Effect of high arterial carbon dioxide tension on efficiency of immunoglobulin G absorption in calves

Objectives-To determine whether high Paco(2) reduced apparent efficiency of IgG absorption (AEA) in calves and whether assisted ventilation of calves with high Paco(2) increased AEA. Animals-48 Holstein calves. Procedures-Arterial and venous blood samples were collected 1, 13, and 25 h ours after birth; an additional venous sample was collected at 37 hours aft er birth. Arterial samples were analyzed for Paco(2), Pao(2), pH, and bicar bonate and base excess concentrations; venous samples were analyzed for pla sma IgG concentrations. On the basis of 1-hour Paco(2), calves were assigne d to nonrespiratory acidosis (Paco(2) < 50 mm Hg; n = 19) or respiratory ac idosis (Paco(2) greater than or equal to 50 mm Hg; 29) groups, Calves in th e respiratory acidosis group were assigned randomly to receive no further t reatment (n = 17) or to be given 5 minutes of assisted ventilation (12). Al l calves received between 1.8 and 2 L of colostrum 2, 14, 26, and 38 hours after birth. Plasma volume and AEA were determined 25 hours after birth. Results-1-hour Paco(2) had no effect on AEA or on plasma IgG concentrations determined 13, 25, or 37 hours after birth, Artificial ventilation had no effect on plasma IgG concentration or AEA. Conclusions and Clinical Relevance-Lack of effect of 1-hour Pace(2) on AEA and IgG concentration indicated that calves compensated for moderate acid-b ase imbalances associated with birth. Calves born with high Paco(2) achieve d adequate plasma IgG concentrations if fed an adequate amount of high-qual ity colostrum early in life. The effect of artificial ventilation on Paco(2 ) was temporary and did not increase AEA.