Comparison of two 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 matter basis) treatment ti'om 1 to 5 wk on the toxicity of endophyte-infected tall fescue seed, 60 male Harlan Sprague-Dawley rats were randomly assigned to the following six treatments during a 28-d trial: endophyte-free (E-), endophyte-infected (E+), 1 wk ammoniated endophyte-fee (1AE-), 1 wk ammoniated endophyte-infected (1AE+), 5 wk ammoniated endophyte-free (5AE-), and 5 wk ammoniated endophyte-infected (5AE+) tall fescue seed. The concentration of total pyrrolizidine alkaloids (N-acetyl and N-formyl loline) or E+ rescue was reduced from 4203 12 g/g to 3009 and 2533 I-tg/g by the 1AE+ and 5AE+ treatments, respectively. Ergovaline was lowered from 3.77 to 1.57 12 g/g by 1AE+ and eliminated by 5AE+. Endophyte-infected treatment groups had depressed (P < 0.0001) dally feed intakes (DFI), daily weight gains (DWG), feed efficiencies (G/F), primary antibody responses, and T cell and B cell mitogenic responses than endophyte-free treatment groups. Ammoniation of endophyte-infected rescue seed improved DFI and DWG (P < 0.0001) and G/F (P < 0.05); however, there was no difference in performance criteria between the 1-wk and 5-wk ammoniation treatments. Endophyte-induced depressions in immune function were not alleviated by ammoniation.