Synergistic Effect of Biofat and Biochar of Cashew Nutshell on Mitigate Methane in the Rumen

The study aimed to evaluate the effectiveness of a combination of biofat with biochar or biosmoke (bioindustrial products of cashew nut shells) at the best level as feed additive in reducing methane production and improving in vitro rumen fermentation. This experiment had two series of combination and each used a randomized block design with 6 treatments and 4 replications. A series of biofat (BF) and biochar (BC) combination were added each to substrate as followed BFBC1 = 0: 100%; BFBC2 = 25:75%; BFBC3 = 50:50%; BFBC4 = 75:25%; BFBC5 = 100: 0%. While, a series of biofat (BF) and biosmoke (BS) combination as followed BFBS1 = 0: 100%; BFBS2 = 25:75%; BFBS3 = 50:50%; BFBS4 = 75:25%; BFBS5 = 100: 0%. Both series used a control treatment which contained only substrate. The in vitro experiment was repeated 4 times and each treatment was done in duplicates. The measured variables were: total gas and CH4 productions, dry matter, organic matter, NDF degradability, NH3 and partial VFA concentrations. The results showed that the combination of biofat and biochar levels resulted in a significant decrease (P<0.01) of CH4 production in the rumen. CH4 production was 88.50% (BFBC1), 63.15% (BFBC2), 61.50% (BFBC3), 58.16% (BFBC4) and 73.93% (BFBC5) compared to control treatment (100% CH4 production). The combination caused higher NH3 at BFBC4 and significantly higher propionate and total VFA in the rumen than control. Dry matter degradation values increased by a combination level biofat and biochar (BFBC4 and BFBC5), but these results were the same as control. Addition of combination of biofat and biosmoke caused a significant decrease (P<0.01) of CH4 production in the rumen. CH4 production was 71.98% (BFBS1), 65.57% (BFBS2), 64.81% (BFBS3),60.21% (BFBS4) dan 80.72 (BFBS5) compared to control treatment (100% CH4 production). At BFBS4 level, NH3 production, DMD and OMD values were lower than control. In conclusion, the best combination producing synergistic effect as feed additive to reduce methane and increase ammonia in the in vitro rumen was combination of biofat and biochar (BFBC4=75: 25%) or biofat with biosmoke (BFBS4= 75: 25%).