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CowdemyBarnFIG. 12Applied11 min

Heat stress

Heat load is temperature plus humidity, not the office thermostat. Mild heat stress starts near THI 68: shade, air, then water.

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BARN · CHAPTER PLATECOMING SOON

Numbers

  • Mild heat-stress THI

    68

    Alarm: High producers already changing breath and intake

    Start of mild heat stress for high-producing Holsteins. Humidity matters as much as the thermostat.

    Penn State Extension

Field notes on this focus

  1. Note 01THI and air speed stage the coolingBarn THI alone can miss the cow's microclimate. Pair temperature-humidity with cow-level air speed so fans, misters, and soakers stage against what she actually feels.Knowledge level in this topic: Intermediate. Barn-side working knowledge in this topic: checks, pairing, and what to do next.3 min · 2026-09-09THI and air speed stage the cooling

Also touches this focus

  1. Note 01Build the stall around the riseLying time is the budget a stall protects. A stall that blocks the rise charges that time back as standing, collisions, and lesions.Knowledge level in this topic: Intermediate. Barn-side working knowledge in this topic: checks, pairing, and what to do next.3 min · 2026-09-09Build the stall around the rise
  2. Note 02Water is the third letter in S-A-WShade and air get the budget meetings. On a muggy afternoon, the queue at the trough is often the first place heat load becomes visible.Knowledge level in this topic: Basic. First-pass in this topic — useful even if you already know another area well.3 min · 2026-09-08Water is the third letter in S-A-W
  3. Note 03Water space is a ration ingredientLinear water space and refill rate behave like ration ingredients. If subordinate cows wait, intake and milk are already slipping.Knowledge level in this topic: Intermediate. Barn-side working knowledge in this topic: checks, pairing, and what to do next.3 min · 2026-09-09Water space is a ration ingredient
  4. Note 04The sensor is a barn alarm, not a diagnosisRumination and activity collars flag deviations from a cow’s own baseline — useful alarms that still need the cow, bunk, and stall before you act.Knowledge level in this topic: Intermediate. Barn-side working knowledge in this topic: checks, pairing, and what to do next.3 min · 2026-09-09The sensor is a barn alarm, not a diagnosis

Quick check

Q 01 / 01

Mild heat stress in high-producing Holsteins is treated as starting near which THI?

Sources

Plate credit

System figures are educational plates drawn from public-domain veterinary teaching anatomy (udder, claw, uterus, and housing relationships). They are not scanned specimens. Educational only.

Not a veterinary diagnosis, prescription, or ration formula.