Fermentation of plant cell walls by ruminal bacteria,protozoa and fungi and their interaction with fibre particle size

Abstract

The objective of the experiment was to evaluate the contribution of various ruminal microbial groups to the fermentation of cell walls of corn stover with different particle sizes based on ruminal gas production in vitro. Physical, chemical, and antibiotical methods were used to differentiate groups of bacteria, protozoa and fungi in rumen fluid, offering following rumen microbial groups: whole rumen fluid (WRF), bacterial (B), protozoal (P), fungal (F), bacterial plus protozoal (B + P), bacterial plus fungal (B + F), protozoal plus fungal (P + F), and negative control (CON). Cell walls from corn stover were ground and ball milled to produce two different particle sizes. The results showed that digestion of the cell walls was undertaken by the interaction among ruminal bacteria, protozoa and fungi, and such co-actions seemed to fail alternation by one of three microbial groups or any combinations. However, B + P group showed a significant contribution to the degradation of milled cell walls, and B + F group revealed a great synergy effect on the ground cell walls degradation. Particle size of cell walls also had a considerable influence on their fermentation extent instead of the fermentative patterns by various rumen microbial groups.     

Changes in pig diet particle size profile and nutrient content during on-farm storage and distribution to the feeders

The present study assessed the effect of silo emptying and feed transport by conveyor systems on particle size and nutrient content of the feed delivered to the pigs. Experiment 1 sampled feed from four feeders along the conveyor system of two barns. Samples were taken immediately after filling the feed silo (Begin) and when the silo was almost empty (End). In Experiment 2, three barns with drag-type conveyors, three with auger-type conveyors and two with spiral-type conveyors were sampled. Along the different conveyors, samples at 10, 20, 50 and 85 m distance from the feed silo were taken from the feeders. In each barn, sampling was repeated for two subsequent batches of feed delivered. In all samples, particle size profile was determined and nutrient content was analysed. In Experiment 2, mineral content was also determined. In Experiment 1, the size of the different particle fractions decreased from Begin to End. An interaction (p < 0.05) between sampling time and conveyor type was detected for the 10% smallest particles. In Experiment 2, an effect of sampling time on the 10% largest particles was detected (p < 0.05). The effect of sampling time on several nutrients was observed in Experiments 1 and 2, but the affected nutrients differed between both experiments. Results implied that it was mainly emptying of the silo that affected mash particle size profile and nutrient content. The potential impact of these changes on pig performance requires further investigation.     

Evaluation of the effects of dietary particle fractions on fermentation profile and concentration of microbiota in the rumen of dairy cows fed grass silage-based diets

The study evaluated the effects of three different theoretical particle lengths (TPL) of grass silage on the distribution of particle fractions of the diet and the resulting effects on fermentation profile and concentrations of protozoa and mixed bacterial mass in the rumen of three lactating Holstein cows fed total mixed rations (45% grass silage, 5% grass hay and 50% concentrate) ad libitum. Decreasing TPL of grass silage (long, medium, short) reduced particles retained on the 19-mm sieve of the Penn State Particle Separator, while particle fractions from 8 mm to 19 mm and smaller than 8 mm were increased. Different TPL did not affect pH and the concentration of volatile fatty acids in the rumen. However, lowering the TPL from long to medium increased significantly the bicarbonate concentration, acetate proportion and protozoal number in the rumen, whereas the proportion of bacterial protein in ruminal digesta and its amino acid concentration were significantly increased by the short TPL. For the current feeding conditions, it can be concluded that increasing the fraction of particles between 8 and 19 mm and probably even the fraction below 8 mm by decreasing TPL of grass silage do not adversely affect rumen conditions and can be beneficial in terms of optimising concentration and activity of ruminal microbiota in high-yielding dairy cows.     

松褐天牛产卵刻痕在黑松树干上分布规律的研究

调查和分析了松褐天牛Monochamus alternatusHope的产卵刻槽在寄主植物黑松上的分布情况,结果表明：产卵刻槽分布与寄主胸径和树高有一定的相关关系,黑松树干胸径在9～15 cm之间,树高在4～7 m之间最适合天牛产卵危害,其中在胸径9～13 cm范围内产卵刻槽数量最多,在此范围的寄主受天牛为害最重。天牛在胸径＞17 cm或树高＞7 m时,没有产卵刻槽分布。产卵刻槽集中分布于树干1～2 m位置,3 m以上很少有刻槽分布,同时,天牛产卵多在光线充足的地方,其中南面产卵刻槽数量最多。     

Oxidative-damage effect of Fe3O4 nanoparticles on mouse hepatic and brain cells in vivo

