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Unit 4: The Integration of Livestock Production in Alley Farming

Main Contributors: L. Reynolds, J. Cobbina


4.0 Performance objectives
4.1 Introduction to alley farming in smallholder livestock production
4.2 Contributions of leguminous trees to livestock nutrition
4.3 Alley farming with food crops and livestock
4.4 Alley farming with grass
4.5 Special considerations for alley farming with livestock
4.6 Research needs for alley farming with livestock
4.7 Feedback exercises
4.8 Suggested reading
4.9 References


4.0 Performance objectives

Unit 4 is intended to enable you to:

1. Discuss the importance of livestock production in tropical Africa.

2. Recall the contributions which leguminous tree can make to livestock nutrition, including increased productivity and provision of protein-rich feed during the dry season.

3 . Demonstrate familiarity with recent research concerning the benefits to livestock productivity from supplemental feeding with hedgerow prunings.

4. Explain the dry-season constraints to livestock production, and the corresponding solutions offered by alley farming.

5. Describe three ways of producing forage for livestock from alley farms on which food crops are grown.

6. Describe the systems for growing grass alongside hedgerows, including intensive feed gardens, alley grazing, and fodder tree banks.

7. Recall special considerations for establishing tree/grass intercrops, such as the need to protect young trees, requirements for fertilizer inputs, and harvesting schedules.

8. Recall recommended practices for managing fodder trees and for feeding their foliage to livestock.

9. List important research issues for the integration of livestock production with alley farming.

4.1 Introduction to alley farming in smallholder livestock production

In alley farming with livestock, the hedgerows of trees or shrubs are managed to provide high-quality fodder for sheep, goats, and/or cattle. There are two main types of systems that integrate alley farming principles with livestock production:

· alley farming with food crops and livestock
· alley farming with grass and livestock

In the first system, the hedgerows are managed to provide fodder for the animals and mulch for the crops. In the second type of system, both the trees and the intercropped grass are fed to animals.

Livestock are a minor enterprise and generally receive little attention in most mixed crop/livestock farming areas of sub-Saharan Africa. Thus, any innovation to improve livestock production should also benefit other farm activities in order to be acceptable to the farmers. Alley farming with food crops and livestock allows smallholders to follow a low-cost pathway to improving both crop and livestock production, reducing reliance on external inputs, and increasing sustainable off-take from the land. Alley farming with grass and livestock is an innovative means of overcoming the nutritional constraints faced by livestock production in many areas of tropical Africa

The importance of livestock production in tropical Africa is many-sided. Livestock products, in the form of meat, milk, and various dairy products, contribute about one fifth of high quality dietary protein in sub-Saharan Africa. These proteins have a higher biological value than pulses and cereals, and are also preferred by consumers. In addition to providing high-value food, livestock provide:

· a means for investing capital and a source of ready cash,
· security against food shortage,
· a means for strengthening social relationships (e.g., through loans for establishment of new herds),
· draught power and manure (especially with cattle), and
· hides and skins.

In southern Nigeria, where ILCA scientists first developed alley farming with livestock, small ruminants are the predominant farm animals. In that region, a typical small farm extends over 2 ha of cultivated land, with perhaps 6 ha of fallow. The major crops are maize, cassava, and yam, and the typical herd size is 3-6 animals. Household production must support 6-8 people. The primary objective of the farmer is to grow sufficient food for the family, with any surplus going for sale. In southwestern Nigeria, animals roam freely, scavenging for household waste to supplement natural grass and the browse that grows around the village. In southeastern Nigeria, where human population pressure on land is greater, confinement and tethering are more common, especially during the rainy season, to limit damage to crops.

Although ILCA's initial interest in alley farming was directed towards sheep and goats, the potential of leguminous tree forage for cattle is also being explored. Feed gardens, comprising tree and grass combinations, are being encouraged for stall-fed dairy or beef cattle in Kenya, Malawi, and Zimbabwe. The derived savannah region of West Africa offers similar possibilities.

4.2 Contributions of leguminous trees to livestock nutrition


4.2.1 Increased Productivity
4.2.2 Solutions to Dry Season Constraints


The leguminous multipurpose trees which in alley farms provide nitrogen-rich mulch to enhance soil fertility can, at the same time, provide an on-farm source of high quality supplementary feed for ruminant livestock. Two tree species, Leucaena leucocephala and Gliricidia sepium, have been most widely used for alley farming with livestock. The foliage from both these species contains over 20% crude protein (3.4% nitrogen) and hence provides a valuable high protein feed supplement for livestock.

The leguminous trees are used as supplements only, and should not become the main feed source. Leucaena is, in fact, toxic to animals when it exceeds 30-40% of their total feed intake. The toxicity is due to the high levels of mimosine in Leucaena Mimosine poisoning leads to hair loss and illness, and can even be fatal.

4.2.1 Increased Productivity

Some of the important results of feeding sheep and goats with Leucaena and Gliricidia foliage are:

· It increases total food intake.

· It increases the overall productivity of dams as measured by weight of offspring weaned/dam/year (Figure 4-1).

· When offered to dams during late pregnancy and lactation, and to the offspring from weaning to 6 months of age, it enhances growth rates and survival rates (Table 4-1).

· Provision of supplementary browse increases the rate of weight gain in growing and fattening sheep (Table 4-2).

