Diseases and Injuries Associated with Mortality of Hatchery Reared Baltic Cod (Gadus morhua L.) Larvae

A cod hatching plant was established in 1992 on the island of Bornholm in the Baltic Sea in order to elucidate the possibilites for restocking of cod fry in this brackishwater system. The disease prevalence in 3 batches of hatchery-reared yolksac larvae from the Baltic cod (Gadus morhua L.) was monitored during the posthatch period. High prevalences of bacteriosis/mycosis, lordosis/scoliosis, injuries and protozoan endoparasitism were recorded. Vibrio sp. and Vibrio anguillarum serovar 04, 06, 08 in addition to nontypable strains and saprolegniaceous fungi were isolated from the larvae. The dinoflagellate-like endoparasites were located in the yolksac of the cod larvae.     

Duration of load revisited

A duration of load study representing 13 years of testing was recently terminated. Preliminary results have been published over the years. This paper represents the final account of the study, which was focused on the influence of moisture content on time to failure for structural timber subjected to bending under constant load conditions. Two constant moisture conditions (MC = 11 and 20%) and one condition of varying moisture (MC between 11 and 20%) were applied. A total of 816 Norway spruce boards of dimensions 44 × 95 × 1,800 mm³ were included. Eight groups of non-destructively matched samples were formed. Four groups were subjected to short-term strength tests, and four groups were subjected to long-term tests. Creep and time to failure were monitored. Time to failure as a function of stress level was established and the reliability of stress level assessment was discussed. A significant mechanosorptive effect was demonstrated both in terms of increased creep and shortening of time to failure. The test results were employed for the calibration of four existing duration of load models. The effect of long-term loading was expressed as the stress level SL₅₀ to cause failure after 50 years of loading. SL₅₀ was found to be of the order 0.60 for MC = 11%, 0.50 for MC = 20% and 0.44 for MC varying between 11 and 20%. The test results revealed no evidence of a threshold stress level. A reliability based calibration of load-duration factors was performed using probabilistic models of loads and of the short-term and long-term strengths. For permanent and imposed library loads, reliability-based estimation of the load duration factor gave almost the same results as direct, deterministic calibration.     

Saponin Adjuvants. Vi. The Adjuvant Activity of Quil a in Trivalent Vaccination of Cattle and Guinea Pigs Against Foot-And-Mouth Disease

The saponin adjuvant Quil A was investigated in trivalent vaccination against foot-and-mouth disease with a concentrated vaccine based on BHK suspension cell virus of the serotypes O, A and G. The activity in cattle was estimated on the basis of seroneutra-lizing antibodies. Five and 10 ml doses with or without 1 mg of Quil A were each injected into 6 animals. Seroneutralizing antibodies were estimated at regular intervals during a period of 29 weeks. The activity in guinea pigs was estimated by experimental challenge. One ml doses of serial 4-fold dilutions of the vaccine with or without 50 µg of Quil A were injected into 24 groups of 20 guinea pigs. Challenge was given 3 weeks after vaccination.It was concluded that Quil A showed adjuvant activity in cattle and guinea pigs with all the serotypes used in the trivalent vaccination.     

Vaccination of Pigs Against Hog Cholera (Classical Swine Fever) With a Detergent Split Vaccine

Four pigs were inoculated subcutaneously with a detergent (triton X 100) split hog cholera virus in Freund’s incomplete adjuvant. Four other pigs were in the same way inoculated with a detergent split bovine viral diarrhoea virus, also in Freund’s incomplete adjuvant. In the experiment were used 3 control pigs. The vaccinations were repeated after 3 weeks. All pigs were challenged with highly virulent hog cholera virus (Tübingen) 12 weeks after primary inoculations. Signs of hog cholera were only noted in the control pigs.This introductory experiment was succeeded by a larger experiment with subcutaneous inoculations of: 10 pigs with detergent split hog cholera virus in Freund’s incomplete adjuvant, 10 pigs with detergent split hog cholera virus in a saponin (Quil A) solution, 10 pigs with detergent split bovine viral diarrhoea virus in Freund’s incomplete adjuvant, 10 pigs with detergent split bovine viral diarrhoea virus in the Quil A solution plus 5 control pigs. The vaccinations were repeated after 3 weeks, and finally all pigs were challenged 9 weeks later with the highly virulent hog cholera virus strain.With the exception of 1 animal which died accidentally, all animals survived in the groups inoculated with the Quil A vaccines and in the group inoculated with the detergent split hog cholera virus/oil adjuvant vaccine. In the group inoculated with the detergent split bovine viral diarrhoea virus/oil adjuvant vaccine, some of the pigs died of hog cholera.     

Assay for Antibody in Pig Fetuses Infected with Porcine Parvovirus

Fetal fluids from field cases of fetal death were assayed for antibody to porcine parvovirus (PPV) using 3 different techniques. An indirect immunofluorescent antibody test, a counter immunoelectrophoresis test and a hemagglutination inhibition test were compared. The indirect immunofluorescent antibody test was found to be the most sensitive of the tests employed. The hemagglutination inhibition test apparently suffered from the occurrence of false positive results.     

