FIGURE 6.1
Schematic presentation of the livestock productivity model

Chapter 6
Livestock productivity

This chapter describes the livestock productivity model (Technical Annex 5). The livestock productivity model is schematically shown in Figure 6.1. It has been conceptualized and applied within the framework of land evaluation guidelines (FAO 1976, 1988a), and follows the FAO Agro-ecological Zones (FAO-AEZ) approach to quantifying land resources and assessing land use potentials (FAO 1978–81; Blair Rains and Kassam 1980).

The livestock productivity model has five parts, namely:

1. Estimation of feed supply potential (primary productivity).

2. Characterization of livestock systems.

3. Determination of herd performance.

4. Estimation of feed requirements.

5. Quantification of livestock productivity potential (secondary productivity).

The model operates on the land resources inventory described in Chapter 3. The five parts of the model, are described in the following sections.

6.1 Estimation of Feed Supply

Animals require a continuous and adequate supply of nutritively satisfactory feed. Part I of the livestock productivity model (Figure 6.1) deals with the estimation of feed supply from different sources. A wide variety of plant biomass is eaten by domestic herbivores. The important sources of feed biomass are the grasses, a small number of herbaceous legumes, leaves and fruits of many shrubs and trees, fodder crops, crop residues, crop by-products and primary products (e.g. grain).

6.1.1 Sources of Feed

At any given location, the ecological potential of one or more of the following sources of feed needs to be quantified by agro-ecological cells of the land resources inventory (Figure 6.2).

1. Grassland or pastures (permanent or long-term, or short-term grass-legume mixtures, natural or sown).

2. Browse (natural woody vegetation of shrubs and trees).

3. Fodder from bush and managed fallows within crop rotations (natural or sown grass-legume mixture).

4. Fodder crops or fodder grasses, legumes and cereals (sown).

5. Fodder trees (sown).

6. Fodder from fuelwood trees (sown).

7. Crop residues.

8. Crop by-products.

9. Crop primary products. Feed supplies from each of these sources are described hereunder.

FIGURE 6.2
Sources of feed supply

6.1.2 Grasslands and Pastures

Biomass production potential from grasslands or pastures in the model is estimated using the FAO-AEZ method (FAO 1978–81), and involves the following activities (Figure 6.3):

1. Selection of the species and definition of land utilization types (LUTs) (e.g. species; produce; technology and input level; labour; capital; markets).

2. Determination of climatic requirements of species and LUTs and matching climatic requirements with the characteristics of the inventoried climatic zones (thermal zones and growing period zones), and quantifying the climatically attainable yield potentials.

3. Determination of edaphic (soil) requirements of species and LUTs, and matching edaphic requirements with the characteristics of the inventoried soil units, textures, phases and stoniness to rate edaphic limitations.

4. Quantifying soil erosion hazards (soil loss) in each climate-soil unit (agro-ecological cell) of the land resources inventory by LUT and the associated productivity losses.

5. Modifying the climatic yield potentials (in ii) according to the soil limitations (in iii) and erosion hazards (in iv) to quantify yield potentials with constraints and ecological land suitabilities of each inventoried climate-soil land unit for each LUT.

Each of these activities is described in the following sections.

6.1.2.1 Land Utilization Types

Considerable work has been done on screening pasture (and fodder grass and legume species) to determine those best suited to particular environments in Kenya (Edwards and Bogdan 1951; Rattray 1960; Pratt and Gwynne 1977; Boonman 1979; Jaetzhold and Schmidt 1982). Table 6.1 sets out a list of some of these pasture (and fodder species) that are considered suitable in Kenya.

FIGURE 6.3
Schematic presentation of suitability assessment for grassland/pasture TABLE 6.1 Pasture and fodder species of grasses and legumes

TABLE 6.1
Pasture and fodder species of grasses and legumes

¹ Common in areas of impede drainage or in seasonally waterlogged areas.
² Fodder species.
³ Includes pasture and fodder types.

Pasture production is considered at three levels of inputs. The attributes of the three levels of inputs circumstances are listed in Table 6.2 and they form the basis of the definition of land utilization types considered in the model.

6.1.2.2 Climatic Adaptability and Suitability

Climatic suitability assessment of grass and legume pasture species is based on the climatic adaptability principles described in FAO (1978–81), and includes:

1. an understanding of the climatic adaptability of pasture species in terms of their ecophysiological characteristics;

2. matching the climatic requirements to thermal and moisture regimes, including the estimation of constraint-free biomass potentials;

3. rating of agro-climatic constraints of water stress/excess; pests, diseases and weeds; and workability; and

4. estimating attainable biomass production potentials with constraints, and the consumable biomass fractions.

TABLE 6.2
Attributes of land utilization types considered for pasture and fodder¹ production

¹ Fodder grasses and legumes.

The list of grass and legume species given in Table 6.1 includes both C4 species (grasses) and C3 species (legumes). Both groups of species include ecotypes that are adapted to operate under warmer (mean daily temperature > 20°C) as well as cooler (mean daily temperature <20°C) conditions. Table 6.3 presents the thermal zone screen for pasture and fodder species showing which species can be considered in which thermal zones.

TABLE 6.3
Thermal zone screen pasture and fodder species

Legume species adapted to operate under cool temperatures (<20°C mean daily temperature) belong to adaptability group I, and those adapted to operate under warm temperatures (> 20°C) belong to adaptability group II. Grass species adapted to operate under warm temperatures (>20°C) belong to adaptability group III, and those adapted to operate under cool temperatures (<20°C) belong to adaptability group IV. The relationships between photosynthesis and temperature for the four adaptability groups are presented in Table 6.4.

