SESSION 5
STRATEGIES

CONSERVATION OF THE NATURAL RESOURCE

J.J. Jackson
P O Box 7, Gutu, Zimbabwe

Our natural resource is the VELD. I think “veld” is a beautiful word. It is a very holistic term. It has many facets, many components, great diversity and its composition varies from one place to another.

From a livestock nutrition point of view we may lump its components together into three main categories namely grass, browse and fruit. For cattle, of course, grass is the most important but the other two can make a vital contribution in the dry season.

Regarding the variation in veld types, for this short paper we can only look at the two more common ones in Zimbabwe. The first we will call the highveld which is found over the higher altitude central plateau, under higher rainfall and mostly on leached soils. The second we will call lowveld, found in the hotter, drier, low lying parts of the country where the soils are generally more fertile.

The highveld has predominantly what we call sour grass. They are strong perennials, upright, tufted grasses, which lignify early and so become unpalatable as they mature. The low veld has what we call sweet grasses. They are annuals and weak perennials which remain palatable and nutritious as they mature.

Regarding nutritional value to cattle the highveld, without additional feeding can only carry one livestock unit (L.U.) per four has. Each L.U. will on average gain 100 kg per year; giving an annual liveweight production of 25 kg per ha. The main limiting factor is not bulk but protein. The lowveld is stocked at a much lighter rate. 10 has per L.U. is an accepted norm. The grass is however significantly more nutritious. Each L.U. will gain 150 kg, sometimes more per year. That gives an annual liveweight production of 15 kg per ha. The potential is much higher in good years, but drought risk is the most serious limiting factor.

The greatest breakthrough in cattle production on the highveld has been dry season protein supplementation. Not only does it directly benefit the beast, but it also is good for the veld. More of the bulk that would have gone to waste is eaten, and more and better quality dung is dropped. This finds its way into the soil as a vital input into that all important biological cycle.

In average years dry season feeding is not necessary in the lowveld. However, dry season veld fattening of any potential slaughter stock in order to get them away before grass runs out is a very viable practice.

Winter feeding on the highveld is by means of calculated quantities of carefully compounded supplements, yet the contribution of the veld, which one is supplementing, is very much an unknown factor. In practice the amount of supplement is increased according to animal response as the dry season progresses. Had it been economically viable to feed to the level where the only contribution required from the veld was roughage then the whole matter would have been very straight forward. Costs are however such that winter feeding at best has to be very strategic.
In other words we cannot get away from the role of the veld. The condition of the veld still has a major impact on the well being of the cattle. Yet even at its best the need for winter protein supplementation remains. But the difference between good veld and bad veld is the amount of supplement required. When veld conditions are bad the response to supplementary feeding can even be disappointing.

This brings me to the subject of my paper. With our focus on the dry season how can we assess the value of the different components of the veld? How can we keep them in good condition? Assessing value is very much a matter of observation of animal response. While qualitative analyses are a great help there remains the matter of the actual quantity of each component the animals eat. One is always observing animal response to a combination of factors. That combination however varies from veld to veld, paddock to paddock and month to month. Then again the type of season is different every year.

Over the years in set stocked situations a picture definitely emerges. This is especially so on farms where paddock differences are a significant part of the scene. Rotating cattle through paddocks on the other hand masks those differences. Assessing the relative values of the different components of the veld then becomes more difficult.

After observing the interaction between cattle and the veld most of my life I have gained some strong impressions. Added to this are the experiences of many farmers, which have been told to me. And of course those principles that have been proven by research. All these form the basis of the contents of this paper.

Looking at the dry season, I would like, for the sake of clarity, to divide it into the following periods: May/June, July/August, September/October, and for the lowveld in years of drought November/December.

May-June

Highveld

Grass

The nutritional status of the grass at the beginning of the dry season will depend very much on the type of rainy season experienced over the preceding months and upon the management of the veld.

In very wet years the grass tends to go rank and is of poorer quality. The cattle also will not have had the best summer gains. On the other hand, in years of average to slightly below average, well spread rain cattle will enter the dry season in peak condition. Grass in the vleis will still be growing until it gets well frosted. That vlei grass which cattle had managed to hold down through the summer will still be their favoured grazing. The slowed down growth rate will however fail to keep up with the grazing rate and cattle will take it down to the ground. Such short grazed grass retains its nutritional value but its yield now falls far short. Cattle have to turn to other sources to fill their bellies. The vlei grass which they had allowed to grow out will by now have fallen below three percent protein and will be very ligneous and not acceptable. The topland grasses, while mostly dry by now, will be softer and more acceptable. There will be patches of sweeter grasses like Panicum under the trees, Cynodon and patches of annuals. At this stage they will be an important part of the diet.
The type of veld management employed through the summer will have had a major impact upon the dry season grazing situation. Summer peak pressure on the vleis while resting the topland will ensure fuller use of the more vigorous high potential vlei grasses while allowing the topland to yield its bulk of acceptable winter reserve. That is a double win situation.
Interruption of summer grazing of vleis can allow the most vigorous, sourest grasses to get away and on return the cattle will find them unacceptable resulting in uneven. species selection. Vleis must therefore be grazed in summer either on a continuous basis or on a quick rotation system. Vlei and topland must never be included in the same rotation as it could easily result in the more vigorous vlei getting away causing the topland to be grazed bare. That is a double loss situation.
Vleis that have been hard grazed and kept short in summer and are then given a late summer (Mar/Apr) rest however, present a much different picture. Such late growth that results, is very acceptable to cattle. The topland also, having rested during peak summer will have produced so much acceptable bulk that it can easily accommodate the cattle for the two months the vlei is resting. Such is a triple win situation.

