Tolerance evaluation of Moringa oleifera extract to Hailan brown laying hens.

The aim of this experiment was to study the effects of dietary addition of high-dose Moringa extract (10 g/kg Moringa extract) on laying performance, haematological parameters, organ index and organ histopathology of Hailan brown laying hens in order to determine the safety limit of Moringa extract in laying hens diet. 270 Hailan brown commercial laying hens with similar body weight were randomly divided into three treatments, 6 replicates per treatment and 15 chickens per replicate. Corn-soybean meal-based diet was used in the experiment, and 0, 0.75 and 10 g/kg extracts of Moringa oleifera were added to the basic diet in the experimental group. The experiment lasted 24 weeks. The results showed that the treatment group given 10 g/kg of dietary Moringa extract had no significant difference in egg-laying performance from the control group (p > .05). Adding 0.75 g/kg Moringa extract had no significant effect on the production performance during the early stage of the experiment (p > .05), but during the later stage, F/E was significantly lower than in the control group (p < .05), and no significantly difference compared with 10 g/kg treatment group (p > .05). The addition of Moringa oleifera extract had no significant effect on serum biochemical indices of laying hens except ALB and UREA (p > .05). The addition of Moringa oleifera extract had no significant effect on blood routine indexes of laying hens except for PLT, MON and HCT (p > .05). The digestive and immune organ indexes of laying hens at the later stage of the experiment (24 weeks) were not significantly affected by the addition of Moringa extract (p > .05) except ceca. There were no obvious abnormalities in histological structure. On the whole, we find it is safe to add Moringa oleifera extract to the diet of laying hens at a dosage of less than 10 g/kg.

Estimation of the net energy requirement for maintenance in broilers.

OBJECTIVE: The net energy requirement for the maintenance (NEm) of broilers was determined using regression models by the indirect calorimetry method (ICM) or the comparative slaughter method (CSM). METHODS: A 2×4 factorial arrangement of treatments including the evaluation method (ICM or CSM) and feed intake (25%, 50%, 75%, or 100% of ad libitum recommended) was employed in this experiment. In the ICM, 96 male Arbor Acres (AA) birds aged d 15 were used with 4 birds per replicate and 6 replicates in each treatment. In the CSM, 116 male AA birds aged d 15 were used. Among these 116 birds, 20 were selected as for initial data and 96 were assigned to 4 treatments with 6 replicate cages and 4 birds each. The linear regression between retained energy (RE) and metabolizable energy intake (MEI) or the logarithmic regression between heat production (HP) and MEI were used to calculate the metabolizable or net energy requirement for maintenance (MEm) or NEm, respectively. RESULTS: The evaluation method did not detect any differences in the metabolizable energy (ME), net energy (NE), and NE:ME of diet, and in the MEI, HP, and RE of broilers. The MEI, HP, and RE of broilers decreased (p<0.01) as the feed intake decreased. No evaluation method× feed intake interaction was observed on these parameters. The MEm and NEm estimated from the linear relationship were 594 and 386 kJ/kg of body weight (BW)0.75/d in the ICM, and 618 and 404 kJ/kg of BW0.75/d in the CSM, respectively. The MEm and NEm estimated by logarithmic regression were 607 and 448 kJ/kg of BW0.75/d in the ICM, and were 619 and 462 kJ/kg of BW0.75/d in the CSM, respectively. CONCLUSION: The NEm values obtained in this study provide references for estimating the NE values of broiler diets.

Compound non-starch polysaccharide enzymes improve growth performance, slaughter performance, immune function, and apparent utilization rate of nutrients in broiler chickens fed a low-metabolizable energy diet.

