Effect of pasture species on milk yield and milk composition

One IO-day experiment in autumn 1994 then four lo-day experiments throughout the 1994195 lactation in a complete Latin square investigated the effect of pasture species on yield, composition and total colour of milk from dairy cows. Treatments were Grasslands Kopu white clover (Trifolium repens L.), Yatsyn1 perennial ryegrass (L&urn perenne L.), Grasslands Kahu timothy (Phfeum pratense L.) and Grasslands Kara cocksfoot (Dactylis glomerata L.) offered at similar allowances of green leaf. Cows grazing white clover produced higher (PcO.05) milk yields than cows grazing the other three pasture species, cows grazing timothy and ryegrass also producing more (PcO.05) than cocksfoot. Timothy produced milk with a higher (P<O.Ol) fat % than the other three species, whereas for cocksfoot protein % was lower (P<O.Ol). Grazing white clover increased (PcO.05) lactose %. Milksolids production was highest from white clover. Within the grasses timothy gave the highest milksolids production. Pasture species did not affect total colour of milk. Ryegrass gave greater (P<O.O5) iiveweight gain than the other three pasture species in autumn 1994, but no significant differences in liveweight and condition score were measured in the trials run during the 1994/95 lac ta t ion. Pasture species fed a t a s imilar a l lowance of green leaf had a significant effect on the yield and composition of milk, which suggests it may be possible to manipulate milk composition by altering pasture composition rather than by processing methods .