Yersinia ruckeri challenge on rainbow trout fed different diet types

A challenge for sustainable rainbow trout production is an increasing use of plant sources in fish feed due to shortage of marine protein and oil sources. Diets with high plant content are known to cause enteritis and injury to the intestine, which will affect the absorption of nutrients, affecting the overall health status and welfare of the fish. The result is a higher risk of disease following exposure to pathogenic microorganisms. The aim of this study was to elucidate how different feed types with varying amounts of marine versus organic plant protein and oil sources affected the survival of rainbow trout in connection with an infection. Enteric redmouth disease caused by Yersinia ruckeri is an economically important disease which causes problems in rainbow trout. Experimental infections (intraperitoneal injection of 150-200 g fish fed the different diets over a two month period) were done and mortalities in the different diet groups were recorded. Two weeks post challenge the mortalities in the different groups were between 50 and 89 %. The mortalities were lowest in the group fed the diet where half of the fish oil was replaced by organic plant oil. Unfortunately, the results were blurred due to a natural infection with Y. ruckeri that had occurred in the diet groups two months prior to the experimental infection (mortalities between 2 and 9 % in the different groups), and the half fish oil half plant oil group had had the highest cumulative mortality percentage in connection with this natural infection

Faecal contamination of lettuce heads after manure application

In recent years, an increasing number of disease outbreaks have been associated with consumption of contaminated vegetables. Thus, it has been speculated to what extent such contamination is associated with application of animal manure as fertilizer, which is particularly practiced in organic vegetable production where conventional fertilizers are prohibited. A field survey was therefore performed aiming to assess the survival and transfer of E. coli from animal manure to lettuces, with E. coli serving as an indicator of bacterial enteric pathogens. Animal manure was applied to 3 Danish fields prior to planting of lettuce seedlings, then 5-8 weeks later at the normal time of harvest, inner and outer leafs of 10 lettuce heads were pooled into one sample unit with a total of 50 pools per field. Additionally, in one field, 15 soil samples were collected weekly until the harvest time. E. coli was enumerated by plating 1 mL of 10-fold serial dilutions of 5 g of homogenized sample material, i.e. manure, soil and lettuce onto PetrifilmTM Select E. coli count plates (3M), which were then incubated 24 h at 44°C. The manure applied to the fields contained 3.0-4.5 Log10 E. coli CFU/g and E. coli was found in 36-54% of the pooled lettuce samples with a detection limit of 10 CFU/g. Numbers of E. coli in 14-20% of pooled lettuce samples exceeded a satisfactory microbiological hygiene criteria level of 100 CFU/g. The highest percentage of faecally contaminated lettuce heads (54%) coincided with the shortest growth period studied indicating that the time gap between application of manure and harvest and the survival of E. coli (and pathogens) influences the contamination of lettuce via manure amended soil. However, at the time of harvest, the numbers of E. coli in 5 of 15 soil samples were reduced below the detection limit and no samples exceeded 100 CFU/g. This is in contrast to the lettuce samples, where 20% of faecally contaminated samples had >100 E. coli/g, which may indicate that faeces contamination of crops could originate from alternative sources, such as contaminated water and wildlife. Comparisons of the genotype of isolated E. coli strains could help to elucidate this

Average Effective Tax Rates in Mexico

The paper estimates average effective tax rates on consumption, labor and capital income for Mexico, using the method of Mendoza et al. (1994) and related extensions, including two novel refinements. On average, it is found that consumption taxes are roughly between 7 and 14%, whereas labor and capital income taxes are between 8 and 12.5%, and 8.5 and 15%, respectively. Tax estimates are found to be consistent with predictions from theory in general, both for Mexico as well as for a sample of OECD countries.effective tax rates, consumption tax, factor income taxes, international tax policy

