Effects of Astragalus Powder on Serum Lipid and Body Fat Content of Fast Large-scale Quality Chickens

[ Objective] To study the effects of astragalus powder on serum lipids and body fat contents of fast large-scale quality chickens, and thus provide a theoretical basis for its application in poultry production,[ Method ] All the 180 1-day-old healthy Liangfeng chickens were randomly divided into six groups. Group 1 was the control group, fed with basal diet; group 2, group 3 and group 4 were fed with basal diet added with 0.75%, 1.0% and 1.25% astragalus powder, respectively; group 5 and group 6 were separately fed with basal diet added with 1.0% and 1.25% astragalus pow- der, but the astragalus powder was used for 10 d and then was forbidden for 10 d in turn during the whole experiment. The content of triglyceride （TG）, total cholesterol （TCHO）, high-density lipoprotein-Cholesterol （ HDL-C）, and low-density lipoprotein-Cholesterol （LDL-C） were respectively determined when the chickens were 35-day-old and 63-day-old, while the percentage of abdominal fat （PAF） as well as intramuscular fat （IMF） and subcutaneous fat ply （SFP） was measured when the chickens were 63-day-old. [ Result] In 35-day-old chickens, the levels of TCHO were sig- nificantly or very significantly lower in group 3, group 4, and group 6 than in control group （ P 〈0.05 or 0.01 ） ; the levels of LDL-C significantly lower in group 3 and group 6 （ P〈0. 05） ; the level of HDL-C significantly higher in group 5 （P〈0.05）. In 63-day-old chickens, the levels of TCHO and LDL-C were significantly or very significantly lower in group 3, group 4, and group 5 than in control group （ P 〈 0.05 or 0.01 ） while the levels of HDL-C were significantly higher in these groups; the PAF was significantly lower in group 3 （ P 〈 0.05）. [ Condasion] Astragalus powder should re- duce the levels of TG, TCHO and LDL-C, promote HDL-C content, and also play a certain regulative role in deposition of abdominal fat.

In-situ TiC Reinforced Composite Coating Produced by Powder Feeding Laser Cladding

A Ni-base alloy composite coating reinforced with TiC particles of various shapes and sizes on medium carbon steel substrate was produced by multilayer laser cladding. The chemical compositions, microstructures and surface morphology of the cladded layer were analyzed using energy dispersive X-ray spectroscopy （EDX）, scanning electron microscope （SEM）, and X-ray diffractometry （XRD）. The experimental results showed that an excellent metallurgical bonding between the coating and the substrate was obtained. The microstructure of the coating was mainly composed of γ-Ni dendrites, a small amount of CrB, Ni3B, M23C6 and dispersed TiC particles. Much more and larger TiC particles formed in the overlapping zone, which led to a slightly higher microhardness of this zone. The maximum microhardness of the coating was about HV0.21200. The effects of the laser processing parameters on the microstructures and properties of coating were also investigated.

A COMPREHENSIVE MODEL OF LASER CLADDING BY POWDER FEEDING

A novel model was presented to predict the evolutionary development of cladding layer, and a method based on Lambert-Beer theorem and Mie's theory was adopted to treat the interaction between powder stream and laser beam. By using the continuum model and enthalpy-porosity method, the fluid flow and heat transfer in solid-liquid phase change system were simulated. The commercial software PHOENICS, to which several modules were appended, was used to accomplish the simulation. Numerical computation was performed for Stellite 6 cladding on steel, the obtained results are coincident with those measured in experiment basically.

