Experiences with deferred grazing at the Taranaki Agricultural Research Station

Deferred grazing is the practice of holding over pasture in situ that has been considered surplus to animal requirements in spring, to be grazed at a later date when a shortage of pasture occurs, usually in summer/autumn. This non-mechanical method of pasture conservation was developedandpractised from 1986-1989 at the Taranaki Agricultural Research Station as part of a low cost dairy system. At the low stocking rate (3.7 cows/ha) 13% of the farm area was conserved as deferred grazing and allowed to naturally reseed before grazing. The reseeding doubled the tiller density of perennial ryegrass, increasing pasture growth by 15 19% the following season. This, combined with the nil cost associated with conserving supplements, made this system more profitable than the traditional haysilage system. For the natural reseeding to be successful, the deferred grazed pasture should be removed from thegrazingrotationduringtheryegrassreproductive phase (mid-October to mid-November) and not grazed until after the ryegrass seed is mature (mid- January). The method developed to Wise deferred grazed pasture has been to strip graze between the morning and night milkings. Cows are offered a pasture allowance of 10 kg DM/cow/day or one, two hundred and fiftieth of the farm per day, to achieve a utilisation of around 50%. Cows graze selectively leavingaresidualofabout4000kg DM/ haofpredominantly dead material. Mowing before grazing increased utilisation, but there was no advantage in milk solids production. No benefits were observed when tall fescue or phalaris pastures were allowed to naturally reseed. Deferred grazing had no effect on grass grub or porina populations if grazed before April. No detrimental animal health effects have been measured with deferred grazing. To reduce farm operating costs and increase pasture growth, it is recommended that 10% of the farm is deferred and allowed to naturally reseed on an annual basis. Keywords deferred grazing, pasture conservation, naturalreseeding, tiller density,pasture growth, dairy production