海南霉素对体外瘤胃微生物发酵和氮代谢的影响

Hainanmycin:Effects on Rumen Microbial Fermentation and Nitrogen Metabolism in Vitro

本试验旨在研究海南霉素对体外瘤胃微生物发酵和氮代谢的影响。试验采用体外24 h培养的方法来评价海南霉素的作用,其中体外培养底物(粗蛋白质18%,中性洗涤纤维30%,酸性洗涤纤维22%)精粗比为40∶60。试验分对照组(CON)、10 mg/L莫能菌素组(MON,阳性对照)以及0.1、1.0、10.0和100.0 mg/L海南霉素组(H0.1、H1.0、H10.0和H100.0)共6个组。发酵24 h后立即测定pH,然后采集样品用于挥发性脂肪酸(VFA)、氨态氮(NH3-N)、肽、氨基酸、蛋白酶和脱氨酶的测定及DNA的提取。结果显示,与CON相比,H100.0显著降低了总VFA浓度并提高了pH(P<0.05);H10.0、H100.0和M ON显著降低了乙酸、丁酸浓度以及乙酸与丙酸比(P<0.05),显著提高了丙酸浓度(P<0.05)。H0.1和H1.0对瘤胃微生物发酵无显著影响(P>0.05)。H10.0、H100.0和MON增加了肽、氨基酸浓度和蛋白酶活性(P<0.05),但显著降低了NH3-N浓度和脱氨酶活性(P<0.05)。H10.0、H100.0和M ON也显著增加了栖瘤胃普雷沃氏菌(Prevotella ruminicola)和总普雷沃氏菌(genus Prevotella)的相对拷贝数(RPS),显著减少了原虫(protozoa)的RPS(P<0.05)。H10.0、H100.0和MON显著减少了溶纤维丁酸弧菌(Butyrivibrio fibrisolven)的RPS(P<0.05),对反刍兽新月形单胞菌(Selenomonasruminantium)、埃氏巨球型菌(Megasphaera elsdenii)和嗜淀粉瘤胃杆菌(Ruminobacter amylophi-lus)均无显著影响(P>0.05)。结果提示,从对瘤胃发酵调控和增加非NH3-N流量2方面考虑,10.0 mg/L海南霉素为最适剂量;海南霉素对瘤胃发酵的调控模式与莫能菌素相似;海南霉素是通过对普雷沃氏菌属细菌和原虫的数量的影响来调控氮代谢。

The effects of hainanmycin on rumen microbial fermentation and ruminal nitrogen metabolism in vitro were investigated in this study.Four doses of hainanmycin were evaluated using a 24 h batch culture of rumen fluid in vitro,with a forage-to-concentrate diet ratio of 60∶ 40（18% crude protein,30% neutral detergent fiber,and 22% acid detergent fiber）.The groups were as follows： control group（CON）,10 mg/L monensin group（MON,positive control group）,and the four doses of hainanmycin groups（H0.1,H1.0,H10.0 and H100.0）,i.e.,0.1,1.0,10.0 and 100.0 mg/L hainanmycin.After 24 h,the pH was immediately measured.Samples were collected and analyzed for concentrations of peptide,amino acids,ammonia nitrogen（NH3-N） and volatile fatty acids（VFA）,activities of protease and deaminase,and DNA isolation.The results showed that H100.0 decreased the total VFA concentration and increased the final pH（P0.05）.H10.0,H100.0 and MON reduced the acetate-to-propionate ratio,as well as the concentrations of acetate and butyrate,but increased the propionate concentration compared with CON（P0.05）.H0.1 and H1.0 had no significant effects on rumen microbial fermentation（P0.05）.H10.0,H100.0 and MON increased protease activity and concentrations of amino acids and peptide（P0.05）,but decreased NH3-N concentration and deaminase activity（P0.05）.H10.0,H100.0 and MON also increased the relative population size（RPS） of Prevotella ruminicola and genus Prevotella,but reduced the RPS of protozoa（P0.05）.H10.0,H100.0 and MON had no significant effects on the RPS of Selenomonas ruminantium,Megasphaera elsdenii and Ruminobacter amylophilus（P0.05）,but significantly decreased the RPS of Butyrivibrio fibrisolvens（P0.05）.In terms of improving rumen fermentation and increasing non-ammonia nitrogen flow,appropriate dose of hainanmycin is 10.0 mg/L.Moreover,Hainanmycin exhibited an action similar to that of monensin on the mode of rumen fermentations.In addition,hainanmycin regulated nitrogen metabolism by changing the number of Prevotella and protozoa.