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. III. Rotavirus infection

The prevalence of rotavirus infection was studied in 1090 litters from 26 sow herds. Samples of normal, semifluid and watery stools were examined for rotavirus by an ELISA-test on faeces. Rotavirus was detected in 77% of the herds and in 30.5% of the litters (prevalence rates). The highest prevalence rate was seen in piglets between 21 and 41 days of age. Gilts' litters had a very high prevalence during the first week of life. Apart from this, no difference was found between litters from gilts and older sows. Rotavirus was detected more frequently in semiliquid, loose stools than in normal or watery stools, and an association between virus detection and diarrhoea could not be demonstrated. However, litters which shedded rotavirus during the suckling period had lower weight gains and higher incidence rates of respiratory diseases than virus-free litters. Litters weaned at 2 weeks in battery cages had slightly increased risk of shedding rotavirus compared to litters weaned in more traditional systems. The study revealed that rotavirus is widespread in Danish swine herds. The findings give evidence to suggest that the type of mild diarrhoea in 3-week-old piglets known as steatorrhoea or "white scours" may be associated with rotavirus infection, possibly in combination with E. coli and other agents. The high prevalence in piglets weaned at 2 weeks plus the higher morbidity and mortality among such piglets sustain the conclusion that piglets should not be weaned before 3 weeks of age or below a body weight of 6-7 kg.     

PrP genotype frequencies of Quebec sheep breeds determined by real-time PCR and molecular beacons

The allele and genotype frequencies of the prion protein gene (PrP), known to have an impact on scrapie susceptibility, were determined by real-time PCR for 500 Quebec purebred rams. Molecular beacons were very efficient in discriminating the 5 alleles investigated. Polymorphisms at coding positions 136, 154, and 171 of the PrP gene were analyzed using 3 separate real-time PCR reactions and a total of 7 molecular beacons. A total of 4 different alleles (ARQ, ARR, AHR, and VRQ) were observed at different frequencies among the 7 breeds of sheep investigated. Results show that more than 50% of the rams in every breed carried at least one ARR allele, which is considered the most resistant to scrapie. The susceptibility ARQ allele was also present in every breed and together with the ARR allele, they were the most frequent alleles found in Quebec rams. The VRQ allele associated with the highest susceptibility to scrapie occurred in 5 of the 7 breeds, although at low frequencies. Overall, the results indicate that the frequencies of PrP alleles and genotypes in common breeds of sheep in Quebec make it feasible to reduce scrapie risk by selective breeding.     

Farm practices to control E. coli O157 in young cattle--a randomised controlled trial

A randomised controlled trial was used to investigate the effect of three complex management intervention packages to reduce the burden of E. coli O157 in groups of young-stock on cattle farms in England and Wales. All intervention farms were assigned measures to avoid buying in new animals and having direct contact or sharing water sources with other cattle. Furthermore, package A (7 farms) aimed to keep a clean environment and closed groups of young-stock; package B (14 farms) aimed for improved water and feed hygiene, whilst package C was assigned both A and B. The control farms (26 farms) were asked not to alter their practices. Farms, which were assigned intervention package A, exhibited a 48% reduction in E. coli O157 burden over the 4.5 months (average) of observation, compared to 18% on the control farms. The effect of package A compared to the control farms in a crude intention-to-treat model was RR = 0.26 (p=0.122). When the risk ratio was adjusted for actual application of the different measures, the effect of intervention package A became stronger and statistically significant (RR = 0.14 p=0.032). Statistical evidence (p< 0.05) showed that dry bedding and maintaining animals in the same groups were the most important measures within the package and weak evidence (p< 0.1) showed that a closed herd policy and no contact with other cattle may also be of importance. Compliance with the other measures in package A had no influence on the effect of the package. No evidence of effect of the other two intervention packages was found.     

Effect of hydrogen peroxide and/or Flavobacterium psychrophilum on the gills of rainbow trout,Oncorhynchus mykiss (Walbaum)

The immune response and morphological changes in the gills of rainbow trout fry after immersion in hydrogen peroxide (H₂O₂), Flavobacterium psychrophilum or combined exposure were examined. The gills were sampled 4, 48, 125 and 192 h after exposure, and the regulation of expression of the following genes was investigated using qPCR: IgT, IgM, CD8, CD4, MHC I, MHC II, IL-4/13A, TcR-β, IL-10, IL-1β, IL-17, SAA and FoxP3. Bacteria were not observed in haematoxylin-and-eosin-stained gill tissue, but the presence of F. psychrophilum 16S rRNA was detected using qPCR. The 16S rRNA levels were correlated with gene expression. Although pretreatment with H₂O₂ before immersion in F. psychrophilum did not significantly alter the amount of bacteria found in the gill, the immune response was influenced: exposure to F. psychrophilum resulted in a negative correlation with expression of IL-17c1, MHC I and MHC II, while pretreatment with H₂O₂ resulted in a positive correlation with IL-4/13A and IgM. Exposure to either H₂O₂ or F. psychrophilum influenced the regulation of gene expression and damaged tissue. Exposure to both combined altered the immune response to infection and postponed healing of gill tissue.     

Mykotoxinbildung während der Infektion der Weizenähre durch den pathogenen Pilz Fusarium graminearum

Fusarium graminearum is one of the most destructive pathogens of cereals and a threat to food and feed production worldwide. Infection especially of wheat leads to yield losses and mycotoxin contamination. Deoxynivalenol is a hazardous mycotoxin inhibiting the biosynthesis of proteins. Its production by the fungus is a prerequisite for the colonization of the wheat spike. Combining molecular genetics with bioimaging techniques allows a fascinating insight into the pathobiology of this cereal pathogen.