Table_1_Effect of Padina gymnospora biowaste inclusion on in vitro methane production, feed fermentation, and microbial diversity.XLSX

In vitro studies were undertaken aiming to study the methane (CH4) mitigation potential of biowaste (BW) of Padina gymnospora at the graded inclusion of 0% (C), 2% (A2), 5% (A5), and 10% (A10) of the diet composed of straw and concentrate in 40:60 ratio. The chemical composition analysis revealed that the BW contained higher crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and ether extract (EE) than the PF (fresh seaweed, P. gymnospora). The concentration of cinnamic acid, sinapic acid, kaempferol, fisetin p-coumaric acid, ellagic acid, and luteolin in BW was 1.5–6-folds less than the PF. Inclusion of BW decreased (P < 0.0001) CH4 production by 34%, 38%, and 45% in A2, A5, and A10 treatments, respectively. A decrease (P < 0.0001) of 7.5%–8% in dry matter (DM) and organic matter (OM) digestibility was also recorded with the BW supplementation. The BW inclusion also decreased the numbers of total (P = 0.007), Entodinomorphs (P = 0.011), and Holotrichs (P = 0.004) protozoa. Metagenome data revealed the dominance of Bacteroidetes, Proteobacteria, Firmicutes, Actinobacteria, and Fibrobacter microbial phyla. At the phylum level, Euryarchaeota dominated the archaeal community, whereas Methanobrevibacter was most abundant at the genus level. It can be concluded that the inclusion of BW in straw and concentrate based diet by affecting rumen fermentation, protozoal numbers, and compositional shift in the archaeal community significantly decreased CH4 production. Utilization of biowaste of P. gymnospora as a CH4 mitigating agent will ensure its efficient utilization rather than dumping, which shall cause environmental pollution and health hazards.

本研究开展体外试验，旨在探究裸叶马尾藻（Padina gymnospora）生物废弃物（BW）在秸秆与精料质量比为40:60的基础日粮中的梯度添加效果，添加梯度分别为0%（对照组C）、2%（A2组）、5%（A5组）及10%（A10组），以评估其甲烷（CH4）减排潜力。化学成分分析结果显示，该生物废弃物（BW）的粗蛋白（CP）、中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）及乙醚浸出物（EE）含量均高于新鲜裸叶马尾藻（PF，P. gymnospora）。其所含肉桂酸（cinnamic acid）、芥子酸（sinapic acid）、山奈酚（kaempferol）、非瑟酮（fisetin）、对香豆酸（p-coumaric acid）、鞣花酸（ellagic acid）及木犀草素（luteolin）的浓度较新鲜海藻（PF）低1.5~6倍。添加生物废弃物（BW）可极显著降低甲烷（CH4）产生量（P < 0.0001），其中A2、A5及A10组的甲烷产量分别下降34%、38%及45%。同时，添加生物废弃物（BW）还使干物质（DM）与有机物（OM）的消化率降低7.5%~8%（P < 0.0001）。此外，生物废弃物（BW）的添加还显著减少了总原生动物（P = 0.007）、内纤毛虫类（Entodinomorphs，P = 0.011）及全毛类原生动物（Holotrichs，P = 0.004）的数量。宏基因组（Metagenome）数据显示，瘤胃微生物群落中拟杆菌门（Bacteroidetes）、变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）、放线菌门（Actinobacteria）及纤维杆菌门（Fibrobacter）的丰度占据主导地位。在门水平上，广古菌门（Euryarchaeota）为古菌群落的优势菌门；而在属水平上，甲烷短杆菌属（Methanobrevibacter）的丰度最高。综上，在秸秆-精料基础日粮中添加裸叶马尾藻生物废弃物（BW），可通过调控瘤胃发酵、改变原生动物数量及古菌群落组成，显著降低甲烷（CH4）产生量。将裸叶马尾藻（Padina gymnospora）生物废弃物用作甲烷减排剂，可实现其高效资源化利用，避免因随意丢弃造成环境污染与健康危害。