Consequently, the suggested thermal zone combination ratings for the grasses and legumes at this stage of the model development are: S1 (very suitable) for the thermal zones T1, T2, T3, T4 and T5, S2 (suitable) for T6, S3 (moderately suitable) for T7, S4 (marginally suitable) for T8 and N (not suitable) for T9. A rating of S1 indicates that there are no thermal constraints during the growing period and the requirements are fully met. A rating of S2 indicates slight to moderate thermal constraints leading to yield suppressions of some 25 %. A rating of S3 indicates that there are moderate to severe thermal constraints leading to yield suppressions of some 50%. A rating of S4 indicates severe thermal constraints leading to yield suppressions of some 75%. A rating of N indicates that the thermal requirements are not met and the zone is not suitable for further consideration. These ratings correspond closely with the correlation between pasture dry matter production and temperature in Kenya (Booneman 1979).

TABLE 6.4
Relationships between temperature and rate of leaf photosynthesis (kg CH20/ha/hr) for legume species in adaptability groups I & II, and grass species in adaptability groups III & IV

Potential biomass estimates were derived according to the method developed by the FAO-AEZ project (Kassam 1977; FAO 1978–81). For the purpose of computing ‘constraintfree’ biomass potential, it is assumed that both C3 and C4 pasture and fodder species of grasses and legumes will be represented, so that maximum photosynthesis rate (Pm) of 37.5 CH20 ha^-1 hr^-1 has been applied.

Estimates of constraint-free total biomass (Bn) at high level of inputs are presented in Table 6.5 together with maximum leaf area index (LAI) values used, the agro-climatic constraint ratings, total biomass with constraints (Bnc), consumable coefficients (Cc) and consumable biomass with constraints (Bcc).

For a variety of reasons only a portion of the plant biomass is eaten by animals. About 20% of the total net biomass (Bn) is in roots, a portion of the biomass is not eaten (particularly under low inputs) due to low palatability; some biomass is lost due to trampling, fire and wind, and part is consumed by invertebrate animals. It is generally assumed that between a third and two-thirds of the total biomass yield of an area will be utilized or consumed by stock, depending on the environment.

Agro-climatic constraints applied to the constraint-free yield relate to water stress in LGP < 210 days and workability in LGP zone 365⁺ days. Total biomass yield with constraint at high inputs range from 0.5 t/ha in LGP zone 1–29 days to 30.6 t/ha in LGP zone 330–364 days.

Consumable coefficients (Cc) range from 0.35 at low inputs in LGP zones with < 120 days to 0.6 at high inputs in LGP zones with > 180 days. Consequently, consumable biomass with constraints (Bcc) range from 0.23 t/ha to 18.9 t/ha for high inputs, from 0.16 to 10.83 t/ha for intermediate inputs, and from 0.09 t/ha to 3.94 t/ha for low inputs.

Constraint-free net biomass (Bn) at low inputs is assumed to be 25% and 50% of those at high input level in the LGP zones > 90 days and < 90 days respectively. Constraint-free total biomass at intermediate level is assumed to be between the high and the low input levels. For areas with no growing period Bc is estimated at 70 kg/ha at the high inputs level and 35 kg/ha at the low and 52.5 kg/ha at the intermediate inputs level.

TABLE 6.5
Potential biomass from pasture and fodder grasses and legumes (t/ha dry weight) at three Input levels¹

¹ Agroclimatic constraints: a = water stress or excess; b = pests, diseases or weeds affecting vegetative growth; c = pests, diseases or weeds affecting reproductive growth; d = workability limitations.

² H = high inputs; I = intermediate inputs; L = low inputs.

Pasture species and biomass potentials are matched to individual component length of growing periods, i.e. L1, L21 L22, L3l, L32, L33, L4l, L42, L43, L44. The LGP-Pattern evaluation for pasture is achieved by taking into account all the constituent component lengths in each LGP-Pattern, thus taking into account the year-to-year variability in the number of LGPs per year.

Yields in Table 6.5 apply to normal lengths of growing periods. For intermediate growing periods, yield reductions are of the order of 50% on all soils except Fluvisols and Gleysols. The percentage of occurrence of intermediate lengths of growing periods in all LGP-Pattern zones combined is 100% in LGP zone 1–29 days; 65% in zone 30–59 days; 25% in zone 60–89 days; 10% in zone 90–119 days and 5% in zone 120–149 days.

An exception to the general methodology for climatic suitability assessment applies to areas occupied by Fluvisols because the inventoried length of growing period does not fully reflect their particular circumstances with regard to moisture regime (Section 5.1.2.3). Fluvisols ratings are presented in Technical Annex 5 for the three levels of inputs circumstances.

6.1.2.3 Edaphic Suitability

In order to assess soil suitability for pasture production, the soil requirements of pasture species must be determined. Further, these requirements must be understood within the context of limitations imposed by landform and other features (e.g. soil phases, stoniness) which do not form part of soil composition but have a significant influence on the use that can be made of the soil.

Basic soil requirements for pasture species relate to the following internal soil properties described in Section 5.1.3.2. From the basic soil requirements for pasture species, a number of responses related soil characteristics have been derived. The correlation between the basic soil requirements and soil characteristics given in Table 5.9 has been used to rate pasture and fodder crop performance.

Also as explained earlier (Section 3.2.5), the soil units (Table 3.16) have been defined in terms of measurable and observable properties of the soil itself, and specific clusters of such properties are combined into ‘diagnostic horizons’ and ‘diagnostic properties’. They are also used to rate soil suitability.

The edaphic suitability classification is input-specific and based on:

1. matching the soil requirements of pasture and fodder species with the soil conditions of the soil units described in the soil inventory (soil unit evaluation); and

2. modification of the soil unit evaluation by limitation, imposed by texture, phase and slope conditions.

