Abstract/Summary

BACKGROUND: Including forage legumes in dairy systems can help address increasing environmental/economic concerns about perennial ryegrass monoculture pastures. This work investigated the effect of substituting fresh-cut grass with increasing quantities of fresh-cut white clover (WC) on milk fatty acid (FA) profile and transfer efficiency of dietary linoleic (LA) and α-linolenic (ALNA) acids to milk fat. Three groups of three crossbred dairy cows were used in a 3×3 cross-over design. Dietary treatments were 0 g kg-1 WC+600 g kg-1 grass, 200 g kg-1 WC+400 g kg-1 grass, 400 g kg-1 WC+200 g kg-1 grass. All treatments were supplemented with 400 g kg-1 concentrates on a dry matter basis. Cows had a 19-d adaptation period to the experimental diet before a 6-d measurement period in individual tie stalls. RESULTS: Increasing dietary WC did not affect dry matter intake, milk yield or milk concentrations of fat, protein or lactose. Milk polyunsaturated FA concentrations (total omega-3, total omega-6, LA and ALNA) and transfer efficiency of LA and ALNA were increased with increasing dietary WC supply. CONCLUSION: Inclusion of WC in pastures may increase concentrations of nutritionally beneficial FA, without influencing milk yield and basic composition, but any implications on human health cannot be drawn.