CHANGES IN TOTAL PLASMA-PROTEIN, SODIUM AND ALDOSTERONE CONCENTRATIONDURING MILKING, FEEDING, AND FOOD-DEPRIVATION IN THE SWEDISH DAIRY-COW

Four nonpregnant, Swedish Red and White dairy cows were exposed to two different management treatments. The aim of the study was to investig ate if lactating dairy cows react similar to feeding and food deprivat ion as small ruminants. In one treatment the cows were milked and fed simultaneously, and in the other treatment the cows were fed and milke d separately. Then the cows were studied during 58 h food deprivation, followed by two days of recovery. During feeding both total plasma pr oteins (TPP) and plasma sodium increased. Aldosterone increased only w hen the cows were fed and milked simultaneously. There were no alterat ions in TPP or plasma sodium concentration during food deprivation. Du ring refeeding in the morning on the first recovery day, when only a s mall amount of hay was fed, both TPP and plasma sodium concentration i ncreased. Plasma aldosterone decreased during food deprivation and rem ained low at the first feeding occasion. During the second day of reco very plasma sodium was still elevated, but TPP and aldosterone had ret urned to basal levels. The feacal sodium content increased step wise d uring the food deprivation period. Food deprivation decreased water in take with 70%, and milk production with 60%.