The soil unit evaluation for pasture and fodder production is expressed in terms of ratings based on how far the soil conditions of a soil unit meet the growth and production requirements under a specified level of inputs. The appraisal is effected in five basic classes for pasture and fodder grasses and legumes as a group, i.e. very suitable (S1), suitable (S2), moderately suitable (S3), marginally suitable (S4), and not suitable (N).

A rating of S1 indicates that the soil conditions are optimal, and that suppression of potential yields (if any) is assumed to be nil or slight. A rating of S2 indicates that there are slight to moderate soil constraints and there would be a suppression of potential yields of the order of 25%. A rating of S3 indicates that there are moderate to severe soil constraints and there would a suppression of potential yields of the order of 50%. A rating of S4 indicates that there are severe soil constraints and there would be a suppression of potential yields of the order of 75%. A rating of N indicates that soil conditions are not suitable for production.

The soil unit ratings are presented in Technical Annex 5 and apply as indicated provided there are no additional limitations imposed by soil texture, phase and stoniness. Modifications are required where such limitations are present.

In the case of soil texture, soil unit ratings remain unchanged if the soil is an albic, cambic, ferralic, calcaro-cambic or luvic Arenosol (Q, Qa, Qc, Qf, Qkc, Ql) or a vitric Andosol (Tv), or where textures are medium (fine sandy loam, sandy loam, loam, sandy clay loam, clay loam, silty clay loam, silt), or fine (sandy clay, silty clay, peaty clay, clay). In all other cases (i.e. with coarse textures: sand, loamy coarse sand, fine sand, loamy fine sand, loamy sand) the soil unit rating is one class (25%) lower.

Limitations imposed by phase and stoniness are rated using the five basic classes already described. The stoniness and phase ratings are presented in Technical Annex 5.

6.1.2.4 Slope Limitations and Soil Erosion

Limitations imposed by slope are taken into account in three steps (Chapter 4). Step one defines the slopes which are permissible for pasture production, and as a model variable this is defined as slopes less than 45% (Table 4.1).

Step two involves the computation of potential topsoil loss which is estimated, by input levels, through a modified Universal Soil Loss Equation (Wischmeier and Smith 1978).

Step three relates the estimated topsoil losses to yield losses through a set of equations in Table 4.4, taking into account soil susceptibility (Table 4.3), level of inputs and regeneration capacity of topsoil (Table 4.2).

6.1.2.5 Land Suitability Assessment

All three assessments: the climatic suitability, the edaphic suitability and the soil erosion hazard, are required to determine the ecological land suitability for grassland/pasture production of each climate-soil unit of the land resources inventory. In essence the land suitability assessment takes account of all the inventoried attributes of land and compares them with the requirements of pasture species, to give an easy to understand picture of the suitability of land for grassland/ pasture production.

The results of the land suitability assessment are presented in five basic suitability classes, each linked to attainable yields for the three levels of inputs considered. For each level of inputs, the land suitability classes are: very suitable (VS) - 80% or more of the maximum attainable yield; suitable (S) - 60% to less than 80% of the maximum attainable yield; moderately suitable (MS) - 40% to less than 60% of the maximum attainable yields; marginally suitable (mS) - 20% to less than 40%; and not suitable (NS) - less than 20%.

FIGURE 6.4
Schematic presentation of the land suitability assessment programms for pasture production

Land suitability assessment is achieved by applying the programme illustrated in Figure 6.4, as explained in Section 5.1.5.

The five classes of land suitabilities are related to attainable yield as a percentage of the maximum attainable under the optimum climatic, edaphic and landform conditions.

Consequently the results provide an assessment of pasture production potentials of each land unit which in turn can be aggregated for any given area in Kenya.

Generalized results of land suitability assessment for pasture production at intermediate level of inputs are presented in Figure 6.5. and in Technical Annex 8. It should be noted that the generalized results presented, include a subdivision of the not suitable class (zero to less than 20% of maximum attainable yield) into two classes (1) very marginally suitable (more than zero to less than 20% of maximum attainable yield) and (2) not suitable (zero yield).

6.1.3 Fodder from Browse, Fodder Trees and Fuelwood Trees

In the low rainfall areas (LGP < 120 days), natural woody vegetation including leguminous shrubs and trees, can be important in the nutrition of domestic stock. However, relatively little is known about the digestibility of biomass materials from browse. By comparison with the large amount of herbage from grasslands or natural pastures, the quantity of fodder biomass from natural woody vegetation is limited. Contribution of browse biomass is assumed to be included in the estimates of biomass from grasslands and pastures given in Table 6.5, and no separate account is taken at this stage of the model development and application.

Trees are planted for fodder in Kenya, and the main species are Acacia, Calliandra, Gliricidia, Grevillea, Leucaena and Sesbania. Again the potential contribution from sown fodder trees is assumed to be included in the estimates of biomass from pastures given in Table 6.5, and no separate account is taken at this stage of model development and application. However, the land suitability procedure for separately quantifying fodder biomass from fodder trees is identical to the procedure of quantifying wood biomass from fuelwood trees in Chapter 7. Consequently, it is now possible, if required, to provide for a seperate assessment of fodder from fodder trees.

Where trees are considered for fuelwood production and carry palatable foliage, it is assumed that about 10% (i.e. 3.3% of mean annual wood biomass increments given in Chapter 7) of the foliage may be utilized by stock without affecting fuelwood yields. Fuelwood species that can contribute fodder are: Acacia gerrardia, A. nilotica, A. Senegal, Calliandra calothyrus, Casuarina equisetifolia, Conocarpus lancifolius, Eucalyptus camaldulensis, E. citridoria, E. tereticornis, Parkinsonia aculeata, Sesbania sesban.

