| Four experiments were performed (1) to ascertain the usefulness of ammoniation as a detoxification procedure for endophyte-infected tall fescue and (2) to investigate immunosuppressive effects of endophyte consumption. In the first experiment, rats were assigned to the following treatments: endophyte-free (E;A second experiment was conducted to determine the influence of ammoniation method, ammonia level and treatment duration on ergovaline and pyrrolizidine alkaloid (N-formyl and N-acetyl loline) concentrations of E+ tall fescue seed. In contrast to pyrrolizidine alkaloids, ergovaline was altered (P ;In experiment three, the effect of extending the incubation period of E+ tall fescue seed with ammonia from 1 (1AE+) to 5 (5AE+) wk on performance and immune function in rats was evaluated. When compared to 1AE+, 5AE+ further diminished pyrrolizidine alkaloids (16%) and eliminated ergovaline from E+ fescue. Performance, antibody response and T and B cell mitogenesis were not significantly different between 1AE+ and 5AE+.;In the final experiment, four mixed cell cultures of T cells and antigen-presenting cells (APCs) were used in an antigen-specific T cell proliferation assay to determine whether the endophyte and associated toxin(s) directly and (or) indirectly suppress T cell function. The four mixed cell cultures were composed of splenic T cells and APCs recovered from mice that were pair-fed endophyte-free (T... |
