Grape marc can be used as a valuable source of supplementary nutrition for dairy cows, and recent research undertaken by the Victorian Department of Primary Industries have linked the feeding of stems,seeds and skins from wine grapes with potential impacts on methane reduction and milk production. However it does not come without risks and these risks need to be well understood and managed.
As a by- product of the wine industry, grape marc, made up of skins and seeds presents a risk of containing residues of agricultural chemicals. This is due to the use of sprays in the vineyards to control pests and fungal diseases on the grapes. The feeding of contaminated grape marc to dairy cows in turn presents a risk of the residues being transferred into the milk (and meat) supply