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Calf health and pneumonia: A breath of fresh air

Jodi Wallace for Progressive Dairy Published on 27 February 2020
Clean air is essential for calf health. Installing a positive-pressure tube ventilation system is one easy way to improve indoor calf facilities.

Calf pneumonia is the second major cause of treatment and loss in pre-weaned dairy calves. Pneumonia is a preventable disease. Although, we can treat pneumonia in calves.

Research has shown calves treated for pneumonia have long-term negative impacts, such as reduced average daily gain (ADG), decreased likelihood of entering the milking herd, increased probability of calving over 25 months old and more difficulty at calving. Therefore, we should focus on pneumonia prevention, not treatment.



What causes pneumonia in dairy calves?

It’s not just bacteria or a virus; it’s management. It’s the way we handle our calves. Calves are born with limited immunity. They must absorb antibodies from colostrum. These antibodies help protect them until their immune system is fully functioning. A strong immune system starts with healthy transition cows and the production of colostrum. As soon as possible after birth, the calf needs 3 to 4 litres of clean, high-quality colostrum. Colostrum and achieving passive transfer are the most important management factors affecting calf health.

What are the baseline objectives for calf health from zero to 60 days old?

Good record-keeping will allow you to benchmark your herd:

  • Mortality rates less than 5% (ideally zero)
  • Treatment rates less than 15%
  • Accelerated growth (double birthweight in 56 days)

What are the clinical signs of pneumonia?

Initially, calves may show subtle signs of sickness then, if not identified and treated, escalate into pneumonia. These signs include: slowness to rise at drinking time; slow, reduced or zero milk intake during feeding; longer standing after drinking; visible discharge in eyes and nose; droopy ears; coughing; head tilt or shake; and elevated temperature and respiratory rate. It is important to work with your veterinarian to identify clinical signs rapidly and establish treatment protocols.

Having an open front and back in calf pens allows for improved air quality between pens that are separated by solid panels.

Housing factors

The calf’s environment is also connected to calf respiratory health. Research from the University of Wisconsin found three major factors associated with reduced respiratory disease:


1. Low total airborne bacteria in the calf’s environment

Calves need fresh, clean air. Measuring the total airborne bacteria is not something we do every day on the farm, as it requires specialized equipment. However, you can use your nose. Notice the first smell when entering the calf’s environment. Do this at the calf level. Breathe through your nose. Are your eyes burning? Is there too much ammonia and noxious gases, which can also be checked using ammonia test strips? Is there dust or signs of mold, condensation or moisture? Identify these obvious problems. Also note calf behaviour. Are there changes in individual or group behaviour? Drafts directly hitting calves?

Airborne bacteria can be reduced by increasing the area of the calf pen, increasing the cleaning frequency and adding supplemental ventilation without creating a draft.

Positive-pressure tube ventilation is an easy way to improve any indoor calf facilities. Fresh air from the outside diffuses through small holes in the tube and dissipates at the calf level without creating a draft. Calves will not feel a draft if the air speed is less than 60 feet per minute. In the winter months, a minimum of four air exchanges per hour is required. During warmer weather, this requirement increases to 20 to 40 exchanges per hour. Air speed should also increase to 150 to 300 feet per minute to combat heat stress.

2. Solid panels between calves

Having a solid panel in between calves will also improve respiratory health. This limits the spread of respiratory pathogens to adjacent calves. Also, having open front and backs of the pens allows for improved air quality.


3. The ability to nest in their bedding in cold temperatures

Nesting scores of 3 reduce pneumonia rates. (The calf’s legs are not visible when lying down.) Calves should be able to “nest” in the bedding, which helps reduce heat loss. Calves are vulnerable to cold stress. Their thermoneutral zone is 10ºC to 26ºC. In cold weather, they will use extra energy to stay warm. Calves lose heat by conduction. That means heat is transferred down through the bedding. Cold concrete, gravel and sand increase conduction losses. These make a good base, but bedding needs to be added on top. The best bedding for calves outside in hutches in cold weather is wood shavings covered with straw. A focus needs to be made on keeping calves clean and dry. Calves will spend 80% of the day lying down.

If you are not sure if the calves have enough dry bedding, kneel on the bedding for 20 seconds – if your knees are damp or wet, it’s time to change or add bedding. When the bedding is wet, the calf’s energy needs for maintenance increase. Make sure calves get enough calories and energy for growth. When calves lack energy, they will lose weight and have a weakened immune system. This will make them more susceptible to pneumonia and diarrhea. It is important a calf’s hair coat is clean and dry. This allows the calf a natural insulation from the cold and limits heat loss through evaporation. Calf coats can also be used when the temperature drops.

An easy way to objectively evaluate the ventilation of indoor facilities is by performing a smoke test. Smoke is created by using mineral oil with an insect fogger and smoking the intake fans. The introduced smoke allows you to see air movement in the barn, evaluate dead spaces and air exchanges. A wind meter is also necessary to evaluate air speed at the calf level.

Calf vaccinations play a key role in preventing pneumonia. Vaccines help to stimulate the immune system, prepare the immune system against infection and disease, decrease severity of disease, decrease the pathogen load in the environment and improve response to treatment. Vaccination programs need to be farm-specific. Discuss the use of intranasal and modified-live vaccines with your veterinarian.

Evaluate indoor ventilation by conducting a smoke test.

Finally, don’t forget the basics of biosecurity: Protect your herd from the introduction of new diseases. Ideally, calves should have a separate air space from the adult dairy herd to limit transmission of airborne pathogens. Handle calves first, when your boots and clothing are clean. Restrict access of the calf facilities and limit entry to visitors with proper biosecurity measures taken (covered or clean boots and clothing).

Smoke allows you to see the air movement in the barn, evaluate dead spaces and air exchanges.

Your calf management procedures are imperative to reducing calf pneumonia. Discuss this article with your veterinarian and your dairy advisers to identify opportunities for improvements. Strive for optimal calf health.  end mark

PHOTO 1: Clean air is essential for calf health. Installing a positive-pressure tube ventilation system is one easy way to improve indoor calf facilities. 

PHOTO 2: Having an open front and back in calf pens allows for improved air quality between pens that are separated by solid panels. 

PHOTO 3 & 4: Evaluate indoor ventilation by conducting a smoke test. Smoke allows you to see the air movement in the barn, evaluate dead spaces and air exchanges. Courtesy photos.

Jodi Wallace
  • Jodi Wallace

  • Veterinarian
  • Ormstown Veterinary Hospital
  • Email Jodi Wallace