Health of farmed fish: its relation to fish welfare and its utility as welfare indicator

This brief review focuses on health and biological function as cornerstones of fish welfare. From the function-based point of view, good welfare is reflected in the ability of the animal to cope with infectious and non-infectious stressors, thereby maintaining homeostasis and good health, whereas stressful husbandry conditions and protracted suffering will lead to the loss of the coping ability and, thus, to impaired health. In the first part of the review, the physiological processes through which stressful husbandry conditions modulate health of farmed fish are examined. If fish are subjected to unfavourable husbandry conditions, the resulting disruption of internal homeostasis necessitates energy-demanding physiological adjustments (allostasis/acclimation). The ensuing energy drain leads to trade-offs with other energy-demanding processes such as the functioning of the primary epithelial barriers (gut, skin, gills) and the immune system. Understanding of the relation between husbandry conditions, allostatic responses and fish health provides the basis for the second theme developed in this review, the potential use of biological function and health parameters as operational welfare indicators (OWIs). Advantages of function- and health-related parameters are that they are relatively straightforward to recognize and to measure and are routinely monitored in most aquaculture units, thereby providing feasible tools to assess fish welfare under practical farming conditions. As the efforts to improve fish welfare and environmental sustainability lead to increasingly diverse solutions, in particular integrated production, it is imperative that we have objective OWIs to compare with other production forms, such as high-density aquaculture. However, to receive the necessary acceptance for legislation, more robust scientific backing of the health- and function-related OWIs is urgently needed.     

Anaesthesia of farmed fish: implications for welfare

During their life cycle as farmed animals, there are several situations in which fish are subjected to handling and confinement. Netting, weighing, sorting, vaccination, transport and, at the end, slaughter are frequent events under farming conditions. As research subjects, fish may also undergo surgical procedures that range from tagging, sampling and small incisions to invasive procedures. In these situations, treatment with anaesthetic agents may be necessary in order to ensure the welfare of the fish. The main objective of this paper is to review our knowledge of the effects of anaesthetic agents in farmed fish and their possible implications for welfare. As wide variations in response to anaesthesia have been observed both between and within species, special attention has been paid to the importance of secondary factors such as body weight, water temperature and acute stress. In this review, we have limited ourselves to the anaesthetic agents such as benzocaine, metacaine (MS-222), metomidate hydrochloride, isoeugenol, 2-phenoxyethanol and quinaldine. Anaesthetic protocols of fish usually refer to one single agent, whereas protocols of human and veterinary medicine cover combinations of several drugs, each contributing to the effects needed in the anaesthesia. As stress prior to anaesthesia may result in abnormal reactions, pre-anaesthetic sedation is regularly used in order to reduce or avoid stress and is an integral part of the veterinary protocols of higher vertebrates. Furthermore, the anaesthetic agents that are used in order to obtain general anaesthesia are combined with analgesic agents that target nociception. The increased use of such combinations in fish is therefore included as a special section. Anaesthetic agents are widely used to avoid stress during various farming procedures. While several studies report that anaesthetics are effective in reducing the stress associated with confinement and handling, there are indications that anaesthesia may in itself induce a stress response, measured by elevated levels of cortisol. MS-222 has been reported to elicit high cortisol release rates immediately following exposure, while benzocaine causes a bimodal response. Metomidate has an inhibitory effect on cortisol in fish and seems to induce the lowest release of cortisol of the agents reported in the literature. Compared to what is observed following severe stressors such as handling and confinement, the amount of cortisol released in response to anaesthesia appears to be low but may represent an extra load under otherwise stressful circumstances. Furthermore, anaesthetics may cause secondary adverse reactions such as acidosis and osmotic stress due to respiratory arrest and insufficient exchange of gas and ions between the blood and the water. All in all, anaesthetics may reduce stress and thereby improve welfare but can also have unwanted side effects that reduce the welfare of the fish and should therefore always be used with caution. Finally, on the basis of the data reported in the literature and our own experience, we recommend that anaesthetic protocols should always be tested on a few fish under prevailing conditions in order to ensure an adequate depth of anaesthesia. This recommendation applies whether a single agent or a combination of agents is used, although it appears that protocols comprising combinations of agents provide wider safety margins. The analgesic effects of currently used agents, in spite of their proven local effects, are currently being debated as the agents are administrated to fish via inhalation rather than locally at the target site. We therefore recommend that all protocols of procedures requiring general anaesthesia should be complemented by administration of agents with analgesic effect at the site of tissue trauma.     

Changes in trimethylamine oxide and trimethylamine in muscle of wild and farmed cod (Gadus morhua) during iced storage

Trimethylamine oxide (TMAO) is found at high levels in wild Atlantic cod. Trimethylamine oxide is reduced to trimethylamine (TMA) during iced storage. In this study, the levels of TMAO and TMA in wild and farmed cod and the impact of storage, gender and season on these levels were investigated. Wild cod had higher levels of TMAO than farmed cod. Wild cod also had higher levels of TMA after 15 days of iced storage. Farmed cod were found to have levels of TMA‐N <5 mg/100 g after 15 days of iced storage, which is below the maximum permitted level for fresh fish. Therefore, TMA appears to be an unsuitable measure of freshness in farmed cod. Female farmed cod had higher levels of TMAO than male farmed cod; no such difference between genders was found in wild cod. Female and male farmed cod had similar levels of TMA after post‐mortem iced storage. The hepatosomatic index (HSI) of female farmed cod was higher than that seen in male cod and this may be the underlying reason for the differences in muscle TMAO. Levels of TMAO in male farmed cod were higher during the autumn and were correlated with a larger HSI during the same period.     

