Composition and nutrient level of the basal diet.

ContextCotton stalk valorization is limited by high lignification, resulting in waste and environmental issues. Biochar, a pyrolysis-derived material, shows promise in reducing ruminant methane emissions. Aims: This study investigates the effects of cotton stalk biochar (CSB) as a feed additive on rumen fermentation, methane emissions, microbial communities, and nutrient degradation in dairy cows.MethodsCotton stalks were air-dried, cut into 2–3 cm segments, oven-dried at 105°C for 6 h, ground through an 80-mesh sieve, and pyrolyzed under N2 (0.5 L/min) at 13.3°C/min to 400°C with a 3 h hold to produce CSB. CSB was added to diets at 0%, 3%, and 6% levels. Each treatment was conducted in triplicate, with two fermentation bottles for each replicate. Rumen fermentation was simulated using an in vitro static culture method with rumen fluid from Holstein dairy cows. Fermentation parameters, gas production, nutrient disappearance, microbial populations, and metabolites were analyzed.Key ResultsCSB addition increased rumen pH and significantly reduced total gas, CH4, CO2, and H2 production (P Implication.The addition of 3% CSB can reduce in vitro gas production in the rumen of dairy cows.

研究背景：棉花秸秆因高度木质化，其资源化利用受到极大限制，进而造成资源浪费与环境问题。生物炭（Biochar）是一种热解衍生材料，在降低反刍动物甲烷排放方面展现出应用潜力。研究目的：本研究旨在探究棉花秸秆生物炭（Cotton stalk biochar, CSB）作为饲料添加剂，对奶牛瘤胃发酵、甲烷排放、微生物群落及营养物质降解的影响。研究方法：将棉花秸秆风干后切割为2~3 cm的小段，于105℃烘箱中干燥6 h，随后过80目筛粉碎；在流量为0.5 L/min的氮气氛围下，以13.3℃/min的升温速率加热至400℃并保温3 h进行热解，制备得到CSB。将CSB以0%、3%、6%的比例添加至奶牛日粮中。每组处理设置3次重复，每个重复对应2个发酵瓶。采用体外静态培养法，以荷斯坦奶牛的瘤胃液模拟瘤胃发酵环境，随后对发酵参数、产气量、营养物质消失率、微生物种群及代谢产物进行分析。主要结果：添加CSB可提升瘤胃pH值，并显著降低总气体、甲烷（CH4）、二氧化碳（CO2）及氢气（H2）的产生量。研究启示：添加3%的CSB可降低奶牛瘤胃体外发酵的产气量。