LOLIUM ENDOPHYTE AND SHEEP PERFORMANCE ON PERENNIAL RYEGRASS CULTIVARS

Abstract

Some effects of lolium endophyte (Acremonium lolioe) on sheep production were evaluated using pure swards of high (SO%>) and low (< 5%) endophyte Nui and Ariki ryegrass. The proportion of infected tillers in high endophyte treatments increased by 19% in 15 months. Ryegrass staggers occurred on both high endophyte ryegrasses - being slightly worse on Nui. The peak ryegrass staggers outbreak did not coincide with peak endophyte mycelium concentration in ryegrass plants. Hoggets grazing the low endophyte ryegrasses had a 1.6 kg advantage in liveweight gain in spring, when allowances were equal, but fewer sheep grazing days. In summer and autumn sward damage by Argentine stem weevil, drought and over-grazing eliminated low endophyte Ariki treatments and reduced herbage production from low Nui to 70% of high endophyte Nui. Tiller densities in low endophyte treatments were 28% of those in high endophyte treatments. High endophyte Ariki had the highest overall production: 7.8 t/ha of herbage and 15 kg/head liveweight gain compared with 6.9 t/ha and 12.5 kg/head for high endophyte Nui and 4.7 t/ha and 9 kg/head for low endophyte Nui. Differences in production due to endophyte highlight the need for caution in interpreting results from trials when endophyte status of ryegrass is unknown. Keywords: Lolium endophyte, Acremonium loliae, ryegrass staggers, Lol~m perenne, live weight gain, pasture production, Ariki, Nui