agricultural production guidelines
m
Veld in KwaZulu-Natal
Co-ordinated Extension KwaZulu-Natal Veld 2.1 1999
PLANNING A VELD MANAGEMENT PROGRAMME FOR A FARM
J M B Smith & K G T Camp
KwaZulu-Natal Department of Agriculture
Identification
of Veld Type Units
Assessment of Veld Condition
Estimation of the Farm Grazing Capacity
Choice of a Livestock
Production System
Herd Composition
Determination of the Number
of Herds
Fencing Layout
Herd Allocations
Veld Management Systems
Economic Considerations
INTRODUCTION
The large variation in climate and topography in KwaZulu-Natal gives rise to 23 Bioresource Groups (see Production Guideline 7.1 of this series). These Bioresource Groups represent various vegetation types which can broadly be grouped into the sourveld and sour/mixed veld of Bioresource Groups 1 to 12, 14, 15 and 17; mixed veld in Bioresource Groups 13, 16 and 18 to 20; and sweetveld in Bioresource Groups 20 to 23. The principles that may be applied to veld management in the sweetveld, mixed veld and sourveld will vary in importance, but the approach to the planning of veld management programmes is essentially similar. The main steps to consider in planning are:
- identification of Veld Type Units (VTU);
- assessment of the condition of the veld;
- estimation of the farm grazing capacity;
- choice of a livestock production system;
- calculation of the herd composition;
- determination of the number of herds;
- fencing layout;
- allocation of herds to camps;
- consideration of potential veld management systems; and
- economic considerations.
Many of these aspects are described in detail in other Production Guidelines in sections A and B of this series. This Production Guideline provides a summary of the procedure that should be followed when planning a veld management programme on the farm.
IDENTIFICATION OF VELD TYPE UNITS
In order to apply sound management principles, it is necessary to demarcate areas of veld which have uniform palatability and productivity. Such a separation will assist in obtaining a uniform grazing pattern which is necessary to reduce area selectivity and patch over- or underutilization. These Veld Type Units (VTU) are demarcated according to certain criteria:
- climate (rainfall, temperature);
- soils (texture, depth, wetness);
- terrain (crest, scarp, midslope, footslope, valley bottom);
- aspect (north, south, east, west);
- slope (level, steep).
The easiest way to identify and demarcate these veld areas is by using stereoscopic pairs of aerial photographs. This permits the recognition of spatial interrelations of various physical features which would not otherwise be apparent without much arduous field work. The information obtained from the stereoscopic pairs is then transferred to a map of the farm, and verified in the field. Alternatively, the VTU’s can be marked out on a 1:10 000 orthophotos of the farm. Assistance in identifying VTU’s on the farm can be obtained from the local Agricultural Extension office.
The assessment of veld condition will assist in the determination of the grazing capacity and also the appropriate periods of stay and absence in the grazing rotation, and the necessity for rests. Veld in good condition will have a higher productivity, and require shorter or fewer rest periods, than veld in poor condition.
The basis of veld condition assessment is the comparison of veld of the particular site with veld in the same ecological zone which is in optimum condition. These optimum condition sites are known as benchmark sites, and have been identified for most Bioresource Groups in KwaZulu-Natal.
The species composition should be recorded in each VTU on the farm. The composition of each VTU is then compared to the benchmark site. (See Production Guidelines 2.4, 2.5, 6.1 to 6.3 of this series.)
ESTIMATION OF THE FARM GRAZING CAPACITY
Once the condition of each VTU is known, an estimate of the grazing capacity can be made. The dry matter production from veld depends mainly on its condition, and on the rainfall which falls during the growing season for veld (October to March). In KwaZulu-Natal this growing season rainfall is approximately 80% of the mean annual rainfall. The relationship between rainfall, veld condition and production is presented in Table 1. For example, in an 800 mm rainfall area the growing season rainfall would be 640 mm (i.e. 800 x 0.8) and, where the condition of the veld is 80% of the benchmark, the dry matter production per ha would be expected to be about 2 560 kg (640 mm x 4 kg). To prevent overgrazing, only half of this production should be utilized by the animal. The production should be related to the needs of the animal and expressed in terms of Animal Units (AU) (an AU is defined as an animal with a mass of 450 kg which consumes 10 kg dry matter of a certain quality per day to gain 0.5 kg per day). The dry matter consumed annually by an AU would therefore amount to approximately 3 500 kg.
