Study on the Correlation between Blood Enzyme Activity and Production Performance in Tibetan Yaks

Yak ( Bos grunniens ) is classified as Bovine genus,they live in Qingzang Plateau with elevation more than 3500m and it's neighbor highland,where the weather is high chilly,short of oxygen and large difference of temperature between day and night.But yak have adapted that circumstance after thousands of years' artificial and natural selection and has great anti adversity capacity.Yak is an important sustenance and means of production to Tibetan.China is a country with the largest number of yak,whose amount of livestock on hand accounts for 95% of the world and Tibet region takes the second place next to Qinghai in the number of yak.Tibetan yak has formed some groups for Tibetan's large area,complicated geological ecosystem conditions,geological isolation.The typical better groups are Yadong yak,Jiali yak and Sibu yak. Study about yak fell behind other animals due to the restriction of inconvenient transportation,difficult sampling and poor experimental technology.Study about the relationship between yak blood enzyme activities and milk production was little,only Jing (1992) studied correlation of milk production with serum amylase,esterase in Gansu Jiulong yak,Maiwa yak and no report was found in other groups.This study discussed six Jiali yak blood enzyme activities lactate dehydrogenase (LDH),alkaline phosphatases (AKP),acid phosphatase (ACP),catalase (CAT),amylase (Amy) and superoxide dismutase (SOD),and explored their relationship with milk production in Jiali yak,so as to supply with theoretical evidence by using blood enzyme activity as biochemical assisted selection marker in the breeding of Tibetan yak milk yield. This experiment investigated activity of six blood enzymes from 28 Tibetan yaks and explored its relationship to production performance.The results showed a extremely positive significant difference ( P <0.01) between activity of LDH and milk yield,CAT activity and length of belly hair respectively,while a positive significant difference ( P <0.05) was observed between AKP activity and body weight,Amy activity and body weight and a negative significant difference ( P <0.05) for SOD activity and body weight.Stepwise Regression Analysis showed that activity of LDH could be used for the prediction of milk yield,AKP,CAT,Amy for body weight,CAT,Amy for length of belly hair.So it is expected to use activity of LDH,AKP,CAT,Amy as biochemical genetic marker in the selection of milk yield,body weight and length of belly hair.

Microplastic Can Decrease Enzyme Activities and Microbes in Soil

An in vitro study was conducted to investigate the impacts of microplastics on enzyme activities and soil bacteria. The study included four different treatments of microplastics including a control. Different levels of microplastics were applied to the soil ranging from 0% to 5%, to assess the impacts of microplastics on soil enzymes and subsequent soil bacteria. After 30 days of incubation, the soil samples were collected and growth parameters of bacteria were assessed. Activities of β-glucosidase, urease and dehydrogenase enzymes were also determined. Our results showed that the presence of microplastics in the soil significantly reduced bacterial population together with bacterial strains. The activities of β-glucosidase, urease and dehydrogenase enzymes were reduced significantly to approximately 32%, 40% and 50% in microplastics treated soils respectively. Concentration of microplastic has a role to play towards this direction;the higher the concentration of microplastic the greater is the impact on enzymes and soil bacteria. The present study on the microbial soil health vis-à-vis microplastic application indicates that the material can have negative effect on the soil bacterial population of and thus ultimately may jeopardize soil health and crop production.

Effect of transferring lignocellulose-degrading bacteria from termite to rumen fluid of sheep on in vitro gas production, fermentation parameters, microbial populations and enzyme activity