When cattle are left to their own devices having continuous access to both vlei and topland in set stocked paddocks they tend to do the right thing. The vlei remains their first choice grazing. They patch graze it when there is more grass than they can handle. The state of equilibrium between growth rate and grazing rate of those patches of vlei gives the major input into summer gains. Such patch grazing is non species selective. In fact the very sourest species are included in those patches and one often sees them still being grazed to the end of summer in preference to the sweetest species like Panicum maximum on the topland. This preference of short grazed sour grasses while more delicate sweeter species are allowed to grow out is an important natural buffer which must have helped to preserve the great diversity we have. But some years this balance can go wrong especially when vleis get waterlogged. Untimely moves of cattle from one paddock to another are however the most common cause of upset of the topland-vlei balance. The safest thing therefore is fencing them off coupled with deliberate topland-vlei management. The summer rests of the topland bring many advantages not least of which is the increase of Panicum maximum.

One other very important factor in sour veld is that of top hamper. All standing grass older than one year must be looked upon as top hamper. It is by then already turning grey. Cattle won't eat it. In the vleis one cannot trample it all to litter. Fire is the most efficient leveller of the playing field. And if one does not level the playing field the unevenness becomes worse and worse each year. Left over standing grass at the end of each dry season should be burned down. At this stage it is still healthy and has a good store of root reserves. After a burn it will come away with vigour taking the pressure off the tired, hard grazed patches that did not get a chance to grow out. But if one delays burning for another year such grass will already be moribund, the burn will be hotter, and the growth response will also be poorer.

On the topland however, litter cover of the soil is of top priority. It is rain infiltration here which supplies dry season moisture in the vleis. Topland grass also more readily breaks up into litter. Situations do arise especially following wet years when topland grass can be more rank and less acceptable than usual. A burn then becomes necessary. That should be done soon after a good rain when the soil and the litter are still wet and only the standing grass burns. The freshness of the grass reflected by its golden colour is a good sign for an easy winter. But entering the dry season with a significant cover of grey grass spells trouble.

Browse

In the highveld, cattle do a significant amount of autumn browsing. Munondo (Julbernardia globifera) is a favourite but as winter progresses into June that browsing ceases. About June fallen leaf browsing commences. The leaves of a wide variety of trees are liked up off the ground. The clumps of trees found on termitaria especially provide a valuable harvest of fallen leaf browse. Among them Zizyphus macronata is worthy of mention. Its yellow-green leaves have been analysed at 13 percent protein. The total leaf canopy of all the Acacia species and Dichrostachys, over the period of June to September, finds its way to the ground still retaining a healthy green colour. Where these trees abound this must be a significant contribution to winter nutrition.

Small legumes are found on the topland in great variety. Where topland is repeatedly summer rested they have greater opportunity to seed and the increase in their abundance soon becomes evident. By their nitrogen fixing they must add to the value of the topland grass and they must themselves be an important component of the late summer early dry season diet. Where veld has been reinforced by introduced small legumes like fine-stem Stylo a summer rest likewise significantly adds to their seeding potential. And the grass where they grow is preferred grazing. But where topland is not fenced off in a set stocked situation such Stylo areas can become first choice grazing in summer, upsetting the vlei-topland balance.

Fruit

The pods of some trees start falling in June. In thornveld areas where Acacia nilotica dominates, pods fall in profusion in June and July and are relished by cattle. They make a significant contribution to the diet. So much so that the cattle enjoy a brief mini-peak of nutrition.

Acacia sieberana pods start dropping in June and continue to the end of September. Some trees are early and others late, providing a full four months of fall. In paddocks where these trees abound, cattle visibly benefit, but where there are only a few trees cattle spend too much time moving from one to the other and even waiting for hours to pick up a few pods. Pods have been analysed at 14 percent protein and 60 percent T.D.N., if there was a tree in the highveld that needs to be preserved, propagated and researched it is the Acacia sieberana. A very big tree can yield 400 kg of pods. Most mature trees probably yield 50–100 kg. A heavy crop is usually followed by a low yield the next season. Fortunately the alternation seems to be more related to the tree than the season so that most years some trees yield well. There is however, a tendency to get the heaviest crops in dry years. Ten trees per L.U. would be a good initial target in a propagation program.

Supplementary feeding

Often in May-June, protein supplementation on the highveld would appear unnecessary. It is however, probably the time for the most cost-effective feeding. A small amount of protein keeps their appetite very healthy and broadens the range of their diet, the benefit of which will carry over into the next months of the dry season.

Lowveld

In the lowveld May and June are normally peak nutrition months. There is usually more than enough grass to carry the cattle that have survived the end of season hazard. More will be said about that hazard later. Grass usually has a very healthy golden colour. Browse also plays a significant role at this stage. Only in dry years will the Mopane start losing its leaves as early as June.

July-August

Highveld

Grass

The vlei grass will usually be well frosted by now through the cattle will continue to spend a lot of time in the vleis. Where vlei management was correct, an abundance of roughage will be available on the topland. The areas of sweeter grasses will now be depleted and the leftover dry grass, through abundant will be of lesser quality. This grass and protein supplement will make an excellent combination. But where protein is not supplemented cattle will suffer significant weight losses.

Browse

Fallen leaf browse will play its most important role during this period. Even though it constitutes a very significant part of the diet, it does not come near to excluding the need for protein supplement.