Table 1. The estimated effect of veld condition and rainfall on dry matter production on offer to livestock
Veld condition (% of benchmark)
1
Production per hectare (kg DM/mm rain)100
80
60
40
20
5
4
3
2
1
For BRG’s 14 and 23 production per ha for veld with 100% condition score is 4 kg DM per mm rain.1
In sourveld areas, the palatability of grasses decreases relatively rapidly through the autumn when compared to sweetveld, and consequently the total consumption of veld by the animal is generally less than in sweetveld when taken over the whole grazing season (Note: intake decreases as palatability declines). The estimated consumption by livestock for different sweet-, mixed- and sourveld is presented in Table 2.
Table 2. The estimated consumption of veld by livestock in KwaZulu-Natal
|
Bioresource Group |
Consumption per AU per annum (kg) |
|
3 to 11 and 15 1, 2, 12, 14 and 17 13, 16 and 18 to 20 21 to 23 |
2 500 2 750 3 000 3 500 |
Knowing the production from veld, and the animal requirements, the grazing capacity for a farm with a veld condition score of 60% in, for example, Bioresource Group 14, with 700 mm rain per annum, could be calculated as:
Annual rainfall - 700 mm Rainfall October to March - 560 mm (i.e. 700 mm x 0.8) Veld condition score - 60% of benchmark Potential veld production - 3 kg per mm rain per ha (Table 1) x 560 mm
1680 kg dry matter per haAvailable DM per AU - 840 kg per hectare (1680/2) Consumption per AU per annum - 3 000 kg (Table 2) Grazing capacity - 3.6 ha/AU
(3 000 kg/AU/840 kg/ha)
In the bushveld areas (Bioresource Groups 19, 20, 21, 22 and 23) trees tend to reduce grass production as a result of competition between the two. Cognisance of this fact must be taken into consideration when estimating the yield of grass production. An estimate must be made of the number of tree equivalents (TE) per hectare and grass production should be reduced, according to the factors presented in Table 3 (a TE is a tree 1.5 m tall, so a 3 m tall tree is 2 TE). For example, where the veld condition score is 60% of the benchmark, and there are 1 200 TE per ha, grass production would be 3 kg (Table 1), but would be reduced by 20% (Table 3) to a potential 2.4 kg per mm rain per ha. With a 700 mm rainfall and a growing season rainfall of 560 mm, the total grass production would therefore be 560 mm x 2.4 kg/mm/ha = 1 344 kg/ha). The introduction of goats to browse the trees should be considered in this situation in order to utilize the veld more efficiently.
Table 3. The reduction of grass yield as a result of competition from trees in sweetveld
|
Number of tree equivalents per ha |
% Reduction in grass yield |
|
<800 800 ) 1 000 1 000 ) 1 200 1 200 ) 1 400 1 400 ) 1 600 1 600 ) 1 800 1 800 ) 2 000 |
0 10 20 30 40 50 60 |
The overall number of animals which the farm can support is the sum of the stock that each VTU can carry.
CHOICE OF A LIVESTOCK PRODUCTION SYSTEM
(A beef production system is used as an example.)
Once the grazing capacity of the farm has been determined, it is essential that the most economical production system is selected, as this will affect the herd composition, the number of livestock groupings, and therefore the number of camps required. The choice of the production system will depend on the availability of markets, the efficiency of management, the frequency of droughts, cropping and pasture programmes, and farmer inclination.
