Agroscope Liebefeld-Posieux Research Station ALP, rte de la Tioleyre 4, 1725 Posieux

Influence of temporary and permanent grassland on milk fat composition

In a trial with three variants of six dairy cows each, forage of temporary and permanent grassland was compared with the aim to examine the influence of forage of different types of grassland and the addition of maize silage on milk fat composition. The trial lasted for five weeks. The forage was given ad libitum in the stable and for the third variant the cows received forage of the permanent grassland and in addition, 5 kg dry matter of maize silage was fed. For all cows the same mineral supplement was added. Both the feed intake as well as the milk production was registered daily. Before the trial and three times during the trial milk samples were taken and besides the fat, protein and lactose content also different fatty acids in the milk fat were analysed. The forage of the temporary grassland contained more than 85 % of grasses, the rest was mainly clover. In the permanent grassland, only 45 % grasses and about 45 % herbs (dandelion) were found in the young forage. The variant with the permanent forage had, in comparison with the temporary forage, higher proportions of unsaturated fatty acids and higher contents of omega 3 and of conjugated linoleic acid (CLA). With increasing age of the forage, the contents of omega 3 fatty acids and CLA in the milk decreased. In the variant with maize silage, the highest proportion of saturated fatty acids was found. Furthermore, in the milk fat the lowest contents of omega 3 and CLA were determined.

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