Changes in epidemiological patterns of sea lice infestation on farmed Atlantic salmon, Salmo salar L., in Scotland between 1996 and 2006

Analyses of a unique database containing sea lice records over an 11 year period provide evidence of changing infestation patterns in Scotland. The data, collected from more than 50 commercial Atlantic salmon farms, indicate that both species of sea lice commonly found in Scotland, Lepeophtheirus salmonis and Caligus elongatus, have declined on farms over the past decade. Reductions for both species have been particularly marked since 2001 when more effective veterinary medicines became available. Treatment data were also available in the database and these show a growing trend towards the use of the in-feed medication emamectin benzoate (Slice), particularly in the first year of the salmon production cycle. However, this trend towards single product use has not been sustained in 2006, the latest year for which data are available. There is some evidence of region to region variation within Scotland with the Western Isles experiencing higher levels of infestation. However, compared to the levels observed between 1996 and 2000, all regions have benefited from reduced lice infestation, with the overall pattern showing a particular reduction in the second and third quarters of the second year of production.     

The effectiveness of a commercial microbial product in poorly prepared tiger shrimp, Penaeus monodon (Fabricius), ponds

The efficacy of a commercial microbial product was tested in commercial tiger shrimp, Penaeus monodon (Fabricius), ponds for one culture period in Kuala Selangor, Malaysia. Four ponds with replicates for treatment and control were used. The pond bottom was dried but the organic sludge was not removed as normally practised in pond preparation. The ponds were stocked with 15 post‐larvae at the rate of 31.m^?2. Physical, chemical and biological parameters of the pond were analysed every 2 weeks during the culture period. Water quality parameters remained within the optimum range for shrimp culture except for ammonia‐nitrogen being significantly higher in control ponds and silica in treated ponds. Benthic organisms were not found in any of the ponds. The average counts of different bacteria were not significantly higher in treated ponds than control. Because of poor health, the shrimp were harvested earlier (72 days) than the usual 120 days. An average of 875.60 ± 67.00 kg shrimp ha^?1 was obtained in treated ponds with a feed conversion ratio (FCR) of 1.57 ± 0.10 and survival rate of 42.35 ± 5.37% compared with 719.50 ± 130.94 kg shrimp ha^?1, 2.99 ± 0.70 and 21.25 ± 3.26%, respectively, in control ponds. Neither the microbial product nor the frequent water exchange was effective in overcoming the problems caused by the poor pond bottom.     

Apparent digestibility of selected ingredients in diets for white shrimp Penaeus setiferus L.

A study was conducted to determine apparent digestibility coefficients for dry matter (ADMD), crude protein (ACPD) and gross energy (AED) of selected ingredients in diets for juvenile Penaeus setiferus . Ingredients tested were corn grain, cottonseed meal, crab meal, grain sorghum, meat and bone meal, menhaden fish meal, rice bran, rice grain, shrimp meal, soybean meal, squid liver powder, wheat flour, wheat gluten, wheat middlings and wheat shorts. ADMD coefficients of test ingredients ranged from 22% to 100% and appeared to be related to the fibre, ash and starch content of the ingredient. ACPD coefficients ranged from 58% to 100%. Plant protein supplements (soybean meal and cottonseed meal) were utilized as efficiently as, or better than, animal protein supplements (squid liver powder, menhaden fish meal, meat and bone meal, shrimp meal and crab meal). ACPD coefficients for meat and bone meal, shrimp meal and crab meal (58–59%) were significantly lower than those for menhaden fish meal (76%) and squid liver powder (82%). AED coefficients (44–100%) varied significantly among plant products of similar proximate composition. Corn grain and wheat flour were better utilized by P. setiferus than other high-starch energy supplements. Wheat gluten exhibited the highest ADMD, ACPD and AED coefficients of all ingredients tested.     

