摘要
Much attention has been drawn to the fatty acids (FA) present in the meat and milk from ruminant animals, which are often blamed for their high content of saturated FA, the intake of which is correlated with an increased risk of cardiovascular diseases in humans, and for the relatively low content of health promoting polyunsaturated FA (PUFA). Ruminal biohydrogenation (BH) can be manipulated to alter the amount of BH intermediates, such as PUFA, and decrease the flow of trans-10, cis-12 conjugated linoleic acid (CLA), which is an inhibitor for milk fat synthesis in dairy cattle. However, the BH of different FA in different feeds for ruminants is not fully understood in terms of microbes and metabolic processes related to BH. Methane mitigation and reducing the excretion of urinary N with dietary strategies are the major foci for ruminant nutritionists in terms of reducing the environmental impact of dairy operations. The combination of monensin and essential oil has been reported to surpress protozoa and methane production, while maintaining normal rumen function and minimizing the risk of metabolic diseases for cows in early lactation. A higher level of concentrate in the ration postpartum than prepartum places cows at high risk for rumen acidosis. Administration of the lactate utilizer, Megasphaera elsdenii, to ruminants has been suggested for reducing the incidence of acidosis.
In the first experiment, the objective was to determine the effects of raw and roasted soybeans, corn oil, soybean oil, and dried distillers grains with solubles (DDGS) and different particle sizes on the BH pattern of FA in vitro. Fat sources combined with grass hay were formulated to achieve 10% FA (dry matter basis; DMB) in each treatment. Incubation was maintained for 24 h in tubes, and fermentations of each treatment were stopped at 0, 1, 2, 4, 8, 12, 16 and 24 h. The fractional rates of disappearance of 18:2 and 18:3 were estimated by a single pool, first-order kinetic model. The BH differed with fat sources. Overall, DDGS had the highest BH among the treatments. Roasted soybeans, corn oil, and soybean oil had similar BH, which were lower compared with DDGS. Roasting and particle size did not affect overall BH. However, the roasting process and particle size affected the rate of disappearance of 18:2 in soybeans. Particle size exerted minimum effect on BH, but the particle sizes differed at most by 1 mm in this study.
The second experiment was conducted in a modified dual flow continuous culture system. The objective was to determine the effects of feeding Rumensin ® (ionophore with active component of monensin sodium) and Cinnagar ® (essential oil of cinnamon and garlic) in diets on ruminal fermentation characteristics. Four continuous culture fermenters were maintained in 4 periods in a 4 X 4 Latin square design with 4 dietary treatments arranged in a 2 x 2 factorial: (1) control diet, 40 g of a 50:50 concentrate:forage diet containing no additive; (2) Rumensin at 11g/909 kg of DM; (3) Cinnagar at 0.0043% (DM basis); and (4) a combination of Rumensin and Cinnagar at the levels used in (2) and (3). Protozoa counts were used to calculate their generation times. A by-difference procedure involving boiling and sonication was developed to determine the protozoal N per cell to minimize feed contamination. There were no effects of treatment on protozoal generic distribution, concentration of NH3-N, total N flow of effluent, production of total VFA, and flows of CLA and total C18.
In summary, the one-stage incubation in vitro allowed us to assess the BH of certain FA sources in a closed system. BH in vitro can provide information to relate BH of FA in different fat sources in vivo. The continuous culture system, as a two-stage in vitro incubation, with retained diverse protozoal population allowed the study on ruminal fermentation characteristics under different dietary conditions in a controlled environment. Further research is needed on cell size change of ruminal protozoa upon the Cinnagar addition and how to inhibit protozoa enough to decrease their negative effects but not so much to disrupt normal microbial ecology of the rumen. The study of dosing M. elsdenii to dairy cows shed light on the potential benefit of this probiotic on the ruminal conditions and performance of dairy cows. The molecular techniques allowed us to monitor the establishment and persistence of M. elsdenii in the rumen. A greater number of cannulated cows are needed to better understand the change of population of M. elsdenii. (Abstract shortened by UMI.)
