PSII-14 Ruminal in situ degradability of warm-season forages under different incubation times with calcium oxide.

摘要

An experiment was performed to evaluate the effects of calcium oxide (CaO) on ruminal in situ degradability of bahiagrass (BH) and bermudagrass (BM) hay. Forages were incubated in 2 different years in 20-L buckets (n = 4/treatment) as follows: 1) untreated dry hay (DH); 2) 50% DM for 7 d (W7); 3) 50% DM for 14 d (W14); 4) 50% DM + 5% CaO for 7 d (CO5-7); 5) 50% DM + 5% CaO for 14 d (CO5-14); and 6) 50% DM + 10% CaO for 14 d (CO10). Water was added to the forages to achieve desired DM. After 7 or 14 d of incubation, bucket contents were dried and ground to pass a 4-mm screen. Ruminal in situ degradability of DM, OM, CP, NDF, and ADF of BH and BM was determined by incubating nylon bags for 24, 48, and 72 h in duplicate, in ruminally cannulated steers consuming bahiagrass hay. Data were analyzed as a generalized randomized block design using bucket as the experimental unit. The model included the fixed effect of treatment and the random effect of year. At all ruminal incubation time points, a treatment effect (P < 0.001) was observed on in situ degradability of DM, OM, CP, NDF, and ADF of BH and BM, where, in general, all 3 CaO treatments promoted greater forage degradability when compared to DH, W7, and W14, which were not different (P > 0.05). Additionally, nutrient degradability was greatest (P < 0.05) for CO10, followed by CO5-7 and CO5-14, which did not differ (P > 0.05). In conclusion, CaO treatment of warm-season forages common to the southeastern U.S., such as bahiagrass and bermudagrass hay, improved in situ ruminal degradability of nutrients. Moreover, incubating forages for more than 7 d to maximize effectiveness of treatment proved to be unnecessary.