Fatty Acid Profiles and Lipid Oxidation Status of Sun Dried,Deep Fried,and Smoked Sardine (Rastrineobola argentea) from Lake Victoria,Tanzania

Freshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constituting 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 µmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.     

The toxicokinetics of benzo[a]pyrene in juvenile coho salmon, Oncorhynchus kisutch, during smoltification

The activities of Phase I and Phase II biotransformation enzymes in the livers of yearling coho salmon (Oncorhynchus kisutch), were measured biweekly from February until the release date from the hatchery in mid-June, in order to observe any alterations in baseline levels during smoltification. Peak enzyme activities occurred in February and March and then declined through to June. Total cytochrome P450 levels ranged from 0.024±0.009 to 0.095±0.010 nmol mg^-1 microsomal protein, ethoxyresorufin O-deethylase activity ranged from 2.74±0.75 to 9.94±0.85 pmol min^-1 mg^-1 microsomal protein, and glutathione S-transferase activity ranged from 0.07±0.01 to 0.33±0.01 μmol min^-1 mg^-1 cytosolic protein during this period. Following an intraperitoneal injection of [3H]benzo[a]pyrene (B[a]P), elimination occurred rapidly (>71% excreted into the bile within 24h) from February to June. Although the distribution of B[a]P in tissues changed through the sampling period, the highest leels of B[a]P-derived radioactivity were found in the liver, bile and fat. Analysis of the bile revealed that 55 to 63% of the radioactivity was Phase I metabolites, 16 to 24% glucuronide conjugates, 8% sulfate conjugates, 7% other conjugates and 6% aqueous-soluble metabolites. These findings suggest that the transformation from freshwater adapted coho ‘parr’ to ‘smolts’, can significantly alter biotransformation enzyme activities and the distribution and elimination of xenobiotics such as benzo[a]pyrene in these fish. This revised version was published online in July 2006 with corrections to the Cover Date.     

Carotenoid Pigments Composition of Two Commonly Discarded Decapod Crustaceans in Grand Sole and the Galician-Northern Portugal Coast Fisheries

ABSTRACT

Carotenoid composition of two commonly discarded decapod crustaceans, Liocarcinus depurator and Munida spp., was assessed in different catching months. Total carotenoid content ranged between 7 ± 1 and 22.4 ± 0.7 μg g^?1. Pigment separation was performed by high-performance liquid chromatography coupled with a diode array detector. Astaxanthin accounted for 21 to 50% of total carotenoids, and the remaining percentage corresponded mainly to esters of astaxanthin. The fatty acid profile of carotenoid extracts for each species was evaluated. Overall total unsaturated fatty acids content ranged from 406 to 1,631 μg g^?1. Both species were rich in omega-3 fatty acids, which on average represented 68% of total unsaturated fatty acids. Therefore, the use of these low value by-catch species as a source of carotenoid pigments and fatty acids (e.g., for aquaculture formulations) is a possible alternative to their disposal at sea.     

The Impact of Diets Supplemented with Different Forms of Rosemary and BHA on Chemical,Microbial and Sensory Properties of Rainbow Trout Fillet

The objective of this study was to evaluate the effect of different forms and doses of rosemary on chemical, microbial, and sensory properties of rainbow trout fed nine different diets: control (C), 20 g.kg^?1 rosemary powder (20RP), 40 g.kg^?1 rosemary powder (40RP), 0.3 g.kg^?1 rosemary extract (0.3RE), 0.6 g.kg^?1 rosemary extract (0.6RE), 0.15 g.kg^?1 rosemary nanopowder (0.15RNP), 0.3 g.kg^?1 rosemary nanopowder (0.3RNP), 0.15 g.kg^?1 butylated hydroxyanisole (BHA) (0.15BHA), and 0.3 g.kg^?1 BHA (0.3BHA). After 8 weeks’ feeding, the fish fillets were sampled on the 1st, 4th, 8th, 12th, and 16th days and then stored on 4°C. Lower value of pH, peroxide value (PV), total volatile base nitrogen (TVB-N), free fatty acids (FFA), and thiobarbituric acid (TBA) were reported in fish fed with RP, RE, RNP, and BHA; among them, RNP groups had the lowest properties (p < 0.05). Furthermore, lower total viable aerobic bacterial counts (TVC) and psychotropic counts (PTC) were observed in the fillets of the fish fed with rosemary treatments, especially in RNP treatments (7.52–9.41 log₁₀ CFU.g^?1), along with a slower spoilage in terms of sensory factors (texture, color, odor, and overall) on the 16th day. Finally, use of natural antioxidant nanorosemary in the diet may positively affect fish fillet quality and delay post-mortem deterioration.     