On-farm studies of alley farming with food crops in southwestern Nigeria have shown that the tree productivity on farmers fields was 5.4 t dry matter (DM) per hectare per year, with 75% being available during the growth of the first-season food crop. Farmers offered 176 kg of foliage DM/year to their goat herds as cut-and-carry browse on 10 days per month, at a rate of 147 g edible DM/animal/occasion. The productivity index of these browse feeders was 11.3 kg as compared to just 7.8 kg for goats that were not fed MPT foliage, an increase of 44%. (The productivity index is the weight of kids at 12 months/doe/year times doe survival rate).

This increase in productivity reflected the improvements in litter size, parturition intervals, and survival rates associated with supplemental feeding. (See Table 4.3.) A number of farmers in subsequent years have planted tree-only feed gardens specifically to increase the amount of forage available.

4.2.2 Solutions to Dry Season Constraints

Nutritional benefits to livestock assume particular importance during the dry season. In vast areas of tropical Africa, farmers face serious problems of low quantity and quality of forage to feed their animals at this time. Tropical grasses are low in protein, especially in the dry season. Most crop residues and other grazing resources are low in digestibility and N content during these months. However, the multipurpose trees and shrubs used in alley farming have long tap roots and so can access water at deeper soil levels than shallow-rooting plants. Thus, the MPTs can produce leaves and branches for forage throughout the year.

Figure 4-1. Effect of browse intake on the productivity of sheep and goats, Ibadan, Nigerian humid zone, 1986/87.

The importance of high-protein fodder in the dry season stems from the basic nutrition mechanism in ruminants. Ruminants (cattle, sheep and goats) have a multi-compartment stomach, unlike the simple stomach found in non-ruminants (pigs, humans). This allows ruminants to make use of the nutrients found in fibrous materials, such as grass, that humans cannot use. The primary breakdown of fibrous food is carried out, not by the animal itself, but by billions of microbes that live in the largest of stomach compartments, the rumen, which acts as a fermentation vat.

Furthermore, ruminants do not require the high quality protein feeds needed by non-ruminants. Rumen microbes can make their own essential amino-acids from simple nitrogenous compounds, such as ammonia, to the benefit of the animal when the microbes die and are digested.

Table 4-1. The effects of supplementary Leucaena and Gliricidia browse on the growth and survival rates of West African Dwarf goats and West African Dwarf sheep. Note that the response of sheep to supplementation is twice that of goats (Source: ILCA, 1988).

 

Browse Intake (g DM/day)

Growth Rate (g/day) Birth to

Survival to 24 weeks

Dam (a) Offspring

(b) Weaning

(c) 24 weeks

Goats

143

39

17.4

14.0

0.36

254

83

28.7

20.1

0.46

554

160

25.9

20.9

0.82

719

246

31.9

28.3

0.94

Sheep

0

0

39.0

25.4

0.50

120

34

46.7

30.7

0.62

239

77

57.2

34.0

0.70

441

136

66.3

44.5

0.89

741

250

84.0

50.3

1.00

(a) During the final two months of pregnancy up to weaning.
(b) From weaning to 24 weeks.
(c) Weaning at 12 weeks for lambs, and 16 weeks for kids.

An active population of microbes in the rumen is, therefore, essential to the well being of the animal, allowing ruminants to exist on feed that is unusable by non-ruminants, and to convert fibrous waste into meat and milk. In the dry season, when the level of protein in grass falls below 6%, rumen microbes are unable to make enough protein to maintain their own growth and reproduction rate. As a result, the microbe population falls, and, because food will not pass out of the rumen until it has been partially digested by the microbes, the flow of food through the intestinal tract slows down. Food intake by the animal is therefore reduced. Animals lose body condition and milk production is reduced.

Supplying additional protein during the dry season will maintain or increase the microbial population, increase digestion rates, and raise food intake. The total amount of nutrients available to the animal will rise in two ways: higher intake and better digestibility. On commercial cattle ranches, oilseed cake or urea are often used to increase crude protein intake, but this is rarely feasible for smallholder farmers raising sheep or goats. Cultivation of leguminous MPTs is a viable alternative.

Table 4-2. Effect of supplementary browse on the growth and fattening rate (g/day) of West African Dwarf lambs offered a basal ration of ad-libitum Guinea grass (Panicum maximum).

Group

Age range

Intake Panicum

(g DM/day) Browse

Total

Growth g/day

Males

6-18 months





1


630a

237a

915a

30.3a

2


613a

491b

1155b

41.7b

3


379b

689c

1116b

48.9c

Females

6-15 months





1


670a

196a

914a

25.8a

2


605b

453b

1196b

29.0a

3


337c

604c

986c

37.7b

Within a sex group, values in columns with different letters me significantly different (P<0.05)
All groups received 50 g/day of sun dried cassava peel.

Table 4-3. Production parameters for free-roaming village West African Dwarf goats in SW Nigeria.


Browse feeders

Non-browse feeders

Litter size

1.48

1.41

Parturition interval (days) (1)

280

298

Weight at 12 months (kg)

9.5

10.1

Survival to 12 months

0.67

0.64

Survival of adults

0.92

0.70

Productivity index (kg) (2)

11.3

7.8

(1) 60% of adult females kidded more than once
(2) Productivity index = wt of kids surviving to 12 month/doe surviving over a 12 month period/year.

