PRODUCTION OF MILK AND MILK COMPONENTS BY COWS GRAZING DIFFERENT RYEGRASS CULTIVARS

Abstract

The production of milk and milk components by identical twin cows given ad libitum access to swards of Nui or Ruanui perennial ryegrasses, or a tetraploid hybrid ryegrass (G4708), for short-term periods in spring, summer, and autumn, showed no consistent differences. Similar trials conducted in the spring with unrelated cows grazing Tama tetraploid Westerworlds ryegrass or a tetraploid Italian ryegrass (G4709) also showed no production differences. The use of these cultivars in dairy production systems is therefore more likely to be determined by such agronomic features as annual and seasonal yields, disease resistance and persistency rather than nutritional characteristics.