Fruit

The continued pod fall from some Acacias can be very important. Where Acacia sieberana abounds, its contribution could significantly reduce the level of protein supplementation required.

Lowveld

The grass will continue to be good. Even good enough to enable lactating cows to cycle and reconceive. The trees will be losing their leaves rapidly. Only patches of Mopane scrub may still be green. In cases where late can rain had fallen, Mopane will hold its leaf longer. Cattle will continue to flourish, but a hazard - like a red warning light lies ahead. After October, if the rains don't come in time, grass could disappear very quickly. Stock numbers must be controlled. Only the bare essential categories must be carried over. Every potential slaughter animal should be fattened and gone by early October. July is a good month to start giving them extra food. It is very practical and cost-effective. They respond very well on this kind of veld.

September-October

Highveld

Grass

In the moister zones of the vleis a significant amount of green grass will appear. In tall grass the new green grass will not be accessible to cattle. Where the grass is shorter, a good mix of green and dry is seen and cattle work their way into it. They get bigger mouthfuls of green in such places than where the veld is very short. But unfortunately they have to taken in too much rubbish with it so that animal response is always disappointing. Protein supplement however solves that to a great extent. Early burning of such moist zones is an option. If one delays burning too long these patches can become too green to burn and can be lost. It is important to get full use of these most productive parts of the veld. Burning however, is followed by about two weeks of nothing, and then very high quality but low quantity green grass emerges. The first rain on such a burnt vlei however produces an immediate dramatic response. While cattle do spend a lot of time on a burn, they definitely use dry topland grass to fill up. In this respect Heteropogon contortus (Spear grass) at this stage is very soft and cattle, after spending most of the day on the burn, take big mouthfuls of this grass.

Browse

The first new leaf browse to appear is Msasa (Brachystegia speciformis) which shows up in August already. Cattle use it, but are not very fond of it. Mnondo (Julbernardia globifera) may come out in September or October, depending upon the moisture status of the soil. In very dry years it may only appear latter. Cattle use it heavily as they do many other species. In fact the quantity of browse they eat in a day could be considerable.

Fruit

In September, Acacia sieberana still gives a significant pod fall. Monkey Bread (Bauhinia thoningii) comes in later, dropping its pods from October into November. Snake Bean (Schwartzia madagascarensis) will have been dropping its pods since about July and come to an end in September. At this stage another very important fruit comes onto the scene and that is the Mobola Plum (Paranari mobola). These trees, which may abound, produce enormous crops of fruit. The fruit which has a high sugar content is relished by cattle.

Supplementary feeding

In spite of all the browse and the green grass in the vleis, October is a bad month. The new season usually seems to come with severe birth pains. October is the month of those birth pains. Even cattle well supplemented with protein often disappoint. The new green grass in the vleis should be very high in protein - so should the new leaf browse which they eat in quantity. Perhaps energy is now suddenly the missing factor. Response to molasses does seem to suggest that. Apart from the nutritional aspect, or aggravated by it, accidents are common. Compètition for food makes animals more aggressive and they butt each other like battering rams. Animals grazing water edge vegetation are knocked into the pools. Beside this, water edge vegetation often brings with it heavy liver fluke invasion to further complicate the whole matter. When the rains come, which they should by the end of October, then the last birth pains are followed by the wonder of the new season.

Lowveld

September and October usually still see the cattle in good condition and well nourished as long as there is grass. The quality of grass slowly declines through the dry season. Out of season showers and drizzles speed up that decline and the beautiful golden colour slowly changes to grey. The value of the grass is easily gauged by its colour. But out of season rain does have this big advantage that it keeps the perennial grasses strong. But when the really hot weather comes, grass disappears quickly. The annual grasses disintegrate into powder and the perennial grasses are rapidly reduced. It is well by now to have sent off all possible sale animals.

November-December

The highveld normally now enjoys phenomenal summer weight gains. Depending upon how the first rains come, the take off may be delayed well into November.

Lowveld

Delay in the coming of the rains sometimes unexpectedly lands the lowveld in a critical drought situation. As the hot weather continues without rain the picture of desolation does not take very long to emerge. Without a leaf on a tree or a blade of grass in sight, and the sun beating down, stress on man and beast becomes unbearable. This is the lowveld hazard which makes its visitation once every so many years. It is because of this hazard that the lowveld finds itself less than half stocked when the rains do fall and the grass is suddenly back again.

How does one ride this hazard? The control of stock numbers has already been mentioned. The control of grazing is also important. Here the most important matter is water distribution and water point control of grazing. Species selection is not a problem but rather the fact that cattle eat all the grass closer to the water points first and the perimeter slowly retreats until when the worst time comes the only grass available is far away. It may be mentioned here that dry fallen leaves, usually blown by the wind into small lines or heaps, contributes significantly to the saving of lives.

Cattle usually still look reasonable when tragedy strikes. Heavily pregnant animals are the first to succumb. Walking the long distances between grass and water does them no good. On arrival at the water in the heat of the day, they drink up to 90 litres. In a weakened state, after a drink and rest, they find they cannot lift that extra 90 kg weight, and there they expend their last energy. To the rancher this point comes unexpectedly and may lead to panic action. Identifying all heavily pregnant animals and putting them on a high energy diet can prevent any further such cases. Other animals can usually still look after themselves and survive off fallen leaves for a further month or two.

Management strategy to avoid this dilemma should be aimed at not having heavily pregnant animals during the months October through to January. Fortunately this can easily be done in the lowveld because the chance of reconceptions of lactating cows seems to even be better in June than in January and February. So the whole calving season can be geared to side stepping the high risk period.

