Host‐seeking activity and avian host preferences of mosquitoes associated with West Nile virus transmission in the northeastern U.S.A.

Mosquito host‐seeking activity was studied using a custom‐designed trap to explore: (1) at which time interval of the night adult mosquito abatement would be most effective, and (2) if there exists an avian‐specific host‐seeking preference. Overnight trials using traps baited with dry ice showed that Aedes taeniorhynchus (Wiedemann) was most active at dusk and was then captured throughout the night. In contrast, Culex spp. (Cx. pipiens (Linnaeus) and Cx. restuans (Theobald) delayed most activity until about two h after dusk and were then captured through the night. This pattern suggests that management activities directed at adult Culex spp. would be most effective if initiated well after sunset. Mosquito capture rates in traps baited with birds in net bags were significantly greater than those with empty net bags, indicating that mosquitoes were attracted to the birds and not incidentally being sucked in by the custom trap's strong fan motor (Wilcoxon matched‐pairs signed‐ranks test, n= 24, t= 30, p < 0.05). Regression analysis showed that bird weight influenced mosquito attraction (r²= 0.21, p= 0.02). Trials with paired traps that contained different native bird species showed that Gray Catbirds, Dumatella carolinensis, attracted more mosquitoes than the heavier Northern Cardinals, Cardinalis cardinalis (paired samples t‐test, t= 2.58, df= 7, p= 0.04). However, attractiveness did not differ substantially among bird species, and Gray Catbirds did not attract more mosquitoes than all other birds combined as a group. American Robins, Turdus migratorius (n = 4) were comparable in attractiveness to other bird species, but not enough American Robins were captured for a comprehensive study of mosquito avian preference.     

土壤中蓖麻碱降解菌的分离及脱毒效果的初步研究

以蓖麻碱为底物,从蓖麻种植地土壤中筛选出脱毒能力强、生长旺盛的菌株6-6t,经初步鉴定为假单胞菌,其最适生长温度为30℃,最适pH为7.0。经脱毒实验,6-6t菌降解蓖麻碱的脱除率达到71.63%,且该菌并不降解蓖麻饼粕中的蛋白质。     

Effect of the solid content on anaerobic digestion of meat and bone meal

The effect of the solid content on anaerobic digestion of meat and bone meal (MBM) was investigated in batch reactors at MBM solid contents of 1%, 2%, 5% and 10%. There was no significant difference in the specific methane (CH₄) production potential with respect to the total volatile MBM solids (TVS) applied at these solid contents, which ranged from 351 to 381 ml CH₄/g TVS. However, the highest CH₄ yield with respect to the removed volatile MBM solids (RVS) was 482 ml CH₄/g RVS at the MBM solid content of 5%; the CH₄ yields were 384–448 ml CH₄/g RVS at the other MBM solid contents. The lag time of CH₄ production rose with the increase in the solid content. The longer lag time at MBM solid contents of 5% and 10% was due to inhibition caused by high concentrations of volatile fatty acids (VFAs) and free ammonia in the reactors, but the inhibition was reversible. The production of VFAs during the digestion varied with solid contents: at the solid content of 1%, only acetic acid was detected; at 2%, both acetic and propionic acids were detected; and at 5% and 10%, acetic, propionic, butyric and valeric acids were detected. After 93-day digestion, the volatile MBM solid reduction was 92%, 91%, 79% and 80% at MBM solid contents of 1%, 2%, 5% and 10%, respectively.     

Nutritional characterization of Mucuna pruiriens: 2. In vitro ruminal fluid fermentability of Mucuna pruriens,Mucunal-dopa and soybean meal incubated with or without l-dopa

