Effect of supplemented fungal phytase on performance and phosphorus availability by phosphorus-depleted juvenile rainbow trout (Oncorhynchus mykiss), and on the magnitude and composition of phosphorus waste output

The effect of a supplemental fungal phytase on performance and phosphorus availability by juvenile rainbow trout fed diets with a high inclusion of plant based protein and on the magnitude and composition of the waste phosphorus production was tested in a 2 × 3 factorial design at a temperature of 11 °C. Two factors comprised of two dietary fungal phytase levels (0 or 1400 U kg^? 1 feed^? 1), and three dietary total phosphorus levels (0.89, 0.97 or 1.12%). All fish were acclimated to the lowest total phosphorus diet for 16 days, which included 0.29% phytate-phosphorus and no supplemental fungal phytase, to ensure that they were depleted of phosphorus prior to the feeding trial.Growth and feed conversion ratios were not significantly affected by the increasing dietary phosphorus level or supplemental fungal phytase. Phosphorus availability increased significantly as a result of phytase supplementation, reaching an upper level of 74% at an available dietary phosphorus concentration of 0.71%. Adding fungal phytase to the diets improved the availability of phytate-phosphorus from an average of 6 to 64%. The fish retained 53–79% of the ingested phosphorus, while 24–44% was recovered in the faeces. The particulate phosphorus waste output was significantly higher in faeces from fish fed diets without fungal phytase compared to fish fed phytase supplemented diets. The dissolved/suspended phosphorus waste output represented 2–13% of the ingested phosphorus, and there was a significant increase in the dissolved/suspended phosphorus waste output from fish fed the phytase supplemented diet containing 0.71% available phosphorus, suggesting that the phosphorus requirement was reached at this phosphorus level. Consistent with this, there was a substantial increase in the dissolved/suspended phosphorus waste output from fish fed the phytase supplemented diet containing 0.81% available phosphorus, suggesting that the phosphorus requirement was exceeded in this group.This study demonstrated that phytase supplementation will be advantageous to the fish and the environment if supplemented to low-phosphorus diets containing a large share of plant-derived protein. Conversely, the results demonstrated that fungal phytase should not be supplemented to diets in which the available phosphorus level already meets the requirement of the fish, as this will lead to a significant increase in the dissolved/suspended phosphorus waste output.     

Sandwich enzyme-linked immunosorbent assay (ELISA) for measuring the concentration of, and detection of antibodies to, Aujeszky's disease virus

A double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for measuring Aujeszky's disease virus (ADV) antigen concentration and an inhibition technique based on the former was developed for detection of antibodies to ADV. The results were checked by determining the cytopathic and serum neutralization titres. The correlation was satisfactory in both cases, with correlation coefficients above 0.8. When measuring ADV antigen concentration, the lower limit of detection was 10(3) TCID 50/0.2 ml. The sensitivity of ELISA in detecting antibodies to ADV was found to be superior to that of the serum neutralization test and, thus, enabled the testing of rabbit and guinea-pig sera.     

Genetic differentiation between and within ecotypes of pike (Esox lucius) in the Baltic Sea

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Field experience with two different vaccination strategies aiming to control infections with Actinobacillus pleuropneumoniae in a fattening pig herd

Background

The prevalence of pleurisies recorded at slaughter is increasing in Sweden, and acute outbreaks of actinobacillosis that require antimicrobial treatments have become more frequent. As an increased use of antimicrobials may result in the development of antimicrobial resistance it is essential to develop alternative measures to control the disease. Vaccinations present an appealing alternative to antimicrobial treatments. The aim of this work was to evaluate the potential of two different vaccination strategies in a specialized fattening herd affected by actinobacillosis.

Methods

The study was conducted in a specialized fattening herd employing age segregated rearing in eight units. The herd suffered from infections caused by Actinobacillus pleuropneumoniae serotype 2, confirmed by necropsy and serology. The study included 54 batches of pigs grouped into five periods. Batches of pigs of the second period were vaccinated against actinobacillosis twice, and pigs in the fourth period were vaccinated three times. Batches of pigs of the first, third and fifth period were not vaccinated. Concentrations of serum antibodies to A. pleuropneumoniae and serum amyloid A (SAA) were analysed and production data were recorded.