A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system

Measures of exoplanet bulk densities indicate that small exoplanets with radius less than 3 Earth radii (R⊕) range from low-density sub-Neptunes containing volatile elements1 to higher-density rocky planets with Earth-like2 or iron-rich3 (Mercury-like) compositions. Such astonishing diversity in observed small exoplanet compositions may be the product of different initial conditions of the planet-formation process or different evolutionary paths that altered the planetary properties after formation4. Planet evolution may be especially affected by either photoevaporative mass loss induced by high stellar X-ray and extreme ultraviolet (XUV) flux5 or giant impacts6. Although there is some evidence for the former7,8, there are no unambiguous findings so far about the occurrence of giant impacts in an exoplanet system. Here, we characterize the two innermost planets of the compact and near-resonant system Kepler-107 (ref. 9). We show that they have nearly identical radii (about 1.5–1.6R⊕), but the outer planet Kepler-107 c is more than twice as dense (about 12.6 g cm–3) as the innermost Kepler-107 b (about 5.3 g cm−3). In consequence, Kepler-107 c must have a larger iron core fraction than Kepler-107 b. This imbalance cannot be explained by the stellar XUV irradiation, which would conversely make the more-irradiated and less-massive planet Kepler-107 b denser than Kepler-107 c. Instead, the dissimilar densities are consistent with a giant impact event on Kepler-107 c that would have stripped off part of its silicate mantle. This hypothesis is supported by theoretical predictions from collisional mantle stripping10, which match the mass and radius of Kepler-107 c

Organic vegetable proteins and oil in feed for organic rainbow trout (Oncorhynchus mykiss)

Fish meal may be partly replaced by a matrix of organic horse bean, pea and rape, and flax seed oil may replace fish oil in diets for organic rainbow trout without compromising growth performance and feed utilization

DIET TYPE AND CHALLENGE BY YERSINIA RUCKERI INFLUENCE THE INTESTINAL MICROBIOTA IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

In warm-blooded animals such as humans and pigs the intestinal microbial composition is dependent on the type of ingested diet. It is known that it also influences the immune system and prevent colonization of pathogenic bacteria. The question is if the gut microbiota has the same impact in lower vertebrates such as fish? To examine this rainbow trout fry were fed two different diets of either a marine or vegetable origin. At a size of about four gram a subset of the fish was bath challenged by Yersinia ruckeri serotype O1 and intestines were then sampled 5 days post challenge from challenged fish (n = 40) and non-challenged control fish (n = 40). Subsequent metagenomic examination based on the 16S rDNA gene was then performed using the Illumina HiSeq 2000 platform. Obtained sequences were paired, sorted, filtered, checked for chimeras and finally mapped against the Greengene database using the open-source package Bion-meta. Analysis of the microbial communities when then made for the non-infected control fish and Yersinia ruckeri challenged fish. For the non-infected control fish, the results showed two distinctly different microbial patterns in the intestines dependent on the administered diet type. Fish fed a marine based diet overall had a significantly higher amount of the class β-proteobacteria, while phylum Firmicutes was significantly higher abundant in the intestines of vegetable fed fish. The genera within phylum Firmicutes present in significantly higher amounts in vegetable fed fish were Weissella, Leuconostoc and Streptococcus. Genus Aeromonas from the γ-proteobacteria class was also present in significantly higher amounts in the vegetable fed fish. The microbial community was different in the fish that were challenged by Yersinia ruckeri. Challenged fish clustered into two groups according to the load of Yersinia ruckeri specific reads in their intestine; the main part of challenged fish (n = 34) had a low amount of Yersinia specific reads (≤ 1.2 % of total amount of reads), while a minor group (n = 6) had a high load ranging between 13.9 and 23.2 % of all reads. These ‘high Yersinia level’ fish had a significantly lower amount of reads from the order Burkholderiales relative to the ‘low Yersinia level’ fish and non-infected control fish. Further, the ‘high Yersinia level’ fish further clustered separately when analyzing the bacterial community on a PCA plot. The immunological examinations were performed by RT-qPCR in order to measure the expression of selected immune genes. The results showed a similar expression pattern between the two diet groups of non-infected fish, but the response differed between the two diet groups in challenged fish. Overall, the results indicate that the gut microbiota in rainbow trout, like in warm-blooded animals, is highly plastic according to the type of diet and does also seem to be involved in the immunological response in connection to pathogenic challenge

Is the intestinal microbiota in rainbow trout influenced by diet type and challenge by Yersinia ruckeri?

