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1.
A feeding experiment was conducted to evaluate the effect of rotifers (Brachionus plicatilis) and Artemia sp. enriched differently on early growth, survival and lipid class composition of Atlantic cod larvae (Gadus morhua). Rotifers enrichments tested were: (1) AlgaMac 2000®, (2) AquaGrow® Advantage and (3) a combination of Pavlova sp. paste and AlgaMac 2000®. The same treatments were tested with Artemia as well as a combination of DC DHA Selco® and AlgaMac 2000® as a fourth treatment. After rotifer feeding, the larvae from treatment 3 [1.50 ± 0.11 mg dry weight (dw)] were significantly heavier than larvae from treatment 2 (1.03 ± 0.04 mg dw). After feeding Artemia, the larvae from treatment 1 were significantly heavier (12.06 ± 2.54 mg dw) than those from treatments 3 (6.5 ± 0.73 mg dw) and 4 (5.31 ± 1.01 mg dw). Treatment 3 resulted in the best survival through the 59 days of larviculture. After rotifer feeding, high larval concentrations of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), arachidonic acid (AA) and ω6 docosapentaenoic acid (ω6DPA) could be linked to better larval growth and survival while after feeding Artemia, high larval DHA/EPA ratios (～3) and high DPA/AA ratios (>1) could be linked to better survival.  相似文献   

2.
Considerable progress has been achieved in the intensive culture of Atlantic cod (Gadus morhua). However, there is little information concerning optimum live-feed enrichments for cod larvae, since many of the techniques used during the larviculture have been borrowed from other fish species and adapted for the production of Atlantic cod. The present study compared four different protocols for the enrichment of Artemia to be used as live feed for cod larvae. The protocols tested were: (1) AlgaMac 2000, (2) AquaGrow Advantage, (3) Pavlova sp. + AlgaMac 2000, and (4) DC DHA Selco + AlgaMac 2000. Larvae were fed differently enriched Artemia between 37 and 59 days post hatch. At the end of the experiment, larvae from treatment 1 [specific growth rate (SGR) = 10.4 ± 0.4% day−1] grew faster than larvae from treatments 3 (SGR = 6.9 ± 0.2% day−1) and 4 (SGR = 4.9 ± 0.4% day−1, P < 0.0001). However, treatments 3 and 4 resulted in better larval survival at the end of the experimental period, estimated to be 3 on a scale from 1 to 5, whereas the survival estimates for the two other groups were 2. The treatments affected the fatty-acid composition of Artemia and of cod larvae. Larvae from treatment 1 had a higher percentage of AA (20:4ω6, P < 0.0001) and ω6DPA (22:5ω6, P < 0.0001) than the other larvae. Levels of DHA (22:6ω3) were similar in larvae from treatments 1 and 4, and higher than in the other larvae (P < 0.0001). Our results suggest that Artemia containing a DHA/EPA/AA ratio of 7/2/1 result in good larval performance. Joseph A. Brown—Deceased September 2005.  相似文献   

3.
We evaluated the effects of enriched rotifers on growth, survival and on the lipid composition of haddock larvae. The treatments tested were (1) AlgaMac 2000®, (2) AquaGrow® Advantage and (3) Pavlova sp. paste and AlgaMac 2000®. The treatments did not influence larval growth rate throughout the experimental period (P = 0.70). Larvae from all treatments grew approximately 8% of their dry weight per day between 1 and 29 days post hatch (dph). Treatment 3 resulted in the best survival, estimated to be 3 on a scale from 0 to 5, whereas for the two other groups the survival estimates were 0 and 2. Rotifers from treatment 1 had low sterol concentrations, high eicosapentaenoic acid/arachidonic acid ratio and their feeding resulted in high larval mortality. Rotifers enriched with Pavlova sp. had the lowest proportions of the sum of saturated fatty acids, docosahexaenoic acid and sum of ω3 and the highest proportions of the sum of monounsaturated fatty acids (ΣMUFA). This was partially reflected in larvae from treatment 3 in that they had the highest proportions of ΣMUFA and the lowest proportions of Σω3 (P < 0.0001 for both analyses). In addition, these larvae had the highest and lowest ΣC20 and ΣC22 polyunsaturated fatty acids (PUFA) respectively (P < 0.0001 for both analyses). We suggest that more research with ω3 and ω6 PUFA can lead to improvements in the rearing of haddock larvae produced in hatcheries.  相似文献   

