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IAD 202

Livestock Production & Development

Wolfgang Pittroff & GirmaGetachewLecture 5

Introduction into Tropical Pastures and Browse

ResourcesTropical grasses, tropical legumes, mixed systems, stability of sown pastures, integrating browse, secondary compounds and their effects on forage quality

Forage Tree Resources

• Great interest: soil improvement, erosion protection, replacement of native trees, reduction of destructive firewood collection, human food, animal feeds, pharmaceutical compounds, living fences, habitat for wildlife, reserve forages

Forage Tree Resources -Examples

• Leucaena (Leucaena leucocephala)• Mulberry (Morus spp.)• Moringa (Moringa oleifera)• Mimosa (Albizia julibrissin)

Leucaena (L. leucocephala)

Leucaena

• Origin: tropical Latin-America (Mexico)• Used primarily as animal feed, also shade tree• Contains an amino acid (mimosine) whose

metabolite is toxic. • Does not tolerate frost (problem tropical

highlands); • Does not tolerate well acidic soils (problem

tropics)

Leucaena

• Mimosine makes up about 2-5% of leaf dry matter, and up to 9% of the weight of seeds

• Goitrogenic• Ruminants can develop resistance by

acquiring rumen microbes that detoxify• Feed quality very good, readily eaten,

aggressive growth where compatible, repeated defoliation unproblematic

Mulberry (Morus alba, M. nigra)

Mulberry• Origin: China• Has been selected for centuries as nutrition for

the silkworm (Bombyx mori)• Widely distributed, lately increased interest as a

forage tree• High nutrient requirements, acceptable drought

tolerance• No negative secondary compounds, excellent

forage quality; good reserve forage

Moringa (M. oleifera)

• Origin: mainly E. Africa and W. Asia• True multi-purpose plant: human food, oil,

water purifier, soap, fire wood, animal feeds

• Recently strong interest, broad evaluation of genetic resources

• Used widely in India, Africa, Central America

Moringa (M. oleifera)

Moringa in silvopastoral system, Nicarargua

Mimosa (Albizia julibrissin)

• Recently ‘discovered’ forage tree• Origin: northern Iran, Turkmenistan towards

western China• Frost resistant, deeply rooted, tolerates higher

levels of soil acidity and salinity than mulberry• High value of the wood (hard wood, paper)• Rapid growth rates, very high biomass

production• Excellent forage values


• Forage yield up to ~ 10 tons/ha (similar to alfalfa)

• Very little input required• With some coppicing, animals can self-

feed• Excellent in associations with grasses

Forage Quality

Forage CP CF EE NFE

Leucaena

27.8 10.4 3.2 55.1

Mora 15 15.3 7.4 48

Moringa 29 19.1 5.2 37.6

Albizia 22 NDF: 34.2 ADF: 23.6DIG: > 70%

Tree Forages

• Species specific disadvantages:– Moringa, Mulberry: not legumes, not suited for

all soils; Leucaena: not frost resistant, toxin– Albizia: largely unknown agronomic

properties; reports on toxicity of seeds; unknown pests

– All: browse may require more labor than other forages resources

Tree Forages

• Recommendations must be site-specific• Nutrient requirements and constraints

must be known• Does the use of tree forages increase

labor requirements?• Is there education for forage budgeting to

go along with the introduction of new species?

Harvesting Systems

• Tree forage can be harvested many different ways:– Lopping and feeding of branches– Lopping and conservation– Browsing alone or in associations– Cut and carry systems– Collection of seeds– Direct ‘grazing’ of fallen leaves

Cut and carry system – hair she(Pelibuey) in Mexico

Cut and Carry System in Morocco

Goat on self-feeding program in Indian railway station

Tethered female buffalo (India)

Local sheep in Mexico peri-urban system – note Pelibuey

Secondary Compounds

• Substances produced by plants that may deter herbivory

• Hypothesized to be produced for that purpose but no definitive conclusions

• May be metabolic trashcan, free radical buffer, or serve to reduce damage such as radiation

Secondary Compounds

• Best known group: tannins– Hydrolyzable tannins (e.g. gallic acid, ellagic

acid); soluble, degradable by rumen microbes, toxic because metabolites (phenol rings) can overwhelm or damage e.g. liver detoxification

– Catechin tannins– Condensed tannins (proanthrocyanidins)

Tannins• Condensed tannins complex protein• CT-P complexes may become unsoluble, or

dissociate in the abomasum• Level of CT in plant material determines type of

effect: < 4% effects mostly beneficial• CT’s affect protein availability and digestibility• May reduce methane output• May increase (at lower levels) microbial protein

production efficiency (likely a defaunation effect)

Tannins• Negative effects of tannins can be reduced by

supplementation with polymers with a higher affinity for tannins than proteins (PEG, e.g.)

