Giuliana Parisi

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.

Use of fresh and preserved Tetraselmis suecica for feeding Crassostrea gigas larvae

Abstract In an attempt to provide cost-effective alternative diets and to simplify hatchery–nursery procedures, substitutes for live microalgae in mariculture were tested and among them, concentrated microalgae have so far appeared to be the best alternative products for bivalves, though there are few experimental studies. The food quality of fresh and preserved Tetraselmis suecica for umboned Crassostrea gigas larvae was studied here and its potential as an algal feed for remote production was evaluated. Because it leads to lower growth and higher mortalities than the control diets (>60%), the use of T. suecica OR (strain Orbetello) for C. gigas larvae is not recommended as a monospecific diet. However, a binary diet that includes T. suecica OR is as efficient as the standard ternary PTC diet for C. gigas larvae. On the other hand, even though microalgal utilisation was not clearly affected by the initial size of the larvae, it seemed that old umboned larvae took full advantage of T. suecica OR. Its usefulness in C. gigas larval rearing is therefore limited, but its potential for oyster spat feeding has to be considered. Lastly, preservation at low temperature is an efficient method to maintain the food value of T. suecica OR.

Nutritional value of fresh and concentrated algal diets for larval and juvenile Pacific oysters (Crassostrea gigas)

Abstract Three species of microalgae commonly used as feed for bivalves, Pavlova lutheri, Isochrysis aff. galbana (clone T-Iso) and Chaetoceros calcitrans forma pumilum, were produced with standard techniques and then harvested by a flocculation procedure. This method was effective for C. calcitrans and P. lutheri though a partial deterioration of cells was observed for the latter, whereas flocculation heavily damaged T-Iso cells (diffuse cellular lysis, majority of cells clumped and/or misshapen, loss in organic matter). Quality of concentrates concentrated at 1 °C was investigated by means of gross composition analysis and pheophytin a/chlorophyll a evolution over 4 weeks of storage. P. lutheri concentrates did not exhibit significant changes in gross composition over the storage period, whereas the value of pheophytin a/chlorophyll a remarkably increased, from 0.05 to 0.35. In T-Iso concentrates, a dramatic decrease in protein and carbohydrate content occurred during the first week of storage. The chemical composition of concentrated C. calcitrans cells did not substantially change during the first 3 weeks of storage; after this period, the organic matter decreased significantly (−18%). The effectiveness of trispecific (P. lutheri+T-Iso+C. calcitrans) and bispecific (P. lutheri+T-Iso; P. lutheri+C. calcitrans; T-Iso+C. calcitrans), fresh or concentrated (1 °C), diets were evaluated on Pacific oyster (Crassostrea gigas) with larval and juvenile feeding trials, lasting 1 and 4 weeks, respectively. For larvae, concentrated diets of P. lutheri+T-Iso and T-Iso+C. calcitrans stored for 7–14 days gave better growth than the equivalent fresh diets (P

Body traits and chemical composition of muscle in the common carp (Cyprinus carpio L.) as influenced by age and rearing environment