4.
Heterobranchus longifilis larvae were reared over a 35 d period to evaluate the effects of stocking densities and feeding regimes on growth and survival. In experiment 1, larvae (12.3?±?2.1 mg) were stocked into glass aquaria at densities of 1, 2, 5, 10, 15, 20, and 25 larvae L?1. Larvae were fed on Artemia nauplii ad libitum. Significant variations in terms of growth performance and feed utilization occurred at all levels of density treatments. Specific growth rate (SGR), body weight gain (BWG), and feed efficiency (FE) of the larvae decreased significantly as density increased. However, survival rate increased with the increase of stocking density. In experiment 2, larvae (13.4?±?1.1 mg) stocked at a density of 15 larvae L?1, in the same conditions as experiment 1, were fed on three different regimes: Artemia nauplii; 35%?protein beef brain; and 35%?protein commercial catfish feed (CN+). SGR, BWG, and coefficient of variation (CV) of larvae fed on Artemia nauplii were significantly higher than those fed on beef brain and CN+. The survival rate of larvae fed on beef brain was significantly higher (88.40?±?9.75%) than those of Artemia (69.21?±?6.69%) and CN+ (40.40?±?6.22%). The results of this study suggest that the optimum stocking density is 15 larvae L?1 and the beef brain can be used as alternative feed to Artemia in rearing H. longifilis larvae.  相似文献   

5.
ABSTRACT

The effect of photoperiod (24L:00D, 12L:12D, and 00L:24D) and temperature (22 ± 1°C and 28 ± 1°C) on performance of Clarias gariepinus larvae was tested. Larvae weighing 3.2 ± 0.24 mg were cultured in aquaria at a stocking density of 20 fish L?1 and fed twice a day on catfish starter diet (40% CP) at 10 % BW day?1. Highest mean weight gain (31.00 mg), SGR (7.56% day?1), and survival (83%) were achieved at photoperiod and temperature combination of 00L:24D and 28 ± 1°C. Percent survival of larvae differed significantly (p < .05) among treatments with optimal survival of (83%) in treatment combination of 28 ± 1°C and 00L:24D, while lowest survival (40%) in treatment combination of 22 ± 1°C and 24L:00D.  相似文献   

6.
A 30‐day feeding experiment was conducted in blue tanks (70 × 50 × 60 cm, water volume 180 L) to determine the effects of dietary lipid levels on the survival, growth and body composition of large yellow croaker (Pseudosciaena crocea) larvae (12 days after hatchery, with initial average weight 1.93 ± 0.11 mg). Five practical microdiets, containing 83 g kg?1 (Diet 1), 126 g kg?1 (Diet 2), 164 g kg?1 (Diet 3), 204 g kg?1 (Diet 4) and 248 g kg?1 lipid (Diet 5), were formulated. Live feeds (Artemia sinicia nauplii and live copepods) were used as the control diet (Diet 6). Each diet was randomly assigned to triplicate groups of tanks, and each tank was stocked with 3500 larvae. During the experiment, water temperature was maintained at 23(±1) °C, pH 8.0 (±0.2) and salinity 25 (±2) g L?1. The results showed that dietary lipid significantly influenced the survival and growth of large yellow croaker larvae. Survival increased with the increase of dietary lipid from 83 to 164 g kg?1, and then decreased. The survival of larvae fed the diet with 83 g kg?1 lipid (16.1%) was significantly lower than that of larvae fed other diets. However, the survival in larvae fed the diet with 16.4 g kg?1 lipid was the highest compared with other artificial microdiets. Specific growth rate (SGR) significantly increased with increasing dietary lipid level from 83 to 164 g kg?1 (P < 0.05), and then decreased. The SGR in larvae fed the diet with 164 g kg?1 lipid (10.0% per day) was comparable with 204 g kg?1 lipid (9.6% per day), but were significantly higher than other microdiets (P < 0.05). On the basis of survival and SGR, the optimum dietary lipid level was estimated to be 172 and 177 g kg?1 of diet using second‐order polynomial regression analysis respectively.  相似文献   

