Dr. agr. Joaquín Castro-Montoya

Animal Nutrition and Rangeland Management

in the Tropics and Subtropics

Finding a consensus on the effects of tropicallegume silages on intake, digestibility andperformance in ruminants:

A meta-analysis

XVIII International Silage Conference

26th July, 2018

2

Feeding ruminants with

forage legumes

The temperate experience

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Medicago sativa

Trifolium pratense

Compared with grasses:

• Higher crude protein content

• Lower fiber content

• Higher digestibility

• High voluntary intake

3

Feeding ruminants with

forage legumes

Lablab purpureus Stylosanthes guianensis

Compared with grasses and whole

crop cereals:

• Higher crude protein content

• Lower fiber content

• Higher digestibility

• High voluntary intake

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

The tropical experience

4

The classical legume feeding experiment

Is it the legume... Or the protein?

Feeding ruminants with

forage legumes

The tropical experience

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

5

Finding a consensus

Literature search

• Legumes fed as silage

• In vivo studies with ruminants

• In tropical/subtropical regions

• Proportion of legume in the diet, anddiet composition

• Measure of dispersion and/ornumber of observations

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RE

Conditions

6

Database summary

Overview

29 trials with small ruminants

33 trials with cattle

51 publications

• 62 trials

• 218 treatments

• (56 controls, 162 legumes)

0

5

10

15

20

25

30

10-20 30-40 50-60 70-80 90-100Axis Title

20 30 40 50 60 70 80 90 100

Legume proportion in the diet (g/100 g DM)

%

INTRODUCTION │ METHODOLOGY │

Studies and treatments

Distribution of treatments by level of legume inclusion

7

Database summary

Legume species

119

4 43

4

4

8

5

4

0

2

4

6

8

10

12

14

16

Stylosanthes Soybean Lablab Leucaena Gliricidia

Nu

mb

er

of tr

ials

Legume species

■ Cattle

■ Small ruminants

• 23 species found

• Herbs, shrubs and trees

INTRODUCTION │ METHODOLOGY │

Most common species

29 trials with small ruminants

33 trials with cattle

8

Effects of the proportion of

legume in the diet

• Regression of diets

containing legumes

Comparison of diets without

legumes and with legumes

at varying levels:

• Control

• 100 to 400 g/kg DM

• 401 to 800 g/kg DM

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Two statistical approaches

Finding a consensus

Data analyses

Results

10

70

80

90

100

110

120

Bajo Alto

Legume proportion in the diet

(g/kg BW0.75)

≈

Low High

High crude protein

Low crude protein

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Tropical legume silage feedingEffects on intake

Dry matter intake per kg metabolic bodyweight

11

70

80

90

100

110

120

Bajo Alto

Legume proportion in the diet

(g/kg BW0.75)

≈

Low High

High crude protein

Low crude protein

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Secondary plant

compounds

Silage fermentation

products

Digestibility

Fiber content and

characteristics

Tropical legume silage feedingEffects on intake

Dry matter intake per kg metabolic bodyweight

12

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Fiber content and

characteristics

Passage rate,

buoyance

0

150

300

450

600

750

0 100-400 >400

Legume proportion in the diet (g/kg DM)

(g/kg)

aab

b

Tropical legume silage feedingEffects on apparent total tract digestibility

Organic matter

13

0

150

300

450

600

750

0 100-400 >400

Legume proportion in the diet (g/kg DM)

(g /kg)

ab

c

Fiber bound nitrogen

Excesive heating during storage in silo

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Tropical legume silage feedingEffects on apparent total tract digestibility

Crude protein

Secondary plant

compounds

14

g/d

Legume proportion in the diet (g/kg DM)

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Tropical legume silage feedingEffects on performance

Average daily gain

15

0

4

8

12

16

0 100-400 >400

Legume proportion in the diet (g/kg DM)

Milk yieldkg/d

0

0.3

0.6

0.9

1.2

1.5

0 100-400 >400

Legume proportion in the diet (g/kg DM)

FCE

kg milk/kg DMI

b

a

c

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

Tropical legume silage feedingEffects on performance

Milk yield and feed conversion efficiency (FCE)

16

Enhancement of

microbial protein

synthesis

Supply of dietary

nutrients

Urea recycling

Changes in

fermentation pattern

INTRODUCTION │ METHODOLOGY │ RESULTS INTAKE│ RESULTS DIGESTIBILITY │ RESULTS PERFORMANCE

ResultsTropical legume silage feeding

Rumen ammonia

-N

N-Energysnchroni-

zation

17

• Tropical legumes fed as silage

• Lower intake and digestibility

• Maintain or increase the performance

• Inclusion rates up to 400 g/kg DM

• Mechanisms of action are still to be understood

• Further research

• Focus on promising legumes

Final remarksThe consensus

18

Enterolobium cyclocarpum

The (other) classical legume feeding experiment

Final remarksThe consensus

Low biomass

Not mechanizable

19

• Tropical legumes fed as silage

• Lower intake and digestibility

• Maintain or increase the performance

• Inclusion rates up to 400 g/kg DM

• Mechanisms of action are still to be understood

• Further research

• Focus on promising legumes

• Quality, quantity, mechanization

• Lablab, stylosanthes, soybean, cannavalia

Final remarksThe consensus

Thank you very much!

Finding a consensus on the effects of tropicallegume silages on intake, digestibility andperformance in ruminants:

A meta-analysis

XVIII International Silage Conference

26th July, 2018

Contact: jcm@uni-hohenheim.de