The effects of forage supplements on the ingestive behaviour and production of dairy cows grazing ryegrass only or mixed ryegrass and white clover pastures

The effects on milk yield and feeding behaviour of offering ryegrass silage ( r ), ryegrass and white clover silage ( c ), or grass hay ( h ) supplements were examined for cows grazing a ryegrass pasture (R) or a ryegrass and white clover pasture ( C ). The chemical composition of the two silages was similar but the hay contained less crude protein. Cows grazing R pasture spent longer feeding on c than r silages, and those consuming the c silage spent less time grazing than those consuming r silage. The cows grazing the C pasture spent longer feeding on r than c silages, and those consuming the r silage spent less time grazing than those consuming c silage. The cows’ intake of hay dry matter (DM) was less than silage DM and it was taken into the mouth at a slower rate, masticated more ana swallowed less frequently than silage. Milk yield and composition were not affected by the type of supplementary forage or pasture type. Thus cows grazing pastures of the two sward types spent longer feeding on forages with dissimilar botanical composition if given the option. However, as this reduced the time that they spend grazing, there was no effect on milk production.