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101.
The invasion of Ambrosia artemisiifolia and Ambrosia trifida from their native range to occupy large areas in China has raised considerable concern. Using the maximum entropy (Maxent) method, we developed models for each Ambrosia species, based on occurrence records from both native ranges (North America) and their invaded ranges (e.g. northern and south‐western Europe) to predict the availability and distribution of suitable habitats for these two species in China. For each species, we also assessed potential shifts in habitat suitability for the year 2050, using three general circulation models (GCMs) and two emission scenarios. Elevation and average mean precipitation in October contributed most to model development for both species. Potential distribution projections under future climatic change scenarios suggested an averaged percentage of suitable area (2.21%) and habitat gain (1.49%) in A. artemisiifolia distribution, with further expansion to environmentally favourable locations in south‐east coastal regions, northern Taiwan and the Beijing–Tianjin–Tangshan area in northern China. Future predicted percentage of suitable area for A. trifida was 0.03% with a very limited suitable habitat gain of <1% although this species had the potential to continue to spread in northern China. Our findings suggest that management priorities should be focused on A. artemisiifolia, whilst effective control strategies for A. trifida may be optimised by concentrating efforts on those relatively fewer regions of China where the species is currently abundant. 相似文献
102.
拉美斑潜蝇(L.huidobrensis)属双翅目、潜蝇科,是一种重要的杂食性害虫,主要在温室或温暖地区为害蔬菜、花卉、装饰植物和杂草。因发现较晚,其生物学特征还不十分清楚。但它作为斑潜蝇的一个种,有其共性,如卵和幼虫都在叶肉内为害,幼虫发育期短,成虫小而灵活,这种共性给化学防治带来了很大困难。因为化学药剂可能杀死其天敌,而它却接受了一个不致死的农药剂量,刺激了它的生长,也促进了它对农药产生抗药性。但它也有个性,如为害特点、生命周期、对寄主植物的偏食性及对药剂的敏感性等,这些因素使适合其它种的综合治理策略不完全适合于它。如Macdonald 1991年比较三叶草斑潜蝇和拉美斑潜蝇对几类药剂敏感性时,发现适合防治三叶草斑潜蝇的综合治理策略要作适当修改才能适合于防治拉美斑潜蝇。因此,为了制定适合于拉美斑潜蝇的综合治理策略, 相似文献
103.
Dong Ruan Qiuli Fan Ahmed Mohamed Fouad Yunyun Sun Shengshu Huang Aiji Wu Chuxiao Lin Zhixiang Kuang Chang Zhang Shouqun Jiang 《Journal of animal science》2021,99(2)
Essential oils are plant-derived aromatic volatile oils, and they contain bioactive compounds that have been shown to improve poultry nutrition. In this study, we investigated the effects of oregano essential oil (OEO) on intestinal antioxidative capacity, immunity, and gut microbiota of young yellow-feathered chickens. A total of nine hundred and sixty 1-d-old female Qingyuan partridge chickens were randomly allocated to four treatment groups with six replicates of 40 birds each, and the feeding trial was lasted for 30 d. The controls were fed on a basal diet without in-feed antibiotics; the birds in the antibiotic group were fed the basal diet supplemented with 20 mg/kg virginiamycin; the remaining birds were fed the basal diet containing 150 or 300 mg/kg OEO, respectively. Dietary supplementation with 150 or 300 mg/kg OEO increased average daily feed intake (P = 0.057) and average daily gain (P < 0.05). The activities of glutathione peroxidase and total antioxidative capacity in plasma, jejuna, and ileal mucosa were increased by OEO supplementation (P < 0.05), with a trend of lower jejunal content of malonaldehyde (P = 0.062). Moreover, dietary OEO increased the content of secretory immunoglobulin A (P = 0.078) and the relative expression of Claudin 1, Mucin 2, and Avain beta-defensin 1 in ileum (P < 0.05). Sequencing data of 16S rRNA indicated that dietary OEO increased the relative abundance of Firmicutes phylum, and Clostridium and Lactobacillus genera, and decreasing that of Romboutsia. Functional analyses indicated that microbial amino sugar and nucleotide sugar metabolism, replication, and repair systems were higher in OEO groups than those of controls and antibiotic treatment. In conclusion, dietary supplementation with OEO enhanced growth performance, alleviated local oxidative stress in intestine, improved production of natural antibodies, and favorably modulated intestinal microbiota composition. 相似文献
104.
Chengquan Tan Yongcheng Ji Xichen Zhao Zhongquan Xin Jiaying Li Shuangbo Huang Zhiying Cui Lijun Wen Caihua Liu Sung Woo Kim Jinping Deng Yulong Yin 《动物营养(英文)》2021,7(1):111
Increased metabolic burdens in breeding sows, which are induced by elevated systemic oxidative stress, could increase the need for nucleotides to repair lymphocyte DNA damage; however, de novo synthesis of nucleotides may be insufficient to cover this increased need. This study investigated the effects of dietary nucleotides on milk composition, oxidative stress status, and the reproductive and lactational performance of sows. Forty multiparous sows were assigned to 2 dietary treatments (Control group, and 1 g/kg Nucleotides group) based on a randomized complete block design using their BW at 85 d of gestation as a block. Sows from 2 groups were fed a restricted diet during gestation and ad libitum during lactation. The experiment lasted from 85 d of gestation to 21 d of lactation. The reproductive performance of sows and the growth performance of suckling piglets were measured. Oxidative stress parameters and milk components were also analysed. Data were analyzed using contrasts in the MIXED procedure of SAS. Sows in the Nucleotides group consumed more feed during the first week (P < 0.01) and from 1 to 21 d (P < 0.05) of lactation than those in Control group. Correspondingly, the litter weight gain of piglets showed a tendency to increase from cross-fostering to 9 d (P = 0.09) and from cross-fostering to 20 d (P = 0.10) in the Nucleotides group relative to the Control group. Additionally, the Nucleotides group was higher (P < 0.01) than the Control group in the concentrations of uridine 5''monophosphate, guanosine 5''monophosphate, inosine 5''monophosphate, adenosine 5''monophosphate and total nucleotides in milk. Furthermore, the Nucleotides group was higher (P < 0.01) than the Control group in the serum levels of total antioxidant capacity (P < 0.01) for sows at 109 d of gestation and glutathione peroxidase for weaning piglets, but lower at the levels of thiobarbituric acid-reactive substances (P < 0.05) in serum of weaning piglets. This study indicated that maternal dietary nucleotides could promote piglet growth, probably due to the higher lactational feed intake and higher concentration of nucleotides in the milk of sows, and lower oxidative stress for both sows and piglets. 相似文献
105.
106.
2021年,沂南县推进动物疫病强制免疫“先打后补”工作,依托“鲁牧云”信息平台,通过强化组织领导,加强政策宣贯,强化人员培训,放开强免疫苗经营渠道,提供抗体检测无偿服务等措施,提升了养殖场户“先打后补”的积极性、自主性、灵活性,强化了养殖场户动物防疫主体责任,满足了养殖场户疫苗多样化需求。但由于 “先打后补”补助金额少、社会化服务不规范、基层动物防疫体系弱化、缺少配套工作经费等原因,部分养殖场户实施“先打后补”的积极性不高。建议通过规范社会化服务组织,强化培训水平,提高补助标准,强化三级(县乡村)基础设施建设,升级“鲁牧云”等措施,确保“先打后补”政策惠及更多养殖场户。 相似文献
107.
108.
Du Yang Xin Mingdao Huang Shaoming 《保鲜与加工》1995,(5):50-56
A new type of three dimenstional inner microfin tube is devoloped. Under four different pressures and in the range of condensing mass velocities from 33 to 153 kg/m2 . s,and by the experimental study of the three kinds of tubes with different microfin parameters, the performances of the condensation heat transfer for R11 in the horizontal microfin tubes and obtained. The experiments show that the inner microfin tube is a hopeful and nighty effective condensing heat transfer enhancement tube. 相似文献
109.
110.
切线泵流动特征的整流场数值模拟 总被引:5,自引:0,他引:5
对单级切线泵在设计工况进行了定常流动数值模拟,分析了叶轮流道及蜗壳内的液体流动情况。结果表明,切线泵内流场非常复杂,叶轮进口有明显冲击,叶轮各流道的速度、压力差异很大,环形蜗壳内流动呈现旋涡推进特征,上、下游流动有强烈的相互作用,整机流场不具有对称性;环形蜗壳的几何结构以及流场上、下游的相互作用是导致整机流场非对称特性的主要原因。计算结果为进一步改进结构、提高性能、减小水力损失提供了理论依据。 相似文献