Keyword Dissertations.Dead space refers to lung areas that are ventilated but not perfused. Cold-induced decreases in particle clearance, and increases in deposition, may predispose calves to respiratory infection. It is speculated that mucociliary clearance rate may be partially genetically determined. It is possible that cold-exposure decreases tracheal mucociliary clearance rate. Nasal mucus velocity NMV was measured in four unanesthetized calves at Ta 2-4 C and Ta 16-18 C, using a radiographic tracking technique. It is speculated that the cold-induced respiratory pattern change was responsible. Deposition of nasally-instilled fluorescent Pasteurella haemolytica was significantly higher for cold-exposed calves. The effect of cold-induced hypoventilation on pulmonary particle deposition was investigated in 10 calves. hypoventilation is suggested as a mode of heat conservation in cold environments in animals which use panting as a means of increasing evaporative heat loss. Calves were capable of conserving respiratory heat during cold exposure by decreasing expired air temperature and by decreasing dead space ventilation while increasing O2 extraction. Total ventilation VE did not change significantly, but the ventilatory equivalent for O2 decreased with decreasing Ta. As Ta decreased, respiratory frequency decreased 29 while tidal volume increased 35.

Effects of ambient temperatures Ta between 4 and 18 C on ventilatory parameters and respiratory heat loss were determined in 4 calves. Abstract: Possible thermoregulatory benefits of cold-induced changes in breathing pattern hypoventilation and the mechanisms by which cold stimulates a change in breathing pattern were investigated in male Holstein calves 1-3 months old.

Ventilation dead space