4.3 Alley farming with food crops and livestock


4.3.1 Forage Production during Cropping
4.3.2 Forage Production from Hedgerows during Fallow


In a typical alley farming system, food crops such as maize or rice are grown in the alleys between hedgerows. In this system, there are three ways to produce forage for livestock:

· Forage production during the cropping phase,
· Forage production from hedgerows during a fallow period, and
· Grazing of the alleys in a fallow period

Here a fallow period refers either to the dry season in a normal cropping year, or to an optional short fallow period during which no crops are grown for one or two years. The first two methods are cut-and-carry systems in which the trees are cut occasionally to feed animals. The animals may be fattening cattle, milking cows, or calves. Cut-and-carry is also for suitable sheep and goats, both free-roaming and confined in pens.

4.3.1 Forage Production during Cropping

The two sources of feed for animals in alley farms with food crops are:

· hedgerow prunings, and
· crop residues (e.g., maize stover)

The hedgerows are pruned occasionally to prevent shading and are generally used as mulch to restore or maintain soil fertility. Some of the prunings are taken out of the cropland to feed ruminant livestock . The crop residue could also be used as mulch, or could be removed for feeding to livestock on a cut-and-carry basis. Alternatively, the crop residue could be grazed by ruminant livestock in situ during the short fallow periods between one crop and the next. The main question to consider here is the amount of fodder that can be made available from hedgerow prunings without detriment to crop yield.

In order for the system to sustain itself, a proper balance needs to be worked out between prunings used as animal feed, and prunings used as mulch and green manure. Total removal of the prunings, a condition that may occur in a cut-and-carry alley farming system, would most likely reduce the crop yield. An on-station trial conducted by ILCA in Ibadan has shown that the most essential pruning to be used as manure and mulch during the growing season of a maize crop is the first pruning prior to planting (Table 4-4). With Leucaena hedgerows, this first pruning increased the maize yield by 35%. The foliage produced after this pruning can be safely fed to livestock without any substantial loss in crop yield. However, if there will be a second crop (e.g., maize, or cowpeas as in Figure 3-7) the pruning just prior to planting of the second crop should also be returned to the land. In the ILCA trials, prunings were at 6-week intervals, for a total of 5 prunings per year. More research is needed in this area with other food crops.

To summarize the current ILCA recommendations, about 75% of hedgerow prunings - those obtained after pre-planting pruning - can be fed to livestock without significant crop yield losses.

Table 4-4. Maize grain yield and forage availability as influenced by quantity of pruning used for mulching.

Maize yield (t/ha

Prunings applied as mulch

Unfertilized plots

Fertilized plots

Foliage for feed (1) (t/ha)

None

3.1

4.8

4.95

First (pre-planting)

4.3

4.9

1.85

First two

4.6

5.3

0.68

All three

4.8

5.3

None

1 Total forage available throughout the cropping season.

4.3.2 Forage Production from Hedgerows during Fallow

As pointed out in Unit 3, short fallow periods are helpful in sustaining the productivity of land and trees in alley farming. Scientists at the ILCA substation in Ibadan have conducted trials to determine the best cutting schedule to produce forage from Leucaena and Gliricidia in followed alley farming plots. From their results, presented in Table 4-5, it is observed that after a uniform cutting in January, the two prunings taken in October (9 months regrowth) and January (13 months regrowth) produced the highest forage dry matter yield.

Table 4-5 Effect of tree pruning scheme and regrowth periods on edible forage dry matter yield of Leucaena in alley farming fallow plots.

Pruning regime

Intermediate Harvest (month)

January harvest

Total harvest

3

6

9


Dry Matter Yield (t/ha)

Pruned Jan.

-

-

-

4.50

4.50

Pruned Apr. and Jan.

1.48

-

-

1.72

3.20

Pruned Jul. and Jan.

-

2.90

-

1.66

4.56

Pruned Apr. Jul. and Jan

1.43

1.18

-

1.33

3.94

Pruned Oct. and Jan.

-

-

5.29

1.06

6.35

Pruned Apr. Jul. Oct. and Jan.

1.40

1.12

1.15

0.72

4.38

During fallow periods in alley farming with food crops, ruminant livestock can be allowed onto the plots. Pruning the hedgerows just after the rainy season helps to maximize fodder production. If left unpruned, Gliricidia and certain other species will tend to lose their leaves and flower during the dry season. When the understorey plant material in grazed alley fallow is sparse and unpalatable, the animals will spend most of their time browsing the hedgerows. In such a situation, a common problem that has been observed is the debarking of the trees which can often lead to serious tree mortalities.

Debarking of hedgerows is more of a problem with goats than with sheep, and does not occur with cattle. Solutions can be found through proper management of the system. For example, animals can be allowed into fenced fallow plots for limited periods. Alternatively, in cases where the fallow period will last 1-2 years, pasture grass species can be planted in the alleys. The grass should be sown just at the time of reverting alleys to fallow to provide palatable, grazeable understorey material for the animals. Pasture species which could be planted may include Guinea grass (Panicum maximum) and herbaceous legume species such as stylo (Stylosanthes guianensis).

4.4 Alley farming with grass


4.4.1 Intensive Feed Gardens
4.4.2 Alley Grazing - Rotational System
4.4.3 Alley Grazing - Permanent System
4.4.4 Fodder Tree Banks


A promising modification of the alley farming system involves planting grass between trees rows, rather than planting food-crops. The result is a low-input forage production system which provides a balanced feed ration on a single plot of land. Alley farming with grass forms a two-storey system that allows more efficient use of light, space, and soil resources. If the tree or shrub mixed with the grass is a legume, such as Leucaena the system can provide cheap but constant energy and protein sources to raise animal productivity through the different seasons of the year.

