Assessment of artificial substrates for lumpfish: effect of material thickness and water current speed

This study assessed the use of different types of substrates (450 g PVC, 130 g plastic) and water speed (5.0, 10 and 20 cm s^?1) on growth and substrate selection in lumpfish. There were no differences between the percentages of fish attached to both types of substrates as they grew for each of the three different water speeds. Substrate adherence was similar on both substrate types and for all water current speed as the study progressed and was between 25 to 30% in all groups at termination of the trial. Results from the present study show that increasing water speed did not affect attachment preferences in lumpfish as they grew. Larger specimens were observed attaching to both thin and thicker substrates equally. Water speed did not affect growth performance as there were no differences in growth observed at the end of the study period between the three groups of lumpfish. However, further studies are required to determine if higher water speeds affect both growth and attachment preference of lumpfish as they grow.     

Comparison of diet composition,feeding, growth and health of lumpfish (Cyclopterus lumpus L.) fed either feed blocks or pelleted commercial feed

Two duplicate groups of individually tagged lumpfish (mean initial weight: 21.5 ± 3.2 g) were fed either a commercially available lumpfish feed or feed blocks for a period of 123 days. The aim was to evaluate and compare the effects of these feed types on growth, cataract development and histopathology in lumpfish. There were significant differences in growth rates between the groups with fish fed pelleted feed having the highest growth rates. The development of cataracts was significantly different with fish fed pelleted feed having a cataract prevalence of 87% at the end of the study period whilst fish fed with feed blocks had 10% prevalence. The results of the histological examination undertaken in this study showed overall small differences between the two dietary treatments. In some individuals in groups receiving both diets, there was mild to moderate expansion of the lamina propria with tissue most likely to represent fibrous tissue with scattered leucocytes. Overall, the findings of the present study show that lumpfish will readily graze from feed blocks and although growth is lower the prevalence of cataract is greatly reduced using feed blocks.     

Type C botulism in dairy cattle from feed contaminated with a dead cat.

Four hundred twenty-seven of 441 adult Holstein dairy cattle from a 1,200-cow dairy died over a 1-week period during early spring 1998. Affected animals were from 4 late lactation pens, one of which included the bull string. Signs included weakness, recumbency, watery diarrhea, and death. Eighty animals from the 4 pens were dead approximately 8 hours after the first ill cows were noted. Affected cows would collapse on stimulation and extend all 4 limbs with moderate rigidity. Several lacked lingual tonus and had abdominal breathing patterns. The animals had been fed a load of total mixed ration that included a rotten bale of oat hay containing a dead cat. No common toxicants were identified, and pathologic examination revealed no consistent lesions. Testing of tissue from the cat carcass found in the feed sample using mouse protection bioassay identified the presence of type C botulinum toxin. Samples of feed, tissue from affected animals, cat tissue from feed, milk, and serum were also tested using an enzyme-linked immunosorbent assay (ELISA) specific for type C botulinum. Two samples of rumen contents were tested and found to be positive for botulism by ELISA, and 1 of 3 liver samples had a weak positive finding. No botulinum toxin was found in milk or sera using the ELISA.     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

The River Bjerkreim in SW Norway - Successful Chemical and Biological Recovery after Liming

On a large scale, the acidified River Bjerkreim, southwestern Norway, has been treated with lime since the autumn 1996. During the Atlantic salmon (Salmon salar) smolting period pH has been above 6.2 and LAl concentrations below 10 µg L-l. Before 1996, only the western part of the watercourse harboured acid-sensitive species, such as the Atlantic salmon, snails, mayflies, daphnids and Gammarus lacustris. Prior to liming in 1996, Atlantic salmon fry (0+) and parr (≥1+) were found in 4 of 20 sampling sites, contrary to 17 (fry) and 12 (parr) in 1999. Atlantic salmon catches have increased from about 0.8 tons in 1994 to about 10 tons in 1998 and 1999. Acid-sensitive invertebrates have invaded the limed parts of the river.     

Effects of restricted feeding regimes on growth and feed conversion on juvenile green sea urchin,Strongylocentrotus droebachiensis

Groups of juvenile green sea urchin, Strongylocentrotus droebachiensis (average wet weight = 3.3 g), were fed five different dry feed rations (0.2%, 0.4%, 0.8%, 1.2% and 2.4% of their body weight per week) under constant light and temperature conditions for 160 days (Experiment I) in groups to examine growth effects, and for 40 days as individual treatments (Experiment II) to examine feeding efficiency. There was 100% survival of the sea urchins during both experiments. In Experiment I, the lowest ration group (0.2%) had significantly lower growth than the rest of the groups. There was no significant differences in growth between the sea urchin fed ration over 0.4% dry feed of the body wet weight per week. In Experiment II, the lowest feed ration groups (0.2%) had significant lowest growth but had the best feed conversion ratio (FCR), using 0.5 g of feed of dry feed per gram of sea urchin wet weight body growth. The FCR increased with increasing feed ration and the 2.4% group had the poorest FCR, using 1.3 g of feed per gram weight gain. Results from Experiments I and II illustrate that juvenile green sea urchin can grow at a restricted feed ration that is under maximum feed intake, without reduction in growth.     