In recent years it has become more and more evident that the bacterial flora in the gut of warm-blooded animals modulates physiological processes and the immunological status of the host. Besides effects on growth parameters, commensal intestinal bacteria balance the immune system and prevent colonization of pathogenic bacteria. The question is if the gut microbiota is also important in lower vertebrates such as fish? And does it play a role in connection to pathogenic challenge? To examine these questions rainbow trout fry were fed two different diets of either a marine or vegetable origin directly after first feeding. At a size of about four gram the fish were bath challenged by Yersinia ruckeri and intestines were then sampled 5 and 18 days post challenge for subsequent metagenomic and immunological examinations. Next-generation sequencing was applied for the metagenomic studies using the Illumina HiSeq platform. The results clearly showed two different microbial patterns in the intestines dependent on the diet type. Control fish fed a marine based diet overall had a higher amount of proteobacteria, while high amount of reads belonging to phylum Firmicutes dominated in the intestines of vegetable fed fish. Several genera within the order Lactobacillales belonged to the many reads from Firmicutes. In challenged fish with a high load of reads from genus Yersinia there was a significantly lower amount of reads from the order Burkholderiales. Further, these fish further clustered separately when analyzing the bacterial community on a PCA plot. The immunological examinations using RT-qPCR showed no different expression patterns between the diet groups in control fish, but the response was very different in connection to challenge. Here, the general pattern was a pro-inflammatory response in the intestine of marine fed fish challenged with Yersinia ruckeri, while several immune genes were down-regulated in vegetable fed fish. Overall, the results indicate that the gut microbiota in rainbow trout is highly plastic according to the type of diet and does further seem to be involved in the immunological response in connection to pathogenic challenge

THE INTESTINAL MICROBIOTA IN RAINBOW TROUT (ONCORHYNCHUS MYKISS) IS INFLUENCED BY DIET TYPE AND YERSINIA RUCKERI CHALLENGE

In recent years it has become more and more evident that the bacterial flora in the gut of warm-blooded animals modulates physiological processes and the immunological status of the host. Besides effects on growth parameters, commensal intestinal bacteria balance the immune system and prevent colonization of pathogenic bacteria. The question is if the gut microbiota is also important in lower vertebrates such as fish? Is the microbiota related to the diet type and does it play a protective role in connection to pathogenic challenge? To examine these questions rainbow trout fry were fed two different diets of either a marine or vegetable origin from first feeding and onwards. At a size of about four gram the fish were bath challenged by Yersinia ruckeri serotype O1 and intestines were then sampled 5 days post challenge for subsequent metagenomic examination. Next-generation sequencing was applied for the metagenomic studies using the Illumina HiSeq 2000 platform. The results showed two distinctly different microbial patterns in the intestines dependent on the diet type. Fish fed a marine based diet overall had a significantly higher amount of the class β-proteobacteria, while the amount of reads belonging to phylum Firmicutes were significantly higher in the intestines of vegetable fed fish. The genera within phylum Firmicutes present in significantly higher amounts in vegetable fed fish were Weissella, Leuconostoc and Streptococcus. Genus Aeromonas from the γ-proteobacteria class was also present in significantly higher amounts in the vegetable fed fish. When challenged with Yersinia ruckeri, fish with a high amount of sequence reads belonging to genus Yersinia had a significantly lower amount of reads from the order Burkholderiales relative to non-infected control fish and fish with a low amount of Yersinia specific sequences. Further, these infected fish further clustered separately when analyzing the bacterial community on a PCA plot. The immunological examinations using RT-qPCR showed similar constitutive expression between the two diet groups, but the response differed between the two diet groups in challenged fish. Here, the general pattern was a pro-inflammatory response in the intestine of marine fed fish challenged with Yersinia ruckeri relative to non-infected control fish, while several immune genes were down-regulated in vegetable fed fish relative to non-infected control fish. Overall, the results indicate that the gut microbiota in rainbow trout is highly plastic according to the type of diet and does further seem to be involved in the immunological response in connection to pathogenic challenge

Salmonella og Campylobacter i økologisk svineproduktion

De mere ekstensive systemer i økologisk svineproduktion formodes at have en positiv effekt på dyrenes robusthed f.eks. over for infektioner. Der er dog ingen dokumentation for, at økologiske svin har et lavere indhold af de almindelige zoonotiske bakterier som f.eks. Salmonella og Campylobacter end konventionelle svin. Et forsøg med økologiske smågrise viste, at salmonellainfektioner kan overføres både mellem grisene men også via et salmonellasmittet miljø. Graden af den smitte grisene udsættes for synes væsentlig for etablering af en infektion. Campylobacter, som anses for at være en naturlig del af grisens tarmflora, blev fundet i alle smågrisene. Desuden var det muligt at påvise både den typisk svineassocierede Campylobacter art C. coli og arten C. jejuni vha. en ny metode