Table 5. Herd composition of 100 AU
|
Class |
Midsummer mass (kg) |
AU equivalent |
Weaners |
1.5-year old |
2.5-year old |
|||||
|
No. |
AU |
No. |
AU |
No. |
AU |
|||||
|
Breeding cows Breeding heifers Bulls Cull cows Calves 1.5 year steers 1.5 year heifers 2.5 year steers 2.5 year heifers |
450 400 650 450 120 270 250 400 380 |
1.25 0.90 1.28 1.25 0.36 0.66 0.62 0.90 0.86 |
46 12 2.5 4 46
12
|
57.5 11 3 5 16.5
7 |
37 10 2 3.5 37 18 19 |
46.5 9 2.5 4.5 13.5 12 12 |
30 8 1.5 3 30 15 15 15 8 |
37 7.25 2 3.5 11 10 9.25 13.5 7 |
||
|
Total |
122.5 |
100 |
126.5 |
100 |
125.5 |
100 |
||||
When considering markets, it is more important to examine future market trends than to base estimates on the current market. Where abattoirs are distant, the production of weaners or stores may be more profitable than finishing livestock.
The profitability of a livestock production system depends more on the efficiency of the operation than on the production system followed. Weaning percentages have a dramatic effect on profitability. However, a low weaning percentage will depress the profitability of weaner production to a greater degree than a system of marketing at an older age.
In areas which are subject to periodic droughts, it may be inadvisable to run breeding herds sufficiently large to justify weaner production. In the production of older animals for slaughter, the proportion of the breeding herd is relatively smaller than that required for weaner production. This reduces the maintenance requirements of the total herds on the farm, and provides for greater flexibility.On farms where crops and pastures can be economically produced, the carrying capacity of the property can be increased, and the choice of production system widened, by intensifying forage production. Personal inclinations should also be taken into consideration in planning, as farmers will generally operate most efficiently within a system of production in which they are interested.
Each production system has a different herd composition, and, in planning, it is necessary to calculate the theoretical composition of the total herd which is suitable for the estimated grazing capacity of the property. In calculating the herd composition, realistic estimates of weaning percentage, mortality, bulling percentage, culling rate, selling age of surplus heifers, and the bulling age of heifers, must be considered.
The total number of animals in the herd must relate to the number of AU’s calculated from the grazing capacity. The different classes of stock can be converted into AU’s using the formula:
AU = (MASS)0.75 x 0.01 x F
where F = 1.25 for lactating animals, and 1 for all other animals. More simply, the mass of the animal can be doubled, 100 added to this, and the total divided by 1 000 (e.g. (400 kg x 2 + 100)/1 000 = 0.9 AU). For sheep add 80 instead of 100. The number of head in the breeding herd, in relation to the total number of AU’s, will vary proportionally (Table 4).
The herd composition of 100 AU in production systems designed to produce weaners, 1.5- and 2.5 year-old steers and heifers (with 80% weaning, 20% culling, 4% bulling and bulling heifers at 2 years old), is presented in Table 5.
Knowing the grazing capacity of the farm, the herd composition can be calculated from Table 5. For example, if the number of stock a farm can carry is equivalent to 370 AU, then all figures in Table 5 are multiplied by a constant of 3.7 (i.e. 370/100).
Table 4. The composition of the breeding herd in terms of proportions of Animal Units (AU) for different production systems.
|
Production system |
Breeding herd (% of AU’s) |
|
Weaners 1.5-year-old 2.5-year-old 3.5-year-old |
60 50 40 33 |
DETERMINATION OF THE NUMBER OF HERDS
The number of separate herd groups will vary with each type of production system, and the total number of livestock involved. However, this will depend upon managerial considerations, such as optimum herd size
for the different classes of stock, subdivisions for winter maintenance feeding to avoid dominance by different age groups, and the number of camps required per herd for a sound veld management system. The capital development cost will limit the total number of camps on the property, and a compromise must be reached between the benefits to herd management with more herd divisions, and the benefit to veld management with more camps per herd. Where it is necessary to group herds because a shortage of capital limits camp development, the groupings presented in Table 6 could be considered.
