Protection from Extreme Weather: High Temperature and Humidity

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Source: National Farm Animal Care Council, Code of Practice for the Care and Handling of Beef Cattle Section 1.1.1

Beef cattle in Canada are housed in a variety of ways depending on age, size, and reproductive state. Systems may include range conditions, fields, corrals or yards, indoor pens or stalls. Treed areas or geographical features (such as coulees) can provide shelter from wind and sun (2).

Animals’ ability to cope with sudden changes in weather or adverse weather events varies with many factors, such as:

  • age (especially newborn calves)
  • body condition score
  • access to feed, water, and shelter
  • degree of acclimation (e.g. winter hair coat)
  • health status
  • stress (such as newly-arrived feedlot cattle).

REQUIREMENTS

Cattle must have access to areas, either natural or man-made, that provide relief from weather that is likely to create a serious risk to their welfare.

Promptly assist individual cattle showing signs of not coping with adverse weather (see Sections 1.1.1 and 1.1.2 for lists of signs).

1.1.1 High Temperature and Humidity

Cattle are generally able to tolerate low temperatures better than high temperatures. Humidity levels and ventilation affect an animal’s ability to cope with heat stress. Extreme heat is generally more stressful to cattle early in the summer season before they have had a chance to acclimate to the increased temperatures (3).

Signs of heat stress in cattle include (4-6):

  • open-mouth panting with tongue protruding
  • laboured breathing
  • drooling or froth around the mouth.

Cattle are at risk of heat stress when combined temperature and humidity exceed a Humidex value of 40. However, factors such as shade, air movement and length of exposure all influence the impact of high Humidex values on cattle (3).

Heat stress can lead to reductions in feed intake, weight gain, reproductive efficiency and milk production. Severe heat stress may result in illness and death (7).

Water requirements are greater during hot weather.

RECOMMENDED PRACTICES

  1. When cattle are showing signs of heat stress, consider the following strategies (3):
    • provide shade
    • avoid handling cattle
    • feed cattle at dusk or dawn
    • moisten the ground in part of the pen
    • sprinkle cattle with water.

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