Blood plasma minerals and vitamins and acid-base status of sheep raised under fluctuating or constant environment

Seasonal changes of concentrations of calcium, magnesium, iron, vitamins A and E, and venous blood, partial pressure of oxygen, pH, and partial pressure of carbon dioxide in blood plasma were measured from May to mid-November, 1980, in 49 nonpregnant ewes housed either in an air-conditioned barn or in a conventional barn with free access to a barnyard. Calcium, iron, and plasma magnesium differed for both location and date. All three constituents were affected by interaction of season with location. Interaction of location and date was highly significant for both vitamins A and E concentrations in plasma. Location was a significant factor only for partial pressure of oxygen of blood whereas interactions of locations with dates was highly significant for both that and pH. The partial pressure of oxygen of blood in the outside group was generally higher than that of the indoor group. It was higher in the outside group when the outside temperature was high. In both groups the lowest partial pressure of carbon dioxide was recorded in August and November.