Lipid metabolism and Sarcocystis miescheriana infection in growing swine

Sixteen 2-month-old pigs were divided into four equal groups and infected with either 500 000, 1 000 000 or 3 000 000 sporocysts of Sarcocystis miescheriana. Four pigs served as uninfected controls. Pigs were bled weekly and serum was collected beginning 14 days prior to infection and continuing until 63 days after infection. Body fat composition, as measured by the specific gravity of the carcass, was not affected by infection. There were no significant effects of infection on serum concentrations of glucose, insulin, triglycerides, and total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol. A slight depression in HDL cholesterol occured during the acute phase of infection. Tumor necrosis factor (TNF) was not detected in serum from infected swine when assayed by a cytotoxicity assay using TNF-sensitive WEHI 164 clone 13 cells. Attempts to stimulate TNF production in RAW 264.7 cells with parasitic lysates gave mixed results. This study suggests that the disruption of lipid metabolism is not the primary cause of growth retardation in growing swine infected with S. miescheriana.