Alternative protein sources in sea bass nutrition

Intensive fish farming profitability is declining word-wide. This situation is mainly due to the extensive reliance on fish meal (FM) as feed ingredient in finfish diets in order to meet the high dietary protein needs. FM quality and prices are variable and its global supply is decreasing and highly dependent on meteoric events (e.g. El niño). Several protein sources are potentially excellent alternatives to FM..

UTILIZATION OF WATER CRESS (NASTURTIUM OFFICINALE L.) IN NOBLE CRAYFISH (ASTACUS ASTACUS) FEEDING

Juvenile Astacus astacus (initial b.w.: 0.98 ± 0.06 g) were cultured (30 crayfish/m2) in 200l tanks for 69 days. The experimental design was composed of three treatments as follows: control diet (C) (crude protein: 28.4% of the total dried matter, “DM”; ether extract: 6.22% DM), water cress (W) (crude protein: 20.7% DM; ether extract: 1.9% DM) and control diet + water cress (C + W) with thee replicates per treatment. Relative growth rate improved significantly (P < 0.05) in crayfish fed C + W (+ 110%) compared to W (+ 43%) and the control diet (+ 36%). Gross protein and lipid retentions of the treatment C + W were significantly higher than the control diet and water cress fed alone. At the end of the experiment, a higher survival rate of A. astacus was observed (P < 0.05) in the treatment C + W (67%) and C (71%) compared to the W (58%). These results suggest that the plant water cress (Nasturtium officinale) can be used as supplemental food in noble crayfish feeding

COMPARISON AMONG PRE-GELATINIZED STARCHES OF DIFFERENT BOTANICAL ORIGINS USED IN NOBLE CRAYFISH ASTACUS ASTACUS DIETS

The objective of the present experiment was to compare the biological value and the binding functionality of four pre-gelatinized starches (wheat, diet 1; waxy maize, diet 2; maize, diet 3 and potato, diet 4) used in crayfish diets. 360 juvenile of A. astacus (initial b.w.: 0.70 ± 0.15 g) were cultured in 12 tanks for 43d. Growth performance were significantly higher in crayfish fed diets containing wheat and waxy maize compared to those containing maize and potato pre-gelatinized starches. Disintegration in water and shear force tests of diets confirmed the superior binding capability of pre-gelatinized starches obtained from wheat and waxy maize. These results suggest that the pregelatinized wheat and waxy maize starches are the best choice for the production of diets for the noble crayfish

EVALUATION OF THE AMERICAN WATERWEED (ELODEA CANADENSIS MICHX.) AS SUPPLEMENTAL FOOD FOR THE NOBLE CRAYFISH, ASTACUS ASTACUS

We conducted a preliminary study to evaluate the capacity of summerling Astacus astacus to consume the American waterweed (Elodea canadensis Michx.).under artificial rearing conditions. Summerling A. astacus (initial b.w.: 0.32 ± 0.02 g) were cultured (50 crayfish/m2) in 600l tanks for 89 days. The experimental design was composed of three treatments as follows: control diet (D) (crude protein: 40.9% DM; ether extract: 7.4% DM), elodea (E) (crude protein: 25.8% DM; ether extract: 1.4% DM) and control diet + elodea (D + E) with three replicates per treatment. Temperature, dissolved oxygen, and other water parameters were measured weekly (T: 20.1°C; O2: 7.2 mg/l; pH: 7.5; N-NH4: 0.05 mg/l; N-NO2: 0.01 mg/l; N-NO3: 29.9 mg/l). The relative growth rate was significantly (P < 0.01) higher in treatment D + E (195%) and D (143%) than in E (65%). The reduced growth observed in crayfish fed elodea only can probably be due to the lower dietary lipid level of the plant respect to the standard crayfish requirements. At the end of the experiment, the survival rate of A. astacus was higher (P < 0.05) for the treatment D + E (87%) and D (81%), compared to E (56%). Our results suggest that E. canadensis can be used as a non-expensive supplemental food in order to increase growth and survival in summerling noble crayfish. They also showed that A. astacus has the potential to consume this macrophyte in nature

EFFECTS OF RATION SIZE AND TEMPERATURE ON MOULT INCREMENT AND METABOLIC PARAMETERS OF JUVENILE NOBLE CRAYFISH, ASTACUS ASTACUS

A laboratory experiment was carried out to test the combined effects of ration size (1 vs 3% body weight, b.w.) and temperature (15 ± 2 vs 22 ± 2 °C) on moult increment and metabolic parameters of 80 juvenile noble crayfish (Astacus astacus). The maximum daily consumption (Cmax) and respiration rate (R) were used to calculate the growth scope (i.e. the difference between maximum daily energy consumption and energy costs at a given temperature). The conversion of R into a food-equivalent unit allowed the comparison with Cmax. Results showed that crayfish obtained the maximum moult increment when fed 3% b.w. while temperature seemed to play a less relevant role on growth rate per moult, affecting only the moulting frequency. Crayfish A. astacus fed ad libitum showed a relative insensitivity to the metabolic parameters (oxygen uptake, R and Cmax) within the analysed range of temperatures, possibly as a reflection of this “species” distribution across a broad variety of habitats with different thermal regimes. In the present study, A. astacus displayed characteristics proper of a K-selected species, as slow to moderate growth

Induction of ovarian maturation by means of dietary hormonal treatment in Austropotamobius pallipes

The freshwater crayfish Austropotamobius pallipes is an annual species with low fecundity and a long embryonic development. Restocking programmes for this species have recently been prompted in many countries in Europe because of its ecological importance in the freshwater ecosystem. The role and interactions of neurotransmitters which intervene in crustacean reproduction have been identified but they are not still completely understood. Ovarian development appears to be under the control of two hormones: the vitellogenesis-inhibiting hormone and the gonad stimulating hormone (Fingermann, 1997)

Indagine sullo stato di salute di astici americani (Homarus americanus) importati.

