Effect of PICB on nutritional quality and bacterial community of High moisture ear corn with different moisture contents

High moisture era corn (HMEC) has become increasingly popular in dairy cow rations. However, the high moisture content of HMEC lead to protein hydrolysis during fermentation. This study aimed to find the effects of Polyphenols from involucres of Castanea mollissima Blume (PICB) on the nutritional quality, fermentation characteristic and microbial communities of HMEC with different moisture contents. Different level of PICB (CON, inoculated with LAB only; PICB1, LAB + 0.1% PICB; PICB2, LAB + 0.15% PICB; PICB3, LAB + 0.2% PICB) were added to chopped maize with cobs at different moisture contents (LM, 40% moisture contents; HM, 45% moisture contents) and silaged for 60 days. The results showed that crude protein (CP), dry matter (DM), neutral detergent fibres (NDF) contents in LM were highly significantly higher than in HM (p<0.01). Among the groups, PICB3 had the highest CP and DM contents, the lowest NDF contents. Lactic acid, the ratio of lactic acid/acetic acid (LA/AA) were significantly higher in LM than in HM, while pH, AA and ammonia nitrogen were highly significantly lower than in HM (p<0.01). Among the groups, PICB3 had the highest LA contents, the lowest NH3-N contents. The alpha diversity of the HMEC bacterial community with PICB was insignificant compared to CON. Spearman's correlation analysis showed that Lactobacillus were positively correlated with LA content. Weissella, Pantoea, Klebsiella and Serratia were positively correlated with ammonia nitrogen content. In conclusion, 0.2% PICB can be used as an additive to preserve nutrients and improve fermentation quality in HMEC.

高水分时代玉米（High Moisture Era Corn, HMEC）在奶牛日粮中的应用愈发广泛。然而，其高水分含量会引发发酵过程中的蛋白质水解。本研究旨在探究板栗总苞多酚（Polyphenols from involucres of Castanea mollissima Blume, PICB）对不同水分含量高水分时代玉米的营养品质、发酵特性及微生物群落的影响。将不同剂量的PICB添加剂（对照组（CON）：仅接种乳酸菌（Lactic Acid Bacteria, LAB）；PICB1组：LAB+0.1% PICB；PICB2组：LAB+0.15% PICB；PICB3组：LAB+0.2% PICB）添加至不同水分含量的带穗切碎玉米中（低水分组（LM）：水分含量40%；高水分组（HM）：水分含量45%），并进行60天青贮。结果显示，低水分组的粗蛋白（Crude Protein, CP）、干物质（Dry Matter, DM）及中性洗涤纤维（Neutral Detergent Fibers, NDF）含量均极显著高于高水分组（P<0.01）。各组间，PICB3组的CP与DM含量最高，NDF含量最低。低水分组的乳酸（LA）含量及乳酸/乙酸（LA/AA）比值极显著高于高水分组，而pH值、乙酸（AA）含量与氨态氮（NH3-N）含量则极显著低于高水分组（P<0.01）。各组间，PICB3组的LA含量最高，NH3-N含量最低。添加PICB的高水分时代玉米细菌群落α多样性（alpha diversity）与对照组无显著差异。斯皮尔曼相关性分析（Spearman's correlation analysis）显示，乳杆菌属（Lactobacillus）与LA含量呈正相关；魏斯氏菌属（Weissella）、泛菌属（Pantoea）、克雷伯菌属（Klebsiella）及沙雷氏菌属（Serratia）与氨态氮含量呈正相关。综上，0.2%的PICB可作为添加剂应用于高水分时代玉米，以保留其营养成分并优化发酵品质。