Some grass species which have been found compatible with Leucaena hedgerows include:

· African star grass (Cynodon nlemfuensis, C. dactylon)
· Buffel grass (Cenchrus ciliaris)
· Elephant grass (Pennisetum purpureum)
· Guinea grass (Panicum maximum)
· Pangola grass (Digitaria decumbens)
· Signal grass (Brachiaria decumbens)

The rationale for alley farming with grass is based on the previously mentioned observation that tropical grasses are low in protein, especially during the dry season. This condition limits livestock production in many areas. In industrialized countries, inorganic fertilizers are used to improve the quantity and quality of grass; however, this management option may prove too costly in most of tropical Africa and would not solve the dry season feed problem.

A low-cost alternative will be to interplant the grasses with legumes. In fact, herbaceous legumes have been used in many places to provide a cheap source of protein for livestock, but have been difficult to sustain under grazing. This problem can be overcome by planting woody legumes instead, such as the leguminous trees and shrubs used in alley farming. They have large carbohydrate reserves in the roots and can tolerate frequent grazing or pruning.

In most areas where Leucaena/grass pastures have been used for grazing, impressive animal performances have been recorded. For instance, researchers in Queensland, Australia, reported that with stocking rates of 2.5 yearlings per hectare, Leucaena pastures persisted over 10 years and produced an average of 311 kg/ha liveweight gains (Jones and Jones, 1982).

Alley farming technology can be combined with grass production in various ways. ILCA scientists have found at least four separate systems showing good potential in the humid tropics:

· Intensive Feed Gardens
· Alley Grazing - Rotational System
· Alley Grazing - Permanent System
· Fodder Tree Banks

4.4.1 Intensive Feed Gardens

Intensive feed gardens are plots where hedgerows are planted at close spacing (2-4 m) and grass is sown in the alleys between. An example of an intensive feed garden is shown in Figure 4-2. This system is intended to produce the maximum amount of fodder per hectare through the intensive cultivation of fodder trees, and grasses on a limited area. It is usually established on a small piece of land (10 × 20 m). This is sufficient to feed 3 to 5 small ruminants.

Figure 4-2. Intensive Feed Garden: Cut-and-Carry System. Crass is intercropped with hedgerows of legume trees (2-4 m spacing). Animals are stall fed.

The intensive feed garden is ideal where increased human population has led to scarcity of land, intensive cultivation, compound farming, and/or compulsory confinement of livestock. Under such conditions, farmers have to practice cut-and-carry feeding to compensate for the dwindling feed resources from natural pasture and fallow lands. Establishment of such a garden close to the household provides good quality supplementary feed for confined animals.

The system is also suitable for more intensive cattle operations, such as stall-fed beef or dairy units. In Kenya, this system is the basis for a successful smallholder dairy project. Crossbred cattle are either completely stall fed (zero grazed) or allowed to graze on natural pasture and offered supplementary forage in their pens at the end of the day.

A recent study at ILCA-Ibadan tested forage yield under different intensive feed gardens design. Leucaena and Gliricidia were planted in rows spaced 2.5 or 4.0 m apart with 2 or 4 rows of Guinea grass (Panicum maximum) or elephant grass (Pennisetum purpureum); the system yielded about 20 t DM/ha/yr. The tall, erect, bunch type grasses such as Guinea grass and elephant grass allow for easy cut-and-carry management. They are also tolerant to some degree of shading by the tree component.

4.4.2 Alley Grazing - Rotational System

In this system, livestock are allowed periodically to graze tree legume hedgerows and interplanted grass. The alley grazing plot is laid out with rows 3-4 m apart to permit easy access by the animals. The system is intended mainly for grazing and not for cut-and-carry.

The livestock will be rotated between pure grass pastures and the alley grazing plots, or they will be rotated between stall feeding from other sources and the intensive feed garden. For a system with Leucaena or Gliricidia, a suitable rotation would comprise 2 weeks of grazing with 8-10 weeks' rest period.

A rotational system has two main advantages over continuous grazing. First, the trees regain lost vigor during the rest periods. Secondly, mimosine toxicity in animals grazing Leucaena is kept to tolerable levels, as toxicity is related to the length of time animals graze Leucaena.

Figure 4-3. Alley Grazing Rotational System. Grass is intercropped with hedgerows of legume trees (3-4 m spacing). Periods of grazing are followed by periods of rest, (e.g., 2 weeks grazing, 8-10 weeks rest).

Figure 4-4. Alley Grazing - Permanent System. Shrubby hedgerows are spaced 7 m or more apart.

The advantage of rotational grazing has been demonstrated in studies such as the one carried out in the Ord Valley of Australia (Blunt and Jones, 1977). Animals that were rotated between pure pangola grass pastures and Leucaena/pangola pastures gained more weight than did those animals that grazed Leucaena pastures all the time.

4.4.3 Alley Grazing - Permanent System

In this system, permanent grass pastures are planted with widely spaced hedgerows of shrubby forage legumes. The spacing between hedgerows should be approximately 7 m. Through pruning, the hedgerow trees should be encouraged to branch heavily close to the soil surface. This system has been studied extensively using shrubby Leucaena cultivars. The shrubby Gliricidia accession ILG 58 is another good choice, due to its dwarfish stature.