摘要译文
反刍动物的肉类和牛奶中存在的脂肪酸（FA）引起了很多关注，这些脂肪酸通常是因为它们的饱和FA含量高而归咎于其摄入量，其摄入量与人类心血管疾病的风险增加有关以及相对较低的健康促进多不饱和FA（PUFA）的含量。可以操纵瘤胃生物氢化（BH）以改变BH中间体的量，例如PUFA，并减少Trans-10，CIS-12，CIS-12偶联的亚油酸（CLA）的流量，这是奶牛脂肪合成的抑制剂。但是，反刍动物不同饲料中不同FA的BH尚未完全了解与BH相关的微生物和代谢过程。在减少乳制品操作的环境影响方面，减少甲烷的缓解和减少尿液的排泄是反刍动物营养学家的主要重点。据报道，Monensin和精油的组合可以覆盖原生动物和甲烷的产生，同时保持正常的瘤胃功能，并最大程度地减少早期泌乳中牛代谢疾病的风险。量化产后的浓缩液比产前的浓缩物更高，使母牛面临瘤胃酸中毒的高风险。建议对反刍动物的Megasphaera Elsdenii施用用于降低酸中毒的发生率。在第一个实验中，目的是确定生和烤大豆，玉米油，大豆油和带有溶解性的干式酿酒厂（DDGS）和不同粒径对体外FA的BH模式的影响。在每种处理中，配制了与草干草结合的脂肪来源，以达到10％的FA（干物质基础； DMB）。在试管中保持孵育24小时，每种处理的发酵在0、1、2、4、8、12、16和24小时停止。通过单个池，一阶动力学模型估算了18：2和18：3的消失速率。 BH与脂肪来源不同。总体而言，DDGS在治疗中的BH最高。烤大豆，玉米油和大豆油的BH相似，与DDG相比，它们的BH较低。烘烤和粒径不会影响整体BH。但是，烘焙过程和粒径影响了大豆中18：2的消失率。粒径对BH的最小效应施加的效果，但在本研究中，粒度最大差异为1 mm。第二个实验是在修改的双流连续培养系统中进行的。目的是确定喂食Rumensin ®（带有Monensin钠的活性成分的离子载体）和cinnagar ®（肉桂和大蒜的精油）在乳液发酵中的影响特征。在4 x 4拉丁方形设计中，在4个时期内将四个连续培养发酵罐保持在4个时期，其中4种饮食治疗在2 x 2阶乘中排列：（1）控制饮食，40 g 50:50浓缩液：不含添加剂的草料饮食； （2）rumensin在11g/909 kg的DM处； （3）cinnagar为0.0043％（DM基础）； （4）在（2）和（3）中使用的水平上的Rumensin和Cinnagar的组合。原生动物计数用于计算其生成时间。开发了一个涉及沸腾和超声处理的偏差程序，以确定每个细胞的原生动物N，以最大程度地减少饲料污染。治疗对原生动物通用分布，NH 3 -N的浓度，流出的总N流，总VFA的产生以及CLA和总C18的流量没有影响。总之，体外的单阶段孵育使我们能够评估封闭系统中某些FA源的BH。 BH在体外可以提供信息，以在体内不同脂肪来源中关联FA的BH。连续培养系统作为两阶段的体外孵化，具有多种多样性的原生动物种群，可以研究在受控环境中在不同饮食条件下进行瘤胃发酵特征。需要进一步研究瘤胃原生动物的细胞尺寸变化，以及如何抑制原生动物足以降低其负面影响，但不会破坏瘤胃的正常微生物生态学。对奶牛的剂量分枝杆菌的研究揭示了这种益生菌对奶牛的瘤胃条件和性能的潜在益处。分子技术使我们能够监测瘤胃中Elsdenii的建立和持久性。需要更多的插管奶牛来更好地了解Elsdenii M. Elsdenii的变化。 （摘要由UMI缩短。）
Ye, Danni. Examining the effects of adding fat, ionophores, essential oils, and Megasphaera elsdenii on ruminal fermentation with methods in vitro and in vivo[D]. US: The Ohio State University, 2013