Influence of radiant heat stress on respiratory water loss in new-born lambs.

Respiratory water loss, oxygen consumption and carbon dioxide production were measured during rest and during moderate radiant heat stress in 9 healthy unanaesthetized lambs, age 4-15 days. The method used is based on an open flow-through system with a mass spectrometer for gas analyses. Respiratory water loss was 12.7 mg/kg min when the lamb was at rest and increased to 24.7 mg/kg min during heat stress. Oxygen consumption was 13.9 ml/kg min at rest and remained unchanged during heat stress. The mean rate of breathing increased from 63 to 125 breaths/min.