6.1.4 Fodder from Fallow Land

In the crop productivity model (Chapter 5), fallow requirements for crop rotation options are formulated. At low level of inputs, fallow land is assumed to carry natural bush vegetation; at intermediate and high levels of inputs, fallow land is assumed to carry sown grass-legume pasture.

FIGURE 6.5
Generalized land suitability for rainfed pasture production at Intermediate level of Inputs

Biomass production from natural fallow under low inputs, and from sown pasture under intermediate and high inputs is taken as one-third of that from normal sown or permanent pastures given in Table 6.5. It is further assumed that only 50% of the biomass may be utilized by stock.

6.1.5 Fodder from Fodder Crops

Fodder grasses, legumes and cereals are grown for fodder production in Kenya. Main fodder grasses are Pennisetum purpureum(Napier or Bana grass), Setaria splendida(Giant setaria), Sorghum sudanense(Sudan grass) and Tripsacum laxacum(Guatemala grass). Main fodder legume species are Centrosema pubescense, Dolichos Lablab purpureus or Ldblab niger(Hyacinth bean), Macroptilium atropurpureum(Siratro), Vigna spp. and Stylosanthes spp. Main fodder cereals are maize, oat, pearl millet and sorghum.

A separate assessment of biomass potential from fodder grasses, legumes and cereals is possible according to the land suitability methodology described in Chapter 5. However, at this stage of model development and application, the range of biomass potentials from pastures given in Table 6.5, are found to adequately cover the biological potentials of fodder crops.

6.1.6 Crop Residues, By-products and Primary Products

In areas with more than 120 days growing period, crop residues are an important source of fodder particularly for the low and intermediate technology livestock systems. Important residues are the haulms of groundnut, cowpea and other grain legumes, and the staves (stalks) of sorghum, maize and millet, and straw from rice, wheat, barley and oat. Quantities of residues that may be available have been estimated by applying the residue factor and the corresponding utilization coefficients and to crop yields (Technical Annex 5).

By-products, defined as edible materials remaining after a crop has been processed, are bran, pollard and germ meal from cereal milling; molasses and bagasse from sugar milling; and cakes (cotton, soybean, groundnut) from oilseeds. Quantities of crop by-products that may be available have been be estimated by applying the by-product factor and the corresponding utilization coefficients to crop yields (Technical Annex 5).

The term primary product applies to grain used for the purpose of feeding to animals either directly in an unprocessed form or in a processed form. Main cereals used in Kenya are maize, sorghum wheat and barley. Direct grain feeding is used mainly at the high level of technology in the dairy and meat production systems with cattle and goat. The intensive livestock industries of poultry and pig production tend to rely on processed feeds.

6.1.7 Feed Supply Potential (Primary Productivity)

When Part I of the livestock productivity model (Figure 6.1) is applied to the land resources inventory, feed supply potential of each agro-ecological cell are quantified by feed source (Figure 6.2), as described earlier.

Once feed supply potential or primary productivity has been quantified, it is possible to quantify livestock productivity potential of livestock systems at specified performance levels and feed requirements. These aspects are taken into account in Parts II, III, IV and V of the model.

TABLE 6.6
Attributes of the non-Dastoral land utilization types considered for livestock production

6.2 Characterization of Livestock Systems

Part II of the livestock productivity model (Figure 6.1) characterizes the livestock systems that are to be considered in assessing secondary productivity potentials. It defines, for three levels of input situations (or technology levels), the livestock types, production systems and herd structures.

Of the six types of livestock which are considered in the model, four are considered under pastoral as well as non-pastoral systems. They are: cattle, goat, sheep, camel. The remaining two, poultry and pig, are considered under intensive systems only and without explicitly defining the production systems at this stage in the model development.

Cattle, goat, sheep and camel systems are considered at three inputs levels. The attributes of the three input level production circumstances for non-pastoral systems are presented in Table 6.6 and form the basis of the definition of the non-pastoral utilization types considered in the model.

For the pastoral systems, three types of cattle herds have been considered. These are: nomadic distant, nomadic with market accesss and semi-nomadic, representing respectively the low, intermediate and high level of inputs circumstances. For sheep and goat, two types of herds have been considered. These are: nomadic distant and semi-nomadic, representing respectively the low and high level of inputs circumstances. For camel, one herd type has been considered, representing the normal circumstances of production at a low level of inputs.

Herd structures have been defined in terms of number of heads of animal as well as in terms of reference Tropical Livestock Unit (TLU) defined as a mature animal weighing 250 kg (Houerou and Hoste 1977; Stotz 1983).

Livestock conversion factors for non-pastoral systems in areas with more than 120 days growing period are taken from Stotz (1983). Livestock conversion factors for pastoral systems in areas with less than 120 days growing period are taken from Houerou and Hoste (1977), and are:

6.2.1 Cattle Systems: Dairy and Meat

At the low level of technology, the systems are characterized by pure Zebu cattle (Stotz 1983).

The feed supply is generally native Kikuyu/star grass pastures, and crop residue (maize stover). Cattle are grazed, herded or tethered during the day and kraaled during the night. Cattle are not supplied with concentrates or mineral supplements.

Calves join their dams during milking and for a short while afterwards, during which time they consume the remaining milk in the udder amounting to about 3 to 5 litres per day (400 litres total during the rearing period). Calves are weaned about 5 to 7 months old.

The animals are driven to water at rivers or reservoirs twice a day if nearby, otherwise once a day. Disease control measures are rarely practised, but cattle are compulsorily vaccinated against rinderpest and in some areas against foot and mouth disease.