Results

Despite vaccinating, medical treatments were required to reduce the impact of the disease. The mean incidence of individual treatments for respiratory diseases during the rearing period ranged from 0 to 4.7 ± 1.8%, and was greatest during the triple vaccination period (period IV; p < 0.05 when compared to other groups). A large proportion of the vaccinated pigs seroconverted to A. pleuropneumoniae serotype 2 in the absence of a SAA-response. The prevalence of pleuritis decreased from 25.4 ± 6.5% in the first period to 5.0 ± 3.7% in the fifth period (p < 0.001).

Conclusions

The vaccine did not effectively prevent clinical expression of A. pleuropneumoniae infections, but seroconversion to A. pleuropneumoniae in the absence of a SAA-response in a large number pigs indicated that the vaccine had activated the immune system. Further, the prevalence of pleuritis decreased with time. This indicates that vaccinations together with intensified medical treatments of affected pigs could be useful in reducing the impact of A. pleuropneumoniae serotype 2 infections.     

Effects of phenylbutazone and indomethacin on the post-operative course following experimental orthopaedic surgery in dogs

Randomized placebo-controlled crossover studies were carried out in dogs to evaluate how two non-steroidal anti-inflammatory drugs (NSAID) might modulate an acute post-traumatic inflammatory reaction. Two "identical" surgical interventions were performed on the forelimbs of each animal with an interval of 28 days, to enable a paired comparison of the inflammatory signs and the wound/bone healing processes. At one operation 8 dogs received 300 mg phenylbutazone twice daily for 8 days starting on the day before surgery, and at the other operation matching placebo tablets were given. In a similar placebo-controlled trial another group of 8 dogs received 5 mg indomethacin twice daily. With phenylbutazone the post-operative swelling was not significantly reduced compared to placebo, but there was less pain and limping. With indomethacin the swelling was somewhat reduced, but there was no consistent difference to placebo in the pain and limping assessments. None of the drugs appeared to distinctly effect the wound or fracture healing, as evaluated by clinical inspection, comparison of radiographs and comparison of bone sections from the sites of surgery. It proved difficult to select an appropriate dosage of indomethacin due to its high potential to induce GI ulceration and bleeding in dogs. In this experimental surgical model with an acute inflammation, neither phenylbutazone nor indomethacin showed impressive anti-inflammatory or analgesic properties. In the same model paracetamol has proved to significantly and more efficiently, reduce both swelling and pain without any noticeable adverse effects, and appears to be a better alternative than the two presently tested NSAID.     

A coat protein transgene from a Scottish isolate of potato mop-top virus mediates strong resistance against Scandinavian isolates which have similar coat protein genes

Resistance tests were made on seedlings of transformed lines of Nicotiana benthamiana which contain a transgene encoding the coat protein (CP) gene of a Scottish isolate of potato mop-top virus (PMTV). This transgene has been reported to confer strong resistance to the PMTV isolate from which the transgene sequence was derived and also to a second Scottish isolate. Plants of lines of the transgenic N. benthamiana were as resistant to two Swedish and two Danish PMTV isolates as to a Scottish isolate, and of five lines tested, greater than 93.5% of transgenic plants were immune. The coat protein gene sequences of these four Scandinavian isolates were very similar to those of the two Scottish isolates. The greatest divergence between the isolates was three amino acid changes and there was less than 2% change in CP gene nucleotide sequence. It is concluded that the PMTV CP transgene used in these experiments could confer resistance against isolates from different geographical areas because it is becoming apparent that the CP genes of PMTV isolates are highly conserved.     

Ultrastructure of Colonic Epithelial Cells in Vitamin E and Selenium Deficient Pigs

Pigs deficient in vitamin E and selenium had a decreased contrast of the intracellular membranes compared with pigs supplemented with vitamin E and selenium. Other common changes in the deficient animals included a reduced number of microvilli, with a short and irregular appearance, numerous swollen mitochondria with empty spaces and intercellular oedema. It is suggested that these morphological changes are attributed to the insufficient supply of vitamin E and selenium, though it is not excluded that particular intestinal factors may participate in the development of the lesions.     