Stando ai dati Eurostat l’importazione di astici (Homarus spp), in prevalenza di origine americana, verso l’UE ammontavano a 8811 tonnellate nel 2012. In termini d’importazione l’Italia ha rappresentato quasi il 30% del totale. Attualmente, da parte dell’opinione pubblica, la problematica del benessere dei crostacei è particolarmente sentita. Nell’ambito di questa problematica, nella primavera del 2013, è stata condotta una prova di stabulazione di astici americani (Homarus americanus) al fine di valutare alcuni indici di benessere utili per un corretto mantenimento in ambiente confinato. È stata effettuata un’indagine sanitaria per valutare il rischio d’introduzione di agenti patogeni esotici per le popolazioni di crostacei autoctoni e potenzialmente trasmissibili al consumatore. Dopo un’indagine preliminare conoscitiva degli impianti di stabulazione presso diversi gruppi del settore della Grande Distribuzione Organizzata, sono stati scelti i parametri fisico chimici dell’acqua, densità e tecnologie da addottare nella prova sperimentale. 42 astici americani (H. americanus) di 540 gr di peso medio, provenienti dagli acquari di un importatore, sono stati stabulati in 5 vasche a ricircolo con un unico filtro refrigeratore (9 animali per acquario). Il periodo di stoccaggio è durato complessivamente un mese ed alla fine di ogni settimana gli animali di un’intera vasca, previo prelievo di emolinfa per esami biochimici e batteriologici, venivano soppressi e sottoposti ad esame necroscopico, parassitologico ed istologico. Durante tutto il periodo della prova gli animali non sono stati alimentati e la qualità dell’acqua era monitorata con prelievi settimanali. I parametri ematici e biochimici degli astici (glicemia, proteine totali e conta degli emociti), hanno fatto registrare il picco massimo dei valori dello stress dopo circa 2 settimane di stabulazione, una riduzione durante la terza settimana, stabilizzandosi alla quarta. L’abbassamento dei valori di stress può essere attribuita ad un miglioramento delle condizioni di stabulazione durante la prova sperimentale rispetto a quelle presso l’importatore. L’indagine sanitaria ha rilevato all’esame batteriologico la presenza di Aerococcus viridans nel 11,90% dei soggetti. Dall’esame istologico le branchie dei primi due acquari apparivano intensamente colonizzate sulla superficie da batteri filamentosi e presentavano reazioni flogistiche che erano assenti nelle osservazioni della terza e quarta settimana Il 45% dei soggetti era affetto da parassitosi: 32,5% gregarine (protozoi Apicomplexa) riferibili a Porospora gigantea, il 12,5% metazoi riferibili a stadi larvali di acantocefali, aventi caratteristiche ascrivibili a Polymorphus botulus. Entrambi i parassiti sono stati oggetto di segnalazioni nella zona d’origine. Lesioni microscopiche, sia fungine sia batteriche, sono state osservate a carico dell’esoscheletro. Le patologie riscontrate potrebbero rappresentare un pericolo se le acque di stabulazione non vengono adeguatamente depurate nei luoghi di importazione. Le acque liberate direttamente a mare potrebbero divenire un potenziale mezzo di diffusione di patogeni pericolosi per il nostro ecosistema. Particolare attenzione dovrebbe essere rivolta alla manipolazioni e al consumo dell'astice previa cottura, in quanto l'aerococcosi è stata segnalata come zoonosi minore in pazienti immunodepressi

Sylvatic rabies in the north-east of Italy: monitoring and evaluation of the effectiveness of prophylaxis in workers at risk and travelers.

Rabies is a global zoonotic disease that occurs in developing and developed countries, producing consistently fatal encephalitis in humans and animals. Rabies virus infects mammals through infected saliva via bites or scratches, although atypical exposures have been documented. In late 2008, wildlife rabies re-emerged in Northeastern Italy in an area bordering Slovenia, spread to Veneto region (Belluno province) and to the autonomous province of Trento and Bolzano. Since then, 287 animal cases have been detected in wild and domestic animals; the last one has been diagnosed in a red fox in February 2011. No human cases have been reported linked to the recent epidemic and Italy has been declared as free from rabies in February 2013. Several oral fox vaccination campaigns accompanied by efficacy monitoring and extensive surveillance of territories affected by the epidemic have been implemented together with education and preventive vaccination of workers at risk of viral exposure (i.e. forestry and wildlife workers, veterinarians, shelters ‘operators and laboratory personnel). The aim of this work was the evaluation of the rabies antibodies level and persistence in workers at risk of exposure and travelers. A total of 347 serum samples were collected: 169 after pre-exposure prophylaxis and 178 after post-exposure prophylaxis performed with different immunization schedules. All sera have been tested to detect rabies virus anti-glycoprotein antibodies by a commercial quantitative indirect ELISA (Platelia TM Rabies II kit; Biorad) and with the reference method FAVN (Fluorescent Antibody Virus Neutralization), according to the procedure recommended by the WHO. The results on the protection level, persistence of antibodies and the comparison between the ELISA and FAVN test will be discussed