Quality attributes,polycyclic aromatic hydrocarbon,and heavy metal profile of traditional drum-smoked Guinean barracuda fish from Lagos State,Nigeria

This study was carried out to assess the quality attributes, polycyclic aromatic hydrocarbon (PAH), and heavy metal profile of traditional drum-smoked Guinean barracuda fish from Lagos State, Nigeria. Fresh Guinean barracuda fish (60) samples were obtained from 20 different fish-processing centers. The fresh fish samples were smoked with traditional drum kiln. The fresh and smoked fish samples were analyzed for proximate composition, quality indices (peroxide value (PV), thiobarbituric acid (TBA), total nitrogen base-nitrogen (TVB-N), trimethylamine acid (TMA), and free fatty acid (FFA)), PAH, heavy metals, and microbiological (coliform, fungi, Listeria monocytogenes (LM), Salmonella paratyphi (SP), and Staphylococcus aureus (SA)) analyses. The results revealed that the mean moisture, protein, fat, crude fiber, ash, and carbohydrate contents of traditional drum-smoked fish samples were in the range 10.93–14.15%, 51.97–60.96%, 11.34–15.99%, 1.74–2.99%, 1.12–1.56%, and 7.70–17.99%, respectively. The values of PV, FFA, TBA, TVB-N, and TMA were in the range of 8.21–10.19 meq.peroxide/kg, 1.13–1.80%, 1.03–1.19 mgMol/kg, 17.29–19.36 mgN/kg, and 2.12–2.68 mgN/kg, respectively. The results of PAH compounds in the traditional drum-smoked fish samples showed that 10 of the 16 PAH compounds detected were above the 5.0 µg/kg B(α)P maximum permissible levels stipulated by EU Regulation 1881/2006. The concentrations of Hg, Pb, Cd, and Cr in the smoked fish samples ranged from 0.001 to 0.0027 µg/g, 0.0013 to 0.0028 µg/g, 0.0014 to 0.0028 µg/g, and 0.0621to 0.0796 µg/g, respectively. The results of microbiological analysis revealed the presence of LM and SA in the traditional drum-smoked fish samples. The study concluded that traditional drum-smoked fish may constitute higher risks (chemical and microbiological) and public health concerns to consumers.     

The effect of different carbon sources on the nutritional value of bioflocs,a feed for Macrobrachium rosenbergii postlarvae

A 15‐day lab‐scale experiment was performed to determine the possible use of bioflocs as a feed for Macrobrachium rosenbergii postlarvae. The bioflocs were grown on acetate, glycerol and glucose. A glycerol‐fed reactor was initially inoculated with a Bacillus spores mixture. The highest protein content was obtained in the (glycerol+Bacillus) bioflocs, i.e. 58±9% dry weight (DW). The glycerol and acetate bioflocs showed a lower, but similar content (42–43% DW) and glucose bioflocs contained 28±3% DW. Higher total n‐6 fatty acid contents were observed in the glycerol and (glycerol+Bacillus) bioflocs. The vitamin C content was variable, up to 54 μg ascorbic acid g^?1 DW in the glycerol bioflocs. Bioflocs were fed to M. rosenbergii postlarvae as the sole feed. High survival levels were obtained in the (glycerol+Bacillus) and glucose groups, i.e. 75±7% and 70±0% respectively. This was significantly higher than the starvation control (0% survival after 15 days). This indicated that the prawns were able to feed on the bioflocs. These results are in accordance with the biofloc's nutritional parameters and suggest that the choice of the carbon source used for growing bioflocs is of prime importance.     

