The effect of feeding a novel multistrain yeast fraction on European seabass (Dicentrachus labrax) intestinal health and growth performance

Fish were fed a single‐strain yeast fraction (SsYF; 2 g/kg) or a multistrain yeast fraction (MsYF; 0.8 g/kg) for 10 weeks. The results demonstrated significant (p ≤ 0.03) elevations in weight gain, specific growth rate, protein efficiency ratio, and feed conversion ratio in fish fed the yeast fraction‐supplemented diets. In the distal intestine, a significant elevation in microvilli density was observed after 5 and 10 weeks of dietary supplementation with MsYF and SsYF, respectively, compared to control fed fish (p < 0.001). A significant elevation (p = 0.02) in the perimeter ratio was observed in fish fed diets supplemented with the yeast fractions. After 10 weeks of feeding on the experimental diets, Rt‐qPCR demonstrated a significant downregulation (p < 0.05) in the stress response genes, heat‐shock protein 70 (hsp70) and proliferating cell nuclear antigen (pcna), in fish fed diets supplemented with the yeast fractions. Significant (p < 0.05) elevations in interleukin 1‐beta (il1β) and interleukin‐10 (il10) gene expression were observed in fish fed diets supplemented with the MsYF compared to the other dietary groups. These findings suggest that feeding an MsYF specifically at a lower incorporation rate < 1 g/kg, compared to a commercial SsYF at 2 g/kg, is effective in improving the intestinal health status and growth performance of European seabass.     

PRRSV弱毒细胞疫苗与灭活疫苗生殖道黏膜免疫效果观察

应用组织学方法比较观察了猪繁殖与呼吸综合征病毒(PRRSV)弱毒细胞疫苗与灭活疫苗生殖道黏膜免疫的效果。试验选用5月龄长白×大约克夏二元杂交母猪18头。PRRSV弱毒细胞疫苗和灭活疫苗通过生殖道黏膜免疫接种。结果表明PRRSV弱毒细胞疫苗生殖道黏膜接种组母猪的子宫黏膜上皮内淋巴细胞数较灭活疫苗生殖道黏膜免疫接种组和对照组母猪显著减少(P<0.01);而且子宫黏膜上皮变矮变薄,变得有些不规则。灭活疫苗生殖道黏膜接种组母猪子宫黏膜上皮内淋巴细胞数与对照组母猪间差异不显著(P>0.05)。本试验结果显示PRRSV弱毒细胞疫苗经生殖道黏膜免疫接种则对生殖道黏膜上皮内淋巴细胞产生抑制作用。说明PRRSV弱毒细胞疫苗和灭活疫苗经生殖道黏膜免疫效果不理想     

朝阳东大桥承台砼施工技术

叙述了朝阳东大桥主桥两个承台大体积砼的施工经过。总结了施工方案优选过程和大体积低水化热砼的配合比试验情况,并在实际施工中,证明,该技术措施可行,方案经济合理,取得了比较成功的经验。     

日粮锌、硒水平对肉鸡肠道黏膜屏障结构的影响

为了探讨微量元素锌和硒相互作用对肉鸡肠道黏膜屏障结构的影响，将24只1日龄AA肉鸡随机分3组，分别饲喂添加有高锌高硒(锌1000mg／kg、硒5mg／kg)、低锌低硒(锌34mg／kg、硒0．08mg／kg)或常锌常硒(锌50mg／kg、硒0．15mg／kg)的日粮45d后，观察肠黏膜上皮细胞、上皮内淋巴细胞和盲肠扁桃体的形态结构变化。结果表明：高锌高硒或低锌低硒组肉鸡的肠黏膜结构有明显的损伤，表现为肠黏膜上皮细胞萎缩，绒毛长度下降，上皮内淋巴细胞数量减少；盲肠扁桃体的弥散淋巴组织和淋巴小结中，淋巴细胞数量减少，细胞出现肿胀，有的核消失，结缔组织增生，淋巴小结萎缩。尤其是高锌高硒组的损伤最为严重。而常锌常硒组肉鸡肠黏膜和盲肠扁桃体的形态结构正常。结论：日粮中按锌50mg／kg、硒0．15mg／kg的比例添加，对于维持肠道黏膜的正常屏障结构是合适的。过高或过低的锌和硒对小肠黏膜有毒性作用，破坏其屏障功能；而且高锌和高硒可相互促进以增强其毒性作用。     

香菇出口生产技术综述

香菇无公害生产全程技术监控，包括优化产地生态环境栽培原材料把关，精选优良菌种，菌袋生产规范化，出菇科学管理，控制农药使用，产品标准化等七个方面。     

我国食用菌出口遭遇贸易壁垒的原因、类型及对策

贸易壁垒正在成为我国农产品出口的瓶颈。本文分析了我国食用菌产品出口遭遇的贸易壁垒类型及其原因，并提出了相关建议。     

Effects of in ovo feeding of L‐arginine on the development of digestive organs,intestinal function and post‐hatch performance of broiler embryos and hatchlings

