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Il cortisolo come indicatore di stress in specie ittiche d'interesse commerciale
Full text linkDuring the last years, fish welfare interest is increasing in the public opinion and, consequently, in scientists, industry and governments. Reared fishes are often exposed to stress conditions, due to practices such as manipulation, grading, high stocking densities, transport, pre-slaughter conditions and slaughter methods.
The stress response in fishes is similar to that of the other vertebrate and, if stress conditions are prolonged, it causes lowered grow rate, immunosuppression and reproductive failure. In aquaculture, stressors are often unavoidable despite the stress control is essential for welfare and productivity.
In this study, cortisol was used to identify the more appropriate practices to improve welfare in two very important farmed species: rainbow trout and European sea bass. Diets with different vegetable protein meal levels and different slaughter methods were evaluated in trout. In sea bass, the study focused on pre-slaughter conditions with different dissolved oxygen concentrations and stocking densities. Due to the difficulties related to blood sampling, cortisol was evaluated also in other matrices such as mucus, muscle, fin and intestinal content. The timing of cortisol diffusion into the various matrices was also evaluated in sea bass exposed to air exposure stress.
The stress response was lastly investigated in the very early stages of sea bass development (zero-fifteen days post hatching). In summary, the electrical stunning is preferable as regard trout welfare and a diet in which fish meal is replaced by plant proteins could not influence the stress response to slaughter in this species.
In sea bass, stocking densities and dissolved oxygen level seemed to be less effective on cortisol level than the fishing and transport procedures during the pre-slaughter practices. So, an accurate planning of this phase is important to reduce stress of the fishes at slaughter. The cortisol levels in the matrices different from plasma, in most cases, were effective in detecting the stress status of fish.
Lastly, the study on sea bass larvae evidenced a precocity in the stress response ontogenesis which impose very soon accuracy in aquaculture managementll benessere dei pesci o “fish welfare” sta riscuotendo negli ultimi anni sempre maggiore interesse nell’opinione pubblica e di conseguenza nel mondo della ricerca, dell’industria e dei governi. In allevamento, i pesci sono sottoposti molto spesso a condizioni stressanti (manipolazione, selezione, densità , trasporto, condizioni di pre-macellazione e tecniche di macellazione), condizioni alle quali non possono sottrarsi dato il confinamento. La risposta allo stress nei pesci è analoga a quella dei cosiddetti vertebrati superiori e, se lo stress si prolunga nel tempo, determina crescita ridotta, immunosoppressione e deficit riproduttivi. Gli stressori in acquacoltura sono in molti casi inevitabili ma la riduzione dello stress e dei suoi deleteri effetti è fondamentale sia per il welfare che per la produttività . Nel presente studio, si è utilizzato il cortisolo per identificare pratiche più idonee al benessere di due specie d’interesse commerciale: la trota iridea e la spigola. In particolare, si sono valutati gli effetti di diete con percentuali diverse di farina proteica vegetale e di diversi metodi di macellazione sullo stress nella trota e di condizioni diverse di densità di stoccaggio e ossigeno disciolto durante le fasi di pre-macellazione nella spigola. Date le problematiche legate al dosaggio del cortisolo nel plasma e alle modalità di prelievo, negli animali adulti lo steroide è stato valutato anche in altre matrici quali muco, muscolo, pinna e contenuto intestinale. I risultati ottenuti dalle sperimentazioni hanno suggerito tempi di diffusione diversi dello steroide nelle diverse matrici e pertanto si è condotta una verifica di questa ipotesi sottoponendo spigole ad uno stress di esposizione all’aria. Infine, data la fragilità delle prime fasi di sviluppo e l’effetto deleterio del cortisolo, si è valutata la risposta allo stress termico in larve di spigola nei primi quindici giorni di vita. La sperimentazione sulla trota ha messo in evidenza che, in questa specie, le diete testate sono ininfluenti sulla risposta allo stress e che, alla macellazione, l’elettrostordimento è da preferire all’asfissia all’aria. Per quanto riguarda la spigola si è visto che le condizioni di densità di stoccaggio e di ossigeno disciolto testate sembrano ininfluenti sulla concentrazione di cortisolo rispetto alle pratiche di pesca e trasferimento che le fasi di pre-macellazione comportano e quindi è soprattutto questa fase che va pianificata con cura per ridurre il lo stress agli animali. Lo studio dell’ontogenesi della risposta allo stress nella stessa specie ha evidenziato una precoce capacità di secrezione endogena del cortisolo che impone agli allevatori una attenta cura a partire dalle primissime fasi di vita della spigola. La valutazione del cortisolo in matrici diverse dal plasma si è rivelata, nella maggior parte dei casi, uno strumento utile per monitorare lo stato di stress oltre che in pesci macellati, in cui il prelievo di sangue non è possibile, anche in animali ai quali non sia possibile ridurre lo stress prodotto dalle pratiche di pesca e manipolazion
Una microtecnica per allestire campioni da singole larve di pesci teleostei per la diagnosi della ploidia tramite citofluorimetria a flusso.
