Scrapie surveillance in Great Britain: results of an abattoir survey, 1997/98

A randomised sample of 2,809 apparently healthy sheep, 55 per cent of them less than 15 months of age, which were slaughtered for human consumption at abattoirs in Great Britain in 1997/98, was taken to establish the prevalence of scrapie infection. The medulla oblongata of each sheep was examined histopathologically at the level of the obex, and fresh brain tissue was examined for scrapie-associated fibrils (SAF) to establish whether there was evidence of scrapie. In addition, histological sections of the medulla from 500 of the sheep were immunostained with an antiserum to PrP, and the same technique was also applied to any animal found positive or inconclusive by the histological or SAF examinations. Any sheep which was positive by any of these diagnostic methods was also examined by Western immunoblotting, for the detection of the disease-specific protein PrP(Sc). A total of 2,798 sheep (99.6 per cent) were negative by all the methods applied. Ten animals were SAF-positive but negative by all the other methods, and in one animal there was immunohistochemical staining which could not be interpreted unequivocally as disease-specific. A mathematical model was used to estimate the prevalence of scrapie infection in the national slaughtered sheep population which would be consistent with these results. By this model, the absence of unequivocally substantiated cases of scrapie in the sample was consistent with a prevalence of infection in the slaughter population of up to 11 per cent.     

Effects of short-term exposure to condensed tannins on adult Trichostrongylus colubriformis

Twelve parasite-naive sheep were used to study the possible direct anthelmintic effect of a condensed tannin extract (quebracho) on the population and fecundity of the intestinal nematode Trichostrongylus colubriformis. The sheep were infected with a single dose of 20,000 L3 of T colubriformis. Twenty-eight days later, six of them were drenched daily for a week with quebracho extract at 8 per cent by weight of their food intake. All lambs were then slaughtered, and their small intestines removed to estimate the worm burdens and the numbers of eggs in utero. Two days after the first drench with tannin extract the faecal egg counts of the treated sheep were approximately 50 per cent of those of the control sheep (P<0.01), but there was no further reduction with continued drenching. In the treated sheep the worm burdens and number of eggs per gram faeces per worm were reduced by 30 per cent compared with the controls (P<0.05), but the sex ratios, the number of eggs in utero and length of the worms were not affected by drenching with tannin.     

Effects of diets with different calcium and phosphorus contents on the skeletal development and blood chemistry of growing great danes

The skeletal development of three groups of great dane dogs, fed a diet composed according to the published nutritional requirements for dogs (controls) or with increased calcium or calcium and phosphorus content, was examined radiographically, histologically and biochemically. The diets were fed from the time the dogs first began eating food in addition to their dam's milk, until they were 17 weeks old. Thereafter, the calcium and phosphorus intakes of the dogs in the high calcium groups were normalised for a further 10 weeks. The dogs fed the high calcium diet without a proportionally high phosphorus intake became hypercalcaemic and hypophosphataemic, and had severe disturbances in skeletal development, growth, and mineralisation which were typical for rickets. After their calcium intake was normalised the lesions of rickets resolved but osteochondrotic lesions became apparent. The dogs fed the high calcium and phosphorus diet became slightly hypophosphataemic, their growth was retarded, and they had disturbances in skeletal development resembling osteochondrosis, which had only partly resolved after 10 weeks on the normal calcium and phosphorus diet.     

Identification of a collectin-like protein in pig serum that binds a component in perienteric fluid from Ascaris suum

A collectin-like protein (CLP) of the acute phase protein family that binds the polysaccharides mannan and alpha-1-6 dextran was isolated from the serum of pigs infected with Ascaris suum. A monoclonal antibody generated against this protein and used to characterize the CLP revealed on SDS-PAGE and western blot analysis that the protein had a molecular weight of approximately 48 kDa under reducing conditions and greater than 100 kDa under nonreducing conditions. Enzyme-linked immunosorbent assay (ELISA) showed that the CLP bound to substances in the perienteric fluid of Ascaris suum (APF). Molecular weight fractionation of APF demonstrated that CLP binds primarily to APF substances of greater than 100 kDa. Binding of CLP to APF was partially blocked by phosphatidylinositol. This is the first report of a porcine CLP and the binding of a CLP to components of the common nematode Ascaris suum.