Effects of varying protein level in practical diets on survival,growth, feed utilization and body composition of juvenile tench (Tinca tinca L.)

The aim of this study was to evaluate the effects of practical diets with different protein content on survival, growth, feed utilization and body composition of juvenile tench (Tinca tinca). A 90-day experiment was conducted with 6-month-old juveniles (34.35 mm total length, 0.411 g weight). Six practical diets differing in the protein level were tested: 40, 44, 48, 52, 56 or 60 %. Survival rates ranged from 96.7 to 100 %. The 52 % protein enabled the highest growth (55.49 mm total length, 2.11 g weight, 1.80 % day^?1 specific growth rate) and the lowest feed conversion ratio (1.61) without significant differences (P > 0.05) from the 48 %. Protein productive value ranged from 15.64 to 22.01. The percentages of fish with visible deformities ranged from 1.1 to 4.4 %. The relationship among amino acid profiles of the diets, growth of juveniles, body composition and amino acid requirements of other fish species is discussed. Second-order polynomial regression analysis showed that the optimum dietary protein requirement for maximum growth of juvenile tench may be 52.7 %.     

Carbon, nitrogen and phosphorus budget in shrimp (Penaeus monodon) culture ponds in eastern India

Nutrient budget for shrimp (Penaeus monodon) culture was performed in ten culture ponds (0.4–1.0 ha) in Orissa, India, at stocking density of 10.0–22.10/m². The average initial body weight of shrimps was 0.02 g. The culture period was for 4 months. Feed was the main input of nitrogen (N), phosphorus (P) and organic carbon (OC). The FCR varied from 1.35 to 1.75. At harvest time, the average weight of shrimps varied from 28 to 32 g. Total N, P and OC applied to these ponds through all the inputs ranged from 106.64 to 292.63, 23.17 to 57.55 kg and 763.10 to 1,831.20 kg per crop, respectively. Feed alone accounted for 94.43–95.03 % total N, 91.92–95.36 % total P and 80.33–92.48 % total OC, respectively. The harvest of shrimp accounted for recovery of 25.45–36.88 (av. 30.12) %, 10.07–12.94 (av. 11.16) % and 15.80–20.81 (av. 18.01) % of added N, P and OC, respectively. N, P and OC accumulated in sediment were 49.11, 64.07 and 64.82 %, respectively, of total nutrient retention in the culture system. Unaccounted N, P and OC were 13.29, 21.83 and 18.14 %, respectively, of the total nutrient retention in the system. N, P and OC outputs in the discharged water during harvest were 7.48, 2.94 and 2.03 %, respectively.     

Study of digestive proteinases and proteinase inhibitors of Daphnia carinata

Quantification of proteases activities and their class structure have been studied in a cladoceran, Daphnia carinata. Protease activity ranged from 0.28 to 0.55 Unit mg⁻¹ protein min⁻¹ with an average value of 0.42±0.06 Unit mg⁻¹ protein min⁻¹. Chymotrypsin activity was more than twofold higher (0.49±0.09 Unit mg⁻¹ protein min⁻¹) than the trypsin activity (0.21±0.02 Unit mg⁻¹ protein min⁻¹). Protease activity and reduction of activity in bands of samples treated with specific inhibitors were documented in photometric assay and substrate SDS–PAGE. Proteinase activity against azocasein was inhibited (91.4±1.5%) with SBTI. PMSF reduced the enzyme activity by 53.1±6.5%, and the azocasein hydrolysis was reduced up to 64.6±3.8% by the specific inhibitor of trypsin, TLCK. In the present investigation, the molecular weight of various activity bands ranged from 16.3 to 51.1 kDa. The molecular weights of several protein bands are similar to protease activity zones. The knowledge of digestive enzyme profiles of fish food organisms generated in the present study may assist in the formulation of age-specific feed.     

