不同精粗比饲粮中添加壳聚糖对体外瘤胃发酵甲烷产量和发酵特性的影响

Effects of Chitosan Supplementation in Diets with Different Concentrate to Forage Ratios on Methane Production,and Fermentation Characteristics of in Vitro Ruminal Fermentation

本试验旨在利用长期人工瘤胃系统——Rusitec系统研究不同精粗比饲粮中添加壳聚糖对体外瘤胃发酵甲烷产量和发酵特性的影响。采用2×2两因子试验设计,2个因子分别为饲粮精粗比[30∶70(低精料饲粮)和70∶30(高精料饲粮)]和是否添加壳聚糖(0和1 500 mg/罐),共构成4组,每组4个重复。结果表明:与低精料饲粮相比,高精料饲粮显著降低了甲烷产量,中性洗涤纤维和粗蛋白质的降解率,发酵液乙酸和丁酸含量、乙酸/丙酸、氨氮浓度(P<0.05),显著提高了总产气量和丙酸含量(P<0.05);添加壳聚糖显著降低了甲烷产量和总产气量、粗蛋白质的降解率、发酵液乙酸和丁酸含量、乙酸/丙酸、氨氮浓度(P<0.05),显著提高了丙酸含量(P<0.05);在甲烷产量和总产气量,粗蛋白质的降解率,0、6 h发酵液氨氮浓度,0、12 h发酵液乙酸/丙酸上,2个因子存在互作(P<0.05),高精料饲粮中添加壳聚糖对甲烷产量和总产气量、粗蛋白质降解率、发酵液氨氮浓度的降低幅度大于低精料饲粮,对总挥发性脂肪酸浓度和乙酸/丙酸的降低幅度小于低精料饲粮。以上结果表明,改变饲粮的精粗比和添加壳聚糖均能够改变瘤胃发酵模式,且二者之间存在互作,壳聚糖在精粗比为70∶30的饲粮中添加效果优于精粗比为30∶70的饲粮。

This experiment was conducted to investigate the effects of chitosan supplementation in diets with different concentrate to forage ratios on methane production,and fermentation characteristics of in vitro ruminal fermentation using long-term artificial rumen system-Rusitec system. A 2 × 2 two factors experimental design was adopted. The two factors were dietary concentrate to forage ratios [30 ∶ 70（ lowconcentrate diet） and70 ∶30（ high concentrate diet） ],and with or without chitosan supplementation（ 0 and 1 500 mg / tank）. Four groups with four replicates were composed. The results showed as follows： compared with the lowconcentrate diet,high concentrate diet significantly decreased methane production,neutral detergent fiber and crude protein degradation rates,as well as acetic acid and butyric acid contents,acetic acid to acrylic acid ratio and ammonia nitrogen concentration of fermentation fluid（ P〈 0. 05）,and significantly increased total gas production and propionic acid content（ P〈 0. 05）; the supplementation of chitosan significantly decreased methane and total gas production,crude protein degradation rate,as well as acetic acid and butyric acid contents,acetic acid to acrylic acid ratio and ammonia nitrogen concentration of fermentation fluid（ P〈 0. 05）,and significantly increased propionic acid content（ P〈 0.05）; there were interaction effects between concentrate to forage ratio and chitosan on methane and total gas production,crude protein degradation rate,ammonia nitrogen concentration of fermentation fluid at 0 and 6 h and acetic acid to acrylic acid ratio of fermentation fluid at 0 and 12 h（ P〈 0.05）,methane and total gas production,crude protein degradation rate and ammonia nitrogen concentration of fermentation fluid were decreased by the supplementation of chitosan in high concentrate diet at a bigger range than that in lowconcentrate diet,while total volatile fatty acid concentration and acetic acid to acrylic acid ratio were decreased by the supplementation of chitosan in high concentrate diet at a lower range than that in lowconcentrate diet. In conclusion,changing of dietary concentrate to forage ratio and chitosan supplementation both can modify ruminal fermentation pattern,there is an interaction between the two factors,and the effects of chitosan supplementation in diets with 70∶30 of concentrate to forage ratio are better than those with30 ∶70.