The other important strategy would be to cut and bale hay when grass is abundant in early winter and always have a good reserve. Sadly this is not often done. The grass is so good and the climate so ideal that an investment into the appropriate equipment and the clearing of some hay fields would be the very best insurance policy.

Prediction of potential disaster is a vital aspect of management with foresight in the lowveld. While one cannot predict the weather one must always know the status of the veld, whether it is healthy and resilient or fragile and vulnerable. That simply means the status of the perennial grasses. If they are still strong, a single good shower of rain will dramatically save the day. But if they are dead as they sometimes are after a prolonged dry season, then the entire new grass crop has to start with germination. That requires follow up rain. Scorching sun may result in two or more waves of germination before the grass gets away. Such situations are very hard on the cattle. To check if perennial grasses are still alive, a watering can on a few tufts will show it up within three days.

Properly handling the lowveld hazard should open the door to fuller utilisation of the valuable lowveld grass when it is there.

A few last management points for the highveld

Whatever grazing system one employs the cattle need the following:

• Access to the topland on cold winter nights
• Access to high points when confined to waterlogged vleis. They will graze in the water but only rest up on dry ground
• Access to vlei and topland in the Spring when they eat green grass in the vlei and go for browse on the topland
• Access to the pod bearing trees during the time they drop their fruit. This access need not be daily but I don't think the interval should be longer than one week. The same would apply to fallen leaf browse
• Access in Autumn to topland for Autumn browse
• The only time cattle don't need access to the topland and can be confined to the vleis is during the peak of summer
• Cattle always like the vleis but one can afford to keep them off for two months in late summer and Autumn (March-April)
• Vleis must be pressurised in summer to exploit their full potential
• Topland must be rested in summer in order to realize its full potential
• Entering the dry season with a rank vlei and bare topland is very bad news
• Old grey grass is always unwanted. The more there is the poorer the veld
• Grass is made to be grazed and cattle are made to eat grass. That is a great biological cycle. Their dung feeds the next generation of grass. Both underutilisation and over utilisation are not good for the cycle. But optimum use boosts it. Every bit of supplementary feed is an important input into that cycle.

LAND USE IN SOUTH EAST ZIMBABWE: TOWARDS UNDERSTANDING RESILIENCE IN RANGELANDS

R. Taylor
WWF Southern Africa Regional Programme Office
PO Box CY 1409 Causeway, Harare, Zimbabwe

Introduction

Five periods of land use in south east Zimbabwe over the past 150 years (1850–1998) are described, together with accompanying environmental trends and events. Attention is focused on land tenure and economic development since 1900 following European colonisation and Independence 80 years later. The region under study includes land in the Large Scale Farming Sector (based on animal production, wildlife tourism and large scale irrigation), adjacent Communal Lands (based largely on subsistence agro-pastoralism) and Parks and Wild Life Land covering in excess of 25000 km². The area lies below 600 m asl between the Save and Nuanetsi rivers and the Zimbabwe-Mocambique border. A seasonal rainfall of 250–550 mm between November and April is low and variable, although precipitation can be recorded in every month of the year due to moisture in-flow from the Indian Ocean. The vegetation is a Colophospermum mopane woodland, tree or shrub savanna typical of the major river valleys of southern Africa. Each period or phase is examined with a view to identifying key ecological, economic and/or social constraints and opportunities, and across different scales where appropriate. Qualitative and quantitative information and data, where possible, are provided to support the arguments presented. The region is characterised by a dual agricultural economy and land tenure reflecting racial divisions of the past.

Phase 1. 1850–1896. Gold, cattle and cultivation: The Shona states

The south-western Rozvi empire of the largely agriculturally-based Shona people displaced the northern Munhumutapa dynasty of the north in the late 17^th century and dominated most of the area of modern Zimbabwe through the 18^th century. Following the disintegration of the Rozvi empire more than 100 small Shona states emerged soon to be challenged by a wave of Nuguni invasions from the south. During the 19^th century the deposition of Mzilikazi's kingdom around Bulawayo in the south west and that of Soshangane's Gaza kingdom along the present Mocambique border in the east brought a greater emphasis on cattle keeping and, consequently, cattle raiding upon the Shona. Although the Portuguese had penetrated Zimbabwe by the 16^th century, they never actually acquired rights either of conquest or occupation, and any such claims were finally dispelled in 1890 by the British South Africa Chartered Company. The earlier intensive exploitation of gold and ivory by the Munhumutapa, aided by the Portuguese and others, was in the mid 19^th century being replaced by a land economy based on cultivation and by 1900, southern Zimbabwe was one of the most heavily populated parts of the country. This Iron Age economy was probably beginning to run into problems of land shortage (as presently understood) and the occupation of southern Africa by agropastoralists can be looked upon as an early experiment in land use, the full results of which will never be known.