Confirming the authenticity of the geographical origin of Naruto dried wakame Undaria pinnatifida using stable nitrogen isotope ratios

In aquatic ecosystems, the stable nitrogen isotope ratio (δ¹⁵N) of wakame is affected by the δ¹⁵N of its nitrogen source. Thus, the δ¹⁵N of wakame is thought to differ between those grown in different aquatic ecosystems. To confirm the authenticity of the geographic origin of Naruto dried wakame (DW), we conducted δ¹⁵N analysis. The δ¹⁵N (mean ± σ) of Naruto DW model samples (n = 72) was 11.1 ± 1.9 ‰. The δ¹⁵N confidence range of Naruto DW from the model was 5.3–16.9 ‰ (mean ± 3σ). The δ¹⁵N values of the DW model of Chinese (n = 23) and South Korean origin (n = 22) were 4.2 ± 1.4 and 1.6 ± 2.3 ‰, respectively. Within the δ¹⁵N confidence range of Naruto DW, two model samples of Chinese DW and one model sample of South Korean DW were found. From those results, DW of Naruto origin was able to be distinguished from DWs of the Chinese and the South Korean.     

Transfer of toxaphene and chlordane into farmed rainbow trout, Oncorhynchus mykiss (Walbaum) via feed

The study was carried out to quantitate the transfer of toxaphene and chlordane compounds from commercial fish feed into the edible part of rainbow trout, Oncorhynchus mykiss (Walbaum) under normal rearing conditions. Trout were fed with unspiked high energy feed for salmon (fat content 26–30%) over a period of 19 months. The average weight of trout increased from 10 g to more than 2092 g, reaching sizes of 51 cm length. Considerable amounts of toxaphene and chlordane residues were transferred from fish feed into trout muscle. Toxaphene concentrations increased up to 8.6 µg (Σ toxaphene indicator compounds 1–3) kg^?1 wet weight (w.w.) and chlordane reached 5.3 µg Σoxy‐, trans‐, cis‐chlordane + t‐nonachlor kg^?1 w.w. Results are also discussed on the contaminant levels based on the fat content and the effect of sexual maturation is considered in this study. The data allow the establishment of transfer rates for toxaphene and chlordane congeners from high energy diet into the edible part of farmed rainbow trout.     

Implications of larval diet concentration on post-larval yield in a production scale flow-through system for scallops (Pecten maximus Lamarck) in Norway

In order to optimize Pecten maximus larval performance and post-larval yield, larvae were fed five algal concentrations in the range 3–20 cells μL^?1 in 2,800-L flow-through tanks without prophylactic antibiotics. Competent larvae were transferred to a commercial hatchery for settlement and provided uniform conditions for 4 weeks to observe effects. Increased diet concentration increased the sum of fatty acids (FA) in the total larval population, reaching 7 and 25 ng FA larvae^?1 at 3 and 16 cells μL^?1, respectively. The FA level in competent larvae was not affected by diet concentration and ranged from 30 to 46 ng larvae^?1. Increased diet concentration increased larval growth rate, and the larvae were ready to settle 5 days earlier when fed 16 cells μL^?1 compared to 3 cells μL^?1. Larval ingestion rate increased during life span and with increased larval diet concentrations, but a considerable amount (40–60 %) of the added algal cells was lost from the larval rearing tanks due to the seawater flow. There was no effect on larval survival, final post-larval shell height, % of competent larvae transferred to settlement, or total yield of post-larvae. Final mean post-larval shell height was 509 μm and 25.5 % of competent larvae settled, resulting in a final post-larval yield between 6.9 and 17.6 % of the initial number of d3 larvae. Competent larvae with similar FA content produced similar numbers of post-larvae independent of diet concentration, even if higher diet concentrations resulted in higher rates of larval development and metamorphosis.     