Effects of palm fat powder and coated folic acid on growth performance, ruminal fermentation, nutrient digestibility and hepatic fat accumulation of Holstein dairy bulls

This study evaluated the effects of palm fat powder(PFP) and coated folic acid(CFA) on growth performance, ruminal fermentation, nutrient digestibility, microbial enzyme activity, microflora, hepatic lipid content and gene expression in dairy bulls. Forty-eight Chinese Holstein bulls((362±12.4) days of age and(483±27.1) kg of body weight(BW)) were assigned to four groups in a completely randomized design with a 2×2 factorial arrangements. Supplemental PFP(0 or 30 g PFP kg-1 dietary dry matter(DM)) and CFA(0 or 120 mg FA d-1 as CFA) were mixed into the top one-third of a total mixed ration. The study included a 20-day adaptation period and followed by a 90-day collection period. The lower(P<0.01) feed conversion ratio with PFP or CFA addition resulted from the constant DM intake and the higher(P<0.05) average daily gain. The higher(P<0.05) ruminal p H, ether extract digestibility, microbial α-amylase activity, Butyrivibrio fibrisolvens copy, and expression of peroxisome-proliferator-activated receptor α(PPARα) and carnitine palmitoyl transferase-1(CPT1), and lower ruminal total volatile fatty acids(VFA) concentration, acetate to propionate ratio, neutral detergent fibre(NDF) digestibility, copies of total protozoa and Ruminococcus flavefaciens, and expression of sterol regulatory element binding protein-1(SREBP1) and acetyl-coenzyme A carboxylase α(ACACA) were observed for PFP addition. Supplementation with CFA increased(P<0.05) ruminal total VFA concentration, acetate to propionate ratio, digestibility of DM, organic matter, crude protein and NDF, activity of cellobiase, pectinase and α-amylase, copies of selected microbial except for total protozoa, as well as expression of PPARα, but decreased(P<0.05) ruminal p H, and expression of SREBP1 and ACACA. The PFP×CFA interaction(P<0.05) was observed for ammonia N, hepatic TG content, and m RNA expression of CPT1 and FAS. There had no significant difference in hepatic TG content when CFA was supplemented in the diet without PFP addition, the lower(P=0.001) hepatic TG content was observed when CFA was supplemented in the diet with PFP addition. The higher(P<0.05) m RNA expression of CPT1, and the lower(P<0.05) m RNA expression of FAS and ammonia N concentration were observed when CFA was supplemented in diet either without or with PFP addition. The results indicated that supplementation of CFA in PFP diet was more effective on increasing hepatic CPT1 expression, and decreasing ammonia N, hepatic TG content and FAS expression than in diet without PFP. Supplementation with PFP or CFA improved growth performance of dairy bulls by promoting nutrient utilization, microbial enzyme activity, microflora, and hepatic gene expression.

Near-infrared Spectral Detection of the Content of Soybean Fat Acids Based on Genetic Multilayer Feed forward Neural Network

In the paper, a method of building mathematic model employing genetic multilayer feed forward neural network is presented, and the quantitative relationship of chemical measured values and near-infrared spectral data is established. In the paper, quantitative mathematic model related chemical assayed values and near-infrared spectral data is established by means of genetic multilayer feed forward neural network, acquired near-infrared spectral data are taken as input of network with the content of five kinds of fat acids tested from chemical method as output, weight values of multilayer feed forward neural network are trained by genetic algorithms and detection model of neural network of soybean is built. A kind of multilayer feed forward neural network trained by genetic algorithms is designed in the paper. Through experiments, all the related coefficients of five fat acids can approach 0.9 which satisfies the preliminary test of soybean breeding.

3-D transient numerical simulation on the process of laser cladding by powder feeding

A 3-D transient mathematical model for laser cladding by powder feeding wasdeveloped to examine the macroscopic heat and momentum transport during the process, based on whicha novel method for determining the configuration and thickness of cladding layer was presented. Byusing Lambert-Beer theorem and Mie's theory, the interaction between powder stream and laser beamwas treated to evoke their subtle effects on heat transfer and fluid flow in laser molten pool. Thenumerical study was performed in a co-ordinate system moving with the laser at a constant scanningspeed. A fixed grid enthalpy-porosity approach was used, which predicted the evolutionarydevelopment of the laser molten pool. The commercial software PHOENICS, to which several moduleswere appended, was used to accomplish the simulation. The results obtained by the simulation werecoincident with those measured in experiment basically.

