Aim.

To evaluate the effect of supplementation with distillers dried grains (DDGS) on in situ ruminal fermentation parameters by cattle grazing on forage sorghum.

Materials and methods:

Four Hereford heifers (793 ± 73 kg live weight) using a ruminal cannula, grazing on forage sorghum, with day-in enclosure and artificial shade, were part of a randomized crossover design study with two treatments: without supplementation (WOS) and with supplementation (WS), fed on DDGS. The experimental design comprised two 14-day periods (10 days for diet transition, and 4 days for measurements).

Results:

Supplementation did not affect DM consumption (P > 0.05), though it increased total consumption (P < 0.05). The WS treatment caused lower ruminal pH (6.17 vs. 6.55; (P < 0.05), and greater N_NH4 concentration (P < 0.05). The effective degradability of DM was 51.25%, the same as the other treatment (P > 0.05), whereas the effective NDF was lower in the WS treatment (P < 0.05). DM digestibility in WS was lower (65.75 vs. 60.75%), whereas NDF digestibility was 68.50 vs. 62.50%.

Conclusion:

DDGS supplementation decreased ruminal pH and raised N_NH4 concentrations, reducing the fiber’s effective degradability of DM and NDF.