium in eastern Uganda were investigated by Wendt (1970). All the species responded to P and S to levels of application of about 70 kg/ha of P and 20-40 kg/ha of S giving yield increases of 40-100%.
Much work has been done to evaluate the compatibility of various grasses and legumes when planted in mixtures. Results of Olsen and Tiharuhondi (1972) discouraged the sowing of Desmodium intortum with Chloris gayana. Both D. intortum and Medicago sativa made good association with Panicum maximum and Setaria anceps (now sphacelata).
Defoliation
Literature on this aspect of forage evaluation is scanty. It appears that few studies on this aspect were undertaken. Horrell and Bredon (1963) working on Panicum maximum at Serere reported highest DM yields at cutting intervals of nine weeks while best yields of CP were obtained at cutting intervals of between six and nine weeks. Although there are no reports on legume defoliation studies in Uganda, Henderlong (1973) observed that the rate of regrowth of lucerne after defoliation was considerably more rapid than for any of the adapted tropical legumes.
Chemical Composition and Nutritive Values
A number of workers evaluated various species for their chemical composition and nutritive values. Some of this work was carried out in different ecological zones. Species were analysed for crude protein, crude fat, crude fibre, ash and silica contents and for the various mineral element contents. This was done on both planted and rangeland pastures but mostly on grasses. The various grass species analysed in greater details in this respect were Pennisetum purpureum, Themeda triandra, Panicum maximum, Chloris gayana, Cynodon dactylon, Digitaria spp., Hyparrhenia spp., Melinis minutiflora, Setaria spp. and many other range species.
Pennisetum purpureum, an indigenous grass of Uganda, has been found to be of very high value as cattle feed with a CP% content ranging between 9.2-20.5 and CF% of 29.3-37.7 (Marshall and Bredon, 1963). It is used both as a pasture plant as well as fodder crop. Although pure pasture leys of individual herbage species are unusual in Uganda, P. purpureum and Setaria sphacelata have proved to be among the most productive pasture grasses and have been proposed for commercial use (Morrison, 1971).
Nutritive value assessments of pastures and forages have been reported by Juko and Bredon (1961), Bredon et al, (1963), Nusangi (1965) and many others. The nutritional value of some common cattle browse and fodder plants of Karamoja, northeastern Uganda, has also been investigated by Wilson and Bredon (1963).
Due to the role played by rangeland for the grazing animal, several workers have attempted to evaluate the quality of range pastures in different parts of the country. Reports of Reid et al. (1973) indicate that natural grasslands in Uganda had lower digestibilities than the planted species. But the higher digestibilities in planted species declined more rapidly with maturity than the natural grasslands. They also reported that Brachiaria generally exhibited one of the highest levels of in vitro digestibilities among the species evaluated which agrees with the in vitro data of Soneji et al. (1971) which indicated higher digestibilities for Brachiaria ruziziensis than either Chloris gayana or Setaria sphacelata. Legume species on the other hand generally had lower digestibilities than the grasses in the early stages of growth, but the decline in legume digestibility was considerably less marked than for the planted grasses (Reid et al., 1973).
Digestibility trials and chemical analyses of indigenous grasses at AHRC indicated adequate starch equivalent values for both maintenance and an element of production throughout the year while protein was frequently limited (Marshall et al., 1961; Bredon and Torrell, 1962; Bredon and Marshall, 1962). Proximate analyses on rangeland grasses of western Uganda indicated lower CP values for Themeda triandra (4.14%) and Hyparrhenia filipendula (4.41%) compared to Brachiaria spp. (6.49-7.64%), Chloris gayana (5.96%), Panicum maximum (6.61%) and Cynodon dactylon (8.27%).
Various workers have analysed various pasture plants for their mineral contents in different localities. Minerals analysed for include: N, Na, K, Mg, P, Mn, Cu, Zn, Co, Mb, S, Sn. Investigations on the mineral status of the commonly used grasses on farms in Buganda and Busoga and also in western Uganda in the Queen Elizabeth National Park indicated adequate amounts of N, K, Mg, Mn, Cu, Mb and S while levels of Na, Ca, P, Zn and Co were marginal or deficient in many grasses thus requiring supplementation (Long et al., 1969; Long et al., 1970).
