Recent advances on the factors of variation of milk vitamin concentrations in ruminants

Abstract

Vitamins are essential nutrients for the proper functioning of mammalian cells, but these cells are generally not able to synthesize them, or not in sufficient quantities to cover the needs of the whole organism. They are involved in most cellular biological functions and at all physiological stages of individuals. Specific needs have to be covered by regular nutritional intake, because of limited body's storage capacity. Epidemiological studies indicate that this is not the case. In addition to the well-known symptomatic pathologies of deficiencies in each of the vitamins (like xerophthalmia due to vitamin A deficiency), the links between these sub-clinical intakes and the risks of developing diseases with age are highlighted. Dairy products can be interesting vitamin sources because of the quantities they contain, their bioavailability, their regular consumption, whether daily or yearly, and their affordability. However, elements to characterize the vitamin content in these products are still far from complete. Some vitamins have not yet been studied (D, K, B₁, B₃, B₅, B₈ and C), some variation factors have been described for others. Grazing ruminants thus seem to produce milk that is richer in vitamins (A, E, B₂, B₉) than in other feeding modes, but this turns out to be to the detriment of vitamin B₁₂ for which dairy products are important provider in human nutrition. A more detailed knowledge of the qualitative and quantitative relationships between production conditions (species, breeds, nature of the feed in particular) would eventually make it possible to propose ways of producing milk and dairy products whose vitamin content could be optimized.