Characterization of functionally graded ZrO_2 thermal barrier coatings sprayed by supersonic plasma spray with dual powder feed ports

The functionally graded thermal barrier coatings （FG-TBCs） with 80%ZrO2-13%CeO2-7%Y2O3 （C-YSZ）/NiCoCrAlY were prepared using a recently developed supersonic plasma spraying（S-PS） with dual powder feed ports system. The thermal shock experiment of FG-TBCs specimens was carried out by means of the automatic thermal cycle device, in which the samples were heated to 1200℃ by oxygen-acetylene flame jet then water-quenched to ambient temperature. The temperature—time curves of specimens and photographs can be watched on-line and recorded by a computer during the test. The results show that the totally 1mm-thick FG-TBCs have excellent thermal shock resistance due to the fact that the coatings have no any peeling-off after 200 thermal cycles. The microstructures and morphologies of FG-TBCs were characterized and analyzed by SEM.

STUDYONANEWKINDOFPOWDER－FEEDINGAPPARATUSOFFLUX－COREDWIREPRODUCTIONLINE

A set of electromagnetic vibration powder feeding apparatus of the flux cored wire production line and its single chip controlling system have been designed in this paper. The parameters of the electromagnatic vibration powder feeding apparatus have been tested, the functional relation between powder feeding velocity V L and current I has been made out so that the controlling system can not only automatically make out the quantity of the powder according to the width of the steel belt, powder density, production speed and filling ratio, but also adjust the powder feeding speed according to the real production speed, keeping a stable filling ratio.

Impact of Particle Size, Thermal Processing, Fat Inclusion and Moisture Addition on Pellet Quality and Protein Solubility of Broiler Feeds

The present study evaluated the effect of feed particle size, thermal processing, several levels of fat inclusion and moisture addition on pellet quality and protein solubility in potassium hydroxide （KOH） in a corn, soybean meal and animal by products based broiler diets. The different processing factors were combined in a 2 x 4 x 4 x 2 factorial arrangement in an eight randomized block consisting of eight production series： two particle sizes （coarse： 1,041 microns and medium： 743 microns）, four fat inclusion levels at the mixer （15, 25, 35 and 45 g/kg of feed）, four moisture addition levels in the conditioner （0, 7, 14 and 21 g/kg of feed） and two thermal processing treatments （conditioner-pellet press treatment or conditioner-expander-pellet treatment） which resulted in 64 different processed feeds. For the determination of the pellet durability index （PDI）, the amount of intact pellets and protein solubility determinations, eight feed samples （replicates） were collected for each treatment. The data were transformed using a variation of Box-Cox transformation in order to fit a normal distribution （p 〉 0.05）. Adding moisture up to 21 g/kg of feed in the conditioner improved pellet quality of the diets （p 〈 0.05）. Expansion of diets before pelleting improved （P 〈 0.05） PDI and amount of intact pellets by 26% and 31%, respectively, as compared to a simple conditioning-pelleting feed processing. Expander treatment （at 110 ℃） decreased （p 〈 0.05） protein solubility in KOH from 686 g/kg to 643 g/kg total protein as compared to pelleting process （at 80-82 ℃）. The amount of intact pellets reduced from 773 g/kg to 746 g/kg of feed （/7 〈 0.05） as particle size increased from medium to coarse grinding. Pellet quality was significantly reduced with fat inclusion levels higher than 35 g/kg of diet.