Mean mineral composition (%) of some Uganda grasses as reviewed by Harrington and Pratchett (1973) are given in Table 1.
Table 1. Mean mineral composition (%) of some Uganda grasses.
|
|
Sodium |
Potassium |
Magnesium |
Calcium |
Phosphorus |
|
Themeda triandra |
0.034 |
0.50 |
0.09 |
0.31 |
0.11 |
|
Chloris gayana |
0.041 |
1.17 |
0.15 |
0.29 |
0.22 |
|
Setaria sphacelata |
0.046 |
1.82 |
0.13 |
0.41 |
0.26 |
|
Brachiaria playtynota |
0.034 |
1.19 |
0.19 |
0.40 |
0.17 |
|
B. brizantha |
0.045 |
1.16 |
0.17 |
0.39 |
0.21 |
Ssekaalo (1972) working on eastern Uganda pastures, concluded that grass species generally contained less cobalt than legumes. Grasses had little difference in their cobalt content and so did the legumes with the exception of Macroptilium atropurpureum. The cobalt content was enough to meet animal requirements except where Pennisetum purpureum was the main fodder. Selenium status of pastures in Uganda has also been analysed by Long and Marshall (1973). The better quality grasses, judged on the bases of CP content and DM digestibilities such as Brachiaria spp., Cynodon dactylon, Panicum maximum and Setaria aequalis tended to have satisfactory mineral contents while the more typical savanna type grasses, Hyparrhenia filipendula and Themeda triandra were generally low in essential minerals (Long et al., 1969).
Animal Productivity
Forage evaluation through livestock productivity has been studied at Serere by Stobbs (1969c) and Otim (1973). Higher values in terms of animal production have been obtained when various legumes have been included in the grazing systems. Stobbs (1969b) investigated Stylosanthes gracilis and Centrosema pubescens as mixtures, top dressed with single superphosphate fertilizer. Stylosanthes gracilis because of its small hairy leaves and woody stems generally had low intake while Calopogonium mucunoides, one of the best legumes tested at Serere, was completely unacceptable to the animal (Otim, 1973). Paspalum notatum was able to maintain excellent beef production at Namulonge Station, indicating its relatively high digestibility.
Seed Production
The availability of planting seed is a major hindrance to pasture development efforts in Uganda. Preliminary evaluations of the various species for seed production have indicated that most of the various recommended species were able to produce seed. Emphasis has been put on legume seed production. Stylosanthes, Neonotonia, Centrosema and Macroptilium spp. have produced reasonable seed yields at Serere while Desmodium and Medicago spp. were not as successful (Wends, 1970).
General planted pasture zones have been established with recommended species for each zone, as follows:
ZONE 1: Pennisetum purpureum
(Hoima, N. Toro, Mubende, Mpigi, S. Busoga, E. Masaka)Grasses:Pennisetum purpureum
Panicum maximum
Chloris gayana
Brachiaria ruziziensis
Setaria sphacelataLegumes:
Desmodium intortum
Desmodium uncinatum
Medicago sativa
Neonotonia wightii
Stylosanthes gracilis (on poor or stony soils)
Centrosema pubescens
Macroptilium atropurpureumZONE 2: Moist western areas
(S.E. Toro, N. and W. Ankole, N. Kigezi, S. West Nile)Grasses:Chloris gayana
Setaria sphacelata
Brachiaria ruziziensis
Melinis minutifloraLegumes:
Desmodium intortum
Desmodium uncinatum
Macroptilium atropurpureum
Trifolium spp. (above 1700 metres).ZONE 3: Highland areas
(S. Kigezi, W. Toro, S. Sebei, E. Bugisu)Grasses:Chloris gayana
Setaria sphacelata
Pennisetum clandestinum
Pennisetum purpureum (for fodder)
Melinis minutifloraLegumes:
Desmodium intortum
Desmodium uncinatum (lower altitudes)
Trifolium spp.
Medicago sativaZONE 4: Hyparrhenia spp.
