Abstract

A three-year beef cow grazing study (2020-2022) was conducted to evaluate the effects of biochar supplementation on grazing cow performance, ruminal fermentation, fecal egg and oocyst count, fecal nutrient composition, and enteric methane (CH₄) and carbon dioxide (CO₂) emissions. Each year, forty-eight spring-calving Angus beef cows (BW = 669 ± 95 kg; mean ± STD) stratified by BW, were randomly assigned to 1 of 2 treatments. Treatments included either (i) pelleted supplement with biochar (Biochar; 405 g/d) inclusion at 2.2% of DMI or (ii) control pellet (Control; base fiber - no biochar). Twenty-four ha meadow bromegrass (Bromus riparius Rehm.)-alfalfa (Medicago sativa L.) paddocks (8.6% CP, 51.1% TDN) were assigned to each treatment group for the 92-d grazing trial. Enteric CH₄ and CO₂ emissions were measured using SF₆ tracer gas technique. Cow and calf performance, rumen fluid parameters were not (p > 0.05) affected by biochar supplementation. During trial biochar supplementation reduced fecal oocyst (Eimeria spp.) count (p < 0.011; 3.9 vs. 15.0 count/g DM) but increased carbon:nitrogen ratio (p < 0.029; 26.1 vs. 21.3) relative to initial measurements. The enteric methane emission reduction in response to biochar supplementation at 2.2% of DMI, was negligible (~6.0% reduced compared to control).

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