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Green biorefineries provide novel opportunities to use the green biomass efficiently and utilize the ecosystem services provided by grasslands more widely. The effects of the inclusion of fractionated grass silage solid fraction (pulp) on feed intake, rumen fermentation, diet digestion and milk production in dairy cows were investigated. Pulp was separated from grass silage using a screw press simulating a green biorefinery. Partial removal of liquid from forage increased DM concentration from 220 to 432 g/kg and NDF from 589 to 709 g/kg DM while CP decreased from 144 to 107 g/kg DM. A feeding trial using an incomplete changeover design with 24 Nordic Red cows and two 3-week periods was conducted. The pulp replaced grass silage in the diet at 0 (P0), 25 (P25) and 50 (P50) percentage of total forage, which was fed ad libitum with 13 kg of concentrate for all treatments. The forage DM intake was highest on P25 (14.1 kg/day) while P0 and P50 did not differ from each other (13.2 and 13.0 kg/day, respectively). There were no differences between the treatments in rumen pH or ammonia N, but the proportion of acetate increased with increasing pulp inclusion. The digestibility was measured using acid insoluble ash and indigestible NDF (iNDF) as internal markers. Neither of the markers detected differences in NDF digestibility, but according to iNDF, apparent total tract organic matter digestibility decreased with increasing pulp inclusion. The cows maintained milk production at P25, but it showed some decline at P50 (energy-corrected milk at P0 and P25 was 39.8 kg/day while for P50, it was 38.5 kg/day, P = 0.056) and the milk protein yield significantly declined with higher pulp inclusion. Simultaneously, the nitrogen use efficiency in milk production increased. It seems that the fibrous grass-based fraction from a biorefinery process has potential to be used as a feed for ruminants.

Microcrystalline cellulose (MCC) has several applications in food and pharmaceutical industries but the nutritional value for dairy cows and effects on in vivo digestion are not known. A feeding experiment was conducted using 24 dairy cows. The cows were offered MCC originating from unbleached softwood kraft pulp at 0, 10 or 100 g per kg diet dry matter (DM) to replace barley grain in the diet. The total daily DM intake was on average 25.6 kg and not significantly affected by the diet. Positive effects on rumen fermentation could not be demonstrated in a feeding situation where total mixed ration and a concentrate proportion of 0.50 on DM basis was used. Diet organic matter digestibility was not affected by MCC inclusion but fibre digestibility improved and the additional MCC fibre was virtually completely digested. The production potential of MCC was lower than that of barley grain as daily yields of energy-corrected milk, milk fat and protein, and milk protein concentration decreased when MCC replaced barley grain in the diet. Based on these results, MCC is not recommended as a dietary component for high-yielding dairy cows.