Milk composition as affected by time grazing combined with restricted indoor feeding

The aim was to study the effect of pasturing time (4 versus 9 hours) combined with restricted indoor feeding on fat content, fatty acid composition, concentration of ¿-tocopherol, ß-carotene, uric acid and ß-hydroxybutyrate in milk from Holstein Friesian dairy cows. Morning and afternoon milk samples were collected three times at the end of week 2, 4 and 6 of the experiment. Morning and afternoon milk from cows at pasture for 4 h varied significantly in medium and long chain fatty acids (C6-C14), C18:1 n-9, C18:2 n-6, C18:3 n-6 and cis 9, trans 11 CLA concentration for all the 3 weeks. Fat percentage, ¿-tocopherol, ß-carotene, milk uric acid and ß-hydroxybutyrate showed significant differences between morning and afternoon milk from 4-h pasture. In the contrary, there was no significant difference observed between morning and afternoon milk for most parameters studied in the 9-h pasture group. Similarly the difference between morning milk from 4- and 9-h was also non-significant for most parameters. Therefore, in general 4-h morning, 9-h morning and 9-h afternoon milk were very similar in their compositions for the parameters studied.