Assessment of infectious organisms associated with chronic rhinosinusitis in cats

OBJECTIVE: To determine detection rates for feline herpesvirus type 1 (FHV-1), Mycoplasma spp, fungi, and bacteria in flush samples and biopsy specimens from the nasal cavities of cats with and without chronic rhinosinusitis (CRS). DESIGN: Prospective study. ANIMALS: 10 CRS-affected cats and 7 cats without signs of respiratory tract disease. PROCEDURES: Nasal flush samples and biopsy specimens were collected from all cats for bacterial (aerobic and anaerobic), fungal, and mycoplasmal cultures; additional biopsy specimens were collected for virus isolation and polymerase chain reaction (PCR) assay (to detect FHV-1 DNA). RESULTS: Aerobic bacteria were detected in flush samples from 5 of 7 control cats; culture of flush samples from CRS-affected cats yielded aerobic bacteria (9/10 cats), anaerobic bacteria (3/10), and Mycoplasma spp (2/10). No fungal organisms were isolated from any cat. Potential pathogens were isolated significantly more often from CRS-affected cats than from control cats. Bacterial culture of biopsy specimens yielded aerobic bacteria (2/7 control cats and 4/10 CRS-affected cats) and anaerobic bacteria (2/10 CRS-affected cats). Although FHV-1 was not detected in nasal biopsy specimens from control or CRS-affected cats, FHV-1 DNA was detected via PCR assay in specimens from 4 of 7 control cats and 3 of 10 CRS-affected cats. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with findings in control cats, anaerobic bacteria, Mycoplasma spp, and a variety of potentially pathogenic organisms were detected more commonly in samples from cats with CRS. In both groups, FHV-1 was detected via PCR assay as a nonviable organism or in noncultivable amounts.     

Bovine blood neutrophil acyloxyacyl hydrolase (AOAH) activity during endotoxin and coliform mastitis

The dynamics of blood neutrophil acyloxyacyl hydrolase (AOAH) activity, the appearance of endotoxin (lipopolysaccharide, LPS) in blood and the role of blood neutrophil AOAH in the severity of Escherichia coli and endotoxin mastitis were investigated in early postpartum dairy cows experimentally challenged with either endotoxin (n = 6) or E. coli (n = 6). The AOAH activity of blood neutrophils started to decrease significantly at post challenge hours (PCH) 6-24 and 12-24 in the endotoxin and E. coli-challenged groups, respectively; it returned to pre-challenged values at PCH 48 in both endotoxin- and E. coli-challenged groups. The cows were classified as moderate and severe responders according to milk production loss in the non-challenged quarters at PCH 48. There were no severe responders in the endotoxin-challenged group. In the E. coli-challenged group, only 1 severe responder was identified. The pre-challenge neutrophil AOAH activity of the severe responder was approximately 30% lower than that of moderate responders. No LPS was detected in the plasma of endotoxin-challenged cows; neither was it found in the plasma of moderate responders in the E. coli-challenged group at any PCH. However, at PCH 6, a remarkable amount of LPS was detected in the plasma of the severe responder from the E. coli-challenged group. Furthermore, neutrophil AOAH activity was increased by approximately 70% in the severe responder at PCH 6, but it increased by only approximately 15% in moderate responders. This was followed by a decreased neutrophil AOAH activity at PCH 12-24 and 24-72 in moderate and severe responders, respectively; the decreased AOAH activity at those PCH was more pronounced in the severe responder. The pronounced decreased neutrophil AOAH activity during mastitis often coincided with extreme leukopenia, neutropenia and a maximal number of immature neutrophils in the blood. Our results demonstrate that a decrease in neutrophil AOAH activity results in the appearance of LPS in the blood, and low blood neutrophil deacylation activity could be considered as a risk factor for severe clinical coliform mastitis.     

Combining ability analysis of Fusarium head blight resistance in western European wheat lines

The inheritance of Fusarium head blight (FHB) resistance was investigated in eight western European wheat lines using a half-diallel of F₁ crosses. The parents and F₁ crosses were point-inoculated, with a highly aggressive isolate of Fusarium graminearum, in replicated field and glasshouse trials. Type II resistance was assessed by measuring the % FHB spread and % wilted tips. There was a good correlation between the two disease parameters, % FHB spread area under the disease progress curve (AUDPC) and % wilted tips AUDPC (r = 0.86, P < 0.01). Correlation coefficients between the field and glasshouse environments were r = 0.46 (P < 0.01) for % FHB spread AUDPC and r = 0.40 (P < 0.05) for % wilted tips AUDPC. Both general combining ability (GCA) and specific combining ability (SCA) effects influenced the inheritance of FHB resistance, suggesting that in this set of parents both additive and non-additive (dominance or epistatic) effects influence the inheritance of type II FHB resistance. Highly significant GCA-by-environment (P < 0.0001) and SCA-by-environment (P < 0.005) interactions were also observed. Specific combinations of western European wheat varieties were identified with type II FHB resistance at a level equal to or more resistant than the winter wheat variety ‘Arina’.     

