G. Zampacavallo

Fish welfare and quality as affected by pre-slaughter and slaughter management

Abstract. A reliable assessment of animal welfare-suffering and of its impact on product quality requires a multidisciplinary approach that takes into account fish behaviour and the different biochemical and physiological processes involved. This might be done by the contemporary study of changes of indicators of brain function, endocrine responses, post mortem tissue biochemical processes and quality changes. This work reviewed some of the most used indices of stress at the time of slaughter, commercial slaughter methods and related stress effects on physical and biochemical parameters of fish quality. The set of the available data seemed to indicate that, although of some results appear contradictory, pre-slaughter and slaughter stressful practices could have an important effect on the flesh quality in fish. A clear effect emerged mostly on the physical properties of flesh, because severe stress at slaughter time exhausted muscular energies, produced more lactic acid, reduced muscular pH, increased the rate of rigor mortis onset. In this way they could have significant negative effects on technological traits, flesh quality and keeping quality of fish. Asphyxia and electrically stunned fish were more stressed than spiked, knocked and live chilled fish. Combining various methods together might be a more satisfactory strategy for both animal welfare and product quality.

Preliminary results on quality and quality changes in reared meagre (Argyrosomus regius): body and fillet traits and freshness changes in refrigerated commercial-size fish

Meagre (Argyrosomus regius) intensively reared in tank by a Tuscany farm and fed commercial diets, were examined to study a) marketable and flesh nutritional traits in commercial-size fish and b) loss of freshness under refrigerated storage condition. Eighty fish, sampled in May, July and November (at 24, 26, 30 months of age) were submitted to linear measurements and weight of the most important body components. Whole fillets were analysed for moisture, lipid and fatty acid composition. Data were analysed by ANOVA (sampling date). A sub sample of fifty-four meagre (902–1840 g b.w.) was stored at 1 °C with ice cover and evaluated every 24 h after death until spoilage for the EU freshness classes, dielectric properties, rigor index, muscular and eye liquor pH, K1% freshness index. Data were analysed by regression on time after death. A small sample of meagre (n = 6) and sea bass (Dicentrarchus labrax) (n = 6), reared in analogous rearing condition in the same farm were compared by ANCOVA on body weight (average b.w. 668 g). Meagre were characterised by 1.04 condition factor, 44% fillets, 6% viscera, negligible mesenteric fat (≅1%) and 94.5% dressing yield. The head incidence increased (P < 0.01) with b.w. increase. Moisture increased while lipid decreased (P < 0.01) in fillet from July to November (74.47 vs 75.96%; 2.93 vs 2.06%). An index of thrombogenicity calculated from the quantitative fatty acid composition was very low (0.10). In comparison with sea bass of the same body weight, meagre had greater length (41.2 vs 37.6 cm), head incidence (29.9 vs 20.7%) and dressing (94.8 vs 89.2%) and lower viscera (5.2 vs 10.9%), mesenteric fat (0.9 vs 7.9%) and intramuscular fat (2.24 vs 12.78%) incidences. Meagre had a 9-day shelf-life (E class from 1st to 3rdd and A class from 4th to 7thd). Rigor index and impedance remained higher than 90% and 66, respectively until the 3rdd after death. The quality traits found for this species indicated meagre as a promising candidate for Mediterranean aquaculture.

Quality outline of European sea bass (Dicentrarchus labrax) reared in Italy: shelf life, edible yield, nutritional and dietetic traits

Abstract The final product quality of European sea bass was outlined through some results on (1) quality traits in a large range of body size (80–1580 g weight) and (2) changes in sensorial and objective quality parameters during shelf life, as influenced by the rearing system, storage and stress. More than 500 European sea bass of commercial size were used in several trials. All fish were subjected to linear and weight measurements. In most trials, sea bass were stored at 4 or 1 °C with ice cover and evaluated every 24 h after death until spoilage for the EU freshness classes and for a large number of physical and chemical quality traits (rigor index, dielectric properties, muscle and eye liquor pH, water-holding capacity (WHC), water, protein, ash, total, neutral and polar lipids, cholesterol, fatty acids, malonaldehyde, adenine nucleotides and biogenic amines). Fillets showed on the average isometric growth, but the dorsal muscle grew faster and the ventral one slower than the body weight. A moderate corpulence increase in fish shape during growth emerged. The size range from 500 to 940 g—when incidences of fillets and dorsal muscle were higher than 48% and 31% and that of viscera was lower than 10%—can be suggested for having sea bass with the better edible portion yield. Protein and ash contents of muscle remained constant with body weight increase, while moisture and cholesterol content decreased; total lipid moderately increased along with the triglyceride incidence. On the whole, the muscular fatty acid pattern determined good indexes of atherogenicity (IA) and mostly of thrombogenicity (IT). Sea bass stored at 4 or 1 °C with ice cover had a 6- and 10-day shelf life, respectively. In the first 2 and 3 days, respectively, sea bass were Extra (always with 100% rigor index) and had Fish Tester values decreasing to 64 or 73, respectively, and negligible levels of malonaldehyde (MDA) and biogenic amines. In the following 2 and 3 days, respectively, sea bass became A fish (good quality), with decrease of rigor index (IR) and Fish Tester (FT) and slight increase in malonaldehyde and putrescine contents. In the following 2 and 4 days, respectively, sea bass became B fish (bad quality), with further decrease of rigor index and Fish Tester and moderate increase of malonaldehyde and putrescine. Thereafter, fish were unfit for human consumption. No difference in quality parameter of fish reared in aerated (4.3 ppm O2) or hyperoxic (9.3 ppm) conditions was found. Stress shortened the pre- and post-rigor phase and shelf life.

