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- Quality parameters of wild white trevally (Pseudocaranx dentex) natural spawn kept in captivityPublication . Nogueira, Natacha; Ferreira, Marilyn; Cordeiro, Nereida; Canada, PaulaThe white trevally (Pseudocaranx dentex Bloch & Schneider, 1801) is a widely distributed carangid, commercially exploited in both the Pacific and eastern Atlantic. Most published works refer to the use of hormonal induction with gonadotropin-releasing hormone for egg supply with generally low fecundities and of poor quality. This study aimed to contribute for a better knowledge on the husbandry conditions that allow for natural spawning of white trevally in captivity. Wild white trevallies were kept in captivity for four years until natural spawning occurred. Nine breeders were kept in a 10m3 concrete tank at a density of 5 Kg/m3 , under natural photoperiod and natural water temperature fluctuations. Spawning started when water temperature reached 19 °C and lasted for two months. Viability rates varied between 35 and 79% and the average number of spawned eggs per female was of 280 × 103 . Egg total lipids (16%DW) and fatty acid profile (expressed as a % total detected) remained constant throughout the spawning season and were not correlated with any egg viability parameters. Neutral lipids, a major energy source in marine fish eggs and larvae, accounted for 50% of lipid classes, followed by glycolipids and phospholipids. Within lipid fractions, the neutral lipids presented high amounts of mono unsaturated fatty acids followed by equally high contents of polyunsaturated fatty acids. Docohexaenoic acid (DHA) was mainly found in the phospholipids fraction, though it was present in high amounts in all lipid classes. However, no significant correlations were observed between the DHA content and the egg viability parameters. The percentage of arachidonic acid (Ara) (< 0.1%) was low, possibly due to a deficiency of this fatty acid in the broodstock diet. Polyunsaturated fatty acids content, mostly represented by DHA and eicosapentaenoic acid (EPA), was positively correlated with hatching rate. Correlations observed between chemical composition of the eggs and viability parameters highlight the fact that egg quality is deeply influenced not only by environmental factors but also by broodstock management techniques
- Separate and combined effects of cyclic fasting and l-carnitine supplementation in red porgy (Pagrus pagrus, L. 1758)Publication . Nogueira, Natacha; Cordeiro, Nereida; Canada, Paula; Silva, Paula Cruz e; Ozório, Rodrigo O. A.We examined the e¡ects of cyclic fasting in red porgy (Pagrus pagrus) fed di¡erent dietary carnitine levels. Ju venile ¢sh (23.58 3.49 g) were divided into eight groups ^ four groups were fed every day to apparent sa tiation, while the other four were fasted for 7 days every 2 weeks. In each feeding regime, two replicates were fed an L-carnitine non-supplemented diet (46 mg kg 1 ) and the other two groups were fed an L-carnitine sup plemented diet (630 mg kg 1 ). Fish fed 630 mg L-carni tine accumulated two times more L-carnitine in muscle than ¢sh fed 46 mg L-carnitine. Cyclic fasting reduced the growth performance and lipid content in the liver. Carnitine supplementation did not a¡ect performance and body composition, but decreased the n-6 PUFA content. Moreover, the combined e¡ects of fasting and carnitine supplementation were observed on reducing the n-3 fatty acid content. Areas of steatosis were found in the livers of red porgy, but the results revealed that supplementation of L-carnitine in cyclic fasted ¢sh con tributed towards a lower degree of vacuolization than in ¢sh fed to apparent satiation. Regardless of the feed ing regime applied, the spleen of ¢sh fed the L-carni tine-supplemented diet was haemorrhagic and hyper activation of melanomacrophage cells was observed.
- Effect of different levels of synthetic astaxanthin on growth, skin color and lipid metabolism of commercial sized red porgy (Pagrus pagrus)Publication . Nogueira, Natacha; Canada, Paula; Caboz, José; Andrade, Carlos; Cordeiro, NereidaA study was undertaken to evaluate the effects of supplementing commercial feeds with Car ophyll® Pink, a gelatin-encapsuled astaxanthin, on growth parameters, lipid composition, pigment concentration and skin color of commercial size red porgy. Three isonitrogenous diets were formulated containing different levels of astaxantin: Ctrl diet (no pigment added), A50 diet (with 50 mg/kg of astaxanthin) and A80 diet (with 80 mg/ kg of astaxanthin). Four groups of fish (386.29 ± 29.50 g initial weight) were grown in triplicate tanks (10 fish per tank). Ctrl, A50 and A80 groups were fed the respective diets to apparent satiation for 180 days, while a fourth group was fed A50 diet for 90 days followed by A80 diet for another 90 days (A50A80). At the end of trial muscle samples were collected for composition analysis, liver and mesenteric fat for lipid composition determination and skin samples for carotenoids quantification. Dietary astaxanthin supplementation had no effect on growth performance and hepatosomatic index. However, A50A80 group displayed a lower muscle protein content and higher fat content when compared to the other groups. There was no clear effect of dietary astaxanthin supplementation on the liver’s and mesenteric fatty acid profile. Although there was no significant effect on skin total carot enoids, the astaxanthin content tended to increase in fish fed astaxanthin supplemented diets, which was reflected on redness values. Accordingly, dietary astaxanthin supplementation (at 50 or 80 mg/kg for 6 months or at 50 mg/kg for 3 months followed by 80 mg/kg for 3 months) influenced positively skin hue and chroma of red porgy on both pectoral and caudal areas, improving the skin color in commercial sized red porgy and achieving hue and chroma values close to those previously reported for wild individuals. The results reported here provide evidence of the applicability of Carophyll® Pink to improve skin color of large size commercial red porgy, but further studies are needed to optimize this carotenoid supplementation in production farming.