The use of fermented soybean meal and squid by-product blend as a substitute for fish meal in practical diets for climbing perch,Anabas testudienus (Bloch, 1792), pond culture: Growth performance and economics analysis

A feeding trial was conducted to evaluate the effects of different ratios of fish meal (FM) to a fermented blend (FB: fermented soybean meal and squid by-product blend) on growth and economic performance of climbing perch, Anabas testudineus (Bloch, 1792), in earthen ponds. Five diets were prepared where FB was substituted for 0 (D1), 25 (D2), 50 (D3), 75 (D4), or 100% FM protein (D5), while a commercial diet (D6) was used for comparison. Triplicate groups of fish (1.03 ± 0.07 g) were fed twice daily up to satiation for 70 days in earthen ponds. No significant (P > 0.05) differences were found in growth performance of fish fed D1, D2, D3, and D6 diets, while fish growth decreased significantly (P < 0.05) in D4 and D5 groups. Feed intake decreased (P < 0.05) with the increasing levels of FB with no significant difference in the feed conversion ratio, which ranged from 1.98 to 2.08. The fish survival decreased significantly in D5 alone. While considering the overall production, the total yield and economic return were found to be highest in D2 (64176.7 TK ha^?1) and lowest in D5 (14418.3 Tk. ha^?1). Based on the present experimental condition, it is concluded that FB can economically be included in aquafeed as a substitute for up to 50% of FM protein from the diets of climbing perch.     

GnRHa‐induced Multiple Spawns and Volition Spawning of Captive Spotted Rose Snapper,Lutjanus guttatus,at Mazatlan,Mexico

Sexual maturation and induced spawning treatments were carried out with captive spotted rose snapper, Lutjanus guttatus. A total of 3013 × 10⁶ eggs (64.7% were floating) were produced from eight treated females in 42 spawns induced with GnRHa implants during the course of the present study. GnRHa ethylene‐vinyl acetate copolymer effective doses were 204 ± 11 µg/kg in June 2005, and 224 ± 13 µg/kg in July 2005. General fertilization was 50.9 ± 34.5% and 12–14 h after spawning, viability of floating eggs was 90.4 ± 12.4%. Mean incubation period at 29–31 C was 18–20 h, and mean hatching was 94.4 ± 8.2% (73–100%). Newly hatched larvae were 2.18 ± 0.15 mm in total length (TL). One month after the last hormone experiment, previously GnRHa‐treated and untreated fish began spawning voluntarily. Hormone‐treated breeders had higher fecundity than untreated fish, producing 72.5 million eggs versus 13.9 million eggs for the untreated fish, over the following 11 mo. Combined data of volitional spawning for total egg fertilization, viability, hatching, and larval TL were 77.7 ± 1.8%, 90.3 ± 1.3%, 87.9 ± 2%, and 2.50 ± 0.12 mm, respectively. These results can ensure the sustainability of a commercial hatchery.     

Effect of algal addition on stability of fatty acids and some water‐soluble vitamins in juvenile Artemia franciscana

A minor stabilization effect was found for the content of total lipids, total fatty acids and docosahexaenoic acid (DHA) when Artemia franciscana was maintained at high concentrations of Isochrysis galbana for 72 h at 12 °C, both in 3‐ and 4‐day‐old individuals. The eicosapentaenoic (EPA) level was only stabilized at higher algal concentrations in the 4‐day‐old A. franciscana. In the 3‐day‐old A. franciscana, the EPA content increased at all algal concentrations during the first 24 h of post enrichment, presumably as an effect of DHA catabolism. Apparently, the 4‐day‐old A. franciscana metabolized DHA, and other lipids, faster than the 3‐day‐old A. franciscana did. During the 72 h incubation with I. galbana, the content of ascorbic acid (AA) in A. franciscana increased approximately to 1000–1200 μg g^–1 dry weight (DW) at algal concentrations above 3 mg C L^–1, close to AA content of the algae. The vitamin B₆ content in A. franciscana decreased from approximately 20 to 4–11 μg g^–1 DW, with highest loss rates at the higher algal concentrations. The thiamin content of A. franciscana was independent of algal concentration and remained at 20–30 μg g^–1 DW. The nutritional effects of the algal incubation on the 3‐ and 4‐day‐old A. franciscana at algal concentrations which can be used during the cultivation of Atlantic‐halibut larvae (<2 mg C L^–1) was insignificant, except for the small enrichment effect of AA already at 1 mg C L^–1. Other beneficial effects of the algae should not be ruled out, like possible effects on the microflora of A. franciscana even at algal concentrations less than 2 mg C L^–1.     

