Effects on milk fat composition and cow performance of feeding concentrates containing full fat rapeseed and maize distillers grains on grass-silage based diets

Two experiments were carried out to determine the effect on milk fat composition and cow performance of including ground full fat rapeseed (FFR) and maize distillers grains (MDG) in the concentrate supplement. Unwilted grass-silage was the basal forage in both experiments. In Expt. 1, 8 kg/day of concentrate containing 0 (control), 80 (low), 140 (medium) or 200 g/kg (high) FFR was fed to four groups of 16 cows each for 7 weeks. Milk yield, milk constituent yield and milk composition which was compared using 13 cows per treatment were not significantly affected by FFR inclusion. The milk fat (using all 64 animals) from cows on the high FFR concentrate contained significantly lower proportions of C6:0, CS:O, C14:0, C14:l (P <0.05) compared to those produced by cows on the other three concentrates. It also contained lower proportions of ClO:O and C12:O (PMilk protein concentration and yield were depressed (P < 0.05) by the inclusion of both levels of MDG. Including both levels of MDG significantly reduced the proportions of ClO:O, C12:0, C14:0, C14:1, C16:0, C16:l and Cl&3 (Pmilk protein concentration.