The digestive tract of termite(Microcerotermes diversus) contains a variety of lignocellulose-degrading bacteria with exocellulases enzyme activity, not found in the rumen, which could potentially improve fiber degradation in the rumen. The objectives of the current study were to determine the effect of inoculation of rumen fluid(RF) with three species of bacteria isolated from termite digestive tract, Bacillus licheniformis, Ochrobactrum intermedium, and Microbacterium paludicola, on in vitro gas production(IVGP), fermentation parameters, nutrient disappearance, microbial populations, and hydrolytic enzyme activities with fibrous wheat straw(WS) and date leaf(DL) as incubation substrate. Inoculation of RF with either of three termite bacteria increased(P<0.05) ammonia-N concentration compared with the control group(free of termite gut bacteria). Termite bacteria inoculation had no effect(P>0.05) on gas production characteristics, dry matter, organic matter and neutral detergent fiber disappearance, pH, and concentration and composition of volatile fatty acids. Population of proteolytic bacteria and protozoa, but not cellulolytic bacteria, were increased(P<0.05) when RF was inoculated with termite bacteria with both WS and DL substrates. Inoculation of RF with termite bacteria increased protease activity, while activities of carboxymethyl-cellulase, microcrystalline-cellulase, α-amylase and filter paper degrading activity remained unchanged(P>0.05). Overall, the results of this study indicated that transferring lignocellulose-degrading bacteria, isolated from digestive tract of termite, to rumen liquid increased protozoa and proteolytic bacteria population and consequently increased protease activity and ammonia-N concentration in vitro, however, no effect on fermentation and fiber degradation parameters were detected. These results suggest that the termite bacteria might be rapidly lysed by the rumen microbes before beneficial effects on the rumen fermentation process could occur.

Comparison of energy-related isoenzymes between production and racing Arabian camels

Native polyacrylamide gel electrophoresis have been applied for the analyses of alkaline phosphatase (ALP), malate dehydrogenase (Mdh) and malic (ME) isoenzymes in Arabian camel for racing and production. Two fractions for each of these isoenzymes have been recorded in the studied breeds. ALP showed very weak patterns without remarkable difference between the two breeds and this is an indication to that the samples used were healthy and being from the same age. The cytosolic Mdh-1 and ME-1 have been recorded in both camel breeds with high intensity. The mitochondrial Mdh-2 and ME-2 have been recorded with small intensity in production breeds commonly. The present data indicate the necessity of the mitochondrialMdh-2 for energy production in racing breed and the responsibility of the cytosolic Mdh-1 for lipogenesis and energy production in both breeds. We therefore may assume that the appearance of both Mdh forms is necessary for both energy and lipid production in the production breeds while Mdh-1 was useful as bioenergetic enzyme necessary for racing. The different expressions are indications of the difference in the physiological adaptations of both camel breeds and are not for a systematic value.

Actinomycetes from Soil of Lachung, a Pristine High Altitude Region of Sikkim Himalaya, Their Antimicrobial Potentiality and Production of Industrially Important Enzymes

Investigations on actinomycetes are profoundly significant area of research since they form major resource for bioactive compounds, antimicrobials, anticancer agents, immunosuppressants, and biological control agents. A total of 59 actinomycetes were isolated from the soil sample collected from Domang, Lachung, North Sikkim, Sikkim, India. Out of the total isolates, 26 isolates with unique and distinct characteristic features were selected and analysed for antimicrobial activity as well as extracellular enzyme production. Out of 26 isolates, 17 (66%) isolates exhibited different level of growth inhibition against the test microorganism. 12 (47%) isolates showed antifungal activity and six (23%) isolates showed antibacterial activity. Most of the isolates showed antifungal activity. Isolate RCS260 was found to exhibit maximum growth inhibition (60%) against Colletotrichum gloeosporioides MTCC 8021. Isolate RCS252 showed maximum growth inhibition (67%) against Bacillus subtilis MTCC 441. Out of 26 isolates, 14 (54%) isolates exhibited chitinase activity, 25 (96%) isolates showed cellulase production, 20 (77%) isolates produced amylase enzyme and 17 (65%) isolates showed positive for protease activity. Potential isolate RCS260 has been characterized and identified as Streptomyces vinaceus strain RCS260 while isolate RCS252 was identified as Kitasatospora aburavienis strain RCS252. The antagonistic profile of strain RCS260 highlights its potential as antifungal agent against phytopathogens.

