Content of vitamins
Vitamins are not synthesized in the udder. Milk content of
the fat-soluble vitamins A and E reflects their content in
the feed (Table 2). In general, the content of these vitamins
in feed plants decrease with maturity and are higher
in fresh than conserved material. There are therefore
regional and seasonal variations in these vitamins due to
feeding regimes, with the highest concentrations in fresh grasses at early stage of maturity. For example a study in Finland shows that the concentration of vitamin E in milk is 3–4 times higher during summer than in winter. Enriching the supplementary feeds with proper
sources of these vitamins may increase the milk content
during the winter season.