Grasslands Kahu timothy: quality pasture for animal performance

Abstract

Evaluations of Kahu timothy (Phleum prutense L.) included agronomy under mowing (1976-1979) and grazing (1980-1983), and animal performance from grazed pasture (1988-1993) and silage feeding (1989-1991). Agronomic testing showed that Kahu timothy was slow to establish, producing only 28% of the Grasslands Ruanui ryegrass (L.&urn perenne L.) swards in the 6 months after sowing. Frequent, close defoliation severely reduced the yields of timothy and caused losses of plants, reducing longevity. A less frequent defoliation regime with a residual sward height of 30-50 mm gave the greatest sustainable yields. Under mowing Kahu produced significantly less than S51 timothy in summer and winter but under grazing Kahu was superior in spring and summer, resulting in significantly greater annual production. Animal performance testing showed hoggets grazing timothy in spring grew at 218 g/day, significantly greater than the 164 g/day achieved on Grasslands Nui ryegrass. The spring stocking rate on timothy was also significantly greater than on ryegrass, though utilisation of the forage was similar. When fed timothy/red clover silage lambs fed in winter grew at 98 g/day while lambs on standard ryegrass/ cocksfoot/white clover silage averaged a growth rate of only 44 g/day. From the assessment of the physiological state of individual tillers it was observed that timothy had a significantly higher proportion of its tillers with growing points present above ground through late spring and summer than ryegrass. This is suggested as a major reason for the depletion of timothy populations -under close grazing. When grazed correctly in late spring and summer timothy can provide a perennial forage of high feeding value for livestock systems. Keywords: animal performance, Grasslands Kahu, pasture quality, Phleum pratense