No full textUna microtecnica per allestire campioni da singole larve di pesci teleostei per la diagnosi della ploidia tramite citofluorimetria a flusso
A method for flow cytometric assessment of ploidy in single early hatched larvae of marine teleost fish.
No full textThe paper describes a method set up for the flow cytometric assessment of ploidy in single early hatched larvae of European sea bass (Dicentrarchus labrax). It represents an useful tool in chromosome set manipulation in fishes
Effect of the diet on the stress response to a simulated transportation experiment of fingerlings of Salmo marmoratus
No full textUnder intensive culture conditions, fish are subjected to increased stress that has negative impacts on the fish overall performance. Though good management practices contributes to reduce stressor effects, the possible role of the diet quality in modulating acute stress response has been poorly investigated in fish. The objective of this study was to evaluate the modulation of acute stress response by different diets in marbled trout, Salmo marmoratus. The results showed that a poor diet, beyond reducing growth and survival, can also affect fish acute stress response and that cortisol levels measured in non-invasive matrices such fins or skin mucus proved reliable to study acute stress response in marbled trout
Effect of age and sex on plasma cortisol and dehydroepiandrosterone concentrations in the dog (Canis familiaris)
No full textLimited data exist on age-related physiological variations in plasma concentrations of cortisol and dehydroepiandrosterone (DHEA) in dogs, despite their potential role in the pathophysiology of ageing. This study examined plasma cortisol and DHEA concentrations and cortisol/DHEA ratio variations, according to age and sex in 311 dogs, aged from two months to 16 years. Before adulthood, DHEA concentrations were higher in peri-pubertal males. During adulthood, cortisol and DHEA were higher in males than females. Among females, DHEA was lower in older dogs, but the decrease was observed at an older age in intact than ovariectomised females. Variations in the cortisol/DHEA ratio inversely reflected those of DHEA. Results indicate that testicles are an important source of DHEA in males, and that DHEA is mainly secreted by the adrenal glands in females. The ovaries’ contribution to circulating DHEA appears to be limited, although it may partially compensate an age-related decrease in adrenal secretion
Alternative indicators to evaluate stress in sea bass (Dicentrarchus labrax, L.)
No full textJoint international conference & exhibition of European Aquaculture Society & World Aquaculture Societ
Effetti dello stress da trasporto sulla produzione di cortisolo e HSP70 in spigole (Dicentrarchus labrax) a diversi stadi di sviluppo.
No full textStress conditions due to transport procedure were highlighted in Dicentrarchus labrax (Osteichthyes, Perciformes) larvae, post larvae and adults. As stress indicators, variation in cortisol levels in whole body or plasma, muscle, mucus and faeces were detected. Also the expression of constitutive and inducible heat shock protein 70 (HSP70) was evaluated to determine the cellular response to stress
Cellular localization of insulin-like growth factor-II protein in the sea bass (Dicentrarchus labrax) from hatching to adult
No full textThe cellular localization of IGF-II protein was investigated during larval and postlarval developmental stages of sea bass (Dicentrarchus labrax) by immunohistochemistry using antisera raised against Sparus aurata IGF-II. At hatching, IGF-II immunoreactivity was already present in the skin, developing intestine and skeletal muscle. During larval life IGF-II protein was also observed in heart musculature, in kidney and gill epithelia as well as in liver. In fry skeletal muscle a moderate IGF-II immunostaining was detected in red fibres, whereas white muscle fibres exhibited a faint immunoreactivity. In adults, a marked IGF-II immunostaining was observed in red muscle fibres. A moderate immunoreactivity was also present in white fibres as well as in heart striated myocardial fibres. These results are in agreement with previous findings on the spatial localization of IGF-II and IGF type 1 receptor in S. aurata and Umbrina cirrosa, confirming the role of IGF system during development and growth of fish
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