Biosensors applied to biochemical fish qualityindicators in refrigerated and frozen sea bass reared in aerated or hyperoxic conditions

Biosensors in the detection of K1 value (a ratiobased on the changes in ATP catabolites contentoccurring in the muscle after death) and biogenicamines for evaluation of fish quality were tested. TheK1 value was determined, every 24 h, from 24 to168 h after death, by HPLC and by a xanthine oxidasebiosensor on 36 sea bass (Dicentrarchus labrax)stored at 1°C with ice covering. TheK1 value by biosensor and the biogenic amines byHPLC and by a diamine-oxidase biosensor were evaluatedevery 24 h after death or thawing until spoilage on150 sea bass, reared under aeration or atsupersaturated oxygen level and stored at 4°C,1°C with ice covering, −20°C × 30 d and−80°C × 90 d. Refrigerated fish were evaluatedby the EU sensory scheme. A close relation betweenHPLC and biosensor-values emerged for K1 value.Reliable estimates by biosensor K1% of both EUfreshness classes and the quality of frozen bass werefound. Biogenic amine levels remained fairly lowwithin the edibility period but putrescine showed moreevident changes, making it promising as a spoilageindicator in frozen fish. Storage conditions markedlyinfluenced changes after death or thawing in K1value or, even less, in biogenic amine levels,putrescine particularly, while dissolved oxygen inwater of rearing did not.

Influence exerted by certain factors during rearing and before slaughter on post-mortem characteristics of sea bass.

The various practices adopted during rearing may cause disturbance to fish, leading to notable physiological reactions and considerably affecting their infra vitam performance, as well as the quality of the food product obtained. The aim of this work was to assess for European sea bass (Dicentrarchus labrax) the influence of the level of oxygen (DO) in the rearing water, of the density of fish in the hour prior to death, and the effect of capture repeated in the same tank 24 hours after the first capture on the values of some parameters measured at a muscular level during the first 24 hours after slaughter.

Haematic parameters of Maremmana breed

Abstract The haematic pattern of Maremmana cattle of Grosseto area was studied, to investigate the causes of the often found low reproductive efficiency. The provided data are related to some haematic parameters measured in different seasons in Maremmana cattle fed three different diets: Standard diet (pasture + hay in critical periods): diet A; standard diet integrated with mineral salts: diet B; standard diet + mineral salts + concentrated mixed feed): diet C. The season influenced all parameters, while no difference was found among diets. Among the mineral elements, phosphorous showed values always above norm.

Welfare and quality of farmed trout fed high plant protein diets. 2 innovative killing method effect on stress and quality indicators

Abstract The fish stunning/slaughtering procedure has an important role both for the ethical aspect related to animal welfare and for the potential quality of the final products. Stressful harvest procedure and killing methods can negatively influence the post mortem biochemical processes with a consequent faster fish freshness loss. In particular, killing procedures causing a long agony are not humane and can shorten fish shelf life; others, more humane, can have risks for the consumers health (anaesthetics or chemical substances) or are not feasible in small/medium size fish industry (spiking and knocking). The aim of this study was to compare the traditional killing method (asphyxia - A) used for rainbow trout (Onchorynchus mykiss) with an innovative stunning/slaughtering method (two-stage electric stun: 2s at a 500Hz electric field of 2.5V/cm and then 58s at a 50Hz electric field of 0.75V/cm - E), through the study of their effects on stress and quality indicators in fish fed with traditional fish meal (FM) or innovative 80% plant protein diet (PV80). Fish (n=30) of each group (FMA, FME, PV80A, PV80E) were stored at 1°C with ice covering and analysed from 0h to 192h from death. The following analyses were done: blood parameters (only at death); rigor index (RI%) and sensorial evaluation with EU Scheme Rule 2406/96 EEC (performed by 5 judge); eye liquor and muscular pH (pHe, pHm); ATP and its degradation products in muscle; lactic acid in muscle and fillet length (FLC) and height contraction % (FHC) (at 0, 3, 6, 24h). Fillet quality appearance was evaluated by absence/presence and size of bloodstains along the midline on the left fillet. Data were analyzed by ANOVA (killing method, diet and their interaction). Asphyxiated fish (A) died within 15-30’ after prolonged struggling and agony, while innovative method stunned/killed fish (E) were immediately stunned and died in 1 minute. Asphyxiated group showed: higher values of blood glucose and muscle lactic acid; lower values of pHe and pHm at 3, 6 and 24h (P<0.01); earlier full rigor (RI 100% at 1h). RI, significantly different (P<0.001) between A and E fish until 6h after death, in E group reached 100% only at 8h. In agreement with this result, FLC of E fish showed lesser contraction both at 3 h (E 6.9 vs A 18.4%, P<0.001) and at 6h (E 13.9 vs A 18.4%, P<0.05). The same emerged for FHC at 3 h (E 0.9 vs 5.3%, P<0.001). The lower values of ATP/IMP ratio at 0, 3 (P<0.001) and 6h (P<0.01) in A fish than in E fish confirmed the stress condition of the first ones. Differences due to the diet were scarce: PV80 fish had higher pHe, pHm and inosine values at 72h (P<0.001). Fish sensorial evaluation indicated A class until 144h in all groups and B class at 192h after death, except in PV80A fish (75% in B class at 144h). As waited, some bloodstains were found in FME (26.7%) and PV80E (53.3%) fillets while A fish had negligible damages (1.7%). The bloodstains should downgraded the fillet acceptance. However, because the portion size trout are traded wholes/gutted by Italian fish industry, the problem seems less serious. The innovative killing procedure, really a fast and humane procedure, need to be improved for fillet appearance.