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1.
Improved performance of gilthead sea bream, Sparus aurata, larvae after ozone disinfection of the eggs 总被引：1，自引：0，他引：1
Isashar Ben-Atia Sigal Lutzky Yoav Barr Kutsal Gamsiz Yariv Shtupler Amos Tandler & William Koven 《Aquaculture Research》2007,38(2):166-173
Ozone (O3) dissolved in seawater (ODS) was evaluated, as an egg disinfectant, on the spawn of captive gilthead sea bream, Sparus aurata, brood stock. Four contact times (CT) were tested (0.6, 1.2, 2.4 and 4.8 mg min L−1) where CT was calculated by multiplying the dissolved O3 concentration (0.3 mg L−1) by different exposure periods (2, 4, 8, 16 min). There was also a disinfected seawater treatment that contained no O3 or derived compounds (CT 0) and an untreated seawater control. All ODS treatments reduced egg surface bacterial counts to zero, which was significantly (P<0.05) lower than the CT 0 and the control groups (194 and 1320 plate−1 respectively). Nevertheless, the hatching rate was high in the control and the CT treatments 0, 0.6 and 1.2 (88.7%, 87.3%, 89.5% and 83.7% respectively) while eggs exposed to a CT 2.4 and 4.8 hatched poorly (36.5% and 20.4% respectively), which was likely due, at least in part, to larvae unable to break the egg chorion successfully. Swim‐bladder inflation was significantly higher in the ODS groups (>97%) compared with the control and CT 0 treatments (ca. 70%). The results suggest that a 2‐min exposure of eggs to 0.3 mg O3 L−1 of ODS (CT 0.6) would improve current protocols in marine larviculture. 相似文献
2.
The effects of photoperiod and water exchange rate on the larvae of gilthead sea bream, Sparus aurata, from hatching to metamorphosis, 60–70 days later, were tested. Survival, growth rate and condition factor were determined with photoperiods of 12 and 24 h, and water exchange rates of 0 and 25%/day.Continuous light supported the highest mean survival (3.25%), with a maximum of 7.8% from hatching to metamorphosis. Growth rate in dry weight was best under continuous light in a water system with no exchange, up to 20 days post-hatching. Highest growth rates of larvae 40–60 days old were obtained in tanks with 25% of their water exchanged daily, along with a 12-h photoperiod. Condition factor was directly correlated with larval age. For the first 30 days after hatching, condition factor was affected by photoperiod and was highest for larvae exposed to continuous light. 相似文献
3.
C.C. Mylonas L. Anezaki P. Divanach S. Zanuy F. Piferrer B. Ron A. Peduel I. Ben Atia S. Gorshkov A. Tandler 《Fish physiology and biochemistry》2003,28(1-4):167-168
The effect of water temperature on sex differentiation was examined in European sea bass (Dicentrarchus labrax) of two strains from the Northwestern and Southeastern Mediterranean Sea, during larval or nursery rearing. Temperatures <17 °C enhanced feminization, while 21 °C during larval rearing induced higher male% compared to the nursery stage, and the overall male% was significantly different among strains (P?<?0.05). The study shows that management of larval rearing temperature can prevent the high male% observed in cultured populations. 相似文献
4.
W. M. Koven S. Kolkovski A. Tandler G. Wm. Kissil D. Sklan 《Fish physiology and biochemistry》1993,10(5):357-364
The present study tested the effect of dietary lecithin and exogenous lipase on the incorporation of oleic acid in the tissue lipids of gilthead seabream larvae (Sparus aurata). Two of four microdiets were prepared by the addition of [14C]oleic acid as free fatty acid (FFA) to diets containing either 5% cuttlefish liver oil (CLO) or 5% soybean lecithin. Glycerol tri[1-14C]oleate was similarly incorporated in two other diets identical in lipid (4% cuttlefish liver oil, 1% soybean lecithin) and non-lipid composition but differed in that one contained a supplement of 0.05% porcine lipase. The effect of these diets was tested by following the incorporation of the label (dpm/mg larvae DBW) in the neutral and phospholipid fractions of seabream larvae at four different ages (21, 27, 32 and 45 days after hatching).A significant (p<0.05) effect of dietary lecithin on the incorporation of labelled FFA in both larval neutral and phospholipid fractions was demonstrated at all ages. This was particularly pronounced during early development (day 21) where fish fed the lecithin supplement incorporated 6.75 times more label than the diet containing [14C]oleic acid in CLO. The dietary lecithin enhancing effect diminished with age but was still significant at day 45 (2.17 times more label). In addition, the label was considerably higher in the phospholipid fraction compared to the neutral lipid, reflecting the high demand for membrane synthesis during rapid growth. Lecithin fed larvae demonstrated a higher consumption rate and efficiency of incorporation than fish consuming the cuttlefish liver oil diet, suggesting an emulsifying function for dietary phospholipid.In contrast, the supplementation with lipase showed a clear effect only in older fish where 45 day old larvae fed the lipase diet demonstrated a 3.42 times increase in radioactivity in their tissue lipids. This late lipase response may be the result of an insufficient level of dietary lecithin (M) and a short intestinal length being ineffective, in the early larval stages, in incorporating labelled free fatty acid from dietary glycerol tri[1-14C]oleate breakdown. 相似文献
5.
