Mineral, vitamin A and fat composition of bulk milk related to European production conditions throughout the year

In many Western countries, milk and dairy products provide both mineral and lipid fractions relevant to our health. The milk contents of these compounds are highly variable, and the identification of husbandry conditions leading to milks favourable for both mineral and lipid fractions is of interest. The aims of this study were to describe throughout the year the changes in bulk milk compounds and to relate them to husbandry practices. Ten compounds with nutritional requirements were selected: a minimum amount is required for Ca, Mg, P, Zn, vitamin A, n-3 fatty acids (FA), oleic acid and n-6 FA, and a maximum amount for trans FA and C12–14-16 FA. Milks and their associated husbandry practices were collected five times during 1 year from 74 groups of farms located in France, Norway, Slovakia and Slovenia. The Ca, Mg, P and Zn contents varied in different ways throughout the year and independently of each other. We showed the absence of milks with the highest contents in these four minerals simultaneously, but we identified groups of farms where milk had high content in Mg or in Zn. Positive links have been confirmed between grass-based-diets and milk n-3 FA content, maize silage-based-diets and n-6 FA content, and diets rich in concentrate and oleic acid content. These results showed that it was possible to identify husbandry conditions leading to milk favourable throughout the year for one or several compounds but not for all compounds considered in this study.