7.
Striped trumpeter have a complex and extended larval phase and are difficult to culture. Two experiments were conducted in replicated, 300-l hemispherical tanks to determine if larval survival, growth, bacterial or fatty acid profile were improved by feeding non-enriched rotifers or rotifers enriched with algae or commercially available products, as well as the effect of an antibiotic, oxytetracycline (OTC). Larvae were stocked at 25 l− 1 and 15 l− 1 and reared until Day 16 and Day 19 in Experiments 1 and 2, respectively. In Experiment 1, the feeding treatments were non-enriched rotifers, or rotifers enriched on algae, DHA Selco (a fish oil based emulsion) or RotiMac (dried Schizochytrium). There were no significant differences in mean survival (± SD) across treatments, which were generally low at 14.6 ± 5.2%. Larvae reared on rotifers fed DHA Selco and RotiMac, had significantly higher proportions of incorporated DHA but no significant increase in growth. In Experiment 2, larvae were fed rotifers enriched on DHA Selco or AlgaMac 2000 and reared with or without the daily addition of 25 mg l− 1 OTC. At Day 19, there was significantly higher survival for larvae reared on AlgaMac 2000 and OTC, (37.4 ± 5.6%), than DHA Selco and OTC, (16.0 ± 7.4%), AlgaMac 2000 without OTC (7.0 ± 8.0) and DHA Selco without OTC (3.3 ± 1.2). Larvae reared with OTC were larger (279 ± 58 μg and 7.4 ± 0.2 mm) than without OTC (177 ± 40 μg and 6.3 ± 0.2 mm). The addition of antibiotics did not significantly influence fatty acid profiles of larvae. There were no significant differences in the percentage of DHA, 27.6 ± 2.8%, EPA 4.6 ± 1.0% or ARA 4.9 ± 0.4%. Larvae reared with OTC had significantly less ‘grey gut’ (a measure of intestinal dysfunction). The results indicated that bacterial infection was a major source of mortality in striped trumpeter larvae and compromised larval growth. Assessment of the bacterial flora indicated that antibiotic use reduced the bacterial load, but did not eliminate potential pathogens. Our study suggests that microbial control has a greater influence than lipid nutrition on the survival and growth of larvae during the rotifer feeding stage.  相似文献   

8.
In the present study, the growth and survival of early life stages (ELS) of Chitala chitala were studied in nylon hapa for 28 days, followed by rearing in fibreglass reinforcement plastic (FRP) tanks for a period of 30 days. Ten‐day‐old ELS of C. chitala reared in hapa were fed with three different diets namely Indian Major Carp (IMC) spawn (<8 mm), live tubifex and fresh fish eggs. In the second phase, 28‐day‐old ELS were stocked in 200‐lit FRP tank and supplied four different live diets namely live tubifex worm, chironomous larvae, zooplanktons and mosquito larvae. Fish accepted all types of diets in the experimental rearing period in both the systems. The experiments conducted in hapa showed a higher specific growth rate (SGR), weight gain per cent and survival rate in larvae fed with live tubifex (SGR=1.76±0.02) than fish eggs (0.77±0.31) and IMC spawn (0.46±0.12). The study carried out in FRP tanks revealed that SGR was higher in ELS fed on chironomous larvae (4.44±0.61), followed by mosquito larvae (3.29±0.40) and live tubifex (3.28±0.36), whereas minimum SGR was recorded with zooplanktons (2.84±0.66). A significant difference (P<0.05) in SGR, final mean weight and weight gain (%) was also recorded. The highest mean survival rate (100%) of ELS in an FRP tank was observed in chironomous larvae and zooplanktons, whereas with live tubifex and mosquito larvae the same survival rate (80%) was recorded. The rate of survival of the ELS reared in hapa varied from 65% to 85%. The experiments showed that ELS of C. chitala could be reared successfully in hapas and fibreglass reinforcement tanks for attaining better survivability and growth.  相似文献   

