Mass mortality among minnows Phoxinus phoxinus (L.) in Lake Tveitevatn, Norway, due to an aberrant strain of Aeromonas salmonicida

Abstract. Mass morality in minnows Phoxinus phoxinus (L) was investigated in the Vinje water system, southern-central Norway. The main clinical feature was the development of extensive haemorrhagic skin lesions from which was isolated a non-pigmented, fish-pathogenic strain of Aeromonas salmonicida.     

The experimental histopathology of Lernaea polymorpha Yu, 1938 infection in naive Aristichthys nobilis (Richardson) and a comparison with the lesion in naturally infected clinically resistant fish

Abstract. Bighead carp, Aristichthys nobilis (Richardson), fingerlings which had not been previously exposed to nauplii of Lernaea polymorpha were infected and sacrificed at various time intervals up to 21 days. Clinical observations showed that punctate haemorrhages developed following skin penetration at 13 days post-exposure. The adult female parasite was observed embedded in the skin and histopathology showed that the parasite penetrated the host tissue at an angle, sliding between the overlapping scales. It caused extensive tissue disruption, necrosis and haemorrhage along its path of entry, which was followed by an acute inflammatory response succeeded by a highly vascular chronic granulomatous fibrosis, whereby collagen fibres encapsulated the horns of the parasite. This contrasted with the predominantly haemorrhagic ulcerative lesions examined on immune fish subjected to natural infection, which were extensive but rarely accompanied by penetration through the dermis. There was a very extensive infiltrate of eosinophilic granular cells, club cells and lymphocytes within the spongiotic epidermis and the extensive haemorrhage was largely subepidermal.     

The influence of ultraviolet-B radiation on the mechanism of wound repair in the skin of the Atlantic salmon, Salmo salar L.

Abstract. Exposure of surgically damaged skin of Atlantic salmon, Salmo salar L., to low levels of ultraviolet-B radiation in clear water showed that the basic mechanism of superficial wound healing, characterized by epidermal migration, was unaffected. However, the migrating cells were more vulnerable to the necrotizing effects of the irradiation than the surrounding donor epithelium and longer standing effects such as wound contracturc and resolution of epidermal structure failed to occur.     

ENZYME ACTIVITIES AND OXYGEN UPTAKES OF SOILS UNDER PASTURE IN TEMPERATURE AND RAINFALL SEQUENCES

Some glycoside hydrolase activities, dehydrogenase activities, and oxygen uptakes were studied in New Zealand topsoils under pasture, arranged in two zonal soil sequences: one in which mean annual temperature varied (5 soils), and another in which mean annual rainfall varied (7 soils). Differences in other site factors were small. All the biochemical activities were negatively, but not usually significantly, correlated with mean annual temperature. Activities did not appear to be influenced by differences in the proportions of grasses and legumes (mainly clovers) or in the clay contents at the different sites. Activities of glycoside hydrolases (a) without added substrate and (b) with added starch were significantly correlated with mean annual rainfall, and with soil moisture and organic C contents; activities of (c) enzymes hydrolysing sucrose were significantly correlated only with soil organic C contents. The ratios of (c) to (b) declined significantly with increasing mean annual rainfall. Dehydrogenase activities were highest in winter samples and significantly correlated with both soil moisture content and pH. Oxygen uptakes were significantly correlated with numbers of viable bacteria in soils of the rainfall sequence although they were not significantly correlated with annual rainfall nor with soil organic C contents. Oxygen uptakes and dehydrogenase activities were not significantly interrelated. Results were compared with previous studies of grassland soils.     

Resurfacing Canine Femoral Trochleoplasties with Free Autogenous Periosteal Grafts

Femoral trochleoplasties resurfaced with autogenous free periosteal grafts in six dogs were compared to femoral trochleoplasties performed without grafts in six dogs. The grafts produced cartilage as early as 4 weeks after surgery; however, it was fibrocartilage rather than normal hyaline articular cartilage. The trochleoplasties not resurfaced with periosteum also healed with fibrocartilage but not until 40 weeks postoperatively. The grafted stifles had less patellar cartilage damage when compared to trochleoplasties left to heal without resurfacing.     

The prevalence and economic significance of liver disorders and contamination in grain-fed and grass-fed cattle

SUMMARY Livers were examined from 5,647 grain-fed and 621 grass-fed cattle of similar breed, age and weight, killed at a Queensland abattoir in 1980–81. The prevalences of disorders found in grain-fed cattle were liver abscesses 5.6% and 11.1% (after 80 and 120 days in the feedlot), telangiectasis 8.4%, Echinococcus granulosis 3.3%, Fasciola hepatica 0.4%, unclassified lesions 7.4%, and contamination 3.2%. In grass-fed cattle liver abscesses were 0.2%, telangiectasis 1.0%, E. granulosis 18.9%, F. hepatica 5.4%, unclassified lesions 6.5%, and contamination 1.0%. Liver abscess disease was the main cause of loss in grain-fed cattle and the mean carcase weight of affected steers was 298kg±42kg, compared wiith 308kg±40kg in non-affected (p 0.01). Liver weights of grain-fed and grass-fed cattle were highly significantly correlated with carcase weights (r - 0.78 and 0.49 respectively). Total losses were $2.25 per head in grain-fed steers and $0.90 in grass-fed steers.