Hypoxia in Neonatal Calves: Effect on Intestinal Transport of Immunoglobulins

Abstract

The effect of reduced oxygen tension in arterial blood (hypoxic hypoxia) for 24h postpartum on the absorption of colostral Ig was studied in 12 neonatal calves. During this period, inspired air for hypoxic calves contained 10.5% O2, whereas that for normoxic calves contained 21% O2. After 24h, inspired air for all calves contained 21% O2. Three dietary regimens also were imposed during the initial 24-h period: colostrum at 0 and 12h, whole milk at 0 and 12h, or fasting. Colostrum was fed to all calves at 24, 36, and 48h.During the initial 24-h period, means for arterial partial pressure of oxygen were 26 and 73mm Hg for hypoxic and normoxic calves, respectively. In those fed colostrum at 0 and 12h, hypoxia extended the period of Ig absorption from 20 to 40.5h. In calves fed whole milk or those that were fasted, no such effect was noted. These observations suggest that the effect of hypoxia on the cessation of Ig absorption by the small intestine is mediated through a secondary and as yet undetermined mechanism.