Cows fed vitamin-rich feed produce vitamin-rich milk

Summary

On five organic dairy farms there was a positive effect of a high vitamin content in the home-grown roughage on the vitamin content of the milk produced.
Vitamins and minerals are of crucial importance for the health and performance of the animals, and they also affect the nutritional value of the products. The highest concentrations of pro-vitamin A (in the form of beta-carotene) and vitamin E (alfa-tocopherol) are found in grass, legumes and other green plants, while seeds and whole-crop silage only contain small amounts of vitamins. While the requirements for for fat-soluble vitamins of grazing cattle are normally met via their intake from pasture, the supply of fat-soluble vitamins may decrease to very low amounts when conserved herbage is used instead of pasture.
The DARCOF III project EcoVit involved five private organic dairy farms. On these farms the two most important types of roughage were monitored from harvest in 2007 and until the roughage was fed to cattle. Seven times during this period (every six weeks) a sample was collected from each of the two types of roughage and from the milk tank, and analysed for the concentrations of pro-vitamin A (in the form of beta-carotene) and vitamin E (alfa-tocopherol). At the same time the feed intake per cow per day was registered at herd level, including the supplement from a vitamin mixture, if any. This registration enabled cow total daily intake of vitamins from feed and supplements to be calculated. The two most important types of roughage in which the vitamin content was analysed constituted 90-100% of the roughage fed to cattle. For the remaining part of the roughage and the concentrated feed, table values were used for the vitamin content. The vitamin content in the vitamin mixture was assumed to be the guaranteed amount.
We found a positive effect of a high vitamin content in the home-grown roughage, and thus ration, on the vitamin content in the produced milk. This article focuses on the vitamin E supply from roughage and its concentration in milk on two of the case study farm – the farms with respectively the highest and the lowest concentration of vitamin E in roughage and milk.