• Supplementation that combines nutrients with polymers most effective

• Some herbivore species (not domestic ruminants) developed saliva components that precipitate tannins before they can bind to feed proteins – increases amount of essential amino acids available to the animal

Tannins

• The presence of high levels of tannins renders conventional fiber analysis methods useless – an important factor in the assessment of nutritional quality of tropical forages that is mostly overlooked

Tropical Forage Evaluation

Girma Getachew, PhD, PAS

Forage Evaluation

hAgronomic

hNutritional

h Laboratory

h Animal

Forages :

Edible parts of plants, other than separated grain, that can provide feed for grazing animals or that can be harvested for feeding.

Forage and pasture Crops:

Generally used

1. As animal feed

2. Soil fertility improvement (N2 fixation, green manure)

3. Land reclamation (control of wind and water erosion)

4. Stabilizing eco-system

Forage based resources include

Pasturelands

Rangelands

Forest range

Cultivated forage crops

Types of Forage Crops (Taxonomically)

1. Legumes

Browse (multipurpose trees MPTs)

Herbaceous legumes

2. Grasses

Growth habit

1. Annuals

2. Perennials

Method of utilization

h Cut and carry

h Grazing

Improving forage production from pasture land

Over sowing higher yielding and nutritious species

Cultivating forage crops on arable land

Multiple uses of browses

h Feed for livestock (fodder banks)

hWindbreaks

h Fuel

h Live fences

h Soil fertility improvements

h Land reclamation

Advantage of browsesh Resistance to harsh environmental conditions

h Heat

h Drought

h Salinity

h Alkalinity

h Grazing

h Repeated cutting

hHigher nutritional quality (higher CP low fiber)

hRemain green longer into the dry season

Choice of establishing forages species

h Soil fertility and species adaptation

h Economic benefits

h Livestock production systems

Germplasm source

h Collection Missionh Taxonomy

h Accessions Passport

h Characterization and Evaluation

h Cooperators

h Material exchange for research purposes

Forage Research

Forage Evaluation

h Agronomic evaluation

h Nutritional evaluation

Agronomic Evaluation

h Acquisition- Genetic Resource Centers

h Germplasm collection mission

Screening (Evaluation)

1 m x 1 m plots

5 m strip trials

Parameters

Survival/ persistence

Insect /pest / disease

Drought

Yield- forage / seed

Yield trial for basic agronomic studiesh Larger plots

h Forage yield

h Sowing rate & fertilizer application, water requirement etc.

h Management (cutting frequencies)

h Yield and nutritional quality (chemical and biological assays)

Grazing trials

h Resistance to grazing and trampling

h Recovery after grazing

h Reseeding ability

Final acceptability of a given variety

Ease of establishment

Yield and seasonal distribution of DM

Forage quality

Chemical composition (nutritional & anti-nutritional components)

Intake

Digestibility

Animal response

Choice of species:

Method of utilization of forages depends on production systems

h Cut and carry- hay, silage

h Grazing

h Pure stand

h Mixture with other forages

h Mixture with food crops

Forage species adapted to tropical environments

Natural Pasture Improvement: Deterioration of natural pastures

h Decreasing productivity & nutritional quality as pasture ages

h Deterioration of botanical composition

h Decline in soil fertility

h Overstocking - over utilization of nutritious plant species

Improving natural pasturesExisting pastures

h Removal of weeds & unwanted species (manual, burning, herbicide etc.)

h Grazing management

h Over sowing with improved varieties

h Rotation grazing (stocking rate and carrying capacity of the pasture)

With improved species

hWithout land clearing

hWith partial clearing

h On a prepared seed bed

h Establishment on fully cultivated seedbed on new land

Genetic material available for research purposes at ILRI (International Livestock Research Institute)

1. Grasses 59 genus 185 species 2, 191 accessions

2. Legumes 54 genus 321 species 4, 375 accessions

2. Browses 108 genus 287 species 1, 248 accessions

221 793 7, 814 accessions

Animal evaluation of forages:

Intake- ways to measure

Digestibility- ways to measure

Animal response- ways to measure

What is forage quality??