Analysis of the Agglomeration of Powder in a Coaxial Powder Feeding Nozzle Used for Laser Energy Deposition

To improve the agglomeration of powder in a coaxial powder feeding nozzle used in the frame of a laser energy deposition technique,the influence of several parameters must be carefully assessed.In the present study the problem is addressed by means of numerical simulations based on a DEM-CFD(Discrete Element Method and Discrete Element Method)coupled model.The influence of the powder flow concentration,powder flow focal length and the amount of powder at the nozzle outlet on the rate of convergence of the powder flow is considered.The role played by the nozzle outlet width,the angle between the inner and outer walls and the powder incident angle in determining the powder flow concentration is also considered.The results show that,with increasing of nozzle outlet width,the powder flow concentration per unit volume at the nozzle focal point undergoes a non-monotonic behaviour(it first increases and then decreases).When the nozzle outlet widthδis 1.00 mm,the powder flow concentration at the focal point is maximal and the powder flow convergence can be considered optimal.By increasing the angle between the inner and outer walls,the powder flow concentration related to the upper focus decreases,the focus diameter increases and the powder flow aggregation worsens.The powder flow concentration increases first and then decreases with increasing incident angle.When the incident angleθis 30°,the powder flow exhibits the best agglomeration properties.When the outlet width is smaller,the angle between the inner and outer walls is larger,and when the incident angle is set at 30°,the powder flow concentration of the coaxial nozzle can be effectively improved.

SIMULTANEOUS DETERMINATION OF FAT SOLUBLE VITAMINS A, D_3, E AND K_1 IN FORTIFIED MILK POWDERS BY HPLC

A high performance liquid chromatographic method for the simultaneous determination of four fat soluble vitamins: retinol (vitamin A), cholecalciferol(vitamin D), tocopherol(vitamin E) and phylloquinone(vitamin K_1) in fortified milk powders and egg yolk has been developed. The method requires enzymatic hydrolysis of lipid component of the sample as a pretreatment. Several factors which influence the enzymatic hydrolysis were studied-Separation was achieved using μ-Bondapak C-18 column(3.9×300mm), 98% methanol as mobile phase, a double channel detection was selected; vitamins D_3 E_1 K_1 were detected by UV spectrophotometry (265 nm) first, then vitamin A by fluorometry (EX 325nm, EM 480mm). The retention times of vitamin A_1 D_3, E and K_1 4.87, 9.00, 10.58 and 15.45 min respectively. Detection limit were 0.64, 0.25, 0.50 and 0.07 ng; and the recoveries were 90.5%～103.6% 90.0%～95.6%, 91.7%～98.8%, 91.5%～98.6%, respectively. The vitamins A, D_0, E, K_1 contents in foods were determined satisfactorily.

脱氢表雄酮对饲喂高脂饲料肉鸡脂肪沉积、血脂、抗氧化能力和血管内皮功能的影响

为探讨脱氢表雄酮(Dehydroepiandrosterone,DHEA)对饲喂高脂饲料肉鸡脂质代谢、抗氧化和血管内皮功能的影响,将200只15日龄青脚麻鸡随机分为5组,其中对照组(CON)饲喂基础饲料,高脂饲料组(High Fat Diet,HFD)、DHEA低剂量干预组(HFD+D5)、DHEA中剂量干预组(HFD+D15)、DHEA高剂量干预组(HFD+D45)分别饲喂添加0、5、15、45 mg/kg DHEA的高脂饲料。于试验第2、4周,测定肌间脂肪宽、皮下脂肪厚、皮脂质量、腹脂质量,计算腹脂率、皮脂率;采集血样检测激素和生化指标;采集肝脏组织检测抗氧化功能和肝脂酶(Hepatic Lipase,HL)活性。与对照组相比,高脂饲料显著增加肉鸡的腹脂质量、腹脂率、皮脂率及血液甘油三酯(Triglyceride,TG)、脂蛋白a(Lipoprotein a,LP(a))、血管紧张素Ⅱ(AngiotensimⅡ,AngⅡ)水平,但降低血清高密度脂蛋白(High Density Lipoprotein,HDL)、T_(3)、T_(4)、FT_(3)、FT_(4)和一氧化氮(NO)水平;同时,高脂饲料显著提高肝脏丙二醛(Malondiadehyde,MDA)含量,但降低肝脏(HL)、总超氧化物歧化酶(Superoxide Dismutase,SOD)和谷胱甘肽过氧化物酶(Glutathione Peroxidase,GSH-Px)活性。与HFD组相比,DHEA处理对饲喂高脂饲料肉鸡的体脂沉积及血清中TG、TC、LP(a)含量均有降低趋势;同时,DHEA能够升高血清T_(3)、T_(4)、FT_(3)、FT_(4)、NO水平及肝脏HL、SOD、GSH-Px活性,并降低肝脏MDA含量和血浆AngⅡ水平。补充DHEA对高脂饲料引发的肉鸡脂代谢紊乱、氧化应激和内皮功能障碍有一定缓解作用,其作用机理可能是通过调节血清甲状腺激素水平,增强肝脏HL活性,从而加速脂肪的分解,抑制脂肪沉积,继而减弱氧化应激,并改善血管内皮功能。