9.
The effect of adding 0%, 1%, 2% and 5% chitin from prawn shells in the diets for Atlantic cod, Atlantic halibut and Atlantic salmon on growth was investigated. Nutrient digestibility and feed utilization was investigated in salmon and cod. Atlantic cod grew from 186 ± 29 to 383 ± 78 g (N = 960) over 13 weeks. Dietary chitin had no effect on length, weight, condition, liver size or specific growth rate (SGR). The apparent digestibility (ADC) for protein ranged from 84.7% to 86.5%, lipid between 88.8% and 93.1% and dry matter from 96.1% to 96.6%. Feed utilization varied between 1.08 and 1.11 and was not correlated with dietary chitin content. Atlantic salmon tripled their weight from 199 ± 9 to 615 ± 75 g (N = 480) during the 13 weeks. High inclusions of chitin (>1%) reduced both growth rate and condition. Protein and lipid ADC was negatively correlated with dietary chitin. Feed utilization ranged between 0.86 and 0.90 and was not significantly affected by dietary chitin. Faecal protein increased significantly with increasing dietary chitin, while faecal dry matter and lipid did not. Individually tagged Atlantic halibut grew from 1300 ± 470 to 2061 ± 714 g (N = 70) during 6 months. Individual growth rates varied within each group from being slightly negative to 0.81%·day?1. Diet had no significant effect on growth rates. Atlantic cod and Atlantic halibut seems unaffected by up to 5% chitin additions in the diet, while chitin >1% of diet negatively affects growth and nutrient utilization in Atlantic salmon.  相似文献   

10.
In this study Atlantic halibut (Hippoglossus hippoglossus L.) larvae (0.12 ± 0.04 g) were, from day 40 post first feeding, offered six diets in which 10% or 30% of the dietary protein was hydrolysed with (a) pepsin (P), (b) pepsin + trypsin (PT) or (c) pepsin + trypsin + chymotrypsin (PTC). In addition, a diet without hydrolysed protein was offered, and enriched Artemia was fed as control. The amount of soluble protein increased progressively with the enzyme treatments P, PT and PTC and with higher inclusion levels of hydrolysed protein. Survival was highest among the larvae offered Artemia (83 ± 0%) or the diet 10P (10% pepsin hydrolysed protein; 67 ± 4%). The diet 10P supported survival significantly better than the more hydrolysed diets 10PTC, 30P, 30PT and 30PTC, but not significantly better than the non‐hydrolysed diet and 10PT. Specific growth rate (SGR) was 1.76 ± 0.20 in average for all groups of larvae and was not significantly affected by the diets. Still, the larvae offered pepsin hydrolysed diets tended to have better growth (2.10 ± 0.05 SGR; P < 0.06) than the larvae offered the other hydrolysed diets. The larvae offered the formulated diets did not differ in chemical composition.  相似文献   

11.
The tongue sole Cynoglossus semilaevis, an inshore fish in China, has showed great potential in aquaculture recently. However, poor survival was recorded during the period of weaning from live Artemia to artificial diets. In this paper, the influence of co‐feeding larvae with live and inert diet on weaning performance was described. The C. semilaevis larvae were reared at 21 ± 1 °C and fed