Lactational Response of Dairy Cows Inoculated with Live Adapted Rumen Microorganisms

Two experiments involved 28 lactating Holstein cows to measure the response to intraruminal inoculation with live rumen microorganisms adapted specifically to the fermentation of starch substrate. In Trial 1, 12 cows at 110 days in lactation were paired and allotted randomly within pairs either to a control or to receive a single inoculation of 355 ml of live adapted rumen microorganisms. Fat-corrected milk production was 9.7% higher for cows with adapted rumen microorganisms over the 8 wk following inoculation. In Trial 2, 16 cows were allotted equally between two groups prior to freshening. One group was inoculated as in Trial 1 at 4 to 7 days postpartum with the other group serving as control. Fatcorrected milk was higher for inoculated cows over the 22 wk following treatment (25.4 versus 22.1 kg/day). Milk fat and solids-not-fat tended to increase in inoculated cows resulting in increases in total solids. Silage and concentrate intake increased slightly in the inoculated group, but dry matter intakes were not significantly different. Cows inoculated with adapted rumen microorganism produced 781 kg more milk and 39 kg more fat than controls during the total lactation.