This study aimed to investigate the effects of compound non-starch polysaccharide (NSP) enzymes on growth performance, slaughter performance, immune function, and apparent utilization of nutrients in broiler chickens fed a low-metabolizable energy diet. A total of 240 healthy 1-day-old AA broilers (Arbor Acres, 47.2 ± 0.31 g) were randomly divided into four treatment groups, each with six replicate groups and 10 broilers per replicate. The control group was fed a basal diet; the EL-H group was fed the basal diet supplemented with 200 mg/kg compound NSP enzyme, including ß-mannanase 5,000 IU/g, ß-glucanase 2000 IU/g, xylanase 10,000 IU/g, and cellulase 500 IU/g. The EL-M group was fed the basal diet with 50 kcal/kg metabolizable energy removed, supplemented with 200 mg/kg compound NSP enzyme. Finally, the EL-L group was fed the basal diet with 100 kcal/kg metabolizable energy removed, supplemented with 200 mg/kg compound NSP enzyme. The results showed that feeding with a low-metabolizable energy diet supplemented with compound NSP enzymes did not significantly affect the growth performance of broilers (p > 0.05). Compared with the control group, the abdominal fat rate of broilers in the EL-L group was significantly reduced, and that of broilers in the EL-M group was significantly increased (p < 0.05). Apparent utilization of dry matter, crude protein, and energy in the diet was lower in the control group than in the EL-L group, but significantly higher in the control group than in the EL-H group (p < 0.05). In addition, apparent utilization of crude fiber was significantly increased in the EL-H, EL-M, and EL-L groups compared with the control group (p < 0.05). In conclusion, this experiment showed that the addition of 200 mg/kg compound NSP enzyme enabled maintenance of the normal growth and development of broiler chickens fed a low-metabolizable energy diet (replacing 50-100 kcal/kg metabolizable energy). This study provides a theoretical basis for the application of the compound NSP enzyme in broiler chickens.

Improvement in catalytic activity and thermostability of a GH10 xylanase and its synergistic degradation of biomass with cellulase.

BACKGROUND: Xylanase is one of the most extensively used biocatalysts for biomass degradation. However, its low catalytic efficiency and poor thermostability limit its applications. Therefore, improving the properties of xylanases to enable synergistic degradation of lignocellulosic biomass with cellulase is of considerable significance in the field of bioenergy. RESULTS: Using fragment replacement, we improved the catalytic performance and thermostability of a GH10 xylanase, XylE. Of the ten hybrid enzymes obtained, seven showed xylanase activity. Substitution of fragments, M3, M6, M9, and their combinations enhanced the catalytic efficiency (by 2.4- to fourfold) as well as the specific activity (by 1.2- to 3.3-fold) of XylE. The hybrids, XylE-M3, XylE-M3/M6, XylE-M3/M9, and XylE-M3/M6/M9, showed enhanced thermostability, as observed by the increase in the T 50 (3-4.7 °C) and T m (1.1-4.7 °C), and extended t 1/2 (by 1.8-2.3 h). In addition, the synergistic effect of the mutant xylanase and cellulase on the degradation of mulberry bark showed that treatment with both XylE-M3/M6 and cellulase exhibited the highest synergistic effect. In this case, the degree of synergy reached 1.3, and the reducing sugar production and dry matter reduction increased by 148% and 185%, respectively, compared to treatment with only cellulase. CONCLUSIONS: This study provides a successful strategy to improve the catalytic properties and thermostability of enzymes. We identified several xylanase candidates for applications in bioenergy and biorefinery. Synergistic degradation experiments elucidated a possible mechanism of cellulase inhibition by xylan and xylo-oligomers.

Functional Analysis of a Highly Active ß-Glucanase from Bispora sp. MEY-1 Using Its C-terminally Truncated Mutant.

