Breath of Fresh Air-Raise Em Right 8-8-09

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Solving Calf Respiratory Problems with Improved Ventilation

Brian HolmesBrian HolmesExtension Agricultural Engineer

UW – MadisonBiological Systems Engineering

Defining Terms

Ventilation = Air Exchange = Bad Air Out & Good Air In

Air Circulation = Moving Air within Barn= Ventilation

Draft = ?

2

Natural ventilation uses the f f t t iforces of nature to cause air

exchange

Wind is the primary forcep y

Natural Ventilation Design(Cow Barns)

412

2 in. / 10 ft WidthRidge Opening

1 in. / 10 ft WidthEve Opening

Width

10 ft Minimum

3

Natural Ventilation - Winter

Wind Air Out

Air In

Wind

Air

Air Out

+ + + + +

+Out

+++

4

Eave Opening

6

Separation DistanceSeparation Distance

Wind Wind

100 ft. + 100 ft. +

C

Summer Wind

Corn FieldTreesHill

7

Summer Wind

Factors to OptimizeOptimize

Respiratory Health of Calves

in Naturally Ventilated Barns

in Winter

Ken Nordlund, DVMSchool of Veterinary Medicine

University of Wisconsin-Madison

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Naturally ventilated calf

barns What’s There:

Compliments of K. Nordlund, 2007

What’s There:Individual pensSolid or mesh sidesPen covers?Variable beddingRespiratory disease


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Field Trial to Examine Respiratory Risk Factors in Calf BarnsLago, McGuirk, Bennett, Cook, & Nordlund. 2006. J g , , , ,Dairy Sci 89: 4014 - 4025

Selection criteria for barns:• Natural ventilation• Single calf pens• Single calf pens• Minimum of 15 preweaned calves• Current health status “typical” for barn• Trial conducted Jan-Mar 2004

Data collected• Respiratory scores -15 or more nursing calves

• Airborne bacterial counts (Total cfu & coliform)Airborne bacterial counts (Total cfu & coliform) in pens and alleys

• Ammonia in pens

• Temperature & humidity – inside and outside

• Bedding depth and dry matterg y

• Building and inlet dimensions

• Animal counts

• Outdoor wind speed & direction, etc…..Compliments of K. Nordlund, 2007

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Calf Respiratory Scoring CriteriaScore: 0 1 2 3

Rectal Temp. (F) 100-100.9 >= 103

Cough None Repeated, Spontaneous

Nasal Discharge Normal Copious,Both Nostrils

Ocular Discharge None Heavy

Ear Droop None One Both orHead Tilt

Scoring system developed by Dr. Sheila McGuirkCumulative Score > = 5 = Respiratory Illness

Findings

There were lots of sick calvesThere were lots of sick calvesAvg prevalence (RS=5+) = 27%Under-diagnosed in industryEnzootic calf pneumoniap


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Percentage of calves scored 5+

50%

60%

20%

30%

40%

50%

% o

f nur

sing

cal

ves

0%

10%

1 2 3 4 5 6 7 8 9 10 11 12 13

Herd

Lago et.al., J Dairy Sci 89:4014, 2006

These appear to

be well ventilated

barns!

Why do we have

endemic calf

pneumonia? Maybe theMaybe the

barns are ventilated and the pens are

not? Differences in gases?

NH3? CO2? Bacteria?


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T i l lT i l lTypical valuesTypical values•• Outdoor air: 100 Outdoor air: 100 –– 1,000 cfu/m1,000 cfu/m33

•• Clean office air: 1,000 Clean office air: 1,000 -- 2,000 cfu/m2,000 cfu/m33

•• WellWell--ventilated barn: 10ventilated barn: 10--15,000 cfu/m15,000 cfu/m33


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Alley and Pen Bacterial Counts

11

4

7

9

8

7

12

2

1

5

Farm

ID Alley

Pen

Well Ventilated Calf Barns

020

,000

40,0

0060

,000

80,0

0010

0,00

012

0,00

014

0,00

016

0,00

018

0,00

020

0,00

022

0,00

024

0,00

026

0,00

028

0,00

030

0,00

032

0,00

0

3

9

Cfu / m3


These appear to

be well ventilated

barns!

•Median barn ventilation rate was 5.5 changes per hour (range 0-93) *

* assistance of Brian Holmes and David

Kammel

• Pen air NH3 avge 2 ppm (0-4)

•Alley cfu/m3 associated with barn ventilation rate P<.0001

P f / 3 NOT i t d ith


• Pen cfu/m3 were NOT associated with barn ventilation rate

• Pens are microenvironments within the barn

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Findings:Total airborne bacterial cfu/m3 in PEN associated with prevalence of respiratory disease P ≤ 0.003

Association is not causation…


Key factors for respiratory health

1) Solid panel between calves1) Solid panel between calves P<0.003

2) Nesting in deep bedding P<0.002

3) Low airborne bacteria counts3) Low airborne bacteria counts P<0.003


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Solid panel between calvescalves

40%

50%

60%

rato

ry d

isea

se Mesh Sides

Nesting Score = 2

10%

20%

30%

reva

lenc

e of

resp

i

Solid Sides

0%27 52 77 102 127 152 177 202 227 252 277 302 327

Airborne bacteria cfu/m3 x 1000

P

Mesh dividers, nesting score 2 Solid dividers, nesting score 2


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Thermoneutral zoneNewborn calf: 50-78˚FMonth old calf: 32-73˚F

Study conditions 19-54˚F


Nesting score = 1Legs entirely visible when lying down

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Nesting score = 3Nesting score = 3Legs generally Legs generally notnot visible when lying downvisible when lying down

40%

50%

60%

70%

irato

ry d

isea

se No Nesting

Mesh Sided Pens

10%

20%

30%

Prev

alen

ce o

f res

p

Deep Nesting

0%27 52 77 102 127 152 177 202 227 252 277 302 327

Airborne bacteria cfu/m3 x 1000

Nesting score 1, mesh sides Nesting score 2 Nesting score 3


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How do we lower airborne bacterial counts?


Factors for ↓ air bacteria in pens

1) Lower temperature P<0.0031) Lower temperature P<0.003

2) Larger pens P<0.02

> 30 square feet

3) Fewer solid sides = more ventilation3) Fewer solid sides = more ventilation P<0.006


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Ridge Opening? Over Pens

Rear Eave Not Open

Limited Front Wall Open

Rear Wall Not Open

Closed Rear Pen Wall

Restricted Front Openings

Clinical Investigation

Endemic calf pneumoniaEndemic calf pneumonia22--yr old barnyr old barn

Originally 4’ x 8’ pens, but panels Originally 4’ x 8’ pens, but panels removed to yield 8’ x 8’ pensremoved to yield 8’ x 8’ pens


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Positive PressureDucts Added



Location August 2004i ti ti

Feb. 2005 ft t binvestigation after tube

Pens, cfu/m3 177,453 42,807 Alleys, cfu/m3 26,459 16,716

After supplementation, respiratory disease treatments estimated to be 25%

of previous years

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Technical pointsFans mounted in wall, not inside barn,Sized at ~15 cfm / calfOne tube per ~25 ft of building widthCustom-punched holes so the air exits at ~ 800 fpmpHoles punched at 4 & 8 o’clock or 5 & 7 o’clock, depending on height of tube


Positive Pressure Duct

Barn End Wall

8Fan

Aim Holes at Center Calf Pens

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Fan IntakeFan Intake

Fan Unit

Perforations

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Duct

Trajectory ofAir Stream

700-800 ft/min

HeightHole Angle

Calf Pen

PenLength

Alley Width

Horizontal Distance

<50 ft/min

<100’

<30’8

Duct Arrangements – Narrow Barns

Perforated Duct

<200’

<30’8 8

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<100’

<60’

8

8W/4

W/2

Duct Arrangements –Wider Barns

Perforated Duct

<200’

W/4

8 8W/4

<60’

8 8

8 8

W/4

W/2

WI Ideal Calf PenRear Top Panel

Rear Lower Panel

Front

Not to Scale

Front Panel

Front Bedding Retainer

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CalfBlanket

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A summary….Preventing chilling by enclosing the pen is the wrong way to gog y gOpening all sides to improve ventilation is the wrong way to goPlace a solid panel between each calfControl chilling with DEEP straw and calf bl k t f N M hblankets from Nov-MarchReduce airborne bacteria with bigger pens, fewer sides, and…..Supplemental positive pressure ventilation


Breath of Fresh Air-Raise Em Right 8-8-09

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