Effects of hook and release on Atlantic salmon in the River Alta, northern Norway

The purpose of the study was to collect information on angling procedures and the effects of hook and release on Atlantic salmon in the River Alta, northern Norway, covering both grilse and multi-sea-winter salmon in a non-artificial setting with real anglers. Information on the angling procedure, handling of the fish and the condition of the fish at release was collected for individual salmon in catch logs (n=543, mean body length 82 cm), whereas physiological stress was studied in a sub-sample (n=15, mean body length 77 cm). To study post-release behaviour, survival and recapture rates, salmon were tagged with radio transmitters (n=30, mean body length 83 cm) and anchor T-tags (n=353, mean body length 79 cm). To evaluate the effects of the hook and release programme on the salmon population, number of spawning redds were recorded from a helicopter in 6 years during 1989–2000.

The results showed that at water temperatures 10.0–14.5 °C, a high proportion of the radio tagged salmon (97%) survived hook and release and stayed in known spawning areas during the spawning period. However, the behaviour after release seemed to be affected by hook and release. Only a small proportion (4%) of the anchor T-tagged salmon was caught more than once within the same season. Increased playing time, increased number of runs during the angling event, hooking in the throat, bleeding at the hook wound, increased handling time, air exposure and water temperature were factors that affected hooked and released Atlantic salmon negatively, either indicated by a poor condition at release, increased stress levels or unnatural behaviour after release. Number of spawning redds were more than doubled after the introduction of compulsory release of all angled salmon in Sautso (the upper 16% of the watershed inhabited by salmon) in 1998, which indicates that hook and release can be an effective management tool to enhance declining Atlantic salmon populations.     

Modelling mineralization of plant residues on soil: effect of physical protection

A mechanistic dynamic model (Verberne et al. 1990) was used to simulate mineralization of white-clover materials in a loam (25% clay) and a sandy loam soil (5% clay). I tested the model‘s ability to simulate the observed temporal patterns and to take account of altered physical protection as affected by soil compaction or spatial residue distribution. With default parameter values, the model greatly overestimated net N mineralization. The model was very sensitive to changes in the C/N ratio of the microbial biomass. Reducing this value from 8.0 to 6.0 improved the model performance. Nevertheless, initial N mineralization was appreciably overestimated. Two hypotheses may explain the discrepancies: (1) the C/N ratio of the microbial biomass is initially low (3–4) and gradually increases because of a succession from bacterial- to fungal-dominated biomass (H ₁); (2) the C/N ratio of the substrates first attacked by microorganisms, i.e. water-soluble components such as sugars and free amino acids, is higher than the average value (6.0) assumed for the readily decomposable fraction (H ₂). Conceptually, this fraction originally included N-containing polymers (proteins and nucleic acids), which in large part are water insoluble and probably attacked somewhat later than the monomers. Modification of the model, either by implementing a dynamic C/N ratio of the biomass and the effect of faunal grazing or by increasing the C/N ratio of the easily decomposable fraction, improved the model performance substantially. The two hypotheses need to be tested experimentally. The model adequately simulated measured effects of spatial residue distribution and soil compaction on N mineralization after adjustment or parameter values regulating physical protection of microbial biomass and metabolites. Moreover, there was a good agreement between simulated and measured microbial biomass N in the two soils. Received: 9 December 1996     

Determination of strophanthidin in ingesta and plant material by LC-MS/MS

An LC-MS/MS method was developed for the semiquantitative determination of strophanthidin glycosides in ingesta from animals. Strophanthidin glycosides were simultaneously extracted and hydrolyzed to the strophanthidin aglycone using aqueous methanolic hydrochloric acid and the extracts cleaned up using solid-phase extraction. Extracts were analyzed using reverse-phase HPLC coupled with positive ion electrospray mass spectrometry. Characteristic product ion spectra were produced by fragmentation of the [M + H](+) precursor ion for each analyte. Quantitation was performed using the internal standard method with digitoxigenin serving as the internal standard. The method detection limit was calculated to be 0.075 microg/g, and the limit of quantitation was calculated to be 0.24 microg/g for strophanthidin in control rumen samples. This method was used in diagnostic investigations to confirm fatal strophanthidin glycoside poisonings in horses.