Phase II. 1896–1950. Pioneering ranchers: Predation, disease and economic depression

Hunters, traders and adventurers characterised early European exploration. Laessoe provides, in 1906, the first scientific account of the south east region following occupation by the British South Africa Company in 1896 of modern-day Zimbabwe, then Southern Rhodesia. His party traversed the Lundi river from Belingwe to the Mamboni on the Mocambique coast returning via the Sabi (Save) river as far as Melsetter (Chimanimani). Poaching for ivory and itinerant trading with speculative forays into cattle buying and selling, together with exploration for commercial activities and agricultural opportunities characterise these early days. Following the Great War, development of the country was centred on the Zimbabwean plateau or “highveld” where environmental conditions were favourable for commercial agriculture based on tobacco, maize and intensive cattle production. The climate also favoured settlement and other development options. Nevertheless, highveld farmers were quick to appreciate the value of the lower lying parts of the country, notably the south east “lowveld”, for its “sweetveld” grazing where they would winter their cattle. But predators - lion, leopard, hyaena and wild dog - exacted a heavy toll in an area which abounded in wildlife, a factor which would increasingly alienate cattle ranchers from wildlife, who felt “you cannot farm in a zoo”. This was further exacerbated by disease, notably Foot and Mouth Disease, Theileriosis and East Coast Fever, all of which were strongly linked to the presence of wildlife. Most important at the time though was Trypanosomiasis, transmitted through the bite of an infected tsetse fly (Glossina spp.). This period was marked by intensive Government campaigns to remove tsetse fly, largely through systematic game eradication programmes. In addition to these environmental hardships, early cattle ranching also had to face falling cattle prices associated with the post-war depression. The effect of this was more marked in the remoter areas of the country such as the lowveld where logistical costs were much greater. The vision of irrigation as an important complimentary or alternative land use option was recognised by the pioneering lowvelder, Tom MacDougall.

Phase III. 1950s–1970s. Cattle, game and irrigation: Development and fragmentation

By the mid 1950s, conventional wisdom recognised the lowveld as best suited to semi-extensive beef production, ranching and large scale irrigation and over the next 20 years or more, attention focussed on these, especially cattle ranching and irrigation. Consequently, efforts at disease control together with an extreme intolerance of wildlife intensified. Large scale irrigation development took place on Triangle and Hippo Valley Estates, strongly supported by Government, with sugar cane the most important crop. Lesser amounts of cotton and winter wheat were grown on both these and other estates. Whilst the variability of rainfall was well recognised by the cattle producers, water for irrigation began to gain increasing importance and with it the need for better water use regulation and catchment management. Despite the intolerance towards wildlife, the Fulbright Scholars, Dasmann and Mossman, drew much attention to the importance of this resource through their pioneering efforts on a few selected ranches, notably Doddieburn and Buffalo Range. Their focus was on game cropping for meat production as an alternative to beef, but financial viability was at best marginal compared to a heavily subsidised cattle industry. Disease control requirements were also a major constraint to marketing game products. Wildlife conservation become a major land use with the proclamation of the Gonarezhou Game Reserve, later to become a National Park in 1975. But this proclamation was accompanied by the eviction of Shangaan people from their traditional homes and exclusion from a lifestyle which was supplemented by hunting and gathering. Tsetse fly control and game eradication continued in certain designated areas. Land use policy and practice focussed on the Large Scale Commercial Farming Sector and land tenure, based on racial lines, continued to contribute to the continuing degradation of over-crowded communal lands, especially in the catchment areas of the lowveld.

Phase IV. 1970s-1980s. Wildlife with or without cattle: Drought and challenge

The cumulative effects of successive droughts undermined the irrigation schemes which were forced to take land out of production. Salinity problems were also affecting production levels as well as contributing to local pollution problems. Importantly, both drought and the declining viability of cattle production was forcing land owners to examine alternative land use options. The most important of these has been wildlife, based now not on meat production but on a range of tourism based options including safari hunting, ecotourism and biodiversity conservation. The role of wildlife increasingly became recognised as a legitimate component of economic development. The involvement of local communal land occupants in community based natural resource management programmes became a reality after Independence in 1980 with rights of access to wildlife resources supported by important institutional reform.

Phase V: 1980s-1990s: Politicians, farmers and ecologists: Consolidation, restoration and interdependence

This has been accompanied by the consolidation of individually owned land holdings into larger entities known as conservancies where wildlife is the primary land use but where in some cases, there may be some cattle and/or irrigation under appropriate circumstances. Veterinary requirements have also been re-assessed and these reflect innovative and adaptive approaches to wildlife production but which nevertheless remain compatible with beef export requirements and normal standards of disease control. Adjacent communal land communities are becoming involved in commercial partnerships often linked to conservancies which reflect important integrated conservation and development initiatives. Nevertheless, the longer term sustainability and resilience of these over-crowded communal agro-pastoral systems remain problematic with negative implications for surrounding land uses where greater progress in tackling these issues has perhaps been made. Politically based solutions are presently being viewed as inappropriate by certain sectors of society who argue for a more process oriented approach, whilst some technical specialists question the reality of land degradation.
Increasing conflicts over land and water allocation, and the need for improved catchment management in the case of the latter, underscores the importance of new land use models and the need for greater interdependence between different land uses and tenurial arrangements.

OPTIMIZING THE UTILISATION OF DRY SEASON VELD FOR COMMERCIAL BEEF PRODUCTION THROUGH SUPPLEMENTATION

D.M. Gammon
Agrifoods (Pvt.) Ltd, P O Box 559, Bulawayo, Zimbabwe

Introduction

One of the most important limitations to beef production in southern Africa is the poor performance of unsupplemented cattle on veld in the dry season. In the lower lying, sweetveld areas liveweight maintenance or a gain may be recorded over the dry season but in the higher, sour- and mixed - veld areas considerable weight losses occur, frequently with high levels of mortality. The result of this is reduced fertility, delay in reaching market weights, increased finishing costs and an overall reduction in off-take. It is with these problems in sour - and mixed - veld areas that this paper is concerned.

