MU

Animal Sciences

CAFNR

Thermal Aid

Recognizing Heat Stress • Normal Animal Values and IndexesHeat Exchange in Livestock

Feed Intake

A large decrease in feed intake can be a good indicator of problems in cattle. First make sure that cool fresh drinking water is easily accessible. Producers may also consider increasing fat levels in the diet to increase palatability. Increasing the moisture content of feed can also lead to better feed intake.

Rectal Temperature

The rectal temperature of a cow is an accurate measure of internal body temperature. Most cows have internal temperatures of around 101° F (38.3° C). Cows with temperatures above this are likely experiencing heat stress and need special attention.

Activity Level

As cattle become heat stressed their behavior changes. Decreases in activity or excessive crowding around a water source are often signs of heat stress. Cattle will also become less workable and more temperamental when stressed. Never ignore changes in a herd’s behavior. If the herd seems “off” there is almost always a cause.

Respiration Rate and Panting Scores

Respiration rate and panting score are very useful indicators of heat load in cattle. They are the first visual responses seen during hot conditions, and panting score, in particular, can be quickly assessed by feedlot personnel.


Panting Score 0 - No panting – Difficult to see chest movement Respiration Rate Under 40 bpm

Panting Score 1 - Slight panting, mouth closed, no drool or foam, Easy to see chest movement Respiration Rate – 40 to 70 bpm

Panting Score 2 - Fast panting, drool or foam present, No open mouth panting Respiration Rate – 70 to 120 bpm

Panting Score 2.5 - Fast panting, drool or foam present, No open mouth panting Respiration Rate – 70 to 120 bpm


Panting Score 3 - Open mouth + some drooling, Neck extended and head usually up Respiration Rate – 120 to 160 bpm

Panting Score 3.5 - Open mouth + some drooling, Neck extended and head usually up Respiration Rate – 120 to 160 bpm

Panting Score 4 - Open mouth with tongue fully extended for prolonged periods with excessive drooling Neck extended and head up. Respiration Rate Greater than 160 bpm

Panting Score 4.5 - As for 4 but head held down, Cattle ‘breath’ from flank, Drooling may cease Respiration rate is variable from low to above 160 bpm