Grazing behaviour of sheep and ryegrass staggers

R.G. Keogh

Grasslands Division DSIR, Palmerston North

Proceedings of the New Zealand Society of Animal Production. 1984, 44: 189-192

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.

Keywords: NZSAPAB; Grazing behaviour; defoliation patterns; sheep; ryegrass staggers; ryegrass endophyte

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