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Management of calf pneumoniathe environmental component
Jamie Robertson
Introduction
• money and risks
ESSENTIAL FACTORS
• moisture management
• fresh air
• air speed
0
200
400
600
800
1000
1200
Growth rate (g/d) dairy calves @54 days age; single group
gr rate
• Provide adequate drainage
• Maintain dry bedding
• Minimise water loss from drinker system
• Check/stop roof leaks
• Maintain gutters and downpipes
• Ensure external ground/plant features do
not direct water towards building
Moisture management
SORT IT!140’ x 40’ (43m x 30m)
1,290m2 roof
Rainfall 42” (1067mm)
1,376m3 water on roof pa.
If 25% hits this downpipe..
= 344 tonnes per year
If 50% hits this downpipe
= 688 tonnes per year
100 cows
One building 20m x 30m
Roof area = 600m2
60 inches rain per annum
1.5m rain/yr = 900m3 on roof
900 tonnes/yr into slurry?
Slurry tanker 5,000 litres
180 loads @ 3 loads per hr.
60 hours for one building......
60 hours labour @ £7/hr = £420
Depreciation @ 10%pa = £80
Fuel @ 60p/l = £240
Alternative costs? TOTAL= £740/yr
WHICH IS MORE COLD?
Moisture content of air at saturation
0.00
5.00
10.00
15.00
20.00
25.00
30.00
-15 -10 -5 0 5 10 15 20 25 30 35
Temperature (oC)
Mo
istu
re c
on
ten
t (g
/kg
)
Viability decay curves for E.Coli induced by Open Air Factor.From Cox C 1987
OPEN AIR FACTOR (OAF)
Aerosol survival of Serratia marcesens 8UK into different Nitrogen: Oxygen mixtures. From Cox C 1987
Oxygen –induced damage to cell wall synthesis or cell division
Air quality factors
+ mould spores (Thermophilic actinomycetes)
Effect of air speed, calf weight and feed level on
lower critical temperature (Webster 1981)
Type of calf Lower critical temperature oC at air speeds of:
0.2 m/s 2.0 m/s
New born (35kg) + 9 +17
One month old (50kg) 0 +9
Veal calf (100kg) -14 -1
+ Excellent individual calf biosecurity
+ Good air quality
- High labour requirement
The stack effect ~ the laws of physics
Total heat production/animal (W)
0
200
400
600
800
1000
1200
0 100 200 300 400 500 600 700 800
Body mass (kg)
Hea
t p
rod
uc
tio
n (
W)
Calves Heifers Lactating cows
Ventilation: the answer....?
•Air changes per hour......
•BS5502 part 40: 1990. Code of practice for design and construction of cattle buildings. m3/h.kg
•Housing the 21st Century Cow. DairyCo. 2006
•Improve beef housing returns. EBLEX. 2008
Practical methodology for calculation of inlets & outlet areas for cattle buildingsBruce J M (1975)
• Lack of high level outlet
• inadequate inlet areas
• inlets to shared airspace with older animals
• low heat production from calves at low stocking
• high moisture levels
• poor design or location of mechanical ventilation
Common problems
50% of naturally ventilated buildings had insufficient openings for the number of animals housed….
(MacCormack, Clark and Knowles, 1984)
33% of buildings outwith design limits……, and a further 13% unable to provide adequate ventilation distribution
(Robertson, 1994)
And now.....? Too many new builds with inadequate ventilation
Arntjen ridge or similar ~ especially suitable where purlins are widely spaced
Open ridge 0.8m2 per bay
10 cows @ 650kg
Cowls 0.272m2 per bay
< 3 cows @ 650
Air inlets
In the absence of wind, they work on pressure differences created by warm air leaving the building.
If inlets become blocked by vegetation, or dirt, or have materials stored against them, they will throttle the building.
This can throttle your profits.
INLETS & OUTLETS:
KEEP THEM CLEAN
6 inch GAP BELOW EAVES
As good as 36 inch height of space board
lms©
500mm
Inlet needed = 1.46m2 x 2
Previous inlet to rear = 0
Current inlet = 0.2m2
Fine gutter……!
Pity about the
inlets….
Less than 4% void
(hole)
Mechanical ventilation
WARNING!!•DO NOT CONFUSE EXCESS INLET AS ADEQUATE VENTILATION.
•CONTROL OF WINDSPEED IS A BASIC DESIGN REQUIREMENT FOR CATTLE BUILDINGS
•WIND CHILL IS A MAJOR STRESSOR
PLUS: ZERO ΔT = ZERO STACK EFFECTPLUS: ZERO ΔT = ZERO STACK EFFECT
3 factors to remember : MOISTURE, FRESH AIR, & AIR SPEED
THANK YOU