To investigate body traits and muscle chemical composition in common carp as influenced by age and rearing environment, 2000 fry were stocked in two earthen ponds (300 m2): warm (W), with warm water (refluent from a thermal power station) at about 10 °C above natural temperature, and natural (N), with water from Lake Trasimeno. Because of the different growth rate, W subjects were sampled 3 times (at 12, 15 and 18 months of age) while N-subjects were sampled only once (at 15 months of age). The W 12-month-old fish weighed on average 102 g while N-fish did not reach this weight even at 15 months. At this age, the W subjects showed, in comparison with N-subjects, higher body weight (143 vs. 85 g), component weights, linear measurements (20.94 vs. 17.8 cm), fins (1.80 vs. 1.63g) and filleting remnants (12.80 vs. 11.25%) and lower incidence of skin and head index; no differences resulted in proximate analysis, but muscles of W-fish were richer in saturated fatty acid and in n − 3 PUFA content and showed a higher n-3n-6 PUFA ratio. By comparison with the 15-month-old subjects collected in October 1992, the 12-month-old W-subjects, collected in July 1992, showed lower fin (0.59 vs. 1.8%), viscera (7.6 vs. 10.2 %) and head (20.36 vs. 22.92%) percentages but higher gill (4.27 vs. 3.24%), filleting remnant (14.99 vs. 12.80%), skin (3.92 vs. 3.37%) and dressing (92.4 vs. 89.79%) percentages. The 18-month-old W-subjects, collected in January 1993, did not differ significantly from the 15-month-old subjects either in body weight (154 vs. 143 g) or in the other traits studied, excluding the incidence of viscera (12.01 vs. 10.21%) and gills (2.69 vs. 3.34%), respectively, in the older subjects. Intramuscular lipid content decreased from July according to a seasonal trend. Allometric coefficient showed tachyauxesis for viscera, pectoral and pelvic fins, skin and total muscle and bradyauxesis for filleting remnants and head.

Use of Tenebrio molitor larvae meal as protein source in broiler diet: Effect on growth performance, nutrient digestibility, and carcass and meat traits

The aim of this research was to study the effect of insect meal from larvae ( larvae meal [TML]) as complete replacement of soybean meal (SBM) on growth performance, nutrient digestibility, and carcass and meat traits of broilers. A total of eighty 30-d-old male Shaver brown broilers were homogenously divided into 2 groups (each consisting of 8 replicates of 5 birds). Up to 62 d of age, the groups were fed 2 isoproteic and isoenergetic diets differing for the ingredient used as the main protein source: the control group was fed a corn-SBM-based diet, whereas in the TML group, the SBM was completely replaced by TML. Broiler growth performance was measured during the trial. At 62 d of age, 2 broilers per replicate (16 per group) were slaughtered and apparent ileal digestibility coefficients and carcass and meat traits were determined. The use of TML as the main protein source in the broiler diet had no significant effect on most growth performance and carcass traits and chemical and physical properties of meat, the latter being important for marketing purposes. The feed conversion ratio in the entire experimental period (from 30 to 62 d) was improved in the TML group compared with the SBM group ( < 0.05). The apparent ileal digestibility coefficients of DM, OM, and CP in broilers fed the SBM diet were greater ( < 0.01) than the other group. The full digestive system in broilers fed SBM had a lower ( < 0.05) absolute and relative weight than that of broilers fed TML. Also, the weight and the percentage of the spleen in the SBM group were lower ( < 0.05) than those in the TML group. The length of the entire intestine in the group fed TML was greater ( < 0.05) than the other group and the same happened when intestinal length was expressed as percentage of broiler BW ( < 0.05). Among the different intestinal tracts, the ileum and ceca of broilers fed TML had a greater ( < 0.05) length than that of broilers fed SBM. Also, ceca weight (as an absolute value or percentage on live weight) in broilers fed TML was greater ( < 0.05) than that of broilers fed SBM. Breast pH and cooking losses in broilers fed TML were greater ( < 0.05) than those of broilers fed SBM. Chemical characteristic of meat obtained from right breast of slaughtered broilers were unaffected by dietary treatments. larvae meal can be a suitable alternative protein source for growing broilers and also when used as principal protein contributor to the diet.

