Dairy cows' diet has a marked impact on vitamin B content in milk but less in yogurts
Résumé
Cows’ diet can have an impact on B vitamins content of milk, thus, their content may vary accordingly in yogurts. This study investigates how the contents in vitamin B1, B2, B5, B6, B9 and B12 vary between raw tank milks and the corresponding yogurts from four 10-cows herds fed different levels of grazed grass. Plain and probiotic (with Propionibacterium freudenreichii and Lactobacillus Casei) yoghurts were produced 3 times from 2 of these milks. It was observed that milk contents of vitamins B2 (p<0.001) and B9 (p<0.10) are higher (18% and 50%) when cows are fed grazed grass whereas it is the opposite for vitamin B5 (p=0.001). Significant correlations were observed between matrices for a given vitamin but only vitamins B6 and B9 contents tended to be higher in yogurts from cows fed diet containing high percentage of grazed grass. Probiotics effect was limited to the vitamin B6 content that was increased. Diet composition induces variations of B vitamins content in milk but only marginally in yogurts. However, this remains to be verified on a larger number of production runs.