At the intermediate technology level the cattle would be first generation crossbreds with exotic or high performing grade cattle bred with the help of artificial insemination. Crossbred cattle are generally acquired through upgrading local Zebu cows by Ayrshire, Friesian, Guernsey or Jersey bulls.

Cattle graze natural ley pastures (Kikuyu/star grass) and fields are usually fenced. With regards to feeding, young stock rearing and watering, the same husbandry practice is employed as for Zebu cattle. Crossbred cattle occasionally receive cattle salt, and cattle are regularly dipped or sprayed. Sick animals are treated.

Under the high inputs situations, the systems are based on exotic cattle, Friesian, Ayrshire, Guersey or Jersey, which have been ‘graded’ up from the original crosses with indigenous cattle bred back to the exotic type.

Stotz (1983) describes these systems as charaterized by grade cows in a combined grazing/stall feeding system (semi-zero grazing) or complete stall feeding (zero grazing). In the case of the semi zero grazing, cattle usually graze Kikuyu or star grass during the daytime. At night cattle are kraaled or stabled where they are fed with napier and bana grass. Sometimes they are also fed during the day with crop residues and napier grass, particularly during the dry season when pasture productivity is low. Where cattle is permanently housed in a shed, the feed is cut and carried to them. Cattle kept in a zero grazing unit are predominantly fed with napier or bana grass which is first chopped. Dairy cows also receive 20–25 kg/cow per year of mineral supplement, and 500 to 1000 kg/cow per year manufactured and compound concentrates when lactating.

TABLE 6.7
Cattle herd structures

¹ Contribution to meat output accounted for in FAO/IIASA (1991:Tech. Annex 5, Table A6.2).

TABLE 6.8
Goat herd structures

Male and female calves are bucket fed and hand reared. Calves usually receive 270 to 400 litres of milk only until they are weaned within 10 to 18 weeks. When the weaning period is shorter in the case of zero grazing system, calves also receive about 165 kg of concentrates during the rearing period. After this time they depend entirely on forage and join the rest of the herd about 6 months old at a weight of about 160 kg, or at two weeks at a weight of about 35 kg in the zero-grazing system.

Animals are watered twice a day and are regularly dipped or sprayed, drenched against internal parasites and receive other health treatment as needed.

Herd structures parameters are presented for the three cattle herd types in Table 6.7. Base herd structures are defined on the basis of a notional herd of 100 cows.

6.2.2 Goat Systems: Dairy and Meat

Under the low input technology, the system is characterized by the local small East African goats which are herded or tethered during the day and kept in store, stable or some kind of shelter at night. Goats feed mainly on natural pasture which supply about 70% of all feed consumed. The remainder is obtained for crop residues and through browsing on farm hedges. There is no definite mating season, hence kids are born the whole year round. Kids suckle the mother for about 5 to 7 months and consume the whole amount of milk produced by the dam.

Under the intermediate technology level, the systems are characterized by the dual purpose goats, usually Fl or F2 cross breeds. Generally, an exotic dairy goat buck such as Toggenburg, Saanen or Anglo-Nubian, is used for upgrading local goats. Animals are kept under semi-zero grazing management system. They are tethered during the day, graze mainly natural pasture, and frequently browse shrubs and farm hedges. Goats are penned during the night when they are fed with crop residues and fodder crops like napier grass and maize. Under these feeding conditions, goats obtain approximately 40% of their dry matter requirements from grazing natural pastures. Another 40% is drawn from fodder crops and 20% supplied through feeding crop residues. Animals are sprayed with acaricides regularly and drenched against internal parasites at regular intervals. Lactating females are partially milked before kids are allowed to suckle with an off-take of 1 to 2 kg of milk daily.

The high level of technology situation is characterized by the intensive goat production system. The main aim of keeping exotic or grade dairy goats like Toggenburg, Saanen or Anglo-Nubian is to produce milk. Other by-products are sales of breeding stock and goat meat. Goats are usually kept in a zero grazing system, where they are fed with napier grass and other fodder crops along with upto 1.5 kg of concentrate per day. Water is provided in containers which are placed inside the stable. Kids are bucket fed with milk, obtain 165 litres over a period of 4 months and are supplemented with 50 kg of concentrates. All animals are sprayed with acaricide regularly.

Herd structure parameters are presented for the three goat herd types in Table 6.8. Base herd structures are defined on the basis of a notional herd of 100 does.

TABLE 6.9
Sheep herd structures

TABLE 6.10
Herd proportions (%) by districts of nomadic herds In areas with LGPs <120 days, expressed in TLUs

6.2.3 Sheep Systems: Meat and Wool

The dominant local breed kept at the low technology level is the Red Maasai or Red Kikuyu. It is a fat tailed hair sheep weighing some 25 to 30 kg. The animals feed mainly on natural pasture both on the farm and adjacent common land, and use crop residues and other consumable dry matter that can be found. Animals are often tethered during the day and kept in some kind of shelter at night. There is no definite mating season or control over breeding and little health care. Ewes on average lamb once a year. No milk is taken and the only product is meat from surplus male lamb and cull ewes.

At the intermediate level of technology, there is controlled breeding and introduction of better class of sire, usually Draper rams, to improve meat production. The preferred crossbred seems to be 3/4 Draper and 1/4 Maasai. In conjunction with this, there is more frequent joining programme, regular dipping and drenching, improvement in fodder provided and mineral supplementation. These inputs are accompanied by fenced paddocks rather than tethering or shepherding.

At the high level of technology, the production system is characterized by the Red Maasai × Draper crosses for meat production. At higher elevations, (thermal zones T5, T6, T7 and T8), another system dominated by dual purpose wool and meat production, using crossbred wool sheep such as Corriedale-Hampshire, is also considered in the model.

