Managing in the Heat

Keeping cows “cool” in summer

Temperatures above 26 °C will start to negatively affect a cow’s ability to produce milk. Intakes can reduce by more than 20%, usually because the cows seek shade rather than graze. Blood flow throughout the body is diverted to the skin to aid cooling, this can effect:

  • Absorption of vital nutrients from the gut
  • Milk production
  • Reproduction


Signs of heat stress include :

  • Increased breathing rate (more than one breath/sec)
  • Seeking shade
  • Crowding around/in the water source
  • Panting
  • Recumbancy – Down Cow
  • Excessive salivation
  • Collapse
  • Death

Strategies for managing in the heat


  • Reduce walking time/distance in the afternoon
  • Cows MUST have shady paddocks on warmer days
  • Ensure adequate water supply
    • dams, more than one trough to avoid crowding
    • Water intakes can double in hot weather, as much as 250L per cow!
    • Consider a water source at the exit of the dairy
  • Milk later in the day, peak temperatures are often as late as 4pm
  • Use sprinkler system in the dairy – use for 5mins every 15mins
    • Fans can assist cooling on still days

Provide shade to minimise heat gain

  • Trees on the west side of paddocks/laneways/yards.
  • Shade cloths on mobile structures can be used in the meantime.
  • DON’T move cows in the middle of the day


  • Feed high quality fibre source to encourage intake and balance increased concentrate ration
    • feed out close to shade and water source
  • Pasture protein is reduced in summer, so this should also be addressed
  • The best pastures should be grazed at night when cows will eat more readily
  • Minerals are increasingly lost in sweat/urine so check potassium, magnesium and sodium supplementation