Selection of Relevant Variables to the Enzyme Production on Red Grape Pomace by Solid-State Fermentation

With the aim of to valorise red grape pomace and to reduce its environmental impact, the production of enzymatic preparations appear as an interesting choice. Statistical experimental Plackett-Burman designs were applied for the selection of relevant medium components and culture conditions for cellulase, xylanase, polygalacturonase and tannase production by Aspergillus awamori, in solid-state fermentation on red grape pomace. Ten variables were tested： initial moisture content （IMC）, particle size （PS）, temperature, initial pH, time of cultivation, mixing （Mx）, and additions of： fructose, tannic acid, sodium phosphate, and ammonium sulphate （ASA）. Results indicate that the production of each enzyme was affected in a distinct way by the different variables. Also, for each of the enzyme activities considered, IMC must be carefully controlled, and optimized above 65%; PS and Mx, must not be taken into account and ASA must be discarded. The other variables studied, must be selected according to the enzyme activity that will be favored.

Peptide self‐assembly as a strategy for facile immobilization of redox enzymes on carbon electrodes

Redox-enzyme‐mediated electrochemical processes such as hydrogen production,nitrogen fixation,and CO_(2) reduction are at the forefront of the green chemistry revolution.To scale up,the inefficient two‐dimensional(2D)immobilization of redox enzymes on working electrodes must be replaced by an efficient dense 3D system.Fabrication of 3D electrodes was demonstrated by embedding enzymes in polymer matrices.However,several requirements,such as simple immobilization,prolonged stability,and resistance to enzyme leakage,still need to be addressed.The study presented here aims to overcome these gaps by immobilizing enzymes in a supramolecular hydrogel formed by the self‐assembly of the peptide hydrogelator fluorenylmethyloxycarbonyldiphenylalanine.Harnessing the self‐assembly process avoids the need for tedious and potentially harmful chemistry,allowing the rapid loading of enzymes on a 3D electrode under mild conditions.Using the[FeFe]hydrogenase enzyme,high enzyme loads,prolonged resistance against electrophoresis,and highly efficient hydrogen production are demonstrated.Further,this enzyme retention is shown to arise from its interaction with the peptide nanofibrils.Finally,this method is successfully used to retain other redox enzymes,paving the way for a variety of enzyme‐mediated electrochemical applications.

Effects of Non-starch Polysaccharide Enzyme Products on Meat Performance in Broilers

[ Objective] To investigate the effects of non-starch polysaccharide （NSP） enzyme products on meat performance of broilers and thus to provide a scientific basis for their rational use. [Method] Two hundred 21-day-old Ross broilers were assigned to five groups. The broilers in group Ⅰ and group Ⅱ were fed positive control diet and negative control diet, respectively, which were slightly different. The broilers in group Ⅲ, Ⅳ and V were fed the negative control diet respectively supplemented with different commercial NSP enzyme products. The broilers were slaughtered at 56 days old, and their meat yield was determined. [ Result] The percentage of carcass yield and percentage of abdominal fat were significantly higher in the group Ⅲ than in the group Ⅱ （P 〈 0.05）. The percentage of small intestine weight in slaughter weight was lower in the group Ⅱ than in other groups. [ Conclusion] Diets supplemented broad-rang and highly active NSP enzyme products can promote absorption of routine feed ingredients, increase meat yield, and improve meat performance.

Engineered microorganisms and enzymes for efficiently synthesizing plant natural products

Plant natural products are a kind of active substance widely used in pharmaceuticals and foods.However,the current production mode based on plant culture and extraction suffer complex processes and severe concerns for environmental and ecological.With the increasing awareness of environmental sustainability,engineered microbial cell factories have been an alternative approach to produce natural products.Many engineering strategies have been utilized in microbial biosynthesis of complex phytochemicals such as dynamic control and substructure engineering.Meanwhile,Enzyme engineering including directed evolution and rational design has been implemented to improve enzyme catalysis efficiency and stability as well as change promiscuity to expand product spectra.In this review,we discussed recent advances in microbial biosynthesis of complex phytochemicals from the following aspects,including pathway construction,strain engineering to boost the production.

