COMPARISON OF 2 AMMONIATION PROCEDURES TO REDUCE THE TOXICITY OF ENDOPHYTE-INFECTED TALL FESCUE SEED FED TO RATS

To determine the effect of extending the duration of ammonia (2% dry m atter basis) treatment from 1 to 5 wk on the toxicity of endophyte-inf ected tall fescue seed, 60 male Harlan Sprague-Dawley rats were random ly assigned to the following six treatments during a 28-d trial: endop hyte-free (E-), endophyte-infected (E+), 1 wk ammoniated endophyte-fee (1AE-), 1 wk ammoniated endophyte-infected (1AE+), 5 wk ammoniated en dophyte-free (5AE-), and 5 wk ammoniated endophyte-infected (5AE+) tal l fescue seed The concentration of total pyrrolizidine alkaloids (N-ac etyl and N-formyl loline) orE+ rescue was reduced from 4203 12g/g to 3 009 and 2533 I-tg/g by the 1AE+ and 5AE+ treatments, respectively. Erg ovaline was lowered from 3.77 to 1.57 12g/g by 1AE+ and eliminated by 5AE+. Endophyte-infected treatment groups had depressed (P < 0.0001) d ally feed intakes (DFI), daily weight gains (DWG), feed efficiencies ( G/F), primary antibody responses, and T cell and B cell mitogenic resp onses than endophyte-free treatment groups. Ammoniation of endophyte-i nfected rescue seed improved DFI and DWG (P < 0.0001) and G/F (P < 0.0 5); however, there was no difference in performance criteria between t he 1-wk and 5-wk ammoniation treatments. Endophyte-induced depressions in immune function were not alleviated by ammoniation.