Rumen Degradation Characteristics of Rumen-Protected Fermented Soybean Meal Investigated Using the Nylon Bag and In Vitro Gas Production Method

Fermented soybean meal (FSM) can improve protein utilization efficiency but is easily degraded in the rumen; therefore, it cannot provide sufficient metabolizable protein (MP) for dairy cows. Here, the rumen degradation characteristics of FSM combined with tannin extracts from quebracho or chestnut trees or heat-treated were investigated regarding in vitro gas production and in situ in the rumens of three fistulated cows. The results of the rumen in situ incubation showed that the dry matter (DM) degradation rate decreased in the three rumen treatments. Compared with those of the FSM, the effective degradation rate of the FSM with chestnut tannin was significantly reduced and the rumen undegradable protein was significantly increased. The MP% (DM%) and MP (DM% x DM recovery) indicators in the FSM with chestnut or quebracho tannins increased, but the difference was not significant, whereas those of the FSM decreased following heat treatment. The results concerning in vitro gas production showed that tannin could reduce the rate of biogas production of the slowly degraded part. In conclusion, chestnut tannin is more suitable for protecting FSM from rumen degradation than heat treatment. This study provides a feasible treatment solution for applying FSM to dairy cows, which improves the soybean meal protein utilization efficiency and reduces the amount of soybean meal used.