Effects of Encapsulated Enzyme and Yeast Products on in Vitro Rumen Fermentation

Batch cultures of mixed rumen micro-organisms were conducted to evaluate the effects of encapsulated yeast(+EY)and encapsulated enzyme(+EE)using plant proteins(barley and oats grain)on rumen fermentation in vitro,investigate the abilities of encapsulated yeast and encapsulated enzyme to prevent rumen digestion in vitro.Treatments of the study were the control,+EY,+EE products(3.33 mg·mL^(-1) of the incubation medium),unencapsulated yeast(-EY)and enzyme(-EE)products(0.17 and 0.17μL·mL^(-1) of the incubation medium,respectively).+EY group increased dry matter disappearance(DMD,P<0.01)and the total volatile fatty acids(TVFA,P<0.01)at 3 h of the incubation compared with the control,regardless of encapsulation of yeast.Gas production(GP)of+EY group was higher(P=0.05,29.94 mL·mL^(-1) organic matter,OM)than that of the control(25.08 mL·g^(-1) OM)at 3 h of the incubation.Supplementation+EY increased DMD(P=0.04,0.394 vs 0.352,respectively)and acetic proportion(P=0.04,52.6 vs 49.8 mol•100 mL^(-1),respectively)at 6 h of the incubation and increased A:P ratio(P<0.01,3.11 and 2.86,respectively)at 24 h of the incubation,as compared to unencapsulation of yeast.Supplementation of enzyme had higher(P≤0.04)GP,DMD and TVFA at 3 and 6 h of the incubation compared with the control,regardless of encapsulation.Moreover,the addition of+EE produced greater GP at 6(P<0.01,92.35 vs 78.21 mL·g^(-1) OM,respectively),12(218.47 vs 159.18 mL·g^(-1) OM)and 24 h(380.97 vs 297.78 mL·g^(-1) OM,respectively)of the incubation,higher DMD(0.347 vs 0.313,respectively)at 3 h of the incubation as compared to-EE group.The study showed that the encapsulation might protect part of yeast and enzyme from releasing to the rumen throughout the digestion in vitro,resulting in higher or no difference of rumen fermentation parameters compared with unencapsulated groups at any incubation times.In comparison with-EY and-EE,the higher rumen fermentation parameters at the early incubation time were observed,which could be attributed to the higher concentration of yeast or enzyme.However,regardless of the encapsulation,the results indicated that both yeast and enzyme only improved the speed rather than the extent of rumen fermentation in vitro.

Microflora in Digestive Tract of Apostichopus japonicus and Enzyme Producing and Hemolytic Analysis

Microflora in the intestinal tract and on the intestinal wall of both cultured and wild Apostichopus japonicus was studied in this paper. The screening for probiotics was performed based on enzyme producing and hemolytic analysis. The results showed that the number of bacteria in the intestinal wall and tract of wild Apostichopus japonicus was（3.30 ± 0.41） ×107cfu/g and（6.39 ± 0.32） ×10~7cfu/g, respectively. The number of bacteria in the intestinal wall and tract of cultured group was（2.83 ± 0.31） ×10~7cfu/g and（5.67 ± 0.53） ×10~7cfu/g, respectively. The dominant species in the intestinal tract of wild group was Vibrio and the Pseudomonas and Shewanella were the secondary dominant species. The dominant species in the cultured group was Vibrio and Pseudomonas. In 224 strains of bacteria, a total of160 strains of bacteria produced enzyme with a ratio of 71.43%. Among these bacteria, 114 strains could produce protease, 114 strains could produce amylase, and108 strains could produce lipase. The percentages were 50.89%, 50.89%, and48.21%, respectively. A total of 23 strains of bacteria could produce hemolytic toxin in 99 strains of bacteria, which accounts for 23.23% of the total bacterial population.Through the comprehensive analysis of test data, we selected 6 strains of bacteria as intestinal potential probiotic strains of Apostichopus japonicus, which were HS1（Pseudomonas）, HS5（Bacillus）, HS7（Shewanella）, HS8（Vibrio）, HS10（Vibrio）, and HS11（Vibrio） respectively.

