Forb-rich silage feeding increases milk n-3 and n-6 fatty acid content in practical dairy farming: results from three Danish organic farms

Abstract

Milk production and milk fatty acid (FA) composition were followed in three Danish commercial organic dairy farms where grass clover silage was substituted with a forb-rich silage. Farms A, B, and C included a total of 50, 189, and 235 lactating dairy cows, and 20 cows in each herd were selected to record the productive performance and milk composition. In all farms, 70% of diets were grass clover silage, and during the experiment, forb-rich silage gradually replaced grass clover silage during the 2–4 weeks, where after cows were fed the forb-rich silage diets for additional 2 weeks. The data were separately analyzed in each farm. Milk production at farms A and B was not affected by diet change, but milk production at farm C decreased by 1.7 kg energy corrected milk (ECM)/cow in cows fed the forb-rich silage. Regardless of farm, the proportion of C18:3n-3, C18:2n-6, and conjugated linoleic acid (CLA) isomers in milk from cows receiving the forb-rich silage increased compared to cows fed grass clover silage based diets. The results indicate the possibility for further increase in the content of poly-unsaturated fatty acids (PUFA) in organic milk by substituting grass clover silage with forb-rich silage.

Keywords

• Botanical composition
• grass clover
• milk fatty acids
• organic milk