Abstract

Defoliation patterns of sheep grazing a staggers-prone, ryegrass-dominant pasture were studied at Palmerston North during the 1982-83 summer-autumn period. The 0.4 ha pasture was grazed for 5 to 8 days each month from November to May by groups of 30 to 50 sheep. Herbage at dung patch sites present in January covered about 25% of the pasture area and remained ungrazed until May. Urine-patch sites covered about 35% (16 to 45%) of the pasture area and although urine- patch herbage was grazed before other types, differences were detected within this category: the most recent urine-patches were defoliated sooner and to a greater extent than older ones. Ryegrass at interexcreta sites was defoliated less frequently and to a lesser extent than that at urine-patch sites, except for those interexcreta sites that also contained white clover. Concentrations of the ryegrass endophyte, Acremonium loliae were higher in live ryegrass sheath at urine-patch than at inter-excreta sites. The results are discussed in relation to the acquisition of neurotoxins by sheep.

PH, Mortimer, PW Young, and di ME Menna

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 181-184, 1984