Effects of Dietary Mineral Supplementation on Quality of Fresh and Salt‐Cured Fillets from Farmed Atlantic Cod,Gadus morhua

The aims of this study were to investigate effects of dietary mineral supplementation on chemical and sensory quality parameters of fresh farmed cod fillets and on the quality of salt‐cured farmed cod. Farmed cod were fed three experimental diets with different levels of mineral supplements (no supplementation, supplementation without zinc and copper, full supplementation) for approximately 2 yr. After slaughter, one‐third of the experimental fish were subjected to chemical and physical analysis, another third were used for sensory analysis and the remaining fish were salt cured. Potassium, copper, and muscle protein were higher in muscle tissue of cod fed full supplementation than cod fed without supplementation. Instrumental color analysis showed that the cut side of fresh fillets of cod fed full supplementation were slightly more green and yellow than fillets of cod fed without extra supplements. A sensory panel could, however, not detect any differences between heated fresh cod given feed with or without mineral supplements. However, the quality of salt ripened cod which had received a complete mineral supplement in the diet was reduced because of increased yellowness, probably caused by the increased level of copper in the muscle.     

The effects of forest patch size and matrix type on changes in carabid beetle assemblages in an urbanized landscape

In this study we compared ground beetles (Carabidae) from a range of different forest fragments along an urbanization gradient in Brussels, Belgium. We address the following questions: (i) How does the degree of urbanization in the surrounding habitat affect forest beetles, and does it interact with the effects of patch size and distance to forest edge? (ii) Do these factors have a different effect at the level of individual species, habitat affinity groups or total community? During 2002 we sampled 13 forest plots in 10 forest patches, ranging in size from 5.27 to 4383 ha. The beetles were captured using transects of pitfall traps from the edge to a distance of 100 m into each woodland and identified to species level. Effects of urbanization, forest size and forest edge were evaluated on total species number, abundance and habitat affinity groups and ten abundant, widespread model carabid species. Overall, the effects of urbanization, forest size and edge effects slightly influenced total species richness and abundance but appeared to have a major effect on ground beetle assemblages through species specific responses. More urbanized sites had significantly fewer forest specialists and more generalist species. Large forest fragments were favoured by forest specialist species while generalist species and species frequently associated with forest (forest generalists) dominated the smaller forests. Forest edges mainly harboured generalist species while forest specialist species were more frequent into the forests if the forest patches were large enough, otherwise they disappeared due to the destruction or impoverishment of their habitat. Our results show the importance of differentiating between habitat affinity, especially habitat generalists versus specialists, the latter having a higher value in nature conservation, and merely the quantity of species represented in human-dominated areas.     

Management of hemodynamic changes associated with removal of a large abdominal myofibroblastic tumor in a pony

A 22-year-old female Welsh-cross pony was evaluated because of intermittent colic, signs of depression, pyrexia, anorexia, muscle wasting with abdominal distention, and weight gain over the preceding 12 months. A large abdominal mass was detected and surgically removed; the hemodynamic alterations and complications caused by the dramatic fluid losses and shifts that can occur in association with removal of a large abdominal mass required extensive postoperative management. Monitoring of clinical and hematologic variables such as attitude, heart rate, mucous membrane color, mean arterial blood pressure, PCV, and plasma total protein concentration provided useful information for successful management of the patient after surgery. On removal, the tumor weighed 19% of the pony's body weight and was characterized as a myofibroblastic tumor. Myofibroblastic tumors should be considered as a differential for large internal abdominal masses in horses, and surgical removal may be feasible and life extending with appropriate postoperative care.     

A dual indicator set to help farms achieve more sustainable crop protection

BACKGROUND: Farmers are being called to use plant protection products (PPPs) more consciously and adopt more sustainable crop protection strategies. Indicators will help farmers to monitor their progress towards sustainability and will support their learning process. Talking the indicators through in farmers' discussion groups and the resulting peer encouragement will foster knowledge acquirement and can lead to changes in attitudes, norms, perception and behaviour. RESULTS: Using a participatory approach, a conceptual framework for on‐farm sustainable crop protection practices was created. The same participatory approach was used to design a dual indicator set, which pairs a pesticide impact assessment system (PIAS) with a farm inquiry. The PIAS measures the risk for human health and the environment exerted by chemical crop protection. The inquiry reveals the farmers' response to this risk, both in terms of the actions they take and their knowledge, awareness and attitude. CONCLUSIONS: The dual indicator set allows for implementation in four tiers, each representing increased potential for monitoring and social learning. The indicator set can be adjusted on the basis of new findings, and the participatory approach can be extrapolated to other situations. Copyright © 2012 Society of Chemical Industry