Effect of dietary protein level on the growth and survival of pre-adult freshwater crayfish Cherax quadricarinatus (von Martens) in monosex culture

Feeding trials with five levels of crude protein (CP) (22%, 27%, 33%, 39%, and 45%) and digestible energy ranging from 14.32 to 15.21 kJ g^?1 were carried out to determine optimum dietary protein for the growth and production of pre‐adult freshwater crayfish Cherax quadricarinatus. Triplicate groups of males (ω=23.1±0.58 g) and females (ω=21.8±0.33 g) were fed diets for 70 days in monosex culture. Optimal digestible protein (DP) was estimated for males by fitting mean weight gain to a quadratic model (y=27.86+0.839x–0.0216x², r²=0.945), and a linear model for females (y=32.84–0.0745x, r²=0.959). Optimal male growth occurred with 25.6% CP, equivalent to 19.4% DP. Male crayfish attained significantly higher final weights and absolute growth rate than females fed the 22%, 27%, and 33% CP diets. The results indicated that a 19.4% DP diet, with a P/E ratio of 11.4 mg kJ^?1, produces an optimum growth response for pre‐adult C. quadricarinatus under experimental conditions.     

Brown trout, Salmo trutta L., production in an Irish coastal stream

Abstract. Brown trout. Salmo trutta L., estimates were obtained for the Owendoher, a tributary of the River Dodder. Data were collected at live stations on 21 occasions from May 1981 to May 1983. Total population densities ranged from 0·07 to 1·29 fish/m² Mean annual densities varied from 0·20 to 0·77 fish/m². Trout in this stream are typically slow-growing fish reaching a maximum length of 7·68, 13·05 and 17·54cm at the end of their first, second and third years respectively. Growth improved in a downstream direction with the highest rates recorded in stretches overlying limestone. There was some evidence of density-dependent growth in the upper reaches Daily instantaneous growth rates were highest for all age groups during the months May to August but became depressed during the winter. There was considerable variation in the total monthly biomass figures with values ranging from 1·32 to 33·46 g/m². Mean annual values ranged from 3·96 to 13·48 g/m². Annual production (somatic) varied from 3·77 to 14·38 g/m². in 1981–1982 and from 6·12 to 12·70 g/m². in 1982–1983. The mean annual production figure for this stream was 11·24 g/m². Production was contributed mainly by 1+ and 2+ trout at all stations. Egg production. accounting for 3–4% of the total estimate, was contributed mainly by resident 1+ and 2+ fish. It ranged from 0·33 to 0·45 g/m² in 1981–1982 and from 0·14 to 0·53 g/m² in the following year. Ratios of annual production to mean biomass (P/B?) were highest for 0+ trout hut decreased with increasing age. The mean P/B? ratios for all age classes varied from 0·95 to 1·17. The mean value for the Owendoher stream was 1·1. The effects on production of changes in age structure, population density and habitat alterations are discussed.     

Utilization of diets with different fish oil content in common octopus (Octopus vulgaris Cuvier, 1797) and resulting changes in its biochemical composition

