Relationship between grassland management and bovine milk quality

Summary

Bulk-tank milk was collected every second month (in 2007) from 32 farms in Middle Norway to examine the effect of grassland management and farming system on milk composition. Sixteen farms with organic farming system were paired with 16 farms with conventional farming system. In both farming systems, 9 farms had short-term rotational grassland and 7 farms had long-term grassland. Milk fatty
acid (FA) composition and milk concentration of α-tocopherol, β-carotene, retinol,phytoestrogens and selenium were analyzed. Only small differences were found in milk composition from farms with different grassland management, except for the concentration of phytoestrogens and selenium that were highest on farms with short-term grassland. Milk FA composition, milk concentration of phytoestrogens and selenium were strongly affected by farming system. Milk from organic farming had higher concentration of phytoestrogens, selenium and higher proportion of C18:3n-3, short-chain FA, long-chain FA, saturated FA and lower proportion of C18:0, C18:1n-9, C18:2n-6 and lower n-6/n-3 FA ratio than milk from conventional farming.