Efficacy of levamisole against Ostertagia ostertagi in Louisiana cattle during maturation of inhibited larvae (September) and during minimal inhibition (December/January).

Levamisole (LEV) was tested in four experiments to compare efficacy values against Ostertagia ostertagi when larval maturation was occurring (September), following inhibition and also when populations were expected to be largely adult (winter). A primary objective was to determine the importance of developing fourth-stage larvae (DL4) and inhibited, early fourth-stage larvae (EL4) in replacing adult worms lost through treatment and the effect of this on reduced efficacy against adult worms. Young crossbred beef calves ranging in weight from 150 to 230 kg were used in the first (September 1981), second (September 1983) and third experiments (January 1987). Jersey calves of 110 kg average weight were used in the fourth experiment (December 1988). Calves were randomized to groups according to weight and group sizes ranged from three to five calves. All parasite infections were naturally acquired, but a mixture of nematode third-stage larvae (L3) (22,500 per calf), including 20% Ostertagia ostertagi, was inoculated into Jersey calves of Experiment 4 following a 2 week exposure to natural infection. All LEV treatments were by subcutaneous injection at dosages of 6 and 8 mg kg-1. Treatment with ivermectin was used only in Experiment 3 as an efficacy reference. All calves were killed at 8-10 days after treatment. The efficacy of LEV against all developmental stages of Ostertagia ostertagi was consistently low in all experiments and a dose-dependent response was not evident. Large numbers of all Ostertagia ostertagi developmental stages were present in non-treated calves in both September experiments. Percent reduction of adults, DL4 and EL4 at the 6 mg kg-1 and 8 mg kg-1 dosages, respectively, were adults, 51.7 and 23.6 (1981), 8.7 and 51.3 (1983); DL4 40.3 and 13.2 (1981), 37.9 and 33.1 (1983); EL4, 19.6 and 0 (1981), 59.6 and 42.9 (1983). Smaller numbers of Ostertagia ostertagi were present in winter experiments and adult worms greatly outnumbered larval stages. Percent reductions of adults, DL4 and EL4, respectively, were (1987) LEV 6 mg kg-1, 40.2, 0 and 0; ivermectin 200 micrograms kg-1, 98.7, 97.7 and 100.0; (1988) LEV 6 mg kg-1, 62.4, 100.0 and 100.0; LEV 8 mg kg-1, 49.1 65.0 and 74.1. Too few larval stages were present in the latter experiment for valid efficacy values.(ABSTRACT TRUNCATED AT 400 WORDS)     

The binding of soybean agglutinin (SBA) to the intestinal epithelium of Atlantic salmon, Salmo salar and Rainbow trout, Oncorhynchus mykiss, fed high levels of soybean meal

A lectin present in soya, soybean agglutinin (SBA), was identified in electrophoretic profiles and immunoblots of dehulled solvent-extracted soybean meal (DSSM), full-fat soybean meal (FFSM) and of aqueous extracts of feeds incorporating them in their formulation. A quantitative estimation was made of the proportion of SBA comprising the total protein in FFSM and a trial diet was prepared containing an amount of pure SBA similar to that in diets incorporating high levels of the whole soya product. Fish fed with this diet exhibited similar pathological disruption of the intestinal tract to that observed in fish given a diet with a high level of DSSM (60% of the diet). Furthermore, immuno-histochemistry revealed the binding of the SBA to the enterocytes lining the intestinal villi both of fish fed a diet incorporating pure SBA and those fed a diet containing a high-level of soya (60%). Our results suggest that SBA binds in vivo to the intestinal epithelium of fish and has a contributory role in pathological changes associated with fish feeds containing high levels of soybean proteins.     

Technique for continuous stride analysis of horses exercising on a treadmill

A technique for continuous computerised recording and analysis of the stride of horses on a treadmill is described. Advantages of the system are low cost, the use of normal shoes and the calculation of stride parameters in real time.     

Direct gas chromatographic determination of methomyl (lannate®) with microcoulometric nitrogen detection

A microcoulometric method is described for the direct determination of nanogram amounts of methomyl (S-methyl-N-[(methylcarbamoyl)-oxy]thioacetimidate). An all-glass gas chromatographic system coupled to a microcoulometer with a nitrogen-specific cell was used. The column was packed with a mixture of 6% OV210 and 4% OV101 on Gas Chrom Q, as was the glass transfer tube which connected the chromatographic column to the pyrolysis furnace. Some loss occurred but response was linear from 125 to 20 ng and sensitivity was such that 20 ng of methomyl could be readily measured.     

