【作者】 沈维军；

【导师】 王加启； 贺建华；

【作者基本信息】 湖南农业大学 ， 生理学， 2012， 博士

【摘要】 本文研制了一套新型全自动控制双外流连续培养瘤胃模拟系统,对其综合性能进行了测试,研究了液相稀释率对系统发酵参数的影响,最后用尼龙袋法对系统日粮营养价值评定的准确性进行了评测。首先在综合分析了目前国内外人工瘤胃模拟系统的结构和运行性能的基础上,对新型双外流连续培养瘤胃模拟系统的工作原理和结构进行了初步研究,结合反刍动物瘤胃结构,确定了系统的主要构成部分为发酵罐、搅拌装置、排液装置、排固装置和排气装置。以发酵罐为系统为设计的关键点,结合了产气法差压排气的原理,进行了双外流连续培养系统结构方面的研制。通过对现有瘤胃模拟装置排气、排固、搅拌方式的比较,采用了差压排气、底部筛分排固、密闭排液的方式,并对本系统进行了整机设计。综合了DCS控制系统和嵌入系统的特点,以嵌入式系统的稳定性和DCS控制模式的可扩展性为中心点,以上层管理的应用便捷性与功能多样性为出发点,确定了整个控制系统总体构成模式,设计了监控层和直接控制层硬件,编写了管理层、监控层和直接控制层软件,开发了一套基于DCS控制模式的双外流连续培养瘤胃模拟装置自动控制系统。其次对新型双外流连续培养瘤胃模拟系统性能进行了综合测试试验。试验结果表明：该瘤胃模拟系统稳定期为4d,从第5d可以进入试验期下；进入稳定期后,4个发酵罐平行性好,大部分发酵参数与反刍动物体内接近,因此该系统可再现反刍动物瘤胃体内发酵状况。而且与目前现有的瘤胃模拟装置相比,解决了连续培养发酵罐内固体食糜累积的问题。同时将批次培养系统(产气法)和连续培养系统(双外流)完美结合。最后研究液相稀释率对系统发酵参数的影响,并进一步验证了系统工作的稳定性。研究结果表明：①无论在高稀释率还是低稀释率条件,本次设计的双外流连续培养系统适应期和试验期各发酵参数波动较小,说明了系统工作的稳定性。②液相稀释率从8%/h增加到12%/h,发酵罐内容物pH和NH3-N浓度显著升高、溢流液中VFA的浓度下降,但对乙酸／丙酸比例没有影响;日粮中常规营养成分DM、OM、CP、NDF降解率随着稀释率增加虽有下降,但差异不显著;日粮中EE降解率与发酵罐内容中原虫数量、酶活、微生物蛋白都不受稀释率的影响。采用尼龙袋法对系统营养价值日粮评定的准确性进行了评测。评测结果表明：双外流连续培养法测定混合日粮的DM、OM、CP、NDF的降解率与尼龙袋法测定的瘤胃内48h降解率相吻合,差异不显著。说明本研究设计的双外流连续培养瘤胃模拟系统能很好的再现反刍动物瘤胃发酵环境。更多还原

【Abstract】 A novel dual-flow continuous culture rumen simulating system by auto controlled was designed in present study. A series of experiments were conducted to test the instrutment performance, analyze the change of fermentation parameters with different dilution rate, and compare the feed digestion between continuous culture rumen simulating stystem and nylon bag.First, the working principle and structure of novel continuous culture rumen simulating system was researched on the bases of structure and performance for all the continuous culture system all over the world. The novel dual-flow continuous culture rumen simulating system combined with the performance of rumen in ruminant contains fermenter, mixing device, and liquid, solid and gas discharge device. The first component is the fermenter which is the key point of design. The other four components includ stirring shaft, liqiud over-flowing apparatus, solid chyme discharging and gas exhausting apparatus. Furthermore these five components were organized in the final design. The typic characteristics of the system are exhausting gas with differential pressure switch, discharging solid chyme with sieving and over-flowing liquid in closed condition.Second, based on the stability of embeded system, the expansibility of DCS and the flexibility in use and operation of upper management computer, the auto control model was conducted. A set of auto control system of the continuous culture system based on DCS and embeded system was designed. The hardware of the direct and supervisory control layer was produced. Furthermore the software of the upper management computer, the dirrect and supervisory control layer was programed.Third, a comprehensive test for this novel dual-flow continuous culture system was conducted in present study. The results demonstrated there was4days adaptation and the system would be stabled from the5th days incubation to the last day. The results during the experiment period shown that there were parallelism among four fermenters, and most parameters for four fermenters were similar to the animal, so the system is a effective equipment to simulate the rumen fermentation. Compared with the currently continuous culture system, it was effective to solve problem for the solid chyme accumulation in fermenter, and it was a combination with the batch culture (in vitro gas production) and continuous culture system.Fourth, the effect of dilution rate on the rumen fermentation was conducted in order to evaluate the stable of present system.The results shown that:the fluctuation of the fermenter during adapation and sampling period were very small no matter how dilution rate it was; the pH and NH3-N concentration in rumen fluid were significant increasing following by the increase of dilution rate from8%/h to12%/h, but the VFA were decreased. There were no differ for the ratio of acetate and propionate; The digestibility of DM, OM, CP, and NDF shown a little decrease, but there were no difference for the treatment of dilution rate.The digestibility of EE, protozoal number, enzyme for cellulose and strarch degradation, and microbial protein were not affected by the dilution rate.Fifth, the technology of nylon bag was used to evaluate the nutrition of same feed which was also used in present system. The digestibilty of feed in continuous cultures sytem were coincided with the value of feed in nylon bag, and there were no differfor both way.更多还原