P. Lindner A. Eshell S. Kolkovski A. Tandler S. Harpaz 《Fish physiology and biochemistry》1995,14(5):399-407
Protein digestibility by gastrointestinal homogenates of Dicentrarchus labrax, was investigated in 5 feeds in relation to their amino acids composition and their ability to sustain growth of D. labrax post larval juveniles. Gastric proteolysis was found to contribute <25% of the total proteolytic capacity. Correlation was found between intestinal proteolytic capacity and the feed protein content of three pairs of amino acids. The sum of basic amino acids, arginine + lysine in the feed protein exhibited a positive correlation with susceptibility to proteolysis. The sum of the acid amino acids glycine and proline showed a negative correlation.Comparison of the intestinal proteolytic enzymatic activities in 3 growth stages of this species revealed similar profiles. Post larval and large juveniles had similar proteolytic capacities when compared on the basis of equal activity on an artificial substrate of Trypsin. Specific growth rates of post larval fish fed on these 5 feeds correlated positively with their protein digestibility as measured with large juvenile's intestinal homogenates. The results suggest that in this species, the efficiency of feeds in sustaining growth at the post larval stage can be estimated by measuring the feed protein digestibility by the proteolytic system of larger sized juveniles. 相似文献
6.
This study tested the effect of the level of dietary phosphatidylcholine (PC) and its constituent medium-chain fatty acids on microdiet ingestion (μg diet larva−1 h−1 ) and the absorption rate of the free fatty acid [14 C]16:0 (pmole larva−1 h−1 ) in 15, 20, 21, 25, 26, 30 and 31-day-old gilthead sea bream, Sparus auratus L., larvae. Fish were fed four microdiets (A, B, C and D): microdiet A contained no phospholipid (PL), while microdiet B included 10 g kg−1 Artemia nauplii PL (3.7 g kg−1 PC). Microdiets C and D contained 10 g kg−1 purified saturated PC dimyristoyl (C14:0 ) and polyunsaturated PC dilinoleoyl (C18:2[cis]−9,12 ), respectively.
Larvae from one or both of the PC microdiets demonstrated significantly higher ( P < 0.05) ingestion rates (μg diet larva−1 h−1 ) than the non-PL microdiet control in 15, 21, 22, 25 and 26-day-old larvae and the Artemia PL microdiet in 15, 22 and 26-day-old larvae. However, microdiet ingestion and fatty acid absorption rate appeared to be independent of the associated medium carbon chain saturated or polyunsaturated fatty acid moiety of the PC diets. Apparent absorption, as measured by the retention of radio-labelled [14 C]16:0 following 8 h of non-labelled microdiet feeding, was possibly related to feeding. 相似文献
Larvae from one or both of the PC microdiets demonstrated significantly higher ( P < 0.05) ingestion rates (μg diet larva
7.
The use of squid protein hydrolysate as a protein source in microdiets for gilthead seabream Sparus aurata larvae 总被引：8，自引：0，他引：8
In the present study, the use of predigested proteins as an ingredient of microdiets offered to gilthead seabream larvae was tested. The protein source (freeze-dried squid powder) was hydrolysed with protease (trypsin and pancreatin). Different levels of raw squid protein and hydrolysate (100% protein, 50% protein/50% hydrolysate, 100% hydrolysate) were added to the microdiets to produce a dietary protein level of 65%. For comparison, cofeeding of Artemia nauplii and microdiet as well as microdiet supplemented with pancreatin were also offered to the larvae. The final average dry weights of 32-day-old larvae were 1.65 ± 0.04 mg, 1.38 ± 0.06 mg and 1.13 ± 0.1 mg, respectively, for larvae cofed 0%, 50% and 100% hydrolysate microdiets and Artemia nauplii. Survival of larvae was not affected by protein source. The survival of larvae cofed Artemia nauplii and microdiet was significantly higher than that of larvae fed exclusively on microdiet (68% and 80%, respectively). These results suggest that the use of hydrolysate (at 50% greater) as a protein source in diets for seabream larvae is not to be recommended. 相似文献
8.