Evolution of chemical composition, somatic cell count and renneting properties of the milk of Massese ewes

Abstract The experiment was carried out on 52 lactations of 37 multiparous Massese ewes. Because of the mating practice of the breed, three types of lactation were detected: Type 1, a short lactation initiated in autumn; Type 2, a short lactation initiated in spring, following the Type 1 lactation; Type 3, a long lactation initiated in autumn. Milk yield was recorded weekly, starting not before the eighth day from lambing. On a total 984 milk samples, contents of fat, protein, casein and lactose, SCC, pH and clotting parameters (R, K20 and A30) were determined. Data were analysed by a mixed model including lactation order, lactation type, DIM, and individual lactation as random effects. Protein and casein content increased from the second to fifth lactation; the highest fat content was detected in the sixth lactation and over; milk of fourth lactation had higher SCC and worse renneting properties than that of second lactation. The pattern of evolution of parameters within the three types of lactation showed that the increase of nutrients with DIM was particularly noticeable for fat content in the Type 2 lactation (spring/short) which exhibited, at an average of 94 DIM, 1.5 percentage units above the other two types. Evolution of lactodynamographic parameters indicates that generally there was a substantial improvement in cheese-making suitability during the first 2–3 months postpartum, and a worsening thereafter. The Type 2 lactation yielded milk with better renneting properties, particularly with respect to milk obtained during the same season from ewes that had an autumn delivery. This suggested that the newly started milk from the spring lactation could have a corrective effect on the total amount of bulk milk produced, a possible advantage for the Massese breed, which is characterised by a particularly pronounced deseasonalisation of lambings.

Assessment of the performance of Pacific oyster (Crassostrea gigas) larvae fed with fresh and preserved Pavlova lutheri concentrates

The Prymnesiophycea Pavlova lutheriwas produced using a traditional technique (batch mode in carboys) and by an innovative technique (semi-continuous mode in alveolarphotobioreactor). Two experimental feedingtrials were carried out with Pacific oyster(Crassostrea gigas) larvae with freshand preserved (4 °C and 1 °C)P. lutheri concentrates used inmonospecific and bispecific diets, incombination with fresh Chaetoceroscalcitrans forma pumilum. Nodifferences in terms of gross composition andlarval performance were noticed between thefresh algae biomass produced by the twotechniques. The low temperatures allowedpreservation of the nutritionalcharacteristics of the P. lutheri freshculture for the time period considered (27days). The P. lutheri concentratespreserved at 4 °C or 1 °C didnot differ substantially in terms ofnutritional value. Larvae fed a monospecificdiet of P. lutheri, both fresh andpreserved, exhibited a modest growth rate (<2.1 µm day−1), in some cases notsignificantly different from that observed inthe unfed larvae (the control), and a lowsurvival rate. In contrast, when Chaetoceros calcitrans forma pumilumwas used as a monospecific diet, good growthperformance (>4.5 µm day−1) and ahigh survival rate (>86%) were observed inlarvae. A substitution of 50% (trial 1) or80% (trial 2) of fresh C. calcitransforma pumilum with the preserved P. lutheri concentrates did not adverselyaffect growth rate or survival of C.gigas larvae.

Application of multivariate analysis to sensorial and instrumental parameters of freshness in refrigerated sea bass (Dicentrarchus labrax) during shelf life

Abstract Freshness by sensory analysis descriptors and instrumental parameters (rigor index (RI), dielectric properties, K1, compactness (IC) and resilience (IEL), pH, free water (FW), cooking losses (CL)) was evaluated in sea bass stored at 4 and 1 °C with ice covering. Sensory scores presented high values of repeatability (≥0.70). The Principal Component Analysis of sensorial parameters revealed that Factor 1, accounting for a 95% of the variation and linked to storage duration, displayed homogenous behaviour. An antithesis between descriptors of external characteristics of fish and those relative to internal parts was observed, particularly in the intermediate phase of the shelf life, during which storage temperature played a discriminating role. The PCA of the sensorial and instrumental parameters together showed that the parameters most correlated with the first factor (83% of overall variance) were the sensorial ones (loading scores >0.96), K1 freshness index, rigor index and dielectric properties (loading scores =−0.96, 0.73 and 0.71, respectively). Data suggest that the external characteristics of the fish alone could be used to measure freshness. The K1, rigor index and dielectrics properties could be used as objective measures of freshness. Sensory ratings are less powerful for freshness analysis at the later stages of shelf life.