To assess the biological safety of Fe3O4 nanoparticles （NPs）, the oxidative-damage effect of these NPs was studied. Twenty-five Kunming mice were exposed to Fe3O4 NPs by intraperitoneai injection daily for 1 week at doses of 0, 10, 20, and 40 mg.kg1. Five Kunming mice were also injected with 40 mg.kg 1 ordinary Fe3O4 particles under the same physiological conditions. Biomarkers of reactive oxygen species （ROS）, glutathione （GSH）, and malondialdehyde （MDA） in the hepatic and brain tissues were detected. Results showed that no significant difference in oxidative damage existed at concentrations lower than 10 mg.kg i for NPs compared with the control group. Fe3O4 NP concentration had obvious dose-effect relationships （P〈 0.05 or P 〈 0.01） with ROS level, GSH content, and MDA content in mouse hepatic and brain tissues at〉20 mg.kg 1 concentrations. To some extent, ordinary Fe3O4 particles with 40mg.kg -1 concentration also affected hepatic and brain tissues in mice. The biological effect was similar to Fe3O4 NPs at 10 mg. kg-1 concentration. Thus, Fe3O4 NPs had significant damage effects on the antioxidant defense system in the hepatic and brain tissues of mice, whereas ordinary Fe3O4 had less influence than Fe3O4 NPs at the same concentration.     

血清尿酸、超敏C 反应蛋白与老年永久性房颤的关系

目的:探讨血清尿酸(UA)、超敏C反应蛋白(hs-CRP)、左心房内径(LAD)与老年永久性房颤的相关性。方法:选取2012年8月至2015年9月于首都医科大学宣武医院综合科住院的老年永久性房颤患者78例作为房颤组,选取同期住院窦性心律且无房颤病史的老年患者72例作为对照组,记录各组一般资料及超声心动图、尿酸、hs-CRP水平等,进行比较及相关性分析。结果:1与对照组相比,房颤组血清UA及hs CRP水平、左心房内径大小明显增高(P0.05),2以房颤是否发生为因变量,多因素logistic回归分析显示血清尿酸(OR=2.016,P=0.004)、左房内径(OR=4.180,P=0.001)和hs-CRP(OR=2.846,P=0.002)是老年永久性房颤发生的独立危险因素。3房颤组患者血清尿酸与hs-CRP水平呈正相关(r=0.28,P0.05),尿酸与左心房内径大小呈轻度正相关(r=0.12,P0.05)。结论:血清尿酸、hs-CRP、左房内径是老年永久性房颤发生的独立危险因素;尿酸参与的炎症反应和结构重构可能参与老年永久性房颤的发生。     

Estimation of hurdle clearance parameters using a monocular human motion tracking method

This paper presents a method of monocular human motion tracking for estimation of hurdle clearance kinematic parameters. The analysis involved 10 image sequences of five hurdlers at various training levels. Recording of the sequences was carried out under simulated starting conditions of a 110 m hurdle race. The parameters were estimated using the particle swarm optimization algorithm and they are based on analysis of the images recorded with a 100 Hz camera. The proposed method does not involve using any special clothes, markers, inertial sensors, etc. As the quality criteria, the mean absolute error and mean relative error were used. The level of computed errors justifies the use of this method to estimate hurdle clearance parameters.     

Disentangling the effects of drought,salinity, and sulfate on baldcypress growth in a coastal plain restored wetland

Because of their dominance in swamps of the southeastern United States, baldcypress (Taxodium distichum) trees are commonly used in wetland restoration. Though baldcypress are known to tolerate moderate flooding and salinity, their growth has been shown to decrease when they experience drought and high salinity. This study examined the effects of drought and elevated salinity on the growth of baldcypress seedlings and saplings. In a restored wetland in North Carolina, we examined the growth of 8‐year‐old baldcypress by measuring height and diameter at breast height (DBH) along salinity, nutrient, and flooding gradients. In a greenhouse, we placed 1‐year‐old baldcypress seedlings in either drought or saturated conditions and applied different water treatments: fresh water, sulfate, and artificial salt water (5 ppt [parts per thousand]). Over 26 weeks, we measured diameter at root collar, height, and biomass. In the field, chloride concentrations in soil solution had a negative effect on DBH and height (51 and 36% decrease, respectively); high water levels had a negative effect on height (47% decrease) and DBH (46% decrease). In the greenhouse, both drought and salinity decreased diameter growth (43 and 61% decline, respectively) and height (64 and 43% decline, respectively). Sulfate did not have a significant effect on diameter growth, but caused a 14% decrease in height. Our results suggest that both drought and salinity (even as low as 1 ppt) can lead to a 20–60% decline in baldcypress growth. Restoration practitioners should consider the negative consequences of both drought and increased salinity on baldcypress growth when planning for wetland restoration.