The goal of mariculture research in Israel is the development of an industry, based on available sea and brackish water, in the Arava Desert, the Gulf of Eilat and along the Mediterranean coast. Urgent progress is needed due to the shortage of fresh water for agriculture. High priced euryhaline fish like Sparus aurata and Dicentrarchus labrax are the obvious choice for development along with the more common grey mullet Mugil cephalus. The aim of this paper is to present the research and zootechnical state of the art in Sparus aurata and Dicentrarchus labrax larval rearing at the National Center for Mariculture (NCM). Fertilized eggs are stocked in 600 L tanks and hatching success estimated from aliquot counts. Rearing continued for 32 d after which larvae are removed from these tanks with minimum mortality. Under normal rearing conditions these tanks produce 15-35 32 d old (10 mg, ww) Sparus aurata larvae/L (20-40% survival). Average seabass survival to 80 mg (40 d) is 35%. Tanks were continuously supplied with filtered (10 μm), temperature and salinity controlled seawater and freshly enriched food organisms through a special delivery system. This system was recently upscaled to 1,700 L tanks with equally good results for seabream larval rearing. Live food enrichment regimes for the two species were developed to maximize their growth and survival. A microdiet is presently being used from the age of 20 d. The problems involved with using dry diets with larvae were found to be associated with both their digestibility and attractivity. As a result of a salinity reduction from the ambient 40 to 25 ppt, swim bladders developed in 90% of seabream and 75% of seabass. In addition, growth rate of larvae improved by 15%. Finally, seabream tend to show strong aggressive behavior once size differences in the population of 32 d larvae is greater than 300%. Therefore, once seabream ended their 32 d hatchery period they are graded to three size groups of 5, 10.3 and 23 mg (ww). The graded fish are counted with a locally developed Computer Aided Fish Counter (CAFIC) and stocked separately in 5 m3 nursery tanks. 相似文献
9.
The aim of the present study was to investigate the mechanisms by which the presence of Artemia nauplii in the rearing medium stimulates the feeding behaviour of gilthead sea bream, Sparus auratus. Sea bream larvae were given a microdiet ad libitum in the complete absence or the presence of chemical or visual stimuli of Artemia nauplii in the following way. The larvae were offered a microdiet in containers in which they had only visual contact with the nauplii. Alternatively, larvae were given the microdiet in the presence of only the Artemia-rearing culture-medium, which served as a chemical stimulus. Finally, larvae were exposed to both stimuli: visual and chemical. The stimuli were given at different levels which were equivalent to Artemia concentrations ranging from 3 to 12 nauplii ml-1. The present study demonstrated that while 20-day old larvae fed at a rate of 2.78 mg larva-1 h-1 in the absence of Artemia stimuli, their feeding rate increased by 120%, to 6.3 mg larva-1 h-1 in the presence of both chemical and visual stimuli. The stimuli work synergistically with each other, where the additive effect of each of the stimuli given alone was smaller than the two stimuli given together. Artemia's chemical stimulation amounted to a 35% improvement in larval microdiet feeding rate as compared with the control. This stimulus could be attributed mainly to the presence of four metabolites that were found in abundance in the Artemia-rearing medium: betaine and the free amino acids, arginine, alanine and glycine. In conclusion, the results suggest that the feeding response of marine larvae on microdiets could be elicited by the presence of visual and chemical stimuli. The latter could be added to the larvae-rearing medium separately or possibly could be made to leach out of the microdiets as they are fed to the larvae. 相似文献
10.
Influence of dietary polar lipids' quantity and quality on ingestion and assimilation of labelled fatty acids by larval gilthead seabream 总被引：2，自引：0，他引：2
Dietary supplementation of phospholipids seems to be extremely important to promote growth and survival in fish larvae. Several studies also suggest the importance of n-3 highly unsaturated fatty acids (HUFA) rich phospholipids to further enhance larval performance. In the present study, four different diets were formulated in order to compare the effect of total dietary polar lipid contents, of soya bean lecithin supplementation and of feeding n-3 HUFA in the form of neutral or polar lipids on ingestion and incorporation of labelled fatty acids in gilthead seabream larvae. These diets were prepared including radiolabelled fatty acids from palmitoyl phosphatidylcholine, glycerol trioleate, free oleic acid (FOA) and free eicosapentaenoic acid (FEPA) and were fed to 25 day-old larvae. The results of these experiments showed that the elevation of the dietary polar lipid levels significantly improved microdiet ingestion, regardless of the origins of the polar lipids. This effect caused an improved incorporation of phosphatidylcholine fatty acids to the larval polar and total lipids (TL) as the dietary polar lipids increased. Nevertheless, a better incorporation of fatty acids from dietary polar lipids in comparison with that of fatty acids from dietary triglycerides into larval lipids was found in gilthead seabream, whereas a better utilization of dietary triglycerides fatty acids than dietary free fatty acids could also be observed. Besides, the presence of n-3 HUFA rich neutral lipids (NL) significanlty increased the absorption efficiency of labelled oleic acid from dietary triglycerides, but the presence of n-3 HUFA rich polar lipids, particularly improved the incorporation of FEPA. This fatty acid was preferentially incorporated into larval polar lipids in comparison with FOA. 相似文献