The increasing attention towards animal welfare also concerns aquaculture species, with special regards to husbandry and slaughter conditions. Both the extent and the duration of stressful events especially before slaughter may affect post-mortem evolution of biochemical processes and product shelf-life (Pottinger, 2001; Zampacavallo et al., 2003). The present work aimed to evaluate the effects of preslaughter conditions in European sea bass according to i) stocking density and ii) time spent in confinement tanks after catch and before slaughter on physiological indicators of stress and meat quality during storage

A. Trocino

C. Poltronieri

C. Simontacchi

G. Xiccato

L. Carraro

Italian Journal of Animal Science

English

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Full Terms & Conditions of access and use can be found athttps://www.tandfonline.com/action/journalInformation?journalCode=tjas20Italian Journal of Animal ScienceISSN: (Print) 1828-051X (Online) Journal homepage: https://www.tandfonline.com/loi/tjas20Effect of pre-slaughter conditions in European seabass (Dicentrarchus labrax)A. Trocino, G. Xiccato, L. Carraro, C. Simontacchi & C. PoltronieriTo cite this article: A. Trocino, G. Xiccato, L. Carraro, C. Simontacchi & C. Poltronieri (2005) Effectof pre-slaughter conditions in European sea bass (Dicentrarchus￿labrax), Italian Journal of AnimalScience, 4:sup2, 606-608, DOI: 10.4081/ijas.2005.2s.606To link to this article:  https://doi.org/10.4081/ijas.2005.2s.606© 2005 Taylor & Francis Group LLCPublished online: 03 Mar 2016.Submit your article to this journal Article views: 20View related articles 606 ITAL.J.ANIM.SCI. VOL. 4 (SUPPL. 2), 606-608, 2005Effect of pre-slaughter conditions inEuropean sea bass (Dicentrarchus labrax)A. Trocino1, G. Xiccato1, L. Carraro1, C. Simontacchi2,C. Poltronieri21 Dipartimento Scienze Animali, Università di Padova, Italy2 Dipartimento Scienze Sperimentali Veterinarie, Università di Padova, ItalyCorrespondig author: Gerolamo Xiccato. Dipartimento Scienze Animali. Viale dell’Università 16, 35020 Legnaro,Italy – Tel: +39 49 8272639 – Fax: +39 049 8272669 – Email: gerolamo.xiccato@unipd.itRIASSUNTO – Effetto delle condizioni pre-macellazione in spigole (Dicentrarchus labrax). Allo scopo divalutare l’effetto delle condizioni pre-macellazione sulla qualità e la freschezza durante la conservazione, 210spigole sono state poste in vasche a bassa densità (20 kg/m3) e ad alta densità (80 kg/m3). Entro densità, le spgole sono state macellate dopo 2 o 24 h. La densità nelle vasche pre-macellazione ha influenzato marginalmentegli indicatori fisiologici di stress e le variabili di freschezza. L’aumento dell’attesa pre-macellazione da 2 a 24 hnon ha modificato il livello plasmatico di cortisolo, ha ridotto la glicemia e ha influenzato negativamente alcunindici di freschezza. Nel complesso, tuttavia, la qualità e la freschezza del pesce durante la conservazione nonsono state sostanzialmente modificate dalle condizioni di pre-macellazione.Key words: sea bass, stress indicators, pre-slaughter conditions, freshness.ASPA_imp11  15-07-2005  10:28  Pagina 606ITAL.J.ANIM.SCI. VOL. 4 (SUPPL. 2), 606-608, 2005 607PROC. 16th NAT. CONGR. ASPA, TORINO, ITALYINTRODUCTION – The increasing attention towards animal welfare also concerns aquaculture species,with special regards to husbandry and slaughter conditions. Both the extent and the duration of stressfulevents especially before slaughter may affect post-mortem evolution of biochemical processes and productshelf-life (Pottinger, 2001; Zampacavallo et al., 2003). The present work aimed to evaluate the effects of pre-slaughter conditions in European sea bass according to i) stocking density and ii) time spent in confinementtanks after catch and before slaughter on physiological indicators of stress and meat quality during storage.MATERIALS AND METHODS – Two-hundred-ten European sea bass (Dicentrarchus labrax) were used.The fish were caught on June from an intensive pond integrated in an extensive fish valley of the Venetoregion. Soon after catch, 10 sea bass were bled to measure plasma basal levels of glucose (spectrophotometri-cally, Sigma Chemical Co.) and cortisol (RIA). The remaining 200 animals were put into four pre-slaughtertanks (50 sea bass/tank): two larger tanks with fish kept at a lower stocking density (D20 = 20 kg/m3) and twosmaller tanks at a higher stocking density (D80: 80 kg/m3). Within stocking density, sea bass waited 2 h (W02,first tank) or 24 h (W24, second tank) before slaughter. Water temperature was constant at 24°C and dissolvedoxygen was maintained near saturation (9-10 ppm). At slaughter in water and ice, 10 sea bass per experi-mental group were used for blood sampling as described above, while the remaining 40 sea bass were movedto the laboratory for carcass and meat quality assessment. Analyses were performed the day of slaughter (3 to5 h after slaughter) and after 4, 7, 11 and 14 days of refrigeration at 2-3°C on 8 sea bass/treatment/day. Rigorindex, biometric measures and dissection were performed as detailed