The epidemiology of adult and larval (tissue) cestodes in dyfed (U.K.). 1. The cestodes of farm dogs

Sixty-three per cent of dogs on 100 sheep farms and 62% of those on 18 wintering farms in Dyfed were found infected with adult cestodes. The prevalence of each species is recorded and the relationship between diet, anthelmintic treatment and cestode infection is discussed.     

Simulation-aided development of the Hawaii swine research programme

A computer model is presented to estimate the quantitative impact of future research/extension activities in various aspects of swine production on the profit of an average swine producer in Hawaii. The model was designed and used to generate information for making decisions regarding funding of future research/extension projects in the swine production area. The computer model has two components. The first simulates the biological production behaviour of a typical pig enterprise of Hawaii. The General Purpose Simulation System (GPSS) language was used to model the stochastic nature of the production. For a given set of biological parameters, this component provides annual production levels, feed consumption and statistics for selecting the capacity of various building facilities. The second component computes annual revenues, costs and rate of return to capital investment over the analysis period by using discounted cash flow method. In addition to other cost and price data, it uses the output of the first component as input.     

The enterotoxin and other plasmids of enteropathogenicEscherichia coli

Several characters ofEscherichia coli enteropathogenic for farm animals and man are determined by transmissible plasmids. These include the production of K88 and K99 antigens, enterotoxin and haemolysin. The construction of bacteria of a desired plasmid composition provides an elegant method of obtaining information on these characters. Such studies have revealed that the K88 antigen is importantly involved in the ability of enteropathogenicE. coli to proliferate in the small intestine of piglets and that the K99 antigen performs a similar function inE. coli enteropathogenic for calves and lambs. Enterotoxin is mainly responsible for the diarrhoea that then ensues.

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Kurzfassung Mehrere pathogene Eigenschaften der E. coli für Mensch und Haustier werden durch übertragbare Plasmiden bestimmt. Dazu gehört auch die Produktion von K88 und K99 Antigenen, von Enterotoxinen und Hämolysin. Die Entwicklung von Bakterien mit der gewünschten Plasmazusammensetzung stellt eine gute Methode dar, Information über diese Eigenschaften zu gewinnen. Untersuchungen dieser Art haben gezeigt, dass K88 Antigene die Vermehrung von E. coli im Dünndarm von jungen Schweinen, fördert, und dass K99 Antigene eine ähnliche Wirkung auf die enteropathogenen E. coli bei Kälbern und Lämmern haben. Enterotoxin ist die Hauptursache für die dabei auftretende Diarrhoea.

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Resume Plusieurs caracteres d'Escherichia coli enteropathogenes pour les animaux de ferme et l'homme sont determines par des plasmides transmissibles. Ceux-ci incluent la production d'antigenes K88 et K99, d'enterotoxine et d'hemolysine. Un modile de bacterie ayant la composition plasmidique desiree fournit une methode elegante pour l'obtention d'une information sur ces caracteres. De telles etudes ont montre que l'antigene K88 intervient de facon marquee dans l'aptitude d'E. coli enteropathogene a proliferer dans l'intestin grole de porcelets et que l'antigene K99 a une fonction similaire pourE. coli enteropathogene des veaux et des agneaux. L'enterotoxine a une respourabilite majeure dans la diarrhee.

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Riassunto Alcuni caratteri dell'E. coli patogeno per l'uomo e per gli animali domestici sono determinati da plasmidi transmissibili. Questi comprendono la produzione di antigeni K88 e K99, di enterotossina e di emolisina. Un modello di batteri della composizione plasmidica desiderata fornisce un metodo ideale per l'ottenimento di informazioni su questi caratteri. Tali studi hanno dimostrato che l'antigene K88 svolge un ruolo importante nella proliferazione dell'E. coli enteropatogeno nell'intestino tenue dei porcellini e che l'antigene K99 svolge una funzione simile per l'E. coli enteropatogeno dei vitelli e degli agnelli. L'enterotossina e il maggior responsbile della diarrea che ne consegue.

     

Determination of residues of isofenphos and its phosphoramidate analogue

A method is described for the gas chromatographic determination of residues of isofenphos (BAY 92114, O-ethyl O-2-isopropoxycarbonylphenyl isopropylphosphor-amidothioate) and its phosphoramidate which is a potential metabolite. When potato, cabbage, rapeseed and a sandy loam soil were fortified with 0.01, 0.1 and 1.0 mg/kg and analysed by the method described, the recoveries ranged from 76 to 98%. The limits of detection of the method were 0.5 and 1.0 ng for isofenphos and isofenphos oxygen analogue respectively. Degradation under field conditions of isofenphos to its oxygen analogue was demonstrated in a sample of field-treated potatoes.