JUICE-EXTRACTED GRASS PELLETS AND SODIUM-BICARBONATE FOR COWS IN MIDLACTATION FED TIMOTHY GRASS-SILAGE

Eighteen midlactation Holstein cows, averaging 80 to 125 d of lactatio n, were used in a trial of switchback design to evaluate two timothy s ilages, wilted or direct-cut and treated with formic acid, and three t reatments, control, NaHCO3 added at 2% of DM, or juice-extracted grass pellets replacing 30% silage DM. Cows fed direct-cut silage that had been treated with formic acid consumed more DM (19.8 vs. 18.6 kg/d) th an those fed wilted silage. The DMI was also increased with NaHCO3 and grass pellet treatments. However, NaHCO3 reduced digestibility of mos t nutrients without affecting pH of rumen fluid or degradation of DM a nd NDF. Compared with wilted silage, direct-cut silage that had been t reated with formic acid contained more degradable NDF (86 vs. 84.5%). Milk yield (24.9 vs. 23.6 kg/d) was higher for cows fed direct-cut tha n wilted silage, but 4% FCM yield remained unchanged. Addition of NaHC O3 tended to increase yields of milk and 4% FCM. Treatments did not af fect milk composition. Serum urea N was higher for cows fed the direct -cut silage than for cows fed wilted silage. Silage type had more impa ct on feed intake and performance than did NaHCO3 or juice-extracted g rass pellets.