Herd structure parameters are presented for the three sheep herd types in Table 6.9. Base herd structures are defined on the basis of a notional herd of 100 ewes.

6.2.4 Pastoral Systems: Meat and Milk

Pastoral systems have evolved as a method of producing human food under climatic conditions where normal rainfed crop production is not possible. It operates in the semi-arid zones where the rainfall is low in total quantity and is erratic both geographically over land in time, that is within seasons and between seasons.

The system comprises various combination of large and small domesticated ruminants with the variations dictated by climate, notably temperature. As a source of food the large ruminants provide milk and some blood and meat while the small ruminants are a source of meat and, in certain locations, of milk. Camels play no part in the market food economy so they are not managed with a view to producing saleable surplus. The role of the camel is mainly to provide milk and be a beast of burden.

All of the pastoral system operates on various combinations of cattle, camels, sheep and goat with some donkeys as pack animals. The combinations are a function of climate, available herbage and water, and local preferences. In the north the herds are principally camels/smallstock with some cattle in certain locations while in the centre and south the herds are almost exclusively cattle/smallstock. The herd proportions for the principal pastoral districts expressed in TLU equivalent (1 TLU = 250 kg animal) are set out in Table 6.10.

The proposed herd structure for cattle, derived from Unesco (1982), Semenye (1982) and Meadows and White (1981), are presented in Table 6.11. Herd structures for sheep and goat, derived from Unesco (1982), de Leeuw and Peacock (1982), Peacock (1983,1984) and King, Sayers, Peacock and Kontrohr (1982), are presented in Table 6.12. The proposed herd structure for camel is given in Table 6.13.

6.3 Quantification of Herd Performance

Part III of the livestock productivity model (Figure 6.1) quantifies livestock productivity potential of each livestock system by quantifying herd performance in acceptable climatic zones.

The thermal zone suitablity ratings for livestock systems are given in Table 6.14. The moisture zone screen, indicating which livestock systems can be considered in which growing period zones, is presented in Table 6. 15.

Livestock products per reference herd TLU for cattle, goat, sheep and camel systems at low, intermediate and high levels of technology are presented in Table 6.16 for zones that are considered as S1 for these livestock systems. Where a thermal zone rating is S2, S3 or S4, reference output must be decreased by 25%. 50% and 75% respectively. Where a thermal zone rating is N, the zone is either deemed not suitable because of temperature constraints (and therefore not considered further), or it is deemed not applicable for further consideration because the zone has not been selected for assessment within a particular planning scenario. Where the thermal zone rating is S, as in the case of poultry and pig under intensive system, it represents a screening device to indicate that the zone is deemed suitable for further consideration.

TABLE 6.11
Pastoral cattle herd¹ structures

¹ Nomadic distant - low inputs; Nomadic with market access - intermediate inputs; Semi-nomadic - high inputs.

TABLE 6.12
Pastoral sheep and goat herd¹ structures

¹ Nomadic distant - low inputs; Semi-nomadic - high inputs.

TABLE 6.13
Pastoral camel herd¹ structure

¹ Nomadic - low inputs.

TABLE 6.14
Suitability ratings for livestock systems by thermal zone

¹ N for wool production in T1,T2,T3,T4 and S2 in T5.

The herd performance parameters calculations for cattle, goat, sheep and camel system are given in Technical Annex 5, and show how output performance values set out in Table

TABLE 6.15
Suitability ratings for livestock systems by LGP zone

¹ Nomadic
² Semi-nomadic
S - Suitable for consideration
N - Not suitable for consideration

TABLE 6.16
Output of livestock products per herd TLU

¹ Milk in litres; Meat in kg dressed weight; Draught animals in TLUs.

² Reduce meat output by 45%, 49% and 13% in low, intermediate and high input systems respectively when considering draught animal output.

³ Meat output of 132 kg/TLU applies when there is no wool production.

⁴ Meat output of 107.2 kg/TLU applies when there is wool production of 25.0 kg/TLU iithamal zones T5, T6, T7, and T8 (Table 60).

6.3.1 Cattle Systems: Dairy and Meat

These systems are considered in thermal zones Tl, T2, T3, T4, T5, T6, T7 and T8 (Table 6.14) in growing period zones of more than 120 days (Table 6.15).

For the low technology system, output performance per TLU is 264.8 litres milk and 24.6 kg meat. If draught animals were desired then upto 0.09 TLU of draught animals per TLU could be produced but there would be upto 45% proportional reduction in the meat output (Table 6.16).

For the intermediate technology system, output performance per TLU is 768.4 litres milk and 26.0 kg of meat. If draught animals were desired then up to 0.11 TLU of draught animals per TLU could be produced but there would be up to 49% proportional reduction in the meat output (Table 6.16).

For the high technology system, output performance per TLU is 901.5 litres milk and 19.8 kg meat. If draught animals were desired then up to 0.02 TLU of draught animals per TLU could be produced but there would be up to 13% proportional reduction in the meat output (Table 6.16).

6.3.2 Goat Systems: Dairy and Meat

These systems are considered in the thermal zones Tl, T2, T3, T4, T5, T6, T7 and T8 (Table 6.14), and in growing period zones of more than 120 days (Table 6.15).

For the low technology system, output performance per TLU is 92.6 kg meat. For the intermediate technology system, output performance per TLU is 263.7 litres milk and 114.6 kg meat. For the high technology system, output performance per TLU is 2166.7 litres of milk and 132.7 kg meat (Table 6.16).

6.3.3 Sheep Systems: Meat and Wool

These systems are considered in thermal zones Tl, T2, T3, T4, T5, T6, T7 and T8 (Table 6.14), and in growing period zones with more than 120 days (Table 6.15).