Production of Alkaline Protease by Bacillus Licheniformis

In this research the results of studies on optimization of alkaline protease production by Bacillus licheniformis are reported. The parameters, which were taken into consideration, are pH, temperature, time course of enzyme production, stirring rate and kinetics parameters. The effect of various carbon and nitrogen sources in culture medium compound on enzyme production was also considered The result of optimization revealed that maximum protease production was obtained at 37 ℃, pH equivalent tol 0.0 and with 150 rpm will occur after 72 hours. By comparing the effect of 5 carbon sources （maltose, glucose, starch, casein and lactose） in enzyme production, it has been known that using lactose will increase about 1.5 times enzyme production, compared to condition in which maltose is used. The result of studies on the effect of five nitrogen sources （i.e., peptone, tryptone, ammonium sulfate, urea and corn steep liquor） shows that corn steep liqour increases enzyme production more than others, while peptone can also be considered as a good nitrogen source; but, ammonium sulfate and urea reduce enzyme production considerably. It was concluded that protease production occurs in the stationary phase of growth. Studying the kinetics parameters resulted that the best model for the enzyme above is Lineweaver-Burk model according to which Km is 0.64 mmol and Vmax is 88 lamol/min.

Mechanism of the Effect of Bacillus coagulans on Production Performance of Laying Hens in Late Laying Period

[Objective]The paper was to investigate the mechanism of Bacillus coagulans preparation in improving production performance of laying hens in late period of laying.[Method]A total of 648 individuals of"Jingfen 1"laying hens(66 weeks of age)in late period of laying were randomly divided into four groups,six replicates each group,and each group had 27 individuals of laying hens.The laying hens in control group were fed with basal diet,and those in experimental groupsⅠ,Ⅱ and Ⅲ were fed with the basal diets added with 3.33×10^6,1×10^7,3.33×10^7 CFU/g B.coagulans,respectively.The pretrial lasted one week,and the formal test lasted eight weeks.[Result]Compared with the control group,the laying rate in group Ⅰ increased significantly,and the feed-gain ratio in experimental group Ⅱ decreased noticeably while the spleen index increased remarkably;the alkaline phosphatase activities and blood calcium content in experimental groups Ⅰ,Ⅱ and Ⅲ increased significantly(P<0.05),while the triglyceride content decreased remarkably(P<0.05);the urea content in experimental groups Ⅰ and Ⅱ decreased obviously(P<0.05).Adding B.coagulans significantly increased the specific activity of amylase,lipase and protease in various intestinal mucosa of small intestine(P<0.05);adding B.coagulans significantly increased the content of follicle-stimulating hormone(FSH)and estradiol(E2),and significantly increased the mRNA expression of follicle stimulating hormone receptor gene(FSHR).[Conclusion]B.coagulans preparation could significantly improve the production performance of laying hens in late period of laying;appropriately enhance the immune capacity of laying hens;improve the serum biochemical indicators;increase the activity of digestive enzymes in the small intestine;and promote the release of gonadal hormone and the mRNA expression of FSHR gene in the ovary.

Effect of Different Additive Combinations on Production Performance of Layer

To explore the effect of different additive combinations on double-low rapeseed cake （meal） utilization and layer production performance, we randomly divided 756 Roman brown shell layers around 50 weeks age into seven groups to detect production performance, of which group 1 was control group supplied with basic diet （added with 9% double-low rapeseed cake）, while groups 2 -7 were experimental groups added with Chinese herbal medicine, enzyme preparation, pro- biotics and peptide antibiotics in basic diet. The results showed that group 4 added with Chinese herbal medicine ＋ enzyme preparation ＋ peptide antibiotics re- ceived the best effect, resulting in significantly increased laying rate （70.50%, P 〈 0.05 ）, significantly reduced feed-egg ratio （2.46, P 〈 0.05 ）, and extremely increased egg Haugh unit （P 〈0.01 ）. This indicated that adding combination of Chinese herbal medicine ＋ enzyme preparation ＋ peptide antibiotics in layer bas- ic diet could improve egg production performance and egg quality of layers.