真空电子束熔覆装备研制

围绕真空电子束熔覆装备战略需求,聚焦核心功能零部件的研制开发。研究电子束枪技术、机械运动机构及控制技术,真空定量送粉技术等关键技术。电子束熔覆装备由电子束枪系统、机械运动及控制系统、真空系统、真空送粉系统、监视系统、PLC总控系统等组成。研制等离子体空心阴极结构的电子束枪,实现电子束在低真空条件下的正常工作,阴极连续工作时间可超过50h,适合送粉式电子束熔覆及增材制造。优化电磁聚焦系统的设计,通过调整磁场分布来控制电子束的聚焦程度。通过聚焦系统保证电子束流良好的聚焦电流稳定性,聚焦电流测量值较设定值偏差≤0.5%。研究实现了五轴联动运动机构及数控系统,实现空间复杂曲面的熔覆及增材。研究了抽真空及真空送粉系统,实现连续可控送粉。通过PLC控制系统将电子枪、真空系统、运动系统等与控制系统进行集成,进行整体调试和优化。解决系统运行中可能出现的兼容性和稳定性问题。实现上述关键技术的突破,是实现电子束熔覆装备国产化集成制造的必要条件。

大柴胡汤加味联合亚硒酸钠VE粉治疗猪黄膘病的效果观察

[目的]验证不同剂量大柴胡汤加味联合亚硒酸钠VE粉对猪黄膘病的治疗效果,为该病的中兽药临床防治提供参考。[方法]试验对象为广西壮族自治区崇左市辖县某生猪养殖场自然感染黄膘病的患猪(110日龄左右,(47.1±1.21) kg)20头,随机分为4个治疗组(试验A组、试验B组、试验C组和试验D组),每组5头患猪,试验A、B、C组分别给予低中高剂量(40、60、80 g/d)大柴胡汤加味散和100 g亚硒酸钠VE粉,试验D组只给患猪喂服100 g亚硒酸钠VE粉,10 d为1个治疗周期,试验期15 d,对猪黄膘病的治疗效果及预后情况进行评价。[结果]给药第5天,4组患猪治愈率相同,均为60%;给药第10天,试验C组患猪治愈率最高,为100%;停药后第5天,4组患猪均治愈率均为100%。与试验D组相比,试验B组和试验C组患猪的平均日增质量分别显著提高13.22%和16.68%,平均日采食量分别显著提高3.43%、4.39%。试验C组患猪的料肉比较试验A组和试验D组显著降低,分别降低了0.31、0.53。[结论]大柴胡汤加味的剂量为80 g/d时联合100 g亚硒酸钠VE粉治疗猪黄膘病效果最佳,且可以改善患猪的预后生产性能。

Circulating leptin and its muscle gene expression in Nellore cattle with divergent feed efficiency

