B-vitamin concentrations in raw milk from dairy cows receiving diets with different forages and grassland contents and the resulting fermented milk products (cheese and yogurt)

This study investigated the effects of diet composition on B-vitamin content in raw milk and cheese, and in yogurt produced therefrom. Forty cows were assigned to either a corn-based intensive or a semi-intensive grassland-based system. B-vitamins were quantified by liquid chromatography or chemiluminescence. Removing fresh grass from the cow diet decreased milk concentration of vitamin B2, and B12 tended to decrease, but vitamin B5 and pyridoxamine increased. Despite significant losses during processing, the feeding system effects were noticeable in cheese: vitamin B2 and pyridoxamine concentrations were higher in the grass-based diet whereas pantothenic acid tended to be lower. Vitamin B1 and pyridoxal concentrations were lower when cows had a reduction to pasture access, whatever the system. Yogurts from the grass-based system were richer in vitamin B9. Pyridoxal concentration also tended to be higher from this latter system and it increased when probiotics were added to milk. This study highlighted diet-related differences in B-vitamin concentrations in raw milk, cheese and marginally in yogurt.