Limiting nutrients

In the early years of commercial beef production, efforts to overcome the problem of poor performance on dry season grazing were concentrated on substitution of grazing, to varying degrees, with conserved roughages of better nutritional quality. This approach was expensive and, in drier areas, unreliable. Research then concentrated on identifying limiting nutrients in dry season grazing.

In 1936 Murray et al, in research conducted at Matopos Research Station, indicated that protein was the primary limiting nutrient in dry season grazing. A supplement of 450 to 680 g of groundnut cake eliminated poverty losses and, by reducing dry season weight losses, reduced the time taken to reach slaughter weight off veld by 14 months. This was a landmark revelation but it is noteworthy that these findings were not widely applied until about 20 years later, after the establishment of a dynamic extension service, under the directorship of Murray.

In the same research Murray and co-workers found no response to supplementation with salt (28 g per day) or phosphorus (21 g dicalcium phosphate per day), although subsequent research revealed positive responses to phosphorus supplementation during the growing season (Ward, 1968a)

A large volume of subsequent research has confirmed the early findings of Murray et al. However, in a series of trials conducted by Grant (1979) it was found that, while supplementation with salt alone had limited or no beneficial effect, the addition of 10 percent salt to various vegetable protein supplements enhanced the response by more than 20 percent. This effect has yet to be elucidated.

In research conducted by Ward (1968a) supplementation treatments included protein, phosphorus, salt, calcium and vitamin A. Only protein produced a positive dry season response. Trials at Matopos Research Station (1967) showed no response to dry season supplementation of copper and cobalt, alone or in addition to protein.

Supplementation of dry season grazing with low-protein, high-energy feeds has generally resulted in little or no improvement in performance. For example, van Niekerk and Jacobs (1985) found no response to low level supplementation with molasses, either alone or in addition to a protein supplement. Hennessy et al., (1983) recorded little or no response from weaners supplemented with 560 to 1120 g of cracked sorghum, alone or in addition to a protein supplement. However, supplementation with higher levels of energy-rich supplements has, in some cases, resulted in improved performance, with an additive effect when fed with protein.

In recent years the use of a “digestion modifier” has been promoted by a commercial company as a means of improving the performance of animals on veld with tannin-containing browse or grasses. The product, marketed as “Browse Plus”, has as the main active ingredient polyethylene glycol (PEG) which binds with and reduces the adverse effects of tannin. Australian research indicates that, to have a significant effect, intakes of the order of 50 g per day for mature cattle would be necessary, at which level it is uneconomical (Miller, 1992 personal communication). The local company reports very substantial improvement in performance with only three g per day of the product. (Duncan and McKenzie, 1996). However, trials conducted by Matopos Research Station (Schur, 1996) revealed no response at levels of one to three g Browse Plus or one to six g PEG. Protagonists of the product argue that this research was invalid since all treatments also received a protein supplement. However, the performance of the control group in this research (+9.1 kg) was poorer than that of a control in the commercial trials (+36.4 kg), indicating that the diet in the research trials, including the protein supplement, was more deficient in protein.

Amplification of the effects of protein and energy supplementation

The effects of the low nutrient content of dry season grass are aggravated by low intake by cattle, typically about 1.5 percent of body weight. This is due to slow digestion by protein-deficient rumen micro-organisms. This level of intake of typical dry season grass provides less than 50 percent of the protein and about 70 percent of the energy required by a dry cow in late pregnancy.

A major effect of supplementation with a protein source, which includes rumen-degradable protein, is to increase the activity of the cellulolytic micro-organisms resulting in more rapid digestion of dry grass. This results in intake being increased by as much as 30 percent to over 40 percent. With an enhanced dry matter intake of 2.1 percent of bodyweight the grass can provide 100 percent of the energy requirement of a dry cow in late pregnancy, although it will still only provides about 60 percent of the protein requirement, which needs to be made up in the supplement. Thus, protein supplementation has the direct effect of meeting the animal's primary need for protein, and an indirect effect of raising energy intake through increased appetite.

In contrast to protein supplementation, supplementation with energy supplements causes a proliferation of fast-growing sugar or starch digesting micro-organisms, which deprive the cellolytic organisms of nitrogen. The result is a reduction in digestion and intake of grass, which can be of sufficient magnitude to reduce the net intake of energy.

The key to optimum supplementation of dry season grazing is to provide sufficient rumen degradable protein (RDP) to maximise grass intake and sufficient undegradable protein (UDP) for the level of performance required. If higher levels of performance are required energy has to be provided in substantial amounts sufficient to compensate for reduced intake of grass.

Protein supplements

Vegetable protein sources, notably cottonseed cake or meal (CSM), have formed the basis of protein supplements in Zimbabwe. CSM has proved particularly successful, probably due to its balance of RDP and UDP. However, the cost of such supplements has led to a search for cheaper alternatives.

Urea, through the action of ruminal micro-organisms can be used for a portion of the RDP requirements. Potentially, it is currently the cheapest source of supplementary protein. However, in a supplement to low quality roughage, conditions are not ideal for efficient utilisation of urea. Table 1 illustrates the relative effectiveness of CSM alone and with increasing levels of urea in pelleted supplements containing 40 percent. C.P.

Table 1. Liveweight changes over the dry season of weaner steers unsupplemented and supplemented with 500 g per day of 40 percent CP pellets containing different levels of urea.

Source: Grant (1979)

Because of the relative cheapness of urea, it is accepted that some loss in efficiency with urea-containing supplements is cost-effective and most producers in Zimbabwe use commercially manufactured 30 to 45 percent CP cubes or blocks containing three to six percent urea. However, considerable use is made also of straight CSM, home mixes with urea, chicken litter and legume hays, and in the past liquid urea-molasses supplements were used.