Because free-ranging livestock tend to prefer pasture grasses to hedgerow browse, overgrazing of hedgerows is not a concern if adequate grass cover is available. However, on poor quality pastures or during the dry season, the permanent system of alley grazing may pose problems of mimosine toxicity (with Leucaena and/or debarking of trees (with goats). Management options include: (1) avoiding Leucaena altogether in favor of fodder species such as Gliricidia, Calliandra or local species; (2) restricting access to the pastures at certain times of year; and (3) encouraging vigorous growth of pasture grasses. Planting Leucaena and another species in alternate rows may not solve the problem, since Leucaena is more palatable and so is preferred.

4.4.4 Fodder Tree Banks

In this system, blocks of closely spaced trees or shrubs are planted in one corner of natural or improved pasture. The trees are planted in hedgerows with 0.25 m spacing between trees and 1.0-1.5 m between rows. Such a layout maximizes protein yield on the available land area, while allowing farmers to enter the blocks with ease.

The blocks of closely spaced hedgerows are planted on 10-30% of the total pasture area. They are managed as "fodder tree banks" - also called "tree protein banks". For improved management, the banks should be fenced off to allow only limited access by grazing animals. Farmers then have the option of allowing access only for certain animals (e.g., pregnant and lactating dams) and for certain time of year (e.g., the dry season).

Figure 4-5 Permanent pasture with fodder banks. Closely spaced blocks of legume trees are planted on 10-30 % of pasture area.

4.5 Special considerations for alley farming with livestock


4.5.1 Choice of MPT Species
4.5.2 Establishment of Tree/Grass Intercrops
4.5.3 Management of Fodder Trees in Alley Farming
4.5.4 Animal Nutrition


Many of the general recommendations for the establishment and management of alley farms (covered in Unit 3) are valid whether or not livestock are included in the system. For example, seed pretreatments and tree planting procedures are the same with or without livestock. However, there are several special considerations which arise when forage production is an objective, namely:

· Choice of MPT species,
· Establishment of tree/grass intercrops,
· Management of fodder trees, and
· Animal nutrition and health.

4.5.1 Choice of MPT Species

The tree species to be used in any alley farming system with livestock should have the following characteristics:

· Easy establishment from seeds or seedlings,
· Rapid growth with high forage productivity,
· Good coppicing ability,
· Excellent nitrogen-fixing capability,
· Efficient nutrient uptake abilities,
· Deep-rooting system,
· High foliage harvest index, and
· Good feeding value and high palatability.

Table 4-6 presents some tree species which have been shown to possess many or all of the above-listed characteristics, and therefore could be used in a tree-based forage production system. The list is by no means exhaustive. More could be added to meet the varied needs and conditions of different ecological zones. The N2 - fixing legumes are much preferred because of their ability to fix their own nitrogen through symbiosis and their resulting high protein content.

Where Leucaena will be used in intensive feed gardens or rotational grazing systems, it may be prudent to plant every second hedgerow with a different species, such as Gliricidia. This helps to avoid the mimosine toxicity problems that result from excessive intake of Leucaena. As previously mentioned, alternating rows may not be a solution in free-grazing, permanent systems.

4.5.2 Establishment of Tree/Grass Intercrops

Planting Hedgerows in Pastureland

On a newly cleared site, the technique for land preparation and tree planting will be similar to that described in Unit 3. However, to establish trees in pastureland, different land preparation techniques should be adopted which would facilitate the clearing of the grass and also the tilling of the land. Narrow cleared strips of land, 50 100 cm wide, could be created by using a hand hoe or a disc plough mounted on a four-wheel tractor.

The appropriate seed pretreatment applicable to each MPT species should be employed. Nursery seedlings could be planted as an alternative to direct seeding. There is a need for more research on appropriate land preparation techniques for the various forage production species.

Protecting Young Trees from Grass

Most tree species have extremely slow shoot growth rate and sparse root systems early in their growth cycle. As a result, they compete poorly with grasses, which have profuse, fibrous roots. Thus, the grass and weeds in the immediate vicinity of the trees should be controlled during establishment. This can be done by hoeing, slashing with a cutlass, or spraying herbicide in strips along the tree hedgerows.

In situations where the associated grass is a tall, bunch type such as Guinea grass, the grass should be prevented from shading the trees. In a high-input system, the grass could be mowed and processed into bales as hay. In contrast, for a low-input system with limited access to tractor and mounted implements, the best option will be to hand-slash the grass. Since livestock may damage young trees, the newly planted trees should be allowed time to establish sufficiently well before the first grazing. More research is needed to determine the optimum timing and prerequisite plant height and stem girth for this first grazing.

Fertilization Needs

The tree hedgerows may benefit from fertilization, as mentioned in Unit 3. When trees and grass are to be established together, manure should be applied on the newly cleared plots. In the absence of manure, apply fertilizer (15-15-15 N:P:K compound) at 150-200 kg/ha in 2 or 3 split applications per year. This will ensure prolonged productivity of the grasses.

Because large quantities of biomass are exported from intensive feed gardens and fodder tree banks, serious shortages of non-renewable nutrient elements such as P, K, Ca, Mg, and some trace elements may ensue in the long run. This situation could lead to marked reduction in forage yields with advancing age. There would be a need, therefore, to work out fertilization schemes to replenish some or all of the nutrient elements that have been taken away from the soil. The alley grazing systems are less susceptible to nutrient depletion than the intensive feed gardens and fodder tree banks.