A salt, detergent, and solvent tolerant protease from <i>Bacillus</i>sp. B001: Low-cost, easy-purified, and enhanced production by raw material based culture strategy

To enhance the protease production and decrease cost, corn flour and soy peptone were screened as cheap raw materials for the production of extracellular proteases by Bacillus strains. Their compositions in the medium suitable for enzyme production of Bacillus sp. B001 were optimized using statistical experiment designs. Under the optimized conditions, the protease production of Bacillus sp. B001 was stable at the stationary stage and reached to 63,200 U/mL, approximately 1.84-fold increase compared with that using the original medium. These improvements could be attributed to the release of the catabolite repression by crude materials corn flour and soy peptone which contained low level of available nutrients. Additionally, a highly pure protease which displayed excellent stability and compatibility with high salinity, commercial laundry detergents, and organic solvents, was rapidly obtained by two-step procedure involving ammonium sulphate precipitation and anion exchange from the fermentation cultures of B001 in the optimized medium. When the culture method applied to other Bacillus strains, their protease yields were all remarkably increased approximately 2.9 to 8.5 folds. In conclusion, a low-cost, easy-purified, and effective producing strategy using the cheap raw materials was developed here, representing a potential application for protease production in various Industrial processes.

Bacterial Groups Concerned with Maturing Process in Manure Production Analyzed by a Method Based on Restriction Fragment Length Polymorphism Analysis

Composting is a biological aerobic decomposition process consisted from different phases. Although the Japanese Standards for manure recommended that it took at least 6 months to complete the maturing phase, there was no reliable ground. In order to find out shortening method of the maturing phase, the microorganisms concerned with a progress of the maturing was determined by using the most probable number method (MPN) and PCR-RFLP of the 16S rDNA, which was found effective to provide numbers and taxonomy of polymyxin B resistant bacterial groups in the former paper [1]. Compared to the numbers after thermophilic phase, those of Actinobacteria, δ-proteobacteria, and the other gram negative bacteria increased to 50 times, 20 times, and 105 times, respectively, after maturing phase, while those of Bacillus spp., and α and β-proteobacteria decreased to 1/10, and 1/105 after maturing phase. Numbers of the other Fumicutes, and γ-proteobacteria remained in the same revel. Actinobacteria, δ-proteobacteria, and the other gram negative bacteria might be concerned with a progress of the maturing phase, because these bacterial groups were detected and enumerated due to their proliferation ability. Although number of Acitinobacteria might be underestimated because of a PCR bias, the method was found effective for the purpose to monitor bacteria actively proliferated in culture medium.

聚酮化合物非天然延伸单元的生物合成与结构改造应用

聚酮天然产物包括10000多种具有广泛生物活性的分子,是获批临床药物中最著名的类别之一。已知活性先导化合物通常需要经过结构修饰改良其吸收、分布、代谢和排泄等特性,从而促进成药开发,但针对聚酮化合物的结构修饰极具挑战,需要应对聚酮骨架中大量的立体中心以及多个惰性碳原子,导致化学合成手段难以对聚酮骨架进行精准和高效的衍生化,因此,通过合成生物学方法实现其结构优化就成为了研究者们关注的热点。自然界中,绝大多数聚酮化合物主要由简单的乙酸盐和丙酸盐结构单元通过聚酮合酶组装而成,而少数存在的具有特殊结构单元的聚酮案例给了研究者以灵感——通过设置和引入非天然结构单元从而有选择性地高效改造聚酮结构。聚酮骨架的生物合成有赖于一个起始单元与多个延伸单元的组装,因此,通过人工设计延伸单元向聚酮引入预期结构被认为是精准高效改造聚酮的有力突破点。本文在此总结了近十年来报道的聚酮非天然延伸单元的三种重要的酶促合成方法,通过挖掘新颖的延伸单元合成酶并探索其底物宽泛性,或利用酶工程手段改造延伸单元合成酶的底物催化范围,获得了大量自然界不存在的延伸单元。此外,本文还归纳了利用非天然延伸单元对聚酮结构进行改造的案例,借助聚酮的天然合成途径或利用改造的合成途径达到预期目的。最后,作者讨论了该研究领域内存在的一些制约因素以及可优化的研究方向,包括聚酮合酶对非天然延伸单元的兼容性问题、非天然延伸单元的前体供给等。近年来,利用非天然延伸单元改造聚酮结构的研究兴趣和热度日益高涨,本文绘制了一份基于延伸单元改造聚酮结构研究的简明清晰的图谱,期望为加速聚酮类药物的高效开发打下坚实基础。