In South Africa far greater use is made of urea, probably as a result of the restricted availability and high cost of oilseed meals. Loose licks containing 15 to 25 percent urea, with little or no true protein and energy are commonly used. The effectiveness of these licks is probably due to relatively low palatability, with high levels of salt, which results in slow intake. For the same reason it may be that higher levels of urea could be used in hard blocks than in rapidly consumed pellets.

Quantification of benefits of protein supplementation

Young stock

Table 2 summarises some of the research done in Zimbabwe on protein supplementation of young stock. Considerable variation is evident between sites and at the same site in different seasons. The performance of unsupplemented stock ranges from approximate liveweight maintenance to a loss of over 15 percent of liveweight, while with the levels of supplement used performance ranged from approximate maintenance to a gain of 30 kg. The average end of dry season difference between unsupplemented and supplemented animals was 28 kg for weaners and 42 kg for yearlings.

Compensatory gains occurred in the following summer in all cases, except one (that with the least difference in dry season performance). On average, 34 percent (weaner) and 36 percent (yearlings) of the end of dry season difference was made up by higher summer gains in the unsupplemented animals, resulting in average end of summer differences of 19 kg in weaners and 26 kg in yearlings. In assessing the economics of supplementing young stock due regard needs to be given to the effects of compensatory gains.

Replacement heifers

Unsupplemented replacement heifers will normally reach a suitable mating weight only at approximately three years, while with supplementation this can be reduced to two years or less. Depending on the production system, this can allow an increase in the size of the breeding herd of more than eight percent and an improvement in fertility of about five percent. At the present costs of protein supplements and returns for weaners it should be profitable to supplement for these benefits.

Table 2. Results of research on protein supplementation of young stock in Zimbabwe

Veld finished steers

Based on the average indications in Table 2, steers starting as 200 kg weaners could reach approximately 500 kg at 3.5 years while unsupplemented steers would be expected to weigh approximately 70 kg less. In addition to the reduced marketing weight, these steers would achieve poorer grades and realise a lower price per kg. Keeping them an extra year would necessitate a reduction in the breeding herd and would result in lower grades due to increased age.

In the case of veld fattening at two to three years with a finishing supplement, steers not supplemented in the dry season will either market lighter with poorer grades or will require more finishing supplement. Usually the cost of the extra finishing supplement will exceed the cost of dry season supplement.

Pen fattened yearlings

Table 3 and 4 give the results of a classical trial conducted at Henderson Research Station to examine the effects of different levels of protein supplementation on dry season and subsequent summer performance and on the time and feed required for pen finishing at eighteen months (Elliott and O'Donovan, 1971).

It is interesting to note that, at the lowest level of protein supplementation, although the weaners were gaining 114 kg live weight per day, they were still losing 42 g per day in carcass weight (Table 3). It was estimated that carcass weight maintenance occurred at a liveweight gain of 170 g per day, which would require a supplement of about 230 g CP per day.

Table 3. Effects of level of protein supplement on winter and summer performance of weaners (initial weight 213 kg)

Table 4. Effects of level of winter protein supplementation on subsequent high-energy feed requirements (fattening to 430 kg live weight)

1. Total gain from weaning
2. Protein costed at $15.90/kg CP, HE diet costed at $3.68/kg

Compensatory gains reduced the end of dry season weight differences between treatments but there were still substantial differences when the animals were penned at the end of summer. Consequently the amount of high-energy (HE) feed required to fatten them to a common end weight of 430 kg was reduced by the previous protein supplementation (Table 4). As there were small differences in final carcass weight the quantities of protein and HE diet required are calculated per kg of carcass gain from weaning to slaughter. At current protein and HE diet prices the most expensive group to produce was the unsupplemented group and the cheapest was the group receiving 311 g CP per day in the dry season. In this group 1 kg of CP in winter saved 8.3 kg of HE finishing feed. In a similar trial at Grasslands Research Station (Grant, 1975), at a winter supplement level of 200 g CP per day, 1 kg of CP saved approximately 6 kg of HE feed. It can be concluded that as long as protein does not cost more than six times the cost of HE feed, it should be profitable to supplement weaners destined for fattening as yearlings, to achieve a gain of up to about 200 g per day.

Breeding herd

Table 5 summarises the major research on supplementation of breeding cows in Zimbabwe.

Table 5. Results of research on protein supplementation of breeding cows in Zimbabwe

(1) Average for first ten years. Calves of supplemented cows late weaned.

This research indicates that protein supplementation can raise the calving percentage to over 80 percent, with a concomitant increase in weaning weight. In addition, protein supplementation greatly reduces cow and calf mortality

Provided the breeding herd is supplemented efficiently, with due precision, so that high calving percentages are achieved, the investment in supplementary feed is profitable.

In practice, in spite of the available knowledge and technology, the national average calving percentage remains at about 65 percent. There are two major reasons for this: first, the perception that, with escalating costs of protein there is a need to discountinue or reduce supplementation and second, that inadequate precision is applied to supplementary feeding.