by Poli et al. (2001). The pH of eye liquorand right fillets was measured using a pHmeter equipped with a specific electrode (FC230B, HannaInstruments). Colour was recorded on right fillets by Minolta Spectrophotometer CM-508 C (Minolta, Milano)according to CIEL*a*b* method. Texture profile analysis was performed on a section of the dorsal left fillet byTA.HDI dynamometer (Stabel Micro System Ldt., UK). An aliquot of fresh minced left fillet was immediatelyanalysed for total volatile basic N (TVBN). Data on blood and quality traits measured the day of slaughterwere submitted to analysis of variance using the GLM procedure of SAS (1991), according to a bi-factorialarrangement (2x2) with pre-slaughter stocking density and wait as main variability factors and their interac-tion. Quality traits during storage were analysed according to a three-factorial arrangement, including also theeffect of storage time.RESULTS AND CONCLUSIONS – Blood glucose concentration averaged 1.66±0.43 g/l in sea bass atcatch and changed with pre-slaughter conditions (Table 1). Increasing stocking density slightly reduced bloodglucose (P=0.06), while increasing pre-slaughter wait from 2 to 24 h reduced it (P<0.001). Sea bass confined for24 h did not likely recover their initial blood glucose levels due to starvation. A significant interaction betweenstocking density and pre-slaughter wait was measured (P=0.03). Blood cortisol was affected by catch and con-finement stress in pre-slaughter tanks, as it raised from 174±44 ng/ml measured soon after catch to more than600 ng/ml after a 2 h confinement regardless from stocking density and did not significantly decrease after 24h. In fact, blood cortisol concentration is known to decrease slowly after an acute stress (Pottinger, 2001).Table 1. Blood variables in sea bass at slaughter and pre-rigor characteristics.Stocking density (D) Pre-slaughter wait (W)ASPA_imp11  15-07-2005  10:28  Pagina 607PROC. 16th NAT. CONGR. ASPA, TORINO, ITALY608 ITAL.J.ANIM.SCI. VOL. 4 (SUPPL. 2), 606-608, 2005RSDD20 D80 Prob. W02 W24 Prob.Sea bass n. 20 20 20 20Glucose1 g/l 2.08 1.83 0.06 2.80 1.11 <0.001 0.41Cortisol ng/ml 539 640 n.s. 614 565 n.s. 2551 DxW, P=0.03, glucose: 3.08, 1.09, 2.52 and 1.13 g/l in groups D20-W02, D20-W24, D80-W02 and D80-W24, respectively.Only few traits of carcass and meat quality measured the day of slaughter were affected by pre-slaughter condi-tions. A higher rigor index was measured in sea bass kept at a lower stocking density (36.4% in D20 vs. 22.6% inD80, P=0.05) and slaughtered after two hours (38.8% in W02 vs. 20.3% in W24, P=0.01) (data not reported intables). Fillet pH, texture, colour and TVBN were not significantly modified, however.During storage from 4 to 14 d, increasing stocking density only increased eye pH and reduced skin lightness,while other variables were not affected (Table 2). On the other hand, increasing pre-slaughter wait up to 24 hincreased carcass dressing percentage (P=0.03), which could be ascribed to a starvation effect. During storage,average rigor index and skin lightness decreased in W24 sea bass, while eye pH increased. Pre-slaughter wait didnot affect fillet pH, lightness or hardness, but a significant increase of TVBN was recorded in W24 fish. However,this latter variable was found to be badly correlated with sea bass freshness (Papadopolous et al., 2003).Table 2. Sea bass and meat quality traits (average value at 4, 7, 11 and 14 d of storage).Stocking density (D) Pre-slaughter wait (W)D20 D80 Prob. W02 W24 Prob.Sea bass n. 64 64 64 64Live weight g 478 482 n.s. 484 476 n.s.Dressing percentage % LW 87.9 87.8 n.s. 87.6 88.1 0.03Fillet percentage % LW 56.8 57.1 n.s. 57.3 56.6 n.s.Rigor index % 74.0 75.0 n.s. 75.9 73.0 <0.01Eye pH 6.61 6.67 <0.001 6.52 6.76 <0.001Skin L* 50.3 47.4 <0.001 50.1 47.7 <0.001Fillet pH 6.34 6.37 n.s. 6.35 6.36 n.s.Fillet L* 36.8 36.9 n.s. 37.1 36.6 n.s.Meat hardness g/cm2 1.34 1.43 n.s. 1.41 1.36 n.s.Meat TVBN mg N/100 g 18.2 18.6 n.s. 17.8 19.0 <0.001Regardless from pre-slaughter treatment, sea bass resulted sufficiently fresh until 14 d (Table 3). As expected,during storage rigor index decreased, while fillet and eye pH raised (P<0.01); skin lightness was reduced, whilefillet lightness and texture did not change. The interaction between storage time and pre-slaughter wait wassignificant for some traits, showing a different evolution in sea bass slaughtered after 2 or 24 h of confinement,even if differences were limited in absolute value. No significant interaction between storage time and stock-ing density was measured.Table 3. Sea bass and meat quality during storage (average value of experimental groups)Days after slaughter (T) Probability RSD4 7 11 14 T T x WSea bass n. 32 32 32 32Live weight g 491 461 486 482 n.s. n.s. 76ASPA_imp11  15-07-2005  10:28  Pagina 608

Effect of pre-slaughter conditions in European sea bass (Dicentrarchus labrax)

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Effect of pre-slaughter conditions in European sea bass (Dicentrarchus labrax)

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