For the low technology system, output performance per TLU is 70.5 kg of meat. For the intermediate technology system, output performance is 123 kg meat. In the high technology system output performance per TLU is 151.8 kg of meat. In thermal zones 6 and 7, output performance per TLU is 126.9 kg of meat and 25 kg wool (Table 6.16) for the meat and wool system.

6.3.4 Pastoral Systems

6.3.4.1 Cattle: Meat and Milk

These systems are considered in thermal zones Tl, T2, T3, T4, T5, T6 and T7 (Table 6.14), and in growing period zones less than 119 days (Table 6.15) except for the semi-nomadic herd (high technology) which is considered only in growing period zones 60–89 days and 90–119 days (Table 6.16).

For the nomadic distant herd (low technology), output performance per TLU is 59.3 litres milk and 15.4 kg meat. For the nomadic herd with market access (intermediate technology), output performance per TLU is 60 litres milk and 18.6 kg meat. For the seminomadic herd (high technology), output performance per TLU is 67.9 litres milk and 24.6 kg meat (Table 6.16).

6.3.4.2 Goat: Meat

These systems are considered in thermal zones Tl, T2, T3, T4, T5, T6 and T7 (Table 6.14). The nomadic distant herd is considered in growing period zones with less than 120 days. The semi-nomadic herd is considered in growing period zones 30–59 days, 60–89 days and 90–119 days (Table 6.15).

The nomadic distant herd is assumed to represent the low technology system, and its output performance per TLU is 7.6 kg meat. The semi-nomadic herd is assumed to represent the high technology system, and its output performance per TLU is 19.8 kg meat (Table 6.16). The output performance per TLU for the intermediate technology system is assumed to be half-way between the low and the high technology performance (i.e. 13.7 kg meat).

6.3.4.3 Sheep: Meat

These systems are considered in thermal zones Tl, T2, T3, T4, T5, T6 and T7 (Table 6.14). The nomadic distant herd is considered in growing period zones with less than 120 days. The semi-nomadic herd is considered in growing period zones 30–59 days, 60–89 days and 90–119 days (Table 6.15).

The nomadic distant herd is assumed to represent the low technology system, with an output performance per TLU of 8.9 kg meat. The semi-nomadic herd is assumed to represent the high technology system, with an output performance per TLU of 19.4 kg meat (Table 6.16). The output performance at the intermediate level is assumed to be half-way between the low and the high technology performance (i.e. 14.2 kg meat).

6.3.4.4 Camel: Meat and Milk

The system is considered in thermal zones Tl and T2 (Table 6.14), and in growing period zones less than 90 days (Table 6.15).

The output performance per TLU for the nomadic herd is 96.2 litre milk and 1.9 kg meat (Table 6.16) This output performance per TLU is assumed to apply at the low inputs level. The output performance per TLU at the high inputs level is assumed to be 50% greater (i.e. 144.3 litre milk and 2.9 kg meat), and the intermediate level performance is assumed to be half-way between the low and the high level performance (i.e. 120.6 litre milk and 2.4 kg meat).

6.3.5 Poultry and Pig: Meat and Egg

Poultry and pig production has been considered to apply only under the intensive system. The feed conversion ratios for poultry meat and eggs and pig meat are given in Section 6.4.5. Performance parameters have not been explicitly formulated for poultry and pig system at this stage of the model development but it is envisaged that these would be incorporated at a later stage.

6.3.6 Pests and Diseases

Major diseases of cattle include rinderpest, trypanosomiasis, contagious bovine pleuropneumonia, dermatophilosis (streoto-thricosis), east coast fever and other tick-borne diseases, and foot and mouth disease. Brucellosis occurs widely and parasitic gastro-enteritis is common, and takes a heavy toll of calves under low management level. Fairly satisfactory control measures for a number of these diseases are available but continued vigilance is necessary to ensure that herds receive protection.

Foot and mouth disease is not important at a low level of production although its occurrence may prevent the export of meat. Ticks can be controlled by dipping or spraying but the provision of facilities and supervision is sometimes difficult.

Sheep and goats are susceptible to a variety of diseases including bacterial pneumonia, internal parasites, foot-rot and in the case of goats caprine pleuropneumonia and in sheep, sheep pox. Treatment is not normally available or sought and losses can be heavy although sick animals are killed and the carcase utilized.

Camels are very susceptible to tick-borne disease and trypanosomiasis. However, they are rarely kept in zones with more than 90 days growing period.

The distribution of trypanosomiasis and its tse-tse vector in Kenya has been mapped and is included in the land resources data base (Chapter 3). It has been assumed that in the thermal zones 1, 2, 3 and 4, loss in livestock production performance would be of the order of 75% in the low technology systems and 50% in intermediate and high technology systems due to trypanosomiasis.

6.4 Estimation of Feed Requirements

Part IV of the livestock productivity model (Figure 6.1) formulates the livestock feed requirements, taking into account maintenance and production needs.

Feed requirements have been formulated to support the herd performances quantified in Section 6.3 for the individual livestock systems.

In order to support the body's processes and promote production, animals must consume regular supplies of various nutrients. These nutrients may be broadly defined as energy (from carbohydrates and fats), protein, vitamins, minerals and water. They are contained in animal feeds, which are largely of plant origin, in different concentration and combination. Under most intensive systems of animal husbandary, the animal may not always be able to obtain a balanced diet throughout the year because of the seasonal variation in the composition of the herbage.

