EFFECTS OF GRADUAL REPLACEMENT OF RAPESEED CAKE WITH LINSEED CAKE IN A GRASS SILAGE-BASED DIET FOR DAIRY-COWS

Eight Finncattle cows were used in two replicated 4x4 Latin squares wi th 21-day periods to study the effects of replacing rapeseed cake with linseed cake in proportions of 0, 1/3, 2/3 and 1 (on air dry basis), the total amount of supplement being 1.5 kg/day (on air dry basis). Th e basal diet consisted of silage fed ad libitum and a 4.5 kg/day (on a ir dry basis) barley:oats (1:1) mixture.The experimental diets had no effect on feed intake. Effective protein degrability (EPD) determined by the nylon bag method was higher for linseed cake than for rapeseed cake. Milk production decreased linearly (P<0.01), from 18.5 to 17.1 k g/day, when the proportion of linseed cake was increased. Milk fat con tent increased (P<0.05) by 3.4 g/kg but milk protein content tended to decrease (P<0.10) with an increase in linseed cake feeding. Despite c lear differences in the fatty acid composition of linseed and rapeseed oils, experimental treatments had only minor effects on milk fatty ac id composition. Several factors, including the slightly higher ether e xtract content, higher EPD and/or lower amino acid content of linseed cake than rapeseed cake, the different fatty acid composition of the t wo supplements and the presence of antinutritional compounds in linsee d cake, may be responsible for the impaired milk production with linse ed cake feeding.