For example, in a system producing eighteen-month-old animals, where financial capital restricts the number of camps to 20, and it is desirable from a veld management point of view to have 5 camps per herd, the number of herd groups would be limited to four. Where 4 camps per herd would meet the veld needs then 5 herd divisions could be used to facilitate herd management.
The fencing layout will depend on the number and distribution of Veld Type Units , water location, camp size, the number of camps required and financial restrictions on capital inputs.
Table 6. Suggested herd groupings for situations where camp development is limited.
|
Class
|
Herd Groupings |
|||
|
A |
B |
C |
D |
|
|
Mature cows and calves First calvers and calves Heifers (bulled) Cull cows and calves Heifers 1 ) 2 years Steers 1 ) 2 years |
1 2 3 4 5 6 |
1 2 2 3 3 4 |
1 2 2 3 3 3 |
1 1 1 2 2 2 |
|
Bulls |
Separate group except in breeding season |
|||
|
Total groups |
6 |
4 |
3 |
2 |
Veld Type Units
Different vegetation/soil/climate complexes (ecotopes) react differently to grazing, so, where possible, the VTU’s should be separated. However, for practical purposes, the VTU’s could be grouped into larger management units with similar potential, depending on aspect, soils, terrain and veld condition. This will form the basis of the fencing layout. Where the VTU’s are grouped into management units, care should be taken to ensure that small, sensitive areas are not included with less sensitive areas.Water provision
Water is an important factor affecting the layout of camps.The position of the camp within a management unit will depend on the locality of the water. The whole area of the management unit must be adequately served by the water point. The grazing potential in flat country is most effectively utilised when all grazing is within 1 500 metres of water. The implications of this are that a single watering point should serve a maximum area of about 900 ha. However, other factors, such as the size of the VTU and terrain, may reduce this area considerably. In many instances it would be necessary to use pipeline schemes to provide water at required localities. The quantity of water required should be based on 40 l/AU/day.
The wagon wheel camping system, with up to eight camps radiating from a central water point, is the most economical system in terms of fencing and water development costs. However, this layout is not suitable where there are even slight differences in veld sensitivity due to the nature of soils, the aspect, or differences in veld condition. The use of corridors to convey livestock to different areas of the farm are labour saving, and confine trampling to smaller, selected areas. However, they are costly in terms of fencing.
Camp size
The optimum camp size will vary according to VTU, cattle and veld management practices, and economics. The more intensive the management, the smaller the camps will tend to be, and, generally, in small camps, veld is grazed more evenly and effectively than in large camps. In addition, animals tend to walk less in smaller camps. A camp should accommodate about 25 to 30 AU’s for the grazing season, and therefore camp size, will vary according to the grazing capacity. Some suggested optimum camp sizes are presented in Table 7.
Table 7. Optimum camps sizes for the Bioresource Groups of KwaZulu-Natal.
|
Bioresource Groups |
Camp size (ha) |
|
1 to 11 and 15 12 13, 14 and 16 to 20 21 to 23 |
40 - 50 50 - 75 75 - 100 100 - 125 |
The shape of camps is also important. Uneven camps are not usually grazed uniformly. Long narrow camps are often grazed more intensively at their ends. Square or rectangular camps are normally grazed evenly, provided the veld is fairly uniform.
Number of camps
For sound veld management, the optimum number of camps per herd lies between four and eight, depending on the ecotope and veld condition. This number may be difficult to achieve in the early stages of implement-ation. It is essential, however, to plan for the optimum number of camps initially, and to develop towards this end. A compromise should be reached, for economic reasons, between the number of camps and the number of herds.Dips and handling facilities
Careful consideration should be given to the location of dips and handling facilities within a camping system. The object should be to reduce the distance walked by livestock (and thus lost grazing time), as body maintenance requirements increase by 1% for each 1.5 km walked. In extensive areas, a dip with handling facilities could be provided for each 2 500 ha. Under more intensive conditions, a dip with a handling facility could serve about 500 head, and should be positioned so that livestock to be dipped are not out of their camps for more than about two and a half hours. However, the terrain could considerably reduce the area and number of stock served by a single dip tank.
