单宁和聚乙二醇对绵羊和山羊瘤胃纤维降解菌数量的影响

摘要

本文旨在研究饲粮中添加不同水平的单宁和高单宁饲粮条件下添加聚乙二醇( PEG )对绵羊和山羊瘤胃纤维降解菌数量的影响。试验选用1.5岁、体重约45 kg、安装永久性瘤胃瘘管的绵羊和绒山羊各4只,采用自身对照试验设计,分4期进行。第1期饲喂基础饲粮(Ⅰ组),第2期在基础饲粮中添加2%的单宁(Ⅱ组),第3期在基础饲粮中添加6%的单宁(Ⅲ组),第4期在基础饲粮中添加6%单宁+12% PEG(Ⅳ组)。每期试验30 d,其中预试期12 d,正试期18 d。每个正试期第1天,采集绵羊和山羊瘤胃内容物,测定瘤胃液pH、氨态氮( NH3-N)和菌体蛋白( MCP)浓度；运用实时定量PCR技术对固相、液相及全食糜中所附着的白色瘤胃球菌、黄色瘤胃球菌、产琥珀酸拟杆菌进行定量检测。结果表明：1)与Ⅰ组相比,添加6%单宁显著降低了山羊瘤胃液NH3-N浓度和绵羊瘤胃液MCP浓度( P<0.05)。添加6%单宁+12% PEG后,这2个指标恢复至与Ⅰ组相当的水平。2)与Ⅰ组相比,添加6%单宁显著降低了绵羊和山羊瘤胃固相、绵羊瘤胃液相白色瘤胃球菌数量( P<0.05)；添加2%和6%单宁显著降低了绵羊和山羊固相黄色瘤胃球菌数量( P<0.05),添加6%单宁显著降低了绵羊和山羊瘤胃液相黄色瘤胃球菌数量( P<0.05)；添加6%单宁显著降低了绵羊和山羊瘤胃固相、绵羊全食糜产琥珀酸拟杆菌数量( P<0.05)。添加6%单宁+12% PEG后,绵羊和山羊瘤胃这3株纤维降解菌数量恢复至Ⅰ组水平或高于Ⅰ组。由此可见,饲粮单宁添加量达到6%时降低了瘤胃液NH3-N的浓度,影响MCP的合成,抑制瘤胃固相纤维降解菌的增殖；添加PEG可以削弱单宁对瘤胃纤维降解菌生长的负面影响,促进瘤胃发酵。%This paper studied the effects of different dietary tannin levels and high tannin diets supplemented with polyethylene glycol ( PEG) on ruminal cellulolytic bacteria quantity in sheep and goats. Four sheep and four cashmere goats aged 1.5 years, weighted 45 kg and fitted with permanent ruminal cannulas were selected as experimental animals. Own control experimental design was used, and the study was conducted in consecu-tive four periods. Animals in the four periods were fed a basal diet ( period 1, group Ⅰ) , and the basal diet supplemented with 2% tannin ( period 2, group Ⅱ) , 6% tannin ( period 3, group Ⅲ) and 6% tannin + 12%PEG ( period 4, group Ⅳ) , respectively. Each period lasted for 30 days consisted of a 12-day pre-test period and 18-day test period. On the 1st day of each test period, ruminal content was collected, rumen fluid pH, and the concentrations of ammonia nitrogen ( NH3-N) and microbial protein ( MCP) were measured, and real-time PCR was used to quantify R. albus, R. flavefaciens and F. succinogenes adherent to solid phase, liquid phase and full chyme. The results showed that as follows: 1) compared with group Ⅰ, the supplementation of 6%tannin significantly decreased NH3-N concentration in rumen fluid in goats and MCP concentration in rumen fluid of sheep ( P<0.05) . These two indices recovered to the same level with group Ⅰ after the supplementa-tion of 6% tannin+12% PEG. 2) Compared with groupⅠ, the supplementation of 6% tannin significantly de-creased the quantity of R. albus in solid phase of ruminal content in sheep and goats, and in liquid phase of ru-minal content in sheep ( P<0.05);the supplementation of 2% and 6% tannin significantly decreased the quan-tity of R. flavefaciens in solid phase of ruminal content in sheep and goats ( P<0.05) , and the supplementation of 6% tannin significantly decreased the quantity of R. flavefaciens in liquid phase of ruminal content in sheep and goats ( P<0.05);the supplementation of 6% tannin significantly decreased the quantity of F. succinogenes in solid phase of ruminal content of sheep and goats, and in full chyme of ruminal content in sheep ( P<0.05) . The quantity of the three cellulolytic bacteria recovered to the same or above level with group Ⅰ after the sup-plementation of 6% tannin+12% PEG. In conclusion, dietary supplementation of 6% tannin can decrease NH3-N concentrations, affect MCP synthesis in rumen fluid, and reduce the quantity of cellulolytic bacteria in rumen; the negative effects of tannin on proliferation of ruminal cellulolytic bacteria were impaired by adding PEG, ruminal fermentation were also improved.