Laying hen responses to acute heat stress and carbon dioxide supplementation: I. Blood gas changes and plasma lactate accumulation

Abstract

Exposure to heat stress lowered partial pressure of arterial blood carbon dioxide (paCO 2), arterial blood bicarbonate ion (HCO − 3), but increased arterial blood pH (pHa) and plasma lactate (LA). Increasing ambient carbon dioxide (CO 2) to 1.5% increased paCO 2 from hypocapnic levels to normocapnic levels, raised HCO 3 − lowered pHa and plasma LA to pre-heat stress levels. Following CO 2 treatment, respiratory alkalosis conditions returned. It was evident in this study that increasing ambient chamber CO 2 to 1.5% was effective in ameliorating acid-base disturbances and reducing elevated levels of plasma LA which normally develops when laying hens are subjected to an acute heat stress exposure.