Cost of protein

The perception that the cost of protein has escalated to uneconomical levels is fueled by statements from advisers and industry officials. However, the increase in the price of stockfeed should not be viewed in isolation but in relation to beef prices, as it is the ratio of the beef price to the feed price that governs the economics of supplementation. The ratio of the beef price (July Super) to the price of protein in 45 percent crude protein cubes from 1980 to 1999 is given in Figure 1. This shows that beef prices have escalated more rapidly than protein prices and that for the last six years the ratio has been more favourable than the 20 - year average of 3:1

Figure 1. Ratio of the beef producer price to the price of protein in 45 percent crude protein cubes

Precision in supplementary feeding

Many producers supplement their breeding herds but still only achieve calving percentages in the region of 60 percent to 70 percent. This is probably largely due to “blanket” rather than strategic supplementation of the herd and a failure to supplement to reach specific performance targets.

Table 6 indicates the responses of different categories of breeding stock to supplementation. The greatest response is obtained from pregnant heifers, and although not revealed in this research, immature cows show similarly spectacular responses. Pregnant mature cows show a smaller, but still large response, while empty cows show little or no response.

Table 6. Subsequent conception rates of different categories of females with and without supplementation.

Not only do heifers and immature cows give a greater response to supplementation, but they also have greater requirements for protein. When different categories of females are supplemented together, the older cows dominate the younger animals, which then receive less supplement. This indicates a need for strategic supplementation, whereby different categories are separated and supplemented according to their needs and responses.

Table 7 categorises breeding stock according to age and pregnancy status with a guide to levels of supplement. On large properties it may be feasible to supplement all categories separately but in most cases some rationalisation will be necessary. An example of how the different categories could be grouped is shown in the table. Strategic feeding in this way reduces costs and is more effective.

Table 7. Categorisation of the breeding herd for strategic feeding.

Age Group(1)	Pregnancy status	Feed level guide (g/CP/day)2	Rationalised groups
Two years	Pregnant heifers (p)
	Empty heifers (e)
Three years	Pregnant consecutively (pp)
	Empty (e)
Four years	Pregnant consecutively (pp)
	Pregnant not consecutively (p)
	Empty (e)
Mature	Pregnant consecutively (pp)
	Pregnant not consecutively (p)
	Empty (e)

1. Assumes beifers mated at two years.
2. Guide only, start at low levels increasing as necessary. Top levels after calving.Groups indicated “nil” may need minimal levels to maintain viable condition.

Performance targets

Many farmers “feed for half a calf”, i.e. at too low a level. The result is that many supplemented cows still fail to conceive and the feeding is uneconomical. The secret of profitable supplementary feeding is to bring cows just to the critical weight or condition required for conception, and no more.

Table 8 gives a guide to the weights that need to be reached for heifers and immature cows to achieve conception rates above 80 percent, derived from research conducted by Meaker (1984). The performance required in the dry seasons between successive matings depends on the summer gains achieved and the time of calving. With spring calving and average summer gains, heifers and immature cows need to gain approximately 30 kg (0.25 kg per day) up to calving to allow for losses at and after calving.

Table 8. Guide to target weights for heifers and immature cows at the start of the bulling season (spring-early summer bulling).

In order to achieve re-conception rates of approximately 80 percent mature cows need to have a minimum condition score of 3 (1–5 scale) or 5 (1–9 scale) at mating. To allow for loss of condition immediately after calving, the condition score at calving needs to be about 3.0 in situations where post-calving losses are regained by the bulling season (e.g. spring calving, lower milk - producing cows) or about 3.5 where there will be an overall loss post - calving to bulling (e.g. winter calving, higher milk-producing cows).

In terms of weight, mature cows can be allowed to lose in the dry season in proportion to their gain in the summer. Provided good summer gains are achieved and cows are in good condition in autumn (over 3.0), they, can afford to lose up to about 12 percent of their autumn weight during the dry season. However, to allow for losses at and after calving, the peak autumn weight needs to be at least maintained up to calving.

Interaction with veld management

The need for and benefits from supplementation are affected by veld condition and veld management. The important effect of stocking rate is well illustrated by research conducted in Kwazulu-Natal. This showed that as the stocking rate was increased to 20 percent and 50 percent above the recommended level, the dry season feeding period had to be extended and the cost of feeding to achieve the same cow condition score was increased by 25 percent and 48 percent respectively.

In a trial at Matopos Research Station cows were run at two stocking, rates (3.6 and 8.1 ha per cow) and supplemented at three levels of protein (0,92,185 g CP per day, with the amounts doubled after calving). Unsupplemented cows at the light stocking rate had a higher average calving percentage over four years than cows run at the heavy stocking rate receiving the high level of protein supplement (Richardson and Khaka, 1982).

The research of Denny and Barnes (1977) revealed no effect of various grazing procedures on animal performance in the dry season. However, at the very heavy stocking intensities that may be applied in ultra - high density grazing it can be expected that animal performance will suffer to the extent that higher levels of supplementation would be necessary.

Conclusions

There is considerable scope for further research aimed at improving the utilisation of dry season veld. Alternative, cheaper sources of protein need to be sought. There is a need to establish optimum levels of urea in blocks and licks and to improve the efficiency of utilisation of urea. Little is known of the effects of different times of commencement of supplementation or of optimum levels at different seasonal or physiological stages. The role of energy supplementation in addition to protein at different stages also needs clarification and there is a need to be alert to the possibilities of major mineral and trace-element deficiencies or excess or vitamin deficiencies in specific situations.

Further clarification is needed on the effects of tannin-controlling and other possible additives. A field which has received no attention in this country is inoculation of the rumen with tannin-active bacteria.

While further research will no doubt lead to improved utilisation of dry season grazing, there is currently still a wide gulf between the available knowledge and the successful practical application thereof. There are, however, sufficient commercial operations which are successfully applying the existing technology to prove that it is practicable.

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