How many breaths per minute do chickens have?

Your question contains an incorrect assumption. Chickens do not breathe; as birds, they respire through lungs and air sacs.

The respiration rate of a chicken varies depending on factors such as age, activity level, and environmental temperature. Newly hatched chicks may have a respiration rate of around 20 breaths per minute, while adult hens typically breathe at a rate of 15 to 30 breaths per minute. Roosters and larger chicken breeds tend to have higher respiratory rates than hens and smaller breeds. These values are approximate and can fluctuate within a range considered normal for the species.

It's worth noting that if a chicken's respiration rate becomes abnormally high (tachypnea) or low (bradycardia), it could indicate a health problem or stress. In such cases, it's important to consult an experienced poultry veterinarian for proper evaluation and treatment.