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Reducing the effects of weather stress in calves

Changes in weather conditions can have an effect on calf health and performance, it is common to see a rise in pneumonia and rotavirus cases after a sudden change in weather conditions.

In the first month of 2024, we have experienced multiple storms, cold snaps, and extreme temperature fluctuations. Temperature fluctuations have been shown to increase pneumonia cases among calves. Research has shown that Mannheimia haemolytica (Pasteurella) a pneumonia-causing bacterial population was found to be seven times greater in a calf’s nose in cold weather. SDSU (2020).

A study which evaluating the effects of abrupt air temperature changes in calf housing showed that an abrupt change in air temperature from 5 degrees to 13 degrees resulted in the calves having the same increase in nasal bacteria despite the increase in air temperature. Jones (1987).

However, the presence of bacteria doesn’t always result in pneumonia. Cilia are tiny hair-like projections that line the surface of the respiratory tract. Beating rapidly they provide an escalator for mucus to be moved from the lower respiratory tract to the back of the throat. In colder weather, the cilia beat less and the movement of bacteria out of the respiratory tract slows down. In other countries when there are prolonged periods of cold weather, the calf’s clearance mechanism improves however, in climates where there are continual temperature fluctuations the calves remain continually challenged as they have little chance of adapting.

Rotavirus is more likely to become a problem amongst calves who have been under stress for example; a change in weather conditions – winds and draughts. Generally, calves penned in larger groups can lie together and out of a draught. The problem lies with smaller pens, in this situation, it is advised to use extra bedding to enable to calves to nest.

How to reduce the problem before it occurs;

  • Lower your stocking density to reduce stress and pathogens. 90% of pathogens come from other calves. CAFRE (2020)
  • Use barriers between groups of calves to reduce pathogens traveling between pens
  • Be mindful of good ventilation in the calf shed, without encouraging draughts
  • Make sure that the pens have adequate drainage to reduce ammonia build-up
  • Provide extra shelter (if required) in the pens for example; straw bales, additional temporary low roof
  • Ensure the calf has received 10% of its body weight in good quality colostrum within the first four hours of life and transition milk or Transformula is given for at least the first ten days following colostrum as part of your calf rearing feeding regime
  • Discuss routine vaccination with your vet

Practical advice for reducing pneumonia and rotavirus amidst variable weather conditions;

  • Avoid tasks that can increase the stress levels in calves; mixing or transporting pens, changes to the nutrition, weaning or disbudding
  • Ensure the calf’s environment is kept as dry as possible, add additional bedding if required
  • Remember to always seek vet advice if an outbreak occurs
  • Give oral electrolytes if an outbreak of scour occurs along with vet advice

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