Abstract

High producing dairy cows struggle to meet energy demands and handle various transitional changes in late gestation and early lactation. Negative energy balance in early lactation is inevitable and metabolic disorders may follow as a consequence of a deep negative energy balance. This thesis studies associations between blood profiles and body condition score (BCS) in dairy cows, and displaced abomasum (DA) or clinical ketosis, and investigates risk factors for the two diseases at the herd level. In study I, blood profiles of cows with and without DA were compared. In studies II and III, blood of cows was sampled to investigate how blood profiles differed among herds with a high incidence of DA or clinical ketosis, and between cows in high-incidence and low-incidence herds, respectively. In study IV, associations between high or low incidence and factors related to housing, feeding, management and milk yield were studied to identify herd-level risk factors for DA and ketosis. The blood profiles included parameters with which to assess energy metabolism, hepatic cell damage, inflammation, and a metabolic index (RQUICKI)used in humans to assess insulin sensitivity. The cows with DA displayed blood profiles indicating a severely altered energy metabolism (NEFA, BHB, insulin, cholesterol, RQUICKI), liver cell damage (AST, GD) and inflammatory responses (haptoglobin). At the herd level, energy markers (NEFA, insulin, glucose, cholesterol, RQUICKI) indicated altered metabolism in cows in high-incidence herds compared with cows in low-incidence herds. The markers of liver cell damage and inflammation were not different between highand low-incidence herds. Among high-incidence herds, BCS and change in BCS, and one metabolic marker (NEFA) were found most useful to pinpoint herd problems. Large herd size, high individual milk production level, keeping all dry cows in one group, and not cleaning the feeding platform daily, were found to be risk factors for a high incidence of DA or ketosis at the herd level. In conclusion, the studies confirm a difference in blood profiles between cows with DA and healthy herd mates as well as a difference at the herd level between cows in herds with high versus low incidence of DA and clinical ketosis.