Investigating the effects of pine biochar on intake and digestibility in beef steers consuming forage

Biochar is a charcoal-like material made from burned organic material of agricultural or forestry biomass. Pyrolysis, the primary method of biochar production, is achieved in limited oxygen conditions which allows the thermally altered biomass to retain most of its carbon. Biochar has potential to enhance soil health and sequester carbon in soils, but must be mixed with an organic material, such as urine or manure, to maximize effectiveness. Feeding biochar to cattle allows them to deposit biochar-enriched manure onto pasture without human intervention while simultaneously receiving any potential benefits associated with 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 steers were utilized in a 4 × 4 Latin square with four 14-d periods, consisting of an 8-d treatment adaptation (d 1 to 8), fecal and diet sampling for intake and digestibility (d 9 to 13) and rumen fluid sampling (d 14). 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 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 (4.29 kg/d) and steers receiving 2.4% biochar consumed the least (3.53 kg/d). There were no linear (P ≥ 0.11) or quadratic effects (P ≥ 0.31) of biochar inclusion on measures of digestibility; organic matter digestibility averaged 64.6% across treatments. Our observations suggest that pinewood derived biochar supplemented from 0.8% to 2.4% of intake did not significantly affect diet utilization, but the tendencies and numerical depressions observed suggest moderate (1.6%) and high (2.4%) doses of biochar may have practical concerns. However, there were methodological limitations that affected our ability to draw definitive conclusions, and further research is necessary to confirm these findings.