(West Nile, Madi-Moyo, Acholi, W. Karamoja, Lango, Teso, N. Sebei, W. Bugisu, Tororo, N. Busoga, Luwero, N.E. Mubende, Masindi, N. Toro)Grasses:Panicum maximum
Hyparrhenia rufa
Chloris gayana
Setaria sphacelata
Brachiaria spp.
Cynodon dactylonZONE 5: Themeda triandra
(Central Karamoja, S.W. Toro, E. and N.W. Ankole, N.W. Masaka, S.W. Mpigi, S. Mubende)Grasses:Chloris gayana
Cenchrus ciliarisLegumes:
Stylosanthes gracilis
Macroptilium atropurpureumZONE 6: Not suitable for leys
(E. Karamoja, Muntain summits)
The climate of Uganda is generally considered as being good. There is adequate well distributed rainfall in most parts of the country. The soils are generally good. Hence many crops including pasture are capable of growing in various parts of the country.
Pasture work in Uganda can be traced as far back as the beginning of this century. The initial aim of pasture establishment was to assist in the regeneration of soil fertility of continuously farmed land for the subsequent crops. The value of grazing these pastures was by then unknown as it was believed that this would interfere with the normal process of soil regeneration and hence affect the yield of the following crops.
A journey across most parts of Uganda will reveal the availability of ample amounts of unutilised herbage. These natural pastures can easily be grazed by livestock. The availability of such herbage has not been an inducement to pasture improvement schemes involving farmers. Increasing pressure on the land as already observed in parts like Kigezi in the southwest, Mbale in the east and a few other places will require efficient management of the resources so as to support the increasing human and animal populations. The provision of better adapted, more nutritious forages for livestock will go a long way in improving the productivity of national herds. Uganda is rich in its plant genetic resources of forage potential which are as yet to be exploited. Many indigenous grass species have been evaluated for their forage value and many have been recommended for various parts of the country. Indigenous legumes on the other hand have not been exploited. Only Neonotonia wightii has been studied in detail and recommended as a useful pasture plant. The rest of the legumes evaluated and recommended are exotic, most of them being of South American origin. They have been evaluated in terms of their establishment and persistence, chemical composition and nutritive values, fertilization and yields, defoliation and seed production. Livestock productivity from such pasture has also been evaluated. Some of these trials have, however, been limited to the research stations only, taking into account the two broad areas i.e. "long grass areas" and "short grass areas". Extensive multilocational trials of various species have not been effected and this could be the cause of poor performance in some areas. This should therefore be carried out.
One of the current problems limiting forage evaluation studies and requiring attention is the lack of planting seed. Many of the species tried have been found to seed well. In the past Kawanda and Serere have produced limited quantities of pasture seed, but this has since stopped. Currently, pasture seed must be imported from abroad if required. For researchers needing small quantities of seed, the solution has been solved by ILCA's FLAG programme which has gratefully supplied small quantities of seed for local multiplication purposes.
Despite the important achievements in pasture research in Uganda, one wonders to what extent this has contributed to the overall livestock productivity in the country. The majority of livestock owners are small peasant farmers who graze their herds on communal land. These have obviously gained very little, and the idea of pasture improvement could as well as be a myth to them. There is lacking an integrated package which can be presented to farmers in different parts of Uganda so as to revolutionise their agriculture and enable them to increase their productivity and incomes. Many factors obviously contribute to the lack of an adequate and acceptable technology package of improvements for farmers which include traditional beliefs of large livestock numbers rather than productivity, land tenure systems, tendency to divorce animal from crop husbandry, lack of coordination between research and extension, and lack of incentives and proper training for both research and extension agents. There is still a need for integrated research into systems of farming. Only a few progressive farmers and government-owned livestock enterprises have gained from the results obtained through research. With increasing population pressure on the land and hence reduction in communal grazing lands, it is likely that alternative methods of feeding and improvements will be sought by the majority of livestock owners, but this must be coupled with a good supply of planting seed to farmers.
The author thanks the PANESA Coordinator for inviting him to attend the Workshop and to present this paper. Thanks also go to the Permanent Secretary, Ministry of Animal Industry, Uganda, for permission to attend the Workshop.
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