菌酶制剂对泌乳奶牛血液生化指标及免疫指标的影响

文章旨在分析不同水平菌酶制剂对泌乳奶牛血液生化指标和免疫指标的影响。试验将选择180头胎次、泌乳天数和产奶量相近的泌乳奶牛随机分为3个处理,每个处理6个重复,每个重复10头,分别为对照组、研究1组和研究2组,在人工干预下,对照组饲喂全混合日粮,研究1组和研究2组分别在全混合日粮中添加15和30 g/头/d菌酶制剂,研究结果表明:(1)研究2组的总蛋白和白蛋白含量显著高于研究1组和对照组(P<0.05);各组白细胞计数、红细胞计数、血小板、血红蛋白等血液生化指标无显著差异(P>0.05);(2)研究1组和研究2组免疫球蛋白A、免疫球蛋白M、免疫球蛋白G和白细胞介素-10均显著高于对照组(P<0.05),研究1组和研究2组组间差异不显著(P>0.05);研究1组和研究2组肿瘤坏死因子α显著低于对照组(P<0.05)。经研究结果证实,在泌乳奶牛全混合日粮中添加菌酶制剂可以提高奶牛群免疫能力,综合考虑,以30 g/头/d菌酶制剂的添加量效果最为理想。

Exploiting natural products to discover multitarget inhibitors of insect chitinolytic enzymes

Multitarget insecticides are more likely to achieve comprehensive regulation of insects with a low risk of resistance.Insect chitinolytic enzymes,including GH18 chitinases and GH20β-N-acetyl-D-hexosaminidase,are attractive targets for multitarget insecticide design by virtue of their similar substrate binding mode and catalytic mechanism.On the other hand,natural products with diverse skeletal structures are potential repositories of chitinolytic enzyme inhibitors.This minireview first presents the theoretical basis of developing multitargeted inhibitors against insect chitinolytic enzymes and then focuses on the progress in developing multitarget inhibitors derived from natural products.These may provide ideas for the exploitation of novel pesticide leads from natural products by targeting multiple targets.

棉粕源菌酶协同发酵饲料在肉种鸡生产中的应用研究

本研究旨在探讨棉粕源菌酶协同发酵饲料对产蛋后期肉种鸡生产性能与氮磷排泄率的影响。试验选择42周龄罗斯(Ross)308肉种鸡群,随机分为对照组和试验组。试验预试期1周,正试期16周。在试验过程中,对照组饲喂玉米-豆粕型基础日粮,试验组用8%的棉粕源菌酶协同发酵饲料代替等量的基础日粮。结果表明,与对照组相比,试验组肉种鸡的产蛋率、合格种蛋数显著提高(P<0.05),死淘率显著降低(P<0.05),种蛋受精率有提高的趋势(P=0.057),氮排泄率显著下降(P<0.05),磷排泄率有下降的趋势(P=0.072)。由此可见,在本试验条件下,用8%的棉粕源菌酶协同发酵饲料代替等量的基础日粮可以显著提高肉种鸡生产的经济效益与社会生态效益。