A ß-1,3-1,4-glucanase-encoding gene, Bisglu16B, was identified in Bispora sp. MEY-1. The deduced BisGlu16B consists of an N-terminal signal peptide, a catalytic module of glycoside hydrolase family 16 (GH16), and a C-terminal serine/proline-rich module. After expression in Pichia pastoris GS115, the purified recombinant BisGlu16B showed maximal activity at pH 4.0 and 55 °C and had broad substrate specificity (ß-1,3-/ß-1,4-mixed, ß-1,3-, ß-1,4-, and ß-1,6-linked glucan, and ß-1,4-mannan). The enzyme possessed high specific activities toward barley ß-glucan (34 700 U·mg-1), lichenan (23 900 U·mg-1), and laminarin (9 000 U·mg-1). After removing the C-terminal module, the truncated mutant, BisGlu16B-ΔC, retained similar enzymatic properties to the wild type but displayed significantly enhanced activities (up to 2.5-fold). Functional and structural analyses indicated that the C-terminal module plays a key role in the substrate binding of BisGlu16B. This study provided an excellent candidate glucanase for industrial purposes and revealed the functions of a C-terminal serine/proline-rich region.

Insight into the functional roles of Glu175 in the hyperthermostable xylanase XYL10C-ΔN through structural analysis and site-saturation mutagenesis.

BACKGROUND: Improving the hydrolytic performance of hemicellulases to degrade lignocellulosic biomass is of considerable importance for second-generation biorefinery. Xylanase, as the crucial hemicellulase, must be thermostable and have high activity for its potential use in the bioethanol industry. To obtain excellent xylanase candidates, it is necessary to understand the structure-function relationships to provide a meaningful reference to improve the enzyme properties. This study aimed to investigate the catalytic mechanism of a highly active hyperthermophilic xylanase variant, XYL10C-ΔN, for hemicellulose degradation. RESULTS: By removing the N-terminal 66 amino acids, the variant XYL10C-ΔN showed a 1.8-fold improvement in catalytic efficiency and could hydrolyze corn stover more efficiently in hydrolysis of corn stover; however, it retained similar thermostability to the wild-type XYL10C. Based on the crystal structures of XYL10C-ΔN and its complex with xylobiose, Glu175 located on loop 3 was found to be specific to GH10 xylanases and probably accounts for the excellent enzyme properties by interacting with Lys135 and Met137 on loop 2. Site-saturation mutagenesis confirmed that XYL10C-ΔN with glutamate acid at position 175 had the highest catalytic efficiency, specific activity, and the broadest pH-activity profile. The functional roles of Glu175 were also verified in the mutants of another two GH10 xylanases, XylE and XynE2, which showed increased catalytic efficiencies and wider pH-activity profiles. CONCLUSIONS: XYL10C-ΔN, with excellent thermostability, high catalytic efficiency, and great lignocellulose-degrading capability, is a valuable candidate xylanase for the biofuel industry. The mechanism underlying improved activity of XYN10C-ΔN was thus investigated through structural analysis and functional verification, and Glu175 was identified to play the key role in the improved catalytic efficiency. This study revealed the importance of a key residue (Glu175) in XYN10C-ΔN and provides a reference to modify GH10 xylanases for improved catalytic performance.

Calculation of intercepted runoff depth based on stormwater quality and environmental capacity of receiving waters for initial stormwater pollution management.

While point source pollutions have gradually been controlled in recent years, the non-point source pollution problem has become increasingly prominent. The receiving waters are frequently polluted by the initial stormwater from the separate stormwater system and the wastewater from sewage pipes through stormwater pipes. Consequently, calculating the intercepted runoff depth has become a problem that must be resolved immediately for initial stormwater pollution management. The accurate calculation of intercepted runoff depth provides a solid foundation for selecting the appropriate size of intercepting facilities in drainage and interception projects. This study establishes a separate stormwater system for the Yishan Building watershed of Fuzhou City using the InfoWorks Integrated Catchment Management (InfoWorks ICM), which can predict the stormwater flow velocity and the flow of discharge outlet after each rainfall. The intercepted runoff depth is calculated from the stormwater quality and environmental capacity of the receiving waters. The average intercepted runoff depth from six rainfall events is calculated as 4.1 mm based on stormwater quality. The average intercepted runoff depth from six rainfall events is calculated as 4.4 mm based on the environmental capacity of the receiving waters. The intercepted runoff depth differs when calculated from various aspects. The selection of the intercepted runoff depth depends on the goal of water quality control, the self-purification capacity of the water bodies, and other factors of the region.