Ruminal Supplementation of Direct-Fed Microbials on Diurnal pH Variation and In Situ Digestion in Dairy Cattle

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      To evaluate the effect of direct-fed microbial (DFM) concentration on diurnal rumen pH profiles and in situ digestibilities, nine ruminally cannulated cows in early lactation were fed treatments consisting of DFM (Enterococcus faecium, Lactobacillus plantarum, and Sacchromyces cerevisiae) at a level of a) 1 × 105 cfu/ml of rumen fluid (105), b) 1 × 106 cfu/ml of rumen fluid (106), and c) 1 × 107 cfu/ml rumen fluid (107). Treatments were directly administered via rumen cannula once daily. Cows were fitted with pH probes in their cannula and connected to dataloggers, which monitor pH hourly. The experimental period was 21 d: 7-d adjustment, 14-d for pH, and in situ measurements. Cows fed 105 were able to sustain a higher nadir pH than were cows fed 106 or 107 . Cows fed 105 had a higher digestion rate of high moisture ear corn (HMEC) dry matter. Corn silage digestion was higher for cows fed 105 and 106 compared with those receiving 107. There were no carryover effects of treatment associated with rumen pH when switching from one treatment regimen to the next. Results from this study demonstrate that incorporation of a specific level of DFM aids in reducing diurnal ruminal acidity.

      Key words

      Abbreviation key:

      AUC (area under the curve), DFM (direct-fed microbials), EF (Enterococcus faecium), LP (Lactobacillus plantarum), ERADM (estimated rumen available DM), HMEC (high moisture ear corn), 105 (1 × 105 cfu DFM/ml of rumen fluid), 106 (1 × 106 cfu DFM/ml of rumen fluid), 107 (1 × 107 cfu DFM/ml of rumen fluid)


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