71. Effect of Increasing Amounts of Pine Derived Biochar on Forage Utilization in Beef Steers

Abstract Biochar is a charcoal-like material made from the burned organic material of agricultural or forestry biomass. Pyrolysis, the primary method of biochar production, is achieved in limited oxygen conditions which allows the decomposed biomass to retain most of its carbon content. Biochar has the potential to enhance soil health, sequester carbon, and reduce enteric methane emissions in cattle. Previous research indicates that biochar must be mixed with an organic material, such as urine or manure, to be an effective soil amendment. Feeding biochar directly to cattle allows them to self-apply the amended manure to the soil without human intervention while simultaneously receiving the potential benefits associated with biochar consumption. The objective of this study was to evaluate diet utilization in beef steers fed one of four treatments in addition to a basal forage diet: no biochar (CON), or a pinewood-based biochar provided at 0.8%, 1.6%, or 2.4% of the previous 3-d forage intake. Four ruminally cannulated beef steers were utilized in a 4´4 Latin square with four 14-d periods where 8-d were for treatment adaptation, 5-d were for measures of intake and digestibility, and 1-d was for measures of rumen fermentation. Steers had ad libitum access to hay and water and were offered treatments once daily mixed with cottonseed meal provided at 125 mg N/kg BW. Statistical analyses were conducted in SAS and employed orthogonal contrasts with fixed effects of treatment and period and a random effect of steer. There was a tendency for biochar to linearly affect (P = 0.08) forage organic matter intake (FOMI) where FOMI was 5.23 kg/d for CON, 4.96 kg/d for 0.8% biochar, 4.52 kg/d for 1.6% biochar, and 4.54 kg/d for 2.4% biochar. There was also a linear trend (P = 0.08) for total digestible organic matter intake (TDOMI) where CON steers consumed the most TDOMI (5.52 kg/d) and steers receiving the moderate dose of biochar (1.6%) consumed the least (4.82 kg/d). There were no linear (P ≥ 0.18) or quadratic effects (P ≥ 0.21) of biochar inclusion on measures of digestibility; organic matter digestibility averaged 87.9% across treatments. Our observations suggest that pinewood derived biochar supplemented from 0.8-2.4% of intake did not significantly affect diet utilization, but the tendencies and numerical depressions observed suggest the moderate (1.6%) and high (2.4%) doses of biochar may have practical concerns. Further research is necessary to confirm these findings and evaluate biochar produced from different substrates.