A field survey of fat mobilization and liver function of dairy cows during early lactation. Relationship to energy balance, appetite and ketosis.

NEFA, total lipids, bilirubin, GOT, acetoacetate and glucose in blood plasma of cows were measured during early lactation. Feeding and yield were also recorded. NEFA and bilirubin values showed a gradual decrease with advancing lactation, while total lipids rose gradually during the first months of lactation. GOT showed no definite trend during early lactation. Acetoacetate values were at maximum 21--30 days post partum and glucose values were high at partus and low during the first weeks of lactation. NEFA were negatively correlated to energy balance during the first month of lactation. Total lipids, bilirubin and GOT seemed not to be dependent on energy balance in cows with normal appetite. NEFA, bilirubin and GOT were significantly elevated in cows with reduced appetite. NEFA were positively correlated to bilirubin, GOT and acetoacetate and negatively correlated to glucose. The correlation coefficients were higher during the first month of lactation than during the second and third month. Cows contracting clinical ketosis showed high values of NEFA a long time before any clinical symptoms appeared. Significantly increased values of acetoacetate occurred only the last days before treatment when plasma glucose had reached low values.