Effect of body condition at calving on tissue mobilization, development of fatty liver and blood chemistry of dairy cows

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Abstract
An experiment was performed with two groups of nine British Friesian cows to compare the effect of calving in fat or thin condition on (1) the mobilization and functional activity of subcutaneous adipose tissue, (2) the mobilization of skeletal muscle, (3) the development and resolution of fatty infiltration of the liver and (4) the chemistry and haematology of blood. Sampling was performed at various times during the dry period and subsequent lactation. There were no differences between groups in the amount of adipose tissue mobilized between 4 weeks before and 26 weeks after calving. The lipogenic and lipolytic capacities of isolated adipocytes were also not different between groups at any time although major changes occurred in both over the calving period and during early lactation. Acetate oxidation to carbon dioxide was higher in adipocytes isolated from thin cows particularly after calving. More muscle fibre area was lost in the fat cows compared with the thin cows between 4 weeks before and 4 weeks after calving and the fat cows had greater infiltration of fat in the liver at 1 and 4 weeks after calving than the thin cows. The mean white-cell count was lower and the packed-cell volume was higher in the fat cows than in the thin cows at 1 week after calving. The major differences between groups in blood composition were increased concentrations of copper, non-esterified fatty acids, bilirubin and enzymes such as ornithine carbamyl transferase in the fat cows after calving. These results suggest that fat and thin cows respond differently to the metabolic demands of early lactation and that some of these differences render fat cows more susceptible to disease.