PS3-10. Forage Utilization and Rumen Fermentation Responses to Different Types of Biochar in Beef Steers.

Abstract Biochar is a charcoal-like material made from the burned organic matter 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. When applied to soils, biochar improves health parameters (e.g., water holding capacity), but must be mixed with an organic material, such as urine or manure, to maximize effectiveness. Further, integrating biochar into soil is labor intensive. Feeding biochar to grazing cattle allows them to self-apply the amended manure to soils, inoculating ingested biochar with rumen microbes and activating it with digestive waste, while also receiving potential benefits associated with biochar consumption (e.g., reduced enteric methane). Previous research has examined the effects of feeding various types of biochar to cattle on intake, digestibility, microbial populations, and methane output; however, there has not yet been a direct comparison of the effects of different types of biochar on these outcomes despite there being stark differences in characteristics of biochar produced from different substrates. Accordingly, the objective of this study was to evaluate diet utilization and fermentation in beef steers fed biochar produced from different substrates. Steers were fed one of five treatments in addition to ad libitum hay, alfalfa cubes (20% of previous 3-d hay intake [as-fed]), and cottonseed meal ([CSM] 125 mg N/kg BW): no biochar (CON) or biochar produced from either pecan shells (PC), pine wood (PW), mixed brush (MB), or bamboo (BB) provided at 1.6% of the previous 3-d hay intake. There was no effect of treatment (P = 0.40) on hay organic matter intake (OMI), which averaged 5.08 kg/d. There was also no effect of treatment (P = 0.52) on total OMI, which averaged 6.59 kg/d across treatment. Total OMI included hay, alfalfa (1.01 kg/d), CSM (0.45 kg/d), and biochar. There was no treatment effect on alfalfa or CSM OMI (P ≥ 0.75), but there an effect on biochar OMI (P < 0.01) such that CON OMI (0 kg/d) was significantly lower (P < 0.01) than MB (0.08 kg/d), PC (0.08 kg/d), and PN (0.09 kg/d). Further, BB OMI (0.03 kg/d) was also significantly lower (P ≤ 0.02) than MB, PC, and PN. There were not differences (P ≥ 0.09) in OMI across MB, PC, and PN. There was no effect of treatment on ruminal ammonia N (P = 0.66), which averaged 2.7 mM across treatments, or ruminal pH (P = 0.19), which averaged 6.73. Our observations suggest that biochar type did not affect intake and fermentation parameters in beef steers consuming a basal forage diet. Further research is necessary to evaluate how different biochar types may affect rumen microbial communities.