A panting score index for sheep

Area of Science:

• Animal Science
• Physiology
• Environmental Biology

Background:

• Respiration rate (RR) is a key indicator of heat dissipation in sheep.
• Measuring RR in field conditions is difficult, necessitating alternative methods.
• Panting score (PS) in cattle offers a visual alternative for assessing heat stress.

Purpose of the Study:

• To evaluate the relationship between respiration rate (RR) and panting score (PS) in sheep.
• To determine the efficacy of a developed PS index for assessing heat load in sheep.
• To adapt and enhance the existing sheep PS index using cattle-based descriptors.

Main Methods:

• One hundred forty-four Merino wethers were subjected to thermoneutral (TN) and hot (HOT) treatments in a climate-controlled study.
• Respiration rate and panting score were recorded at 3-hour intervals daily.
• Pearson's correlation and general linear models were used to analyze the relationship between PS, RR, and other factors.

Main Results:

• A strong positive correlation (r=0.71, P<0.0001) was found between respiration rate and panting score.
• Sheep in the HOT treatment exhibited significantly higher mean PS (1.49) compared to the TN treatment (1.17).
• Increased RR was associated with standing posture, and individual animal ID influenced RR variations.

Conclusions:

• The developed comprehensive PS index is a viable visual tool for assessing heat load in sheep.
• The PS index provides a practical alternative to direct RR measurement for field evaluations.
• Individual animal characteristics and environmental conditions influence thermoregulatory responses in sheep.