Water is also needed by the animal, this is obtained from three sources: (a) drunk as water, (b) contained in the herbage or other feed, and (c) resulting from the oxidation of carbohydrates in the tissues. Availability of water is a problem in some parts of Kenya, and much of the pastoral zone has limited permanent water forcing nomadic behaviour. Certain stretches of the country have no water resources. Such a situation must be taken into account in final estimates of livestock carrying capacities. The available sources of information include data which would enable these areas to be identified and measured at the district level and this should be incorporated in the model for a more effective treatment.

TABLE 6.17
Feed requirements per herd TLU (kg/day dry weight)

¹ Includes 1.2 kg/day primary products (3.2 kg/day per lactating cow)

² Includes 4.8 kg/day primary products (0.6 kg/day per lactating doe).

A summary of reference feed requirements per herd TLU is given in Table 6.17 for non-pastoral and pastoral systems for three levels of inputs situations. In the non-pastoral systems, intake requirements for cattle, goat and sheep are based on field verification for the herd structures presented in Section 6.2 for the performance output levels described in Section 6.3. In the model, crop residue intake in the non-pastoral systems is limited to 30%, 20%, and 10% of total feed intake respectively in the low, intermediate and high technology system.

For pastoral systems, feed requirements are based on Boudet and Riviere (1968) for the herd structures and performances presented in Sections 6.2 and 6.3 For poultry and pig, the standard requirements are used (FAO 1988b).

Feed requirements for each system are presented hereunder.

6.4.1 Cattle Systems: Dairy and Meat

In the low technology system, one cow unit requires about 3,740 kg dry matter (DM), corresponding to 1,650 kg total digestable nutrients (TDN) and 210 kg digestible crude protein (DCP) per year, for maintenance and production. These feed requirements are met by grazing Kikuyu/star grass pasture and maize stover.

In the intermediate technology system, one cow unit requires about 5,200 kg DM (2,560 kg TDN and 300 kg DCP per year) for maintenance and production. These feed requirements are met by grazing Kikuyu/star grass pasture and maize stover.

In the high technology system, one cow unit requires about 7,200 kg DM (3500 kg TDN and 420 kg DCP per year) for maintenance and production. This is provided by the napier/bana grass, by feeding maize stover and by feeding 1,165 kg concentrates.

The above requirements correspond to 7.8, 8.5 and 8.9 kg/day per reference herd TLU for the low, intermediate and high technology systems respectively (Table 6.17).

6.4.2 Goat Systems: Dairy and Meat

In the low technology system, one doe unit requires about 470 kg DM per year, provided by natural pasture.

In the intermediate technology system, one doe unit requires about 700 kg DM per year. This is provided by a combination of sources: natural pasture (280 kg), fodder crops (280 kg) and crop residue (140 kg).

In the high technology system, one doe unit requires about 960 kg DM per year. This is provided by fodder crops (610 kg), crop residue (140 kg) and concentrates (210 kg).

The above requirements correspond to 10.0,11.5 and 16.1 kg/year per reference herd TLU for the low, intermediate and high technology systems respectively (Table 6.17).

6.4.3 Sheep Systems: Meat and Wool

In the low technology system, one ewe unit requires about 360 kg DM per year, provided by natural pasture.

In the intermediate technology system, one ewe unit requires about 610 kg DM per year. This is provided by a combination of sources: natural pasture, fodder crops and crop residue.

In the high technology system, one ewe unit requires about 750 kg DM per year. This is provided by natural pasture, fodder crops, crop residue and concentrates.

The above requirements correspond to 9.1, 11.3 and 11.6 kg/year per reference herd TLU for the low, intermediate and high technology systems respectively (Table 6.17).

6.4.4 Pastoral Systems: Milk and Meat

For the pastoral systems (< 120 days growing period), feed requirements are based on a daily intake of 2.5 kg dry matter per 100 kg liveweight or 6.25 kg dry matter for the 250 kg reference TLU. Maintenance requirements are 2.9 FU/day and 160 g/day digestible protein (DP). The annual maintenance dietary needs of a reference TLU are thus 1,060 FU or 2,280 kg DM (1FU = 2.15 kg DM) and 58 kg DP. Production requirements are in addition at 350 extra FU/year (0.95 FU/day) and 28 kg DP (75 g/day) for weight gain of 100 kg/year (300 g/day) or a production of 1,000 kg/year(2.74 kg/day) of milk.

The above requirements correspond to 7.0, 7.2 and 7.4 kg DM/day per TLU for the low, intermediate and high technology systems respectively for cattle; 6.6, 6.8 and 7.0 kg DM/day per TLU for goat and sheep; and 6.5, 6.6 and 6.7 kg DM/day per TLU for camel (Table 6.17).

6.4.5 Poultry and Pig: Meat and Egg

These animals are considered only under the intensive systems and standard requirements are used (FAO 1988b). For poultry these are 2.5 kg of feed (primary products) for 1 kg of meat, and 3,5 kg of feed for 1 kg of egg mass. For pig it is 4 kg of feed for 1 kg of meat.

6.5 Livestock Productivity Potential

Part V of the livestock productivity model (Figure 6.1) deals with quantification of livestock productivity potential (secondary productivity) of land (agro-ecological cells). This is achieved by setting feed requirements of livestock systems from Part IV against feed supply fromParti.

However, before it is possible to set feed requirements against feed supply, the latter from its various sources as applicable must be quantified by agro-ecological cell in relation to the objective function driving the model.

The permissible thermal and LGP zones for the different livestock systems is taken from the Tables 6.14 and 6.15, and the expected output of the products per herd TLU is taken from Table 6.16 for cattle, goat, sheep and camel, and from Section 6.4.5 for poultry and pig. Where output performance is assumed to be affected by constraints such as temperature stress, tse-tse, the expected loss in performance output is taken into account.