Background： Leptin has a strong relation to important traits in animal production, such as carcass composition,feed intake, and reproduction. It is mainly produced by adipose cells and acts predominantly in the hypothalamus.In this study, circulating leptin and its gene expression in muscle were evaluated in two groups of young Nellore bulls with divergent feed efficiency. Individual dry matter intake（DMI） and average daily gain（ADG） of 98 Nellore bulls were evaluated in feedlot for 70 d to determinate the residual feed intake（RFI） and select 20 animals for the high feed efficient（LRFI） and 20 for the low feed efficient（HRFI） groups. Blood samples were collected on d 56 and at slaughter（80 d） to determine circulating plasma leptin. Samples of Longissimus dorsi were taken at slaughter for leptin gene expression levels.Results： DMI and RFI were different between groups and LRFI animals showed less back fat and rump fat thickness,as well as less pelvic and kidney fat weight. Circulating leptin increased over time in all animals. Plasma leptin was greater in LRFI on 56 d and at slaughter（P = 0.0049）. Gene expression of leptin were greater in LRFI animals（P = 0.0022） in accordance with the plasma levels. The animals of the LRFI group were leaner, ate less, and had more circulating leptin and its gene expression.Conclusion： These findings demonstrated that leptin plays its physiological role in young Nellore bulls, probably controlling food intake because feed efficient animals have more leptin and lower residual feed intake.

Analysis of York Pigs Feeding Behavior Using Stepwise Regression and Principal Component Regression

A statistical analysis was conducted on the feeding behavior of 106 York breeding pigs.Pearson correlation analysis,principal component correlation analysis and multiple stepwise regression equation methods were applied to establish regression equations of the York breeding pigs total feed intake per time and average feed intake per time with corrected fat thickness,feed conversion rate,and corrected daily gain.The results showed that:①there were three peak feed intake periods for the pigs,and the correlation coefficient between the feed intake and the corrected fat thickness of the pigs in the 24 h period was positive or negative,that is,increasing the number of feeding times and the feed intake was not necessarily conducive to the fat thickness accumulation,but the breeding goal of fat thickness could be achieved by controlling the feeding times and feed intake;②the average feed intake of pigs in the 60-90 kg body weight stage was 30%-50%higher than that of the 30-60 kg body weight stage,but the number of feeding times decreased,the peak feeding time was more concentrated,and the feeding duration per time was 3.0 min longer,indicating that as the weight of pigs increased,the feed intake increased significantly;and③the stepwise regression equations and the principal component equations showed that the feeding behavior of York pigs in the 30-90 kg growth stage was not only affected by the feeding time within 24 h,but also by environmental factors such as temperature and humidity.The feeding behavior of York pigs is a complex process of interaction between environmental factors and animal factors.

Potentiality of Bioconverted Leafy Vegetable Waste as Aquaculture Feed Supplement

Purple non-sulfur bacteria (PNSB) are well known for their ability in transforming organic substrates for their own source of nutrients. The nutritional values of leafy vegetable waste could be improved through bioconversion with PNSB. This study was conducted to access nutritional status of leafy vegetable waste bio-converted product and efficacy of derived product as aquaculture feed supplement. Proximate compositions of bio-converted leafy vegetable wastes were improved after 6 days with 30% inoculums of Afifella marina strain ME (KC205142). The crude proteins (%) and ashes (%) in derived product was increased to 51.7% and 19.6% respectively. On the other hand, the fiber (%) in the bio-converted derived product was decreased by 21%. During feeding trial in Tilapia (Oreochromis niloticus), no significant differences were observed in the feed intake (g/fish/day), but significant differences were observed in the value of feed conversion ratio and weight gain (%) among the used diets. However, lower ingestion rate (g/d/fish) and better feed conversion ratio were obtained while fishes were fed with diet composed of commercial feed mixed with 5% of the bio-converted product. The higher ingestion rate (g/d/fish) and lower feed conversion ratio were observed with only commercial diet. There observed no significant differences in the ingestion rate (g/d/fish) and FCR values among the diet composed of commercial feed with 5% (D5) and 10% (D10) of the bio-converted product. The derived bio-converted product can be a promising approach to open new market segment in aquafeed industry.

