Animal Genetic Improvement in Tropical Area

Animal Genetic Improvement in Tropical

Area

Dr. Wuttigrai BoonkumDr. Wuttigrai Boonkum

Department of Animal Science, Faculty of AgricultureKhon Kaen University

Why is heat stress important ?

The Tropics

HOT, HOTTER Temperatures have risen more in the Arctic than in the tropics.

Why is heat stress important ?

well-beingwell-being

low fertilitylow fertility

diedie

low feed intakelow feed intake

low milk yieldlow milk yield

Economic losses

Economic impacts of heat wave on dairy industry about $1 Billion 2003 economic loss $897 to $1500 million in US

2006 California heat wave kills 16,500 dairy cows statewide>2,000 cattle died in Nebraska during June 2009

2002 to 2007, Summer was the seasons with the highest of dairy deaths (15,773) in Italy

How heat stress occur ?

Cold stress

Heat stress

Thermoneutralzone

Heat

pro

du

ctio

nH

eat

pro

du

ctio

n

Ambient temperatureAmbient temperature

4-24 oC

Lower critical temp.Upper critical temp.

humidity

Heat stress effects

THI > 72 for production and around 68 for reproduction are considered to indicate heat

stress in dairy cattle

THI > 72 for production and around 68 for reproduction are considered to indicate heat

stress in dairy cattle

How heat stress occur ?

panting

sweating

respiration

feed intake

rumination

water intake

How to reduce the effects of heat stress ?

adjustment of housing and facilities

adjustment of housing and facilities

Feed and Feeding management

Feed and Feeding management

Crossbreeding systemCrossbreeding system

x

B.indicus B.taurus

Production traits

How to reduce the effects of heat stress ?

avoiding breeding during hot conditions

avoiding breeding during hot conditions estrus synchronizationestrus synchronization

timed artificial insemination

timed artificial insemination

Fertility traits

Alternative method

Housing and Shadingmanagement

Housing and Shadingmanagement

Feed and Feeding management

Feed and Feeding management

Crossbreeding systemCrossbreeding system

x

B.indicus B.taurus

Temporary/non sustainable

Production traits

avoiding breeding during hot seasonavoiding breeding during hot season estrus synchronizationestrus synchronization

timed artificial insemination

timed artificial insemination

Fertility traits

Temporary/non sustainable

Genetic selectionGenetic

selection

What traits are interest to study?

• Using regular monthly milk records• THI information at the collecting date

Ravagnolo and Misztal, (2000)

• Using days open records

Genetic selectionGenetic

selection

How heat stress affect on genetic ?

How heat stress affect on genetic ?

Heat stress in Thailand

Stress all time

Results: Determination of heat stress threshold

Publication

Results: LSM and HI for DO

summer

winter

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• Length of exposure to heat stress• Level of production• Stage of lactation• Cooling management• Feed consumption• Feed offered• Breed• cattle species• Size of the animal

National genetic evaluation under hot-humid climates of Thailand

Department of Animal Science, Faculty of Agriculture, Khon Kaen University

Implications :

Est

imate

d b

reed

ing

valu

e;

EB

V

THI

Threshold pointBest genetic

performance for milk production

under heat stress conditions

Ent1 Ent2

Gen

etic

effec

t Animal 1

Animal 2

Ent1 Ent2

Gen

etic

effec

tAnimal 1

Animal 2

No G x E interaction

Reranking G x E interaction

Ent1 Ent2

Gen

etic

effec

t

Animal 1

Animal 2

Scaling G x E interaction

Conclusions

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