Heat stress load

Field notes

Short articles on this topic

Two to four minutes. The weekly unit an agent can add without rebuilding the system.

• 3 min · 2026-09-08

  Water is the third letter in S-A-W

  Shade and air get the budget meetings. On a muggy afternoon, the queue at the trough is often the first place heat load becomes visible.

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• 4 min · 2026-09-07

  The holding pen was the hottest room

  Parlor fans were fine. The packed pen before the gate was still.

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• 3 min · 2026-09-07

  Walk the dry yard at two o’clock

  The milk barn can look cooled while the next lactation pants in a still pocket.

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The numbers

Benchmarks, not a ration

Ranges from extension and textbooks. Use them to read the cow, not to write a formula.

• Mild heat-stress THI

  68

  Alarm: High producers already changing breath and intake

  Penn State heat-abatement bulletin — start of mild heat stress for high-producing Holsteins. Humidity matters as much as the thermostat.

  Heat Stress Abatement Techniques for Dairy Cattle — Penn State Extension

• Abatement order

  Shade → air → water

  Soak only if air can dry the hide. Wet plus still plus humid is not cooling.

  Heat Stress Abatement Techniques for Dairy Cattle — Penn State Extension

• Dry-cow heat cost

  Next lactation

  Alarm: Panting dry cows at 14:00

  Penn State: heat-stressed dry cows can give less milk next lactation; calves can be affected too.

  Cooling Dry Cows to Improve Health and Production — Penn State Extension

Spot it

What you see · what it means · what to check

1. Sign 01

   Open-mouth panting in the stall

   Close

   MeaningNot just after a run from the parlor. Resting cows with flared nostrils have already spent the cheap cooling.

   Next checkCount breaths on ten resting cows. Walk the hold and the dry pen the same afternoon.

2. Sign 02

   Bunching in a still corner

   Open

3. Sign 03

   Bunk left at 16:00 on a muggy day

   Open

Check yourself

Five questions from this universe