Cutting Schedule for Tree/Grass Intercrop

The grasses are ready for cutting 8 weeks after planting, while the trees may require 8 to 12 months growth prior to the first pruning. Grasses should be cut every 4 to 6 weeks, and the trees cut every 8 to 12 weeks, depending on the season. More information on tree pruning practices is provided in the next section.

Table 4-6. List of fodder species, their characteristics and seed pretreatment information

Species Name

Sub-Family

Description

Distribution

Seed pretreatment requirement

Rhizobium

Acacia senegal (L.) Willd.

Mimosoiceae

Bush or tree up to 5 m high

Common in northern tropical Africa

Hand scarify

Cowpea miscellany

Acacia seyal Del.

Mimosoiceae

Slender tree 6-11 m tall

Widespread in northern Africa

Hand scarify

Cowpea miscellany

Albizia adianthifolia (schum) W.F. Wight

Mimosoiceae

Tall tree with flattened crown

Widespread in tropical Africa

No pretreatment required

Cowpea miscellany

Albizia lebbeck (L.) Benth.

Mimosoiceae

Large, tall tree

Native to India but common to all tropics

Hot water. Hand scarify

Cowpea miscellany

Cajanus cajan (L.) Millsp.

Papilionoiceae

Annual or short term perennial shrub

Native to India and Africa

No pretreatment required

Nodulates freely

Gliricidia sepium (Jacq.) Steud.

Papilionoiceae

Shrub or small tree

Native to tropical America now widespread in most tropical agroforestry systems

No pretreatment required

Nodulates freely

Leucaena leucocephala (Lam.) de Wit

Mimosoiceae

Tree but often slender shrub

Native to Mexico, now pantropical in moist regions at low altitude

Hot water. Hand scarify

Fast-growing rhizobia

Sesbania sesban (L.) Merr.

Papilionoiceae

Shrubs, annual or perennial

Widespread in warmer latitudes of both hemispheres

Hot water. Hand scarify

Reciprocal affinity between cowpea and soybean rhizobia

4.5.3 Management of Fodder Trees in Alley Farming

The parameters of MPT management in alley farming were covered in Unit 3. The management of fodder trees requires special attention to the control of three of those parameters:

· spacing of tree hedgerows,
· frequency of cutting trees, and
· height at which trees are cut.

In manipulating these parameters to advantage, we must consider their effects on quantity and quality of forage produced and on the long-term sustainability of the system.

Spacing of Tree Hedgerows

ILCA recommends a spacing within rows for Leucaena and Gliricidia of 25-35 cm in areas of high rainfall (more than 1000 mm) and 50 cm for areas with rainfall less than 1000 mm. The spacing between rows depends on the type of system preferred: whether alley farming with food crops (4-8 m), intensive feed gardens (2-4 m), alley grazing - rotational system, (3-4 m), alley grazing - permanent system (7 m or more), or fodder tree banks (1.0 - 1.5).

The optimum spacing to be used depends on the purpose for which the tree is grown and the form in which it is to be harvested. When growing trees for forage, the primary objective is a high yield of good quality fodder. The aim in such situation is a high leaf: shoot ratio which requires a high plant density. Generally, the higher the planting density, the greater the productivity per hectare (Table 4-7). However, there is a tendency for individual plants to survive better at low densities, and for lower individual plant yields at high densities.

Frequency and Height of Hedgerow Pruning

In alley farming with livestock, periodic pruning of the tree hedgerows is required for the following purposes:

· to provide fodder for animals in a cut-and-carry system,
· to keep the greater proportion of leaves and branches accessible to animals in an alley grazing or fodder tree bank system,
· to provide mulch for food crops, and
· to prevent shading of the grass or food crop planted in the alleys.

The last two purposes are also present in alley farming without livestock. They are covered in Unit 3.

ILCA recommends that Leucaena and Gliricidia in tropical Africa should be pruned to a height of at least 50 cm above ground about every 10 to 12 weeks for optimum forage productivity. It appears that the regrowth can be grazed when it attains a branch length of 1.0 m, although this requires further confirmation through research.

Table 4-7 Effect of plant density and pruning frequency on edible dry matter yield of Leucaena. (Source: ILCA, 1987.)

Plant density (number/ha)

Number of prunings per year

Mean

8

6

5

4

(Dry Matter t/ha/year)

80,000

16.9

22.6

29.2

38.2

26.7

40,000

11.9

15.1

20.9

28.2

19.0

26,666

9.1

11.7

15.8

20.7

14.3

20,000

6.7

10.8

12.4

20.3

12.5

The pruning frequency should be short enough to maintain a good leaf-to-stem ratio, but long enough to allow the plants time to recover. Since cutting removes the photosynthetic portions of the trees, time is required for replenishment of the reserves used in new tissue formation. As longer cutting intervals are adopted, greater dry matter yields are realized but the quality of forage (as % protein) declines, as shown in Table 4-8.

The height of cut also influences forage production of trees. As the pruning height is increased, tree foliage dry matter increases as well. But there is an optimum height beyond which foliage dry matter yield will not increase (Table 4-9). The increased foliage production with increasing height of cut is due to the fact that the quantity of fodder produced is influenced by the number of buds that develop into new shoots on the stumps. In general, the taller the stump, the greater the numbers of buds. Thus, in a study in Mexico that used a Hawaiian-type Leucaena cultivar, plants that were cut at 30 cm formed an average of 89 buds while those cut at 50 cm produced 112 buds (Perez and Melendez, 1980).