The aim of the present work was to obtain the lipid utilization of Octopus vulgaris supplying formulated semi‐moist diets with different contents in cod oil (reduced from water content): 0 g kg^?1 (A0, 138 g kg^?1 lipids DW; N = 4), 100 g kg^?1 (A100, 286 g kg^?1 lipids DW; N = 6) and 200 g kg^?1 (A200, 388 g kg^?1 lipids DW; N = 6). The rest of the ingredients were constant in the three diets: 200 g kg^?1 gelatin, 100 g kg^?1 egg yolk powder, 150 g kg^?1 freeze‐dried Todarodes sagittatus and 50 g kg^?1 freeze‐dried Sardinella aurita). Survival was 100% with the three diets. The highest absolute feeding (15.8 ± 1.2 g day^?1), growth (9.6 ± 1.4 g day^?1; 0.91% BW day^?1) and feed efficiency rates (60.3%) were obtained with diet A0. This diet also showed greater retention of lipid and protein than A100 and A200. Protein digestibility was above 95% in all of the diets. Only diet A0 led to a high lipid digestibility coefficient (81.25%), which fell drastically to 12.3% in A200. It was notable the high polar lipid digestibility rates (83–89%) respect to neutral lipids (2–87%) in all diets. The best results were obtained with lipid feeding rates of around 1 g day^?1 and a suitable lipid content on 130–140 g kg^?1 DW in formulated diets for O. vulgaris.     

Pond production of Pacific white shrimp,Litopenaeus vannamei,fed grain distillers dried yeast

The objective of this study was to demonstrate the feasibility of four diets formulated to contain increasing levels (0, 50, 100 and 150 g kg^?1 of diet) of grain distillers dried yeast (GDDY) in production diets for Litopenaeus vannamei, reared in outdoor tanks or production ponds. The production pond trial was carried out in 16, 0.1‐ha ponds using four replicates per diet. Juvenile shrimp (38.1 ± 4.26 mg, initial weight) were stocked at 30 shrimp m^?2 for a 16‐week period. The same four diets and a commercial reference diet were offered to shrimp maintained in outdoor tanks over a 12‐week period. A total of 20 tanks were stocked with juvenile shrimp (3.05 ± 0.22 g, initial weight) obtained from production ponds at a density of 30 shrimp per tank (40 shrimp m^?2). At the conclusion of these trials, mean final weight ranged from 19.77 to 23.05 g, yield ranged between 4760 and 5606 kg ha^?1, survival ranged from 69.6% to 89.4%, and feed conversion ratio (FCR) was between 1.02 and 1.23. Shrimp reared in the outdoor tanks confirmed the results of the pond trial. Mean final weight ranged between 18.12 and 18.97 g, survival ranged from 93.3% to 98.3%, and FCR was between 1.25 and 1.29. In both trials, there were no significant differences regarding mean final weight, FCR and survival among dietary treatments. Based on this study, GDDY up to 150 g kg^?1 of diet can be used in L. vannamei commercial feed formulation.     

Effect of esterification on the absorption of astaxanthin in rainbow trout, Oncorhynchus mykiss (Walbaum)

Gastrointestinal and serum absorption of astaxanthin was studied in rainbow trout, Oncorhynchus mykiss (Walbaum) (217 ± 2 g) fed diets supplemented with either esterified astaxanthin (from Haematococcus pluvialis) or free astaxanthin (synthetic, as 8% w/w beadlets) at similar levels (50 mg kg^?1). After 56 days of feeding, there was a significant difference (P = 0.0582) between steady‐state serum astaxanthin concentrations for fish fed free (2.0 ± 0.3 μg mL^?1) or esterified astaxanthin (1.3 ± 0.1 μg mL^?1) at the 90% confidence level. However, following ingestion of a single meal supplemented with free or esterified astaxanthin, the rates of astaxanthin absorption into serum were not significantly different (P > 0.1) (0.8 ± 0.2 µg mL^?1 h^?1 and 1.0 ± 0.4 µg mL^?1 h^?1 respectively). In fish fed both free or esterified astaxanthin, higher absorption (P < 0.05) of astaxanthin by the ileal (0.8 ± 0.14 μg g^?1 and 0.9 ± 0.15 μg g^?1 respectively) compared with the posterior (0.2 ± 0.01 μg g^?1 and 0.3 ± 0.14 μg g^?1 respectively) intestine was recorded. This confirmed the role of the anterior intestine in carotenoid absorption. Non‐detectable levels of esters in digesta taken from the hind intestine suggest the anterior intestine is also the primary region for ester hydrolysis.