Grazing pressure and acquisition of Ostertagia ostertagi in calves

The effect of stocking rate on the acquisition of Ostertagia ostertagi infection and performance of yearling calves grazing a marshland area in the southwest of Jutland (Denmark) was examined. During the early part of the grazing season, when grass growth was high and pasture infectivity low, there was little stocking rate effect on performance. However, during the late part of the grazing season (characterized by poorer grass growth and high pasture infectivity) gains were significantly lower at high, compared with moderate stocking. At both stocking rates, the beneficial effect of moving animals to aftermath in mid-summer was significant, but was most pronounced at the high stocking rate. Interactions between stocking rate and acquisition of parasitism are discussed in the light of grazing behaviour and climatic factors.     

A Study on the Effects of Tactical Drenchings with a Benzimidazole against Ostertagiasis in Calves

In the present study tactical fenbendazole treatments against ostertagiasis in calves were given at short intervals towards the end of the grazing season. This prevented clinical disease and had moderate effects on parasitic loads in animals that stayed on the same pasture throughout the season. The feasibility of tactical treatments is discussed in relation to various strategical control measures.     

Dictyocaulus viviparus in Denmark. A survey of 15 years' diagnostic examination of faeces samples (author's transl)]

On the basis of routine diagnostic examinations of 12424 bovine faeces samples for larvae of Dictyocaulus viviparus, performed during the period 1963 through 1977, some calculations and reflections have been made on the incidence and epidemiology of lungworm infection in cattle in Denmark. It seems justified to conclude that dictyocaulosis is an important disease in heifers and cows as well as in calves. A distinct seasonal variation in the incidence of lungworm infection is apparent, in that more than 85% of the faeces samples were submitted within the period July through October. Lungworm larvae could be demonstrated in faeces samples from cattle during the winter and spring- This is considered to be of great importance with a view to re-establishment of the infection in the following grazing season. Overwintering of larvae on pastures seems possible. too, since patent infections among calves were demonstrated already in May and June. A comparison of meteorological data with totals of samples submitted and with relative numbers of positive samples seems to confirm, that both the level and the spread of lungworm infections are influenced by the amount of rainfall during the period June through August.     

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.     

Capacity of model biobeds to retain and degrade mecoprop and isoproturon

Biobeds are used to increase the adsorption and degradation of pesticide spillage on sites used for mixing and loading and for cleaning of sprayers. The adsorption and the rate of degradation of 14C-labelled isoproturon and mecoprop (MCPP) at concentrations from 0.0005 to 25 000 mgkg(-1) were determined in biobed soil. Further leaching of the two herbicides was determined in a model biobed with a surface area of 2 m2. The biobed material showed enhanced ability to adsorb the two herbicides. Kd was 5.2 litre kg(-1) for isoproturon and 1.6 litre kg(-1) for MCPP in biobed material, which is higher than in natural soil. In different experiments with natural soil, Kd ranges from 0.07 to 0.6 litrekg(-1) for MCPP and from 1.5 to 4.6 litre kg(-1) for isoproturon in soils with varying organic carbon content. Degradation of MCPP was rapid at concentrations from 0.0005 to 500 mg kg(-1), delayed at 5000 mg kg(-1), and very slow at 25 000 mg kg(-1). For isoproturon, the relative degradation was most rapid at the lowest concentration and decreasing with increasing concentrations. After 120 days, between 55% and 8% 14C was evolved as 14CO2 at concentrations between 0.0005 and 25 000 mg kg(-1). The rate of evolution of 14CO2 indicated that degradation rates at low concentrations were of first-order and at higher concentrations of zero-order. Leaching of MCPP and isoproturon was determined in a newly established model biobed during a 2-year period. About 13% of applied MCPP and 1.4% of applied isoproturon leached out during the winter following the first autumn application (worst-case scenario). Leaching was completely prevented when the biobed had a well-developed grass cover and was covered during the winter.     