In most instances, to facilitate management, it is desirable, but not essential, to allocate specific camps to herds. For instance, breeding herds should be kept away from areas which have a predator problem while they are calving down, or a sensitive herd may require the best grazing. First calvers and heifers to be bulled are the most sensitive herds, and should receive preference grazing. In-calf cows, cows that have skipped calving, and weaners should receive the second, third and fourth best grazing, respectively. In areas where steers are finished off the veld, they should also receive preference grazing. Where a herd is allocated to a set of camps, the overall grazing capacity involved must equate to the number of AUs in the herd. For example, in weaner production, 60% of the farm would be allocated to the cow herd.
The principles governing the management of different sweetveld, mixed veld and sourveld will be similar, but different factors will receive different emphasis in their management. The more sour the veld, the shorter should the grazing cycle, period of stay, and period of absence be, in the management system. In sourveld, the period of absence is so short that a full growing season's rest period is required every four or so years, followed by a burn. This practice is often not necessary in the sweetveld where the period of absence from a camp is relatively long, and therefore acts in a similar manner to a rest. Also, burning in the sweetveld should be done opportunistically, and not on a regular basis. Recommended periods of stay and absence, and grazing cycles for different Bioresource Groups are presented in Table 8.
The grazing system should be based on the recommended grazing cycle for a particular Bioresource Group. This will ensure that irrespective of whether a 2, 4, 6 or 8 camp per herd system is used, the number of
grazing days per ha for each period of stay will be the same resulting in similar levels of animal performance.
The appropriate number of grazing days is obtained by dividing the number of ha per camp into the number of AU’s, and multiplying this by the period of stay in days. Periods of stay and absence for an area of 192 ha supporting 96 AU’s, and with a grazing cycle of 40 days, are presented in Table 9. In the two-camp system, the period of absence is too short, while the period of stay is too long, with the result that, in the long term, the veld would suffer.
Table 8. Periods of stay and absence, and grazing cycles recommended for the Bioresource Groups of KwaZulu-Natal.
|
Bioresource Group |
Period of stay (days) |
Period of absence (days) |
Grazing cycle (days) |
|
1 to 11 and 15 12 13, 14, 16 to 20 21 to 23 |
10 14 21 28 |
20 28 42 56 |
30 42 63 84 |
Compared to most cropping enterprises, livestock production has a low percentage return on investment.
Because the percentage return on capital is low, the amount of debt or loan which can be serviced from the net farm income is also relatively low. This, however, will depend on the redemption period and the interest rate of the loan. It is important, therefore, when planning the development of a farm, to calculate the maximum debt load that the net farm income can service.
Table 9. The effect of different numbers of camps on periods of stay (POS) and absence (POA) in a 192 ha mixed veld system of 96 AU’s.
|
Number of camps |
Camp area (ha) |
POS (days) |
POA (days) |
Grazing cycle (days) |
Grazing days/ha |
|
2 4 6 8 |
96 48 32 24 |
20 10 7 5 |
20 30 33 35 |
40 40 40 40 |
20 20 20 20 |
Where additional development is required on an existing operational farming enterprise, the extra capital needed would have to be redeemed from income generated by enhanced animal performance, or increased stocking. The question to pose is whether the additional development can enhance animal per-formance from improved calving percentage or weight gain. Instead of looking at animal performance from existing stock to generate income, increased stocking due to benefits from development could be assessed to fulfil this purpose. In most instances, the level of increased stocking due to the advantage of development could be justified.
LITERATURE CONSULTED
HOLNESS, D.H. (ed.). 1988. Beef Producers'Manual(rev. ed.). Harare:Cattle Producers' Association Zimbabwe.
TAINTON, N.M. (ed.). 1981. Veld and pasture management in South Africa. Pietermaritzburg : Shuter & Shooter.