Saltwater performance of triploid Atlantic salmon Salmo salar L. brown trout Salmo trutta L. hybrids

Survival and growth in a saltwater net-pen of sexually immature triploid Atlantic salmon Salmo salar L. brown trout Salmo trutta L. hybrids was comparable to that of immature diploid Atlantic salmon. Following 17 months of freshwater rearing, the experimental fish were individually tagged and transferred to a saltwater net-pen where they were raised communally for 376 days. Initial and final average weights were 158 and 760 g per fish for the diploid Atlantic salmon and 209 and 1010 g per fish for the triploid hybrids; weights for the hybrids were significantly larger in both cases (α= 0.05). Survival from transfer to harvest was 43% for the Atlantic salmon and 48% for the hybrids. Average specific growth rate of fish which survived to harvest was 0.42% day^-1 for Atlantic salmon and 0.41% day^-1 for hybrids; these values were not significantly different. No significant differences were observed in average condition factor and dress-out percentage between crosses. Average gonadal weights and gonadosomatic indices were not significantly different for male diploid Atlantic salmon, female triploid hybrids and male triploid hybrids, but were significantly greater for female Atlantic salmon.     

De ovicide werking van 3,5-Dinitro-O-Cresol

Conclusies De toxiciteit van dinitro-o-cresol-oplossingen moet toegeschreven worden aan de giftige werking van ongedissocieerde diniţro-o-cresol-moleculen. Aangezien een zure oplossing van deze stof veel meer ongedissocieerde zuurmoleculen bevat dan een alkalische, is de giftige werking van dit toxicans sterk afhankelijk van de pH der oplossing. Er is een sterke evenredigheid geconstateerd tusschen de hoeveelheid aanwezige dinitro-o-cresol-moleculen in oplossingen van verschillende pH en de toxische werking ervan op meelmoteieren en op bladluiseieren. De hooge toxische werking van deze moleculen komt zoowel in waterige oplossing als gecombineerd met minerale olie naar voren, zoodat in beide gevallen de pH de belangrijkste factor vormt voor het toxische effect van de vloeistof. Aan de dinitro-o-cresolaat-ionen moet waarschijnlijk geen toxische werking worden toegeschreven, evenmin aan ongedissocieerde dinitro-o-cresolaat-moleculen. Van de vier onderzochte alkalizouten van dinitro-o-cresol is het ammoniumzout toxischer dan het kalium-, natrium- en lithiumzout, welke drie laatste een even groote werking uitoefenen. De hoogere toxiciteit van het ammoniumzout moet waarschijnlijk ook teruggebracht worden tot de werking van ongedissocieerde dinitro-o-cresol-moleculen. Voor de nieuwe gezichtspunten, welke dit onderzoek voor de bereiding van sproeimiddelen heeft opgeleverd, werden octrooien aangevraagd. Publicatie van het Laboratorium der N.V. De Bataafsche Petroleum Maatschappij te Amsterdam, afdeeling Plantenziektenbestrijdingsmiddelen     

Infective polyarthritis and multiple discospondylitis in a dog due to Erysipelothrix rhusiopathiae

A seven-month-old Irish wolfhound suffered an infectious polyarthritis and multiple discospondylitis. Erysipelothrix rhusiopathiae was cultured from several of the joints at post mortem examination.     

Comparison of HPLC and GLC techniques for the determination of the triglyceride profile of cocoa butter

Current methods for the authentication of cocoa butter (CB) are mainly based on a knowledge of its triglyceride (TG) composition. The performances of capillary GLC and nonaqueous HPLC with an evaporative light-scattering detector (ELSD) for the quantification of TG of CB of different geographical origins were compared. Use of capillary columns coated with a polarizable stationary phase or two reversed-phase HPLC columns coupled in series efficiently separated the major TG species contained in CB. The velocity of the GLC carrier gas influenced the FID response factors of TG standard compounds, which were linearly related to the retention times of the analytes studied. Within a certain mass range the ELSD response of standard TG solutions did not deviate from unity to a greater extent, independent of the molecular structure of the TG species. The quantities of individual TG as obtained by both methods were in close agreement, and the precisions of the methods were also of comparable magnitude, so that either method can be applied to assess the purity of CB. Capillary GLC has the advantage of higher sample throughput due to a shorter run time and because the consumption of chemicals is negligible.