Palatability- will the animals eat it

Intake- How much will they eat

Digestibility- How much of the forage digested

Nutrient content- will the forage provide adequate level of nutrients

Anti-quality factors- presence of compounds that either affect

feed quality or animal performance

Animal Performance- ultimate test of forage quality

How can we assess the quality of forages??

Chemical composition- the level of useful nutrient

Biological assay- Enzymatic, rumen bacteria

Animal response- intake, meat and milk production

Tropical Forages – General Considerations

• When choosing a tropical forage resource, a set of decision variables apply

• All objectives must be known and carefully evaluated

• The target group for the improvement must be consulted, and their needs, constraints and goals must be clearly understood


• Environmental considerations:– Climate:

• Precipitation: amount• Precipitation: distribution• Incidence of frost• Day length

– Soils:• Acidity• Mineral status (Al, P, K)• Organic matter content• Water holding capacity• Soil depth


• Environmental considerations:– Versatility in adaptation vs. specific high

performance: the highest yield varieties are often adapted only to a narrow range of environmental conditions – high risk


• Agronomic considerations:– Where to be established?

• After land clearings: timing of clearing; resilience in competition with native species; resistance to fire; responsiveness to inputs and opportunities

• In integrated systems:– As a pioneering crop: Improvement of soil

organic matter; reduce competitiveness of natives in subsequent crops; use of legumes in preparation for grass forage grass crops (suppression of native

i id )


• Agronomic considerations:– Integrated Systems:

• In crop rotations: break weed-, pest-, or disease manifestations; improve soil fertility; reduce competition by weeds; improve water holding capacity;


• Livestock production considerations:– Forage quality– Timing of availability (reserve forage,

complementary forage, supplement forage for better utilization of crop residues and rank native pastures)

– Sward characteristics (many tropical forages produce swards that are not dense enough for maximum intake (remember properties of the grass-roughage eater feeding type)


• Livestock production considerations:– Production goals must be clear: target

livestock (wool production vs. meat or milk; high stocking tolerance required; fencing possible or not (perennial cultivated pastures require fencing); integration with tree crops for either diversification (e.g., palm plantations) or better animal performance (forage trees)


• Production System/socio-economic considerations:– Constraints: is cut and carry possible

(labor); can fences be built and maintained (if not, use annual crops); how expensive are seeds or vegetation propagation; how stable is the improved pasture (many perennial legumes are shorter lived than often assumed); is the yield compatible with the production system management (no shortages, no excesses); is there the potential to harm crops if rotations are planned;


• Management considerations:– Integration with weed control; grazing

strategy: perennial pastures require careful balance of harvesting efficiency and root care (resilience requires well developed root system); if forage conservation is planned, are skills and available technology sufficient (many tropical grasses and legumes are difficult to hay or ensile)

Soil effects of improved pastures (tropical Australia)

Soil Property Virgin Soil After 15 yr pasture (grass/legume

mixture)pH 5.2 5.0Organic carbon (%) 0.84 1.56Nitrogen (%) 0.047 0.103Sulfur (ppm) 70 205Total Phosphorous (ppm)

18 160Total Potassium (ppm) 31 202Calcium (ppm) 30 320Bulk density 1.55 1

Note: bulk density effects might as well be negative! Also, thesepastures were grazed and fertilized – results not applicable everywhere

Effects of use of legumes on forage consumption (sheep, Australia)

Diet DM Intake (g/day, sheep)

CP (%)D.

decumbensM. sativa

D. decumbens(only, at lib)

607 0 3.6

D. decumbens(+ 100 g legume)

783 100 5.7


844 200 7.2


682 400 10.3

Legume only, ad lib

0 1530 22.5

Note: observe the clearly synergistic effect in the third treatmen

General Conclusions• Livestock production in tropical ecoregions is

characterized by low productivity• Pasture improvement and new crop-pasture

integration concepts hold the key to long term sustainable improvement

• Local conditions are sufficiently diverse to require local experimentation

• Explicit formulation of goals and constraints is essential for success

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