不同能量水平及玉米加工饲粮对瘤胃体外发酵参数的影响

利用体外产气法研究不同能量水平与不同加工方式玉米对瘤胃体外发酵参数的影响。试验以玉米秸秆为主要粗饲料来源设计精粗比为65∶35的等氮饲粮,选用玉米青贮与过瘤胃脂肪调整低、高能量水平,普通玉米与蒸汽压片玉米作为不同加工方式,采用2×2因子试验设计。结果表明,高能水平饲粮的理论最大产气量、48 h总产气量、干物质降解率均显著高于低能(P0.05),普通玉米高能组的乙酸、丙酸含量显著高于低能组(P0.05)。同一能量水平下,蒸汽压片处理组的48 h总产气量均显著高于普通玉米组(P0.05);而低能条件下蒸汽压片组的总挥发酸、丙酸含量显著高于普通玉米组(P0.05)。不同饲粮营养水平与体外产气参数相关性分析表明48 h总产气量与中性洗涤纤维(NDF)呈显著负相关(P0.05),与中性洗涤可溶物(NDS)、非纤维性碳水化合物(NFC)和NDS/CP呈显著正相关(P0.05)。因此,使用蒸汽压片方式处理玉米以及提高饲粮能量水平均可以显著增加体外发酵48 h总产气量;低能水平下,蒸汽压片玉米对改善瘤胃的发酵特性更为明显。

Effects of different energy levels and corn processing diets on ruminal fermentation parameters in vitro

In vitro batch cultures were grown to investigate the effect of different energy levels and corn pro-cessing diets on ruminal fermentation parameters in a 2×2 factorial experiment.Isonitrogenous diets were con-structed with a concentrate-to-forage ratio of 65∶35 using corn straw as the main forage,and corn silage and rumen-protected fat were added to adjust the diets’energy levels.In addition,steam-flaked corn and ground corn were tested as different corn processing products.The results showed that the theoretical maximum gas production,48 h total gas production and dry matter degradability of the high-energy diets were significantly higher than for the low energy diets (P <0.05).The acetate and propionate of high-energy diets were signifi-cantly higher than low-energy diets with ground corn (P <0.05).At the same energy level,the 48 h total gas production of diets with steam-flaked corn was higher than for ground corn (P <0.05).Furthermore,at the low-energy level the total volatile fatty acid and propionate of diets with steam-flaked corn were higher than for ground corn (P <0.05).Correlation analysis between the different feed nutrition levels and fermentation pa-rameters in vitro showed that 48 h total gas production was significantly negatively related to neutral detergent fiber (P <0.05),while it had a significantly positive correlation with neutral detergent-soluble (NDS)and non-fiber carbohydrates and with NDS/crude protein (P <0.05).In conclusion,both steam-flaked corn and high-energy level diets can increase 48 h total gas production in vitro ,and steam-flaked corn can improve ruminal fermentation under low-energy level diets.