316L不锈钢掺杂SiC环状同轴送粉TIG熔覆层组织结构与性能

TIG熔覆是经济高效的表面修复方法,与传统的预置粉末法相比,同轴送粉法具有优良的适应性,但是试验研究相对较少.自主设计制造了环状同轴送粉TIG熔覆焊枪,与管状同轴送粉TIG熔覆焊枪相比,制造的熔覆层不存在熄弧位置凹坑、焊缝不够平直以及焊缝熔宽不一致等问题,而且具有更高的熔覆效率.结果表明,采用优化的焊接热输入、送粉量和SiC含量参数匹配,在316L不锈钢表面进行环状同轴送粉TIG熔覆,获得了外观优良的单层单道熔覆层、单层多道熔覆层.对熔覆层进行显微硬度测量、微观组织及元素成分分析、宏观电化学腐蚀试验、微区电化学腐蚀试验以及耐磨性能测试,并与母材进行了比对,环状同轴送粉TIG熔覆导入的SiC粉末有效地提升了熔覆层的耐蚀性与耐磨性.

不同比例桑枝叶粉复合饲料对肉鸡血液生化指标及胆固醇含量的影响

桑树是在我国广泛栽种且兼具药食两用价值的木本植物,其营养丰富产量又高。随着机械化栽培生产技术升级和应用推广,桑多元化应用前景十分广阔。为探究机械化收获的杂交桑枝叶粉制备复合饲料对肉鸡生产的影响,在等氮等能的基础上,按基础日粮含0%(对照组)、2%(低剂量组)、4%(中剂量组)、6%(高剂量组)的不同比例配制桑枝叶粉复合饲料,经连续8周的饲养观察,测定肉鸡生长性能、血液理化指标,分析与脂质代谢相关基因的表达特征。结果显示,与对照组相比,桑枝叶粉复合饲料组鸡生长状态、觅食表现和增重无明显变化,但肉鸡的血清总蛋白含量、抗氧化能力、淋巴细胞增殖活性和血清溶菌酶活性显著升高;同时,桑枝叶粉饲养组肉鸡的血清谷丙转氨酶(ALT)活性、谷草转氨酶(AST)活性、尿素氮(UREA)含量和胆固醇含量降低,其中4%桑枝叶粉复合饲料组表现尤为明显。经定量PCR检测表明,内源性胆固醇含量的变化可能与HMGCR、SREBP-2等蛋白基因水平的表达受到抑制,以及LDLR外运蛋白基因的表达量增加有关。综上所述,桑枝叶粉可改善肉鸡体内的物质代谢,提高肝肾及抗氧化和免疫保护功能,促进胆固醇脂质代谢,具有较好的市场应用潜力。

喂料方式对粉体气力分级性能的影响及成因分析

【目的】为了提高粉体气力分级设备的分级性能,研究螺旋喂料和振动喂料2种不同喂料方式对气力分级性能的影响。【方法】采用高速摄像机对不同喂料方式下粉体下落运动(喂料)进行图像采集,运用图像处理技术对采集到的图像进行处理,通过图像观察法和引入喂料时连续时刻粉体面积分布变异系数分析喂料方式对粉体分散性的影响;通过碳酸钙粉体分级实验方法探讨喂料方式对分级性能的影响。【结果】相较于螺旋喂料,振动喂料有利于粉体解团,提升粉体喂料时的均匀性和分散性;相较于螺旋喂料方式,振动喂料有助于提升气力分级机的分级性能,尤其在较高的喂料速度下,分级性能提升效果显著,喂料速度为18 kg/h时,分级精度提升185%,旁路值减小75%,“鱼钩效应”峰值点高度降低29%;粒径小于10μm的超细颗粒在粗粉中占比从螺旋喂料时的11.4%减小到振动喂料时的4.4%,粗粉中细粉占比大幅减小,粗细颗粒分离效果得到改善。【结论】螺旋喂料不适合输运黏性较强、流动性较差的粉体,如碳酸钙;振动喂料可改善粉体材料的喂料均匀性和分散程度,有利于提高气力分级机分级性能。