Husbandry, parasitic and other diseases as factors in the reliability of the enzyme linked immunosorbent assay (ELISA) for detection of trichinellosis in pigs

Serum samples were obtained from pigs originating from specified pathogen-free farms, large industrialised farms and small conventional farms. All animals proved to be free of Trichinella spiralis by a pooled sample digestion method. Careful meat inspection studies on parasitic infections other than trichinellosis, and other inflammatory reactions were recorded and used for subdivision of the animals in different groups. It was concluded that animal husbandry, parasitic infections, or inflammatory reactions have not influenced the mean extinction values of an ELISA for the detection of T. spiralis antibodies, however, the specified pathogen free animals yielded somewhat lower results.     

Trichinella spiralis in wild boars (Sus scrofa)

During the period 1.7. 1972--31.6. 1977 muscle samples from 137 wild boars were examined for Trichinella spiralis. Larvae of T. spiralis were demonstrated in 4 animals. The major part (83) of the wild boars examined, including the 4 positive ones, originated from one particular game park. The rate of infection with T. spiralis in the game park concerned was 4.8%. Calculated on the basis of the total of animals examined, the rate of infection was 2.9%.     

Evidence for the Colonization of Lactic Acid Bacteria in the Gastrointestinal Tract of Suckling Mink

Lactic acid bacteria are considered indigenous members of the gastrointestinal microflora in a number of animal species (Savage 1977a). Some intestinal strains of lactobacilli and streptococci are aWe to adhere to stratified squamous epithelium of some animals (Tannock et al. 1987), in the non-secreting part of the stomach of piglets (Barrow et al. 1980, Fuller et al. 1978) and rodents (Tannock et al. 1982), and in the crop of poultry (Fuller 1978). The presence of lactic acid bacteria in the digestive tract is believed to be of beneficial value to the host animal (Fuller 1989). The production of organic acids in the stomach or the crop helps maintaining a low pH which may be important for inhibiting the colonization of potentially pathogenic bacteria, particularly in the newborn animal (Barrow et al 1980, Fuller 1977, Fuller 1978). The adhesion of lactobacilli to squamous epithelium is host specific: strains capable of adhering to the epithelium of piglets are usually not able to adhere in rodents or poultry and vice versa (Fuller 1978, Lin & Savage 1984, Tannock et al 1982). Adhesion of lactic acid bacterial strains to other epithelia than stratified squamous epithelium has been reported. Thus, the attachment of lactobacilli to cells from the secreting epithelium of the murine stomach (Kotarski & Savage 1979), to intestinal cells of humans (Goldin & Gorbach 1987), and to columnar epithelial cells of piglets and calves (Mäyrä-Mäkinen et al 1983) has been demonstrated using in vitro methods. In another study the in vivo attachment of Enterococcus faecium to duodenal epithelium of gnotobi-otic chickens was demonstrated (Fuller et al 1981). Recent research indicated that in adult mink lactic acid bacteria are not indigenous members of the intestinal flora, and they do not attach to epithelium in any part of the gastrointestinal tract (Federsen & Jørgensen 1992). The present paper presents evidence that Gram positive cocci may colonize the gut of suckling mink kits and attach to the gut mucosa.     

A comparison of two methods and two additives for faecal cultivation of bovine trichostrongyle larvae

The larval recovery rates of Ostertagia ostertagi and Cooperia oncophora from monospecific copro-cultures were determined by the methods of Corticelli and Lai, and Henriksen and Korsholm using vermiculite or polystyrene pellets as inert additives. The addition of either vermiculite or polystyrene pellets in the two culture methods significantly (P less than 0.05) improved larval recoveries of both parasite species. Recovery rates with the Henriksen and Korsholm method were higher (P less than 0.05) for both species than with the Corticelli and Lai method. Advantages and disadvantages inherent in the use of the two culture methods with and without additives are discussed.