Abstract
Weaned lambs when growing to hoggets on old pasture acotype ryegrass, had shown significantly lower weight gains immediately prior to clinical signs of FIGS, than those on Ruanui ryegrass pasture. The difference was not correlated to quantity of harbaga on offer. Enzyme linked immunosorbent assay of plant tissue showed higher concentration of Lolium endophyte in that period than prior to subsequent periods. Keywords: ryegrass staggers, Lolium andophyte, live weight