Three in vitro experiments were conducted to determine the rumen fermentability of Mucuna (M) pruriens (24 g 3,4-dihydroxy-l-phenylalanine (l-dopa)/kg dry matter (DM) and soybean meal treated with (SBD) or without (SB) 138 g l-dopa/kg DM). Additional objectives were to determine if l-dopa inhibits rumen fermentation, and if ruminal microbes can adapt to l-dopa or M. In Experiment 1, ground (1 mm) substrates were incubated in triplicate at 38 °C in 9 ml nutrient media and 1 ml rumen fluid in a series of six, 48 h, consecutive batch cultures. The first culture was inoculated with rumen fluid from two donor cows. Subsequent cultures were inoculated with fluid (1 ml) from the previous culture. The DM digestibility (DMD, 616 g/kg vs. 540 g/kg; P<0.01) and gas production (51.7 ml/g vs. 44.2 ml/g DM; P<0.05) were higher from fermentation of M versus SB but similar for SB and SBD (540 g/kg vs. 554 g/kg and 44.2 ml/g DM vs. 43.5 ml/g DM, respectively). The slopes of the relationships between DMD (g/kg) or gas production (ml/g DM) and fermentation period were not reduced by fermenting M (−0.014 DMD slope; 2.28 gas production slope) or SBD (−0.014 DMD slope; 0.459 gas production slope), instead of SB (−0.002 DMD slope; 1.039 gas production slope), indicating microbial adaptation to M and SBD. Total volatile fatty acid concentration (VFA; 53.7, 54.9 and 54.9 mmol/l) and molar proportions of VFA were similar among substrates. Gas production kinetics of M versus SB (Experiment 2), and SB versus SBD (Experiment 3) were also measured after substrates were incubated in triplicate in buffered rumen fluid for 24 h using a non-linear exponential model to fit the data. Residual l-dopa was measured after separate fermentation of substrates in triplicate for 0, 4, 8, 16 and 24 h. Fermentation of M versus SB produced more (P<0.05) gas (250 ml/g vs. 100 ml/g DM) and total VFA (203 mmol/l vs. 180 mmol/l) and a lower (P<0.05) acetate:propionate ratio (1.35 vs. 1.87; P<0.05). Adding l-dopa to SB increased (P<0.01) gas production (92 ml/g DM vs. 200 ml/g DM), and total VFA concentration (132 mmol/l vs. 188 mmol/l), but reduced (P<0.05) gas production rate (0.08 ml/h vs. 0.05 ml/h). The concentration of l-dopa in fermented M and SBD decreased by 53 and 47%, respectively during fermentation. In conclusion, M was more fermented than SB and degradation of l-dopa during ruminal fermentation and microbial adaptation to l-dopa were confirmed. Adding l-dopa to SB did not impair ruminal fermentation.     

角蛋白酶水解豆粕的微生物多样性分析

【背景】酶解饲料底物在酶解至干燥过程中微生物的变化影响着酶解饲料的营养成分以及风味的改变,从而影响动物对其进行采食、消化和吸收,最终影响动物肠道健康。【目的】探究两种酶解物料(纯豆粕和豆粕麦麸混合物)在酶解至干燥过程中的微生物多样性变化。【方法】实验室条件下,采用平板计数法测定物料总细菌数、总霉菌和酵母菌数变化。中试条件下,采用16S rRNA基因和ITS rDNA的高通量测序,检测物料中细菌和真菌多样性随酶解时间(0-36 h)的变化。【结果】酶解前后的平板计数结果显示,加入角蛋白酶处理24h后,两种物料中的细菌数量相对于原料提升了1 000-10 000倍。而经过风干过后,细菌和真菌的数量较风干前下降90%-99%。通过MiSeq平台的16S rRNA基因和ITS rDNA测序结果表明,两种酶解豆粕均具有相似的α多样性指标,微生物丰富度水平相近。然而,16S rRNA基因测定的β多样性结果显示,Fructobacillus属和魏斯属(Weissell)在36h的酶解进程中成为优势菌属;纯豆粕酶解物中的Fructobacillus属在数量上更占优势,豆粕麦麸混合酶解物中则魏斯属更具数量上的优势。ITS rDNA测定的β多样性结果显示,纯豆粕酶解物中曲霉属(Aspergillus)一直占据着数量上的绝对优势,而豆粕麦麸混合酶解物中链格孢属(Alternaria)、赤霉属(Gibberella)和曲霉属(Aspergillus)则在前18 h相对含量较高,但随着时间的延长相对数量减少;毕赤酵母属(Pichia)和酵母属(Remersonia)逐渐占据数量上的优势。【结论】小麦麸作为酶解豆粕辅料能够改变酶解豆粕中的微生物多样性,并使其中的微生物生长更偏向于魏斯属细菌和酵母类真菌。     

利用蛋白酶产生菌固态发酵去除豆粕中抗原蛋白

从实验室保藏的菌种中,筛选出固态发酵所需的高产蛋白酶菌株,进行豆粕发酵。以抗源蛋白去除情况作为考察指标,通过条件优化发现,在豆粕水分质量分数为45%,颗粒直径在1.0-2.0 mm,发酵温度35℃,发酵时间为50 h时,抗原蛋白的去除率在90%以上。通过十二烷基磺酸钠（SDS）聚丙烯酰胺凝胶电泳,发现抗源蛋白得到有效降解,分解为相对分子质量小于10 000的肽类物质。     

灭幼脲对小地老虎、粘虫及黄粉(虫甲)幼虫内部器官和组织的作用及毒理

小地老虎[Agrotis ypsilop (Rottemberg)]、粘虫[Mythimna separata(Walker)]及黄粉(虫甲)(Tembrio molitor L.)的幼虫经灭幼脲处理后,含几丁质组分的体壁表皮层、气管壁内膜和中肠围食膜等组织,分泌激素的咽侧体、前胸腺等内分泌腺体,以及代谢器科管脂肪体,都分别出现明显可辨的组织学改变和病理症状,同是地表现一些差异程度并不显著的现象.根据中毒症状和组织学的改变,本文详细分析和讨论了死幼脲处理后对上述两种夜蛾幼虫和一种拟步(虫甲)幼虫的毒理学基础.     

Identification of the economics,composition, and supplementation of maggot meal in broiler production

The primary goal of this study was to conduct a preliminary assessment of maggot meal protein supplements in broiler production. Maggot meal comprises 55 percent crude protein (CP), 27.65% ether extract, 8.33% Ash, 3.37 crude fiber (CF), 2.14 NFE, 94.7 percent Dry Matter, 5702 kcal/kg gross energy, and 3955 kcal/kg metabolizing energy, according to proximate analysis. Maggot meal supplementation affected broiler meat feed intake, body weight gain, FCR, dressing %, mortality, antibody titer against ND, and organoleptic features. The cost-effectiveness of maggot supplementation was also evaluated. Birds were put into four experimental groups after a week of adaptation:Control group (M0), the first experimental group (M1), the second experimental group (M2), and the third experimental group (M3), which received supplements of 0, 2, 3, and 4 g/kg, respectively. A plane ratio was given to the control group as well. The overall feed intake findings were inversely proportional to the supplementation rate. Thus, the highly supplemented group (M3) showed the lowest feed intake than the control group (M0). Bodyweight gain was directly proportional to the supplementation rate, as evident by a considerable increase in the highly supplemented group (M3) compared to the control group.     

水华蓝藻对鱼类的营养毒理学效应

水体富营养化导致蓝藻水华的发生已成为全球关注的水环境问题,很多鱼类处于水生态系统食物链的最高级,蓝藻水华的主要次级代谢产物-微囊藻毒素可通过鱼类的摄食活动或生物富集作用在鱼体组织中累积,并通过食物链危及人类健康。近年来,微囊藻毒素对鱼类的毒性效应引起众多科学家的关注。在天然水体中不少鱼类可以主动摄食蓝藻,所以,水华蓝藻对鱼类来说既具有营养物作用、也具有潜在的毒性作用。鉴于目前机械收获的水华蓝藻生物量资源化利用问题以及水产饲料业亟需大力开发鱼粉替代蛋白源的需要,从营养学和毒理学这两个角度来研究水华蓝藻对鱼类的营养作用和毒性效应具有较高的理论和现实意义。主要概述了蓝藻粉、蓝藻细胞对鱼类的营养学和毒理学效应,以期拓展水华蓝藻对鱼类毒性效应的研究视野,同时也为水华蓝藻的资源化利用提供新的思路。