Germination of <Emphasis Type="Italic">Juniperus procera</Emphasis> seeds in response to stratification and smoke treatments,and detection of insect-damaged seeds with VIS + NIR spectroscopy

Seeds of Juniperus procera collected from five provenances across its geographic range in Ethiopia were subjected to cold-moist stratification at 5°C or 10°C for 6–12 weeks. The effect of aqueous smoke solution in overcoming the light requirement for germination, and the potential of visible (VIS) and near infrared reflectance (NIR) spectroscopy for sorting sound and insect-damaged seeds were also investigated. Highly significant differences in germination were detected among provenances (P < 0.0001) and stratification periods (P < 0.0001), but not between temperature regimes (P=0.111). Seeds from the south and southeast distribution ranges had higher percentage germination after 6 weeks of stratification than seeds collected from north, northwest and central ranges of distribution. The smoke treatment did not affect germination regardless of whether the seeds were exposed to light. Exposure to light increased germination capacity three fold. Sound and damaged seeds were distinguished with 90% accuracy using VIS + NIR spectroscopy. It can be concluded that dormancy in juniper seeds varies with provenances, and cold stratification for 6 weeks alleviates dormancy in some seed lots. Tentatively, smoke treatment seems ineffective in overcoming photo-dormancy in juniper seeds. VIS + NIR spectroscopy has demonstrated a great potential for sorting damaged seeds, thereby upgrading seed lot purity.     

The impact of phenology,exposure and instar susceptibility on insecticide effects on a chrysomelid beetle population

Direct topical impact of an insecticide spray on a population of a non-target leaf-eating beetle, Gastrophysa polygoni, was studied, and the relative importance of phenology, instar susceptibility and instar specific exposure was evaluated. Two insecticides, cypermethrin and dimethoate, were investigated. In the laboratory, topical toxicity to eggs, second-instar larvae and adults was recorded in dose-response experiments. The spatial distribution of larvae and eggs were measured in the field. Deposition of insecticide onto eggs, second-instar larvae and adult specimens was measured at different positions within the crop canopy by use of a dye tracer technique. A temperature-driven population model was constructed to simulate population development of all life stages in the field. The model was based on laboratory measures of growth and development at various temperatures. Mortality due to direct insecticide exposure was calculated as a function of population demography, spatial distribution of individuals, spatial deposition of the insecticide, and stage-specific susceptibility. Cypermethrin had the greatest impact, reducing population size by 19–32%. The life stages most sensitive to cypermethrin were the larval instars. As the population developed from eggs to larvae and imagines, the impact of one spraying first increased and then decreased according to the proportion of larvae in the population. Dimethoate had less effect on the population, i.e. 1·9–7·6% reduction. Dimethoate was most toxic to the egg stage, and consequently the effect on the population decreased as the proportion of eggs decreased due to hatching. The direct effect of insecticide spraying was significantly affected by all three factors investigated, i.e. phenology, life stage susceptibility and stage-specific exposure. The latter factor is composed of both spray flux at various spatial positions in the canopy and the ability of different life stages to retain spray droplets. © 1998 SCI     

Spatial variability in the mineralisation of the phenylurea herbicide linuron within a Danish agricultural field: multivariate correlation to simple soil parameters

The spatial variability in the mineralisation rate of linuron [N-(3,4-dichlorophenyl)-N'-methoxy-N'-methylurea] was studied within a previously treated Danish agricultural field by sampling soils from eleven different plots randomly distributed across an area of 20 x 20 m. The soils were characterised with respect to different abiotic and biotic properties including moisture content, organic matter content, pH, nutrient content, bacterial biomass, potential for mineralisation of MCPA [(4-chloro-2-methylphenoxy)acetic acid] and linuron. Five soils had a potential for mineralisation of linuron, with 5-15% of the added [ring-U-14C]linuron metabolised to 14CO2 within 60 days at 10 degrees C, while no extensive mineralisation of linuron was observed in the six remaining soils within this period. A TLC analysis of the methanol-extractable residues showed no development of 14C-labelled metabolites from linuron in any of the samples. Multivariate analysis was conducted to elucidate relationships between the intrinsic properties of single soil samples and initial rate of linuron mineralisation. The analysis indicated that important soil parameters in determining the spatial heterogeneity included the C(total)/N(total) ratio, pH and the water-extractable potassium contents, with the first of these highly negatively correlated and the last two highly positively correlated to the initial linuron mineralisation rate. This study shows that enhanced biodegradation of linuron may develop with successive field treatments, but that considerable in-field spatial heterogeneity in the degradation rate still exists. Combined with a parallel enrichment study focused on the underlying microbial processes, the present results suggest that intrinsic soil properties affect the linuron-metabolising bacterial population and thereby determine the spatial variability in the linuron mineralisation activity.