4.5.4 Animal Nutrition

Amount of Feed Produced on Alley Farms

From an alley farming plot with food crops grown between Leucaena and/or Gliricidia hedgerows, farmers can expect 3 tonnes or more of edible dry matter (DM/ha/yr). The crude protein content will be 20%. An 0.2 ha farm thus will produce 1.6 kg DM/day. This can be used for mulch or for animal feed. Assuming that only 25% is taken for animal feed, the farmer will have 400 g DM/day for his or her animals. Not surprisingly, researcher-managed, on-station plots generally produce higher yields of fodder.

From an intensive feed garden with grass grown between legume tree hedgerows, a farmer can expect 10 tonnes DM/ha/yr. Thus an 0.02 ha/yr plot produces 200 kg annually, or 550 g DM/day. Since intensive feed gardens do not have a food crop component, all the tree foliage will be available for animal feed.

Table 4-8. Effect of pruning frequency on yield and quality of Leucaena. (After ILCA, 1987).

Number of prunings per year

Dry matter yield (t DM/ha/yr)

Protein content (%)

Protein yield (t/ha/yr)

8

11.18

30.28

3.38

6

15.08

29.60

4.46

5

19.61

26.36

5.16

4

26.88

25.75

6.92

Table 4-9. Effect of pruning height on Leucaena dry matter yield (t/ha) during 6-month period. (Source: Duguma et al, 1988.)


Pruning height (cm)

Season

25

50

75

100

150

Wet

3.72

4.32

5.10

5.91

7.74

Dry

2.70

3.42

3.90

4.02

3.90

Animals will eat, in total, the equivalent of 4% of their body weight daily, so a 15-kg goat would consume a total of 600 g DM/day. The amount of fodder available from an alley farm will only provide a supplement to what the animal normally receives.

Feeding Practices

Forage from the legume trees is intended as a supplement to existing food supplies. Leucaena can constitute up to 40% of small ruminant diets without toxicity problems. Gliricidia can be offered up to 100% of total feed intake, but where possible should be offered in equal quantities with Leucaena. In practice, farmers using both Leucaena and Gliricidia from alley farms and intensive feed gardens as feed supplements are unlikely to experience any toxicity problems, because of the limited amount of Leucaena that will be on hand and the availability of other feeds.

Figure 4-6. Feeding hedgerow prunings to confined cattle.

In many countries, consumer demand, and hence market price, of rams and bucks is particularly high for certain festivals, such as the Muslim festival of Id el Kabir. It may be an appropriate use of available browse to offer it selectively to animals that will be marketed for this or other festivals.

One simple way to offer the feed and avoid waste is to hang up equal amounts of Leucaena and Gliricidia in a bundle (Figure 4-7). Bundles of grass can also be offered. Alternatively, a hayrack can be used.

Figure 4-7. Goats browsing Leucaena and Gliricidia branches which have been hung in a bundle.

4.6 Research needs for alley farming with livestock

Alley farming was originally designed for food crop production systems with no livestock component. Its adaptation to suit integrate a livestock production component has been highly successful. Nevertheless, further research is needed to make the intervention truly a "two-edged sword" as intended. Some researchable issues are as follows:

1. So far, most studies on alley farming have been carried out using the tree legume species Leucaena and Gliricidia. Research should be conducted to involve other promising woody species.

2. In alley farming with both food crops and livestock, the proportions of prunings used as mulch and fodder must be carefully balanced. More research is needed to determine which prunings, and what proportion of prunings obtained during the growing season of a crop can be taken away without telling drastically on crop yields or harming the long-term sustainability of the system.

3. In order to avoid undue mining of plant nutrients (P, K, Ca, Mg, and some micronutrients), research should be conducted to determine schemes for restoring nutrients lost in harvested forage, especially in the intensive feed garden system - for example, by recycling animal manure into the system.

4. Research on fallows in alley farming should be undertaken to determine optimum pruning regime(s) that produce the greatest forage and permit better preservation of the foliage for use at the height of the dry season. Low-cost methods of drying the foliage for preservation should be developed.

5. For systems in which trees or shrubs are to be established in undisturbed, native, or improved pasture, research is needed on the best land preparation method.

6. For intensive feed gardens in which tree or shrubs are planted at about the same time as tall, erect, bunch-type grasses, more research is needed to determine the best schedule for tree pruning, grass harvesting, and/or grazing.

7. In tropical Africa, most of the work on cultivated leguminous browse has been aimed at small ruminants. For areas such as the derived savannah zone of West Africa, in which cattle populations are increasing and high quality forage is becoming scarce, more work is needed on adapting the system for cattle.

4.7 Feedback exercises

All answers can be found in the text and figures of Unit 4.

1. The following statements concern livestock nutrition in tropical Africa and the potential contributions of leguminous trees. Circle T for true statements or F for false ones:

i) In most mixed crop/livestock systems of sub-Saharan Africa, livestock nutrition is the overriding concern of farmers.

T

F

ii) In southwestern Nigeria, as in the highlands of Kenya, farmers cut fodder and carry it to confined animals.

T

F

iii) Leguminous multipurpose tree are a source of high-quality, nitrogen-rich supplemental feed for livestock.

T

F

iv) Feeding goats and sheep with Leucaena and Gliricidia has been shown to decrease overall food intake.

T

F

v) Problems of livestock nutrition in the dry season include the low digestibility and low protein content of grasses.

T

F

vi) A low-protein diet has no effect on the populations of microbes in the gastro-intestinal tract of cattle, sheep, and goats.

T

F

2. In alley farming with livestock, hedgerow prunings can be used as mulch for food crops as well and as fodder for livestock. Explain the importance of balancing these two uses, and suggest how this can be achieved.

3. List eight characteristics of the ideal MPT species for use in alley farming with livestock.

1. ________________________
2. ________________________
3. ________________________
4. ________________________
5. ________________________
6. ________________________
7. ________________________
8. ________________________

4. This unit covered four different variations on alley farming in which pasture crops (grasses) are grown alongside hedgerows of multipurpose trees or shrubs. The table below has been scrambled. Draw lines to connect the name of each system (column A) with its correct text description (B) and the recommended spacing between hedgerows (C).

(A) Name

(B) Description

(C) Spacing

Intensive Feed Garden

Shrubby hedgerows in permanent pastures

1.0 - 1.5 m

Alley Grazing-Rotational System

Grazing alternates with rest periods.

7 m or more

Alley Grazing-Permanent System

Cut-and-carry system.

3 - 4 m

Fodder Tree Banks

Block of trees on 10-30% of pasture area

2 - 4 m

5. Provide brief answers to the following questions:

i) Describe a technique for planting hedgerows in pre-established pastureland.

ii) Young trees should be protected from competition with grasses. Name as many different techniques as you can for accomplishing this.

iii) Explain why an intensive feed garden requires fertilization for sustained production.

6. a.) List four reasons for pruning tree hedgerows in alley farming with livestock.

1. ________________________
2. ________________________
3. ________________________
4. ________________________

b.) Fill in the blanks: ILCA has developed recommendations for management of Leucaena and Gliricidia. The recommended pruning height is ____________ cm, while the recommended pruning frequency is once every ____________ weeks.

7. Circle the correct answer to the following questions:

i) If 25 % of hedgerow prunings are used for animal feed, a typical 0.2 hectare alley farm will produce how much dry matter of feed per day?

a. 100 kg DM
b. 5 kg DM
c. 400 g DM
d. 50 g DM

ii) Each day a goat will consume the equivalent of what percentage of its body weight?

a. 1%
b. 4%
c. 33%
d. 75%

iii) Leucaena can be toxic to small ruminants if it constitutes too large a portion of their diet. What portion?

a. more than 40%
b. more than 75%
c. more then 5%
d. less than 20%

8. Section 4.6 contains a list of seven issues warranting further research. Which two issues would be of most interest in your organization or home area, and why?

Issue: ________________________________________________
Why important in my area: ________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________

Issue: ________________________________________________
Why important in my area: ________________________________
_____________________________________________________
_____________________________________________________
_____________________________________________________

4.8 Suggested reading

Cochan, W.G., T.H. Stobbs, and D.J. Minson. 1979. The influence of the legume Leucaena leucocephala and formal-casein on the production and composition of milk from grazing cows. Journal of Agricultural Science, Cambridge. 92: 351-357.

Francis, P.A., and A.N. Atta-Krah. 1989. Sociological and ecological factors in technology adoption: fodder trees in southeast Nigeria. Experimental Agriculture, 25:, 1-10.

Nordblom, T.L., A. Ahmed, K.H. El, and G.R. Potts. (eds). 1985. Research Methodology for Livestock On-farm Trials. Ottawa, Canada: IDRC,

Reynolds, L., A.N. Atta-Krah, and P.A. Francis. 1988. Alley farming with livestock - Guidelines. Ibadan, Nigeria: ILCA, (Largely superceded by this Training Manual).

Smith, O.B., and H.G. Bosman. (eds). 1988. Goat Production in the Humid Tropics. Wageningen, The Netherlands: PUDOC.

Van Eys, J.E., I.W. Mathius, P. Pongsapan, and W.L. Johnson. 1986. Foliage of the legumes Gliricidia, Leucaena and Sesbania as supplement to Napier grass diets for growing goats. Journal of Agricultural Science, Cambridge. 107: 277-233.

4.9 References

Blunt, C.G., and R.J. Jones. 1977. Steer liveweight gains in relation to the proportion of time on Leucaena leucocephala pastures. Tropical Grasslands 11: 159-164.

Brewbaker, J.L. 1987. Leucaena: a multipurpose tree genus for tropical agroforestry. In: H.A. Steppler and P.K.R. Nair (eds). Agroforestry a decade of development. Nairobi, Kenya: ICRAF.

Duguma, B., B.T. Kang, and D.U.U. Okali. 1988. Effect of pruning intensities on three woody leguminous species grown in alley cropping with maize and cowpea on an alfisol. Agroforestry Systems 6: 19-35.

ILCA (International Livestock Centre for Africa) 1987. ILCA Annual Report 1986. Addis Ababa, Ethiopia.

ILCA (International Livestock Centre for Africa) 1988. ILCA Annual Report 1987. Addis Ababa, Ethiopia.

Jones, R.J., and R.M. Jones, (1982). Observations on the persistence and potential for beef production of pastures based on Trifolium semipilosum and Leucaena leucocephala in sub-tropical coastal Queensland. Tropical Grasslands 16: 2429.

Perez, J., and F. Melendez. 1980. The effect of height and frequency of defoliation on formation of buds of Leucaena leucocephala in the state of Tobasco, Mexico. Tropical Animal Production 5: 280 (Abstract).


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