Alterations in bovine serum biochemistry profiles associated with prolonged consumption of endophyte-infected tall fescue

Tall fescue (Festuca arundinacea) is a forage grass that is widely used in pastures in the eastern US for cattle, sheep and horses. The endophytic fun gus Neotyphodium coenophialum is endemic in tall fescue pastures In the US. The turf grass industry intentionally infects fescue cultivars with strain s of the fungus to impart desirable growth and disease tolerance qualities to the,plants. In contrast, ergot and pyrrolizidine alkaloid toxins produce d by fungus-infected plants have been incriminated causally in bovine tall fescue toxicosis, a poorly defined syndrome of morbidity that occurs in cat tle that consume endophyte-infected tall Fescue (E+TF). Ve compared the ser um biochemistry profiles from cattle that grazed E+TF with those from contr ol cattle that grazed on endophyte-free tall fescue (E-TF). Cattle were ble d an 7 dates from April 1 to August 30, 1996 and on 5 dates from May 1 to J uly 30, 1997. Cattle that grazed E+TF retained rough winter haircoats and h ad lesser weight gains, typical of tail fescue toxicosis, compared to those grazing E-TF. They had decreased activities of alkaline phosphatase and al anine aminotransferase. Compared to controls, they had lower values for ser um prolactin and gobulin concentrations. The concentration of creatinine an d the albumin/globulin ratio were increased in the cattle grazing E+TF. Iso zyme determination of alkaline. phosphatase indicated that the decrease in serum activity of cattle grazing E+TF was due to decreases in both intestin al and bone isozymes. Serum protein electrophoresis indicated that the decr ease in serum globulin concentration was due to decreases in both alpha and gamma globulin fractions of this protein. The data-collected in these expe riments add to our understanding of the alterations that occur in the serum chemistry profiles when cattle consume E+TF for prolonged periods of time.