This study was to investigate the effects of in ovo feeding (IOF) L‐arginine (Arg) solution on the development of digestive organs, the duodenal mucosa of broiler embryos and hatchlings, and the growth performance of chicks during the first week post‐hatch. A total of 720 fertilized eggs with similar weight were randomly allocated to three groups, consisting of eight replicates of 30 eggs each. Three treatments were arranged as non‐injected control, diluent‐injected (0.75% NaCl solution) group and Arg solution‐injected group containing 1% Arg, dissolved in diluent. At 17.5 days of incubation, 0.6 ml of IOF solution was injected into amniotic fluid of each egg of injected groups. Results showed IOF of Arg solution increased (p < .05) the chick embryo weight at 19 days of incubation; the body weight gain of post‐hatch broilers during 1–7 days; the weights of liver, pancreas, proventriculus and gizzard; the concentrations of duodenal ghrelin, vasoactive intestinal peptide and glucagon‐like peptide 2; and the duodenum mucosal enzyme activities of alkaline phosphatase, maltase, sucrase and inducible nitric oxide synthase of 7‐day‐old post‐hatch broilers compared with other groups. The IOF of Arg solution also increased (p < .05) the villus height (VH) and the ratio of VH to crypt depth (CD) and decreased (p < .05) the CD in duodenum of broiler embryos and post‐hatch hatchlings, except for the CD at 19 days of incubation. In conclusion, IOF of 1% Arg solution into the amnion at 17.5 days of incubation could improve the development of digestive organs, the duodenal morphology, the releasing of gastrointestinal hormones and mucosal enzyme activities of broiler embryos and hatchlings and finally the growth performance of chicks during the first week post‐hatch. Therefore, IOF of appropriate Arg solution could be an effective technology for regulating early nutrition supply and subsequent growth development in poultry industry.     

Effects of oral administration of different dosages of carvacrol essential oils on intestinal barrier function in broilers

Essential oils are widely used in the pharmaceutical, food and cosmetic industries, and many plant essential oils have shown that they have positive effects on broilers nutrition. This experiment was conducted to study the effects of orally administered different dosages of carvacrol essential oils on intestinal barrier function in broiler chickens. A total of eighty 28‐day‐old (1.28 ± 0.15 kg) ROSS 308 broilers were randomly allocated to four groups of 20 replicates each, with one chicken per replicate per cage, and all were fed with the same diet. Four experimental groups were orally administered 0, 200, 300 or 400 μl carvacrol essential oils at 18:00 hr every day during the 2‐week experimental period. As a result of which, the gene expression of the occludin, claudin‐1, claudin‐5, ZO‐1 and ZO‐2 in intestinal mucosa of small intestine (p < 0.05) and the goblet cell content in small intestine epithelium (p < 0.05) were significantly increased; test subjects with 300 or 400 μl carvacrol essential oils reduced the microbial counts of Salmonella spp. and Escherichia coli in the intestines (p < 0.05); Essential oils administration also significantly increased activity of the sucrase (p < 0.05) and lactase (p < 0.05) in intestinal mucosa. In conclusion, the carvacrol essential oils have positive effects on growth performance and intestinal barriers function of broilers; those effects may be related to the dosage, as administration of 300 or 400 μl was more effective than that of 200 μl.     

线性红利界下带干扰风险模型的破产概率

考虑到保险公司在实际经营中收益所具有的不确定性和分红策略，建立一类具有线性红利界和带随机扰动的双复合Poisson风险模型，利用鞅方法给出模型关于破产概率的一个定理及上界．     

Whistle signal variations among three Indo-Pacific humpback dolphin populations in the South China Sea: a combined effect of the Qiongzhou Strait's geographical barrier function and local ambient noise?

Geographic variations in the dolphin whistles could be useful in assessing association and isolation among populations. Whistle of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) among the Pearl River Estuary (PRE), Leizhou Bei (LZB) and Sanniang Bay (SNB) populations were investigated. A total of 2850 whistles with legible fundamental contour were extracted and 15 acoustic parameters were measured. Contrary to SNB, PRE and LZB had the same relative proportion of tonal type compositions with flat and sine representing the most frequent types. The generalized linear model analysis showed significant acoustic difference among populations and tonal types. All frequency parameters in SNB were significantly higher than those in PRE and LZB, where no significant variation was observed in most of the parameters either at the population level or within each tonal type. Canonical discriminant functions analysis showed a smaller difference between PRE and LZB than between PRE and SNB and between LZB and SNB. Compared with previous recordings, recent recordings demonstrated a consistent pattern of becoming higher in whistle frequency parameters in both LZB and SNB populations, suggesting that noise pollution in LZB and SNB increasing with time according to the acoustic niche hypothesis. Dolphin whistle's geographic variations could be shaped by the combined function of the geographical barrier function of the Qiongzhou strait and local ambient noise. Considering the isolated condition and the relatively smaller population size of the humpback dolphin in the SNB, more effective and proactive conservation actions should be taken to prevent the extinction of small populations.