Proportions of Calf Raising Cost. Calf Housing Costs (Birth to Weaning) Hutches. Calf Housing Hutches with protection for worker

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1 Calf Barn Ventilation a Breath of Fresh Air Brian Holmes Extension Agricultural Engineer UW Madison Biological Systems Engineering Proportions of Calf Raising Cost Veterinary & Medicine 5% =$16 Variable = 15% = $49 Feed =34% = $111 Fixed = 4% = $13 Labor & Mg. =47% = $153 (Total Cost = $326/calf) Calf Housing Costs (Birth to Weaning) Hutches Group Pens Home Built Calf Hutch Purchased Hutch Greenhouse Calf Barn Calf Barn Calf Barn $200 $200 $350 $325 $700 $1,300 $0 $200 $400 $600 $800 $1,000 $1,200 $1,400 Cost per calf ($) Winter Housing Calf Housing Hutches with protection for worker Summer Housing 1

2 Defining Terms Ventilation = Air Exchange = Bad Air Out & Good Air In Air Circulation = Moving Air within Barn = Ventilation Draft =? Natural ventilation uses the forces of nature to cause air exchange Wind is the primary force Natural Ventilation Design (Cow Barns) Ridge Opening 2 in. / 10 ft Width Wind Natural Ventilation - Winter Air Out Eve Opening 1 in. / 10 ft Width ft Minimum Air In Air Out Width 2

3 Eave Opening Locate Alleys Under Open Ridge Minimize Water In Stalls or Pens Natural Ventilation - Summer Air Out Wind Air Out Air In Rain and Sun Control 3

4 Separation Distance Wind 100 ft. + Summer Wind Corn Field Trees Hill Summer Wind Factors to Optimize Respiratory Health of Calves in Naturally Ventilated Barns in Winter Naturally ventilated calf barns Ken Nordlund, DVM School of Veterinary Medicine University of Wisconsin-Madison 4

5 Individual pens Field Trial to Examine Respiratory Risk Solid Factors or mesh in Calf sides Barns Pen covers? Lago, McGuirk, Bennett, Cook, & Nordlund J Variable Dairy Scibedding 89: Respiratory Selection criteria disease for barns: Natural ventilation 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) in pens and alleys Ammonia in pens Temperature & humidity inside and outside Bedding depth and dry matter Building and inlet dimensions Animal counts Outdoor wind speed & direction, etc.. Topics Prevalence Pen microenvironments Disease prevalence factors Positive pressure supplementation Calf Respiratory Scoring Criteria Score: Rectal Temp. (F) >= 103 Cough None Repeated, Spontaneous Nasal Discharge Normal Copious, Both Nostrils Ocular Discharge None Heavy Ear Droop None One Both or Head Tilt Cumulative Score > = 5 = Respiratory Illness Scoring system developed by Dr. Sheila McGuirk Findings There were lots of sick calves Avg prevalence (RS=5+) = 27% Under-diagnosed in industry Enzootic calf pneumonia % of nursing calves 60% 50% 40% 30% 20% 10% Percentage of calves scored 5+ 0% Herd 5

6 These appear to be well ventilated barns! Why do we have endemic calf pneumonia? Maybe the barns are ventilated and the pens are not? Differences in gases? NH3? CO2? Bacteria? Typical values Outdoor air: 100 1,000 cfu/m 3 Clean office air: 1,000-2,000 cfu/m 3 Well-ventilated barn: 10-15,000 15,000 cfu/m Alley and Pen Bacterial Counts 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 Farm ID Alley Pen Well Ventilated Calf Barns Pen air NH3 avge 2 ppm (0-4) Alley cfu/m 3 associated with barn ventilation rate P<.0001 Pencfu/m 3 were NOT associated with barn ventilation rate 0 20,000 40,000 60,000 80, , , , , ,000 Cfu / m3 200, , , , , , ,000 Pens are microenvironments within the barn 6

7 Key factors for respiratory health Findings: Total airborne bacterial cfu/m 3 in PEN associated with prevalence of respiratory disease P Association is not causation 1) Solid panel between calves 2) Nesting in deep bedding P< ) Low airborne bacteria counts Solid panel between calves Prevalence of respiratory disease 60% 50% 40% 30% 20% 10% 0% Mesh Sides Nesting Score = 2 Solid Sides Airborne bacteria cfu/m 3 x 1000 Mesh dividers, nesting score 2 Solid dividers, nesting score 2 Key factors for respiratory health 1) Solid panel between calves 2) Nesting in deep bedding P< ) Low airborne bacteria counts Thermoneutral zone Newborn calf: Month old calf: Study conditions F F F 7

8 ompliments of K. Nordlund, Nesting score = 1 Legs entirely visible when lying down Nesting score = 3 Legs generally not visible when lying down Prevalence of respiratory disease 70% 60% 50% 40% 30% 20% 10% 0% No Nesting Mesh Sided Pens Deep Nesting Airborne bacteria cfu/m 3 x 1000 Key factors for respiratory health 1) Solid panel between calves 2) Nesting in deep bedding P< ) Low pen airborne bacteria counts Total bacterial counts significant Coliforms (EMB) not significant Nesting score 1, mesh sides Nesting score 2 Nesting score 3 Factors for air bacteria in pens How do we lower airborne bacterial counts? 1) Lower temperature 2) Larger pens P<0.02 > 30 square feet 3) Fewer solid sides = more ventilation P<

9 Clinical Investigation Endemic calf pneumonia 2-yr old barn Originally 4 x 8 pens, but panels removed to yield 8 x 8 pens Location August 2004 investigation Feb 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 9

10 Technical points Fans mounted in wall, not inside barn Sized at ~15 cfm / calf One tube per ~25 ft of building width Custom-punched holes so the air exits at ~ 800 fpm Holes punched at 4 & 8 o clock or 5 & 7 o clock, depending on height of tube A summary. Preventing chilling by enclosing the pen is the wrong way to go Opening all sides to improve ventilation is the wrong way to go Place a solid panel between each calf Control chilling with DEEP straw and calf blankets from Nov-March Reduce airborne bacteria with bigger pens, fewer sides, and.. Supplemental positive pressure ventilation Positive Pressure Duct Barn End Wall Fan Intake Aim Holes at Center Calf Pens 8 Fan Duct Trajectory of Air Stream Fan Unit ft/min Perforations Hole Angle Height <50 ft/min Calf Pen Alley Width Horizontal Distance Pen Length 10

11 Duct Arrangements Narrow Barns <100 <60 8 <100 W/4 W/2 Duct Arrangements Wider Barns < W/4 Perforated Duct <200 < Perforated Duct < < W/4 W/2 W/4 Rear Top Panel WI Ideal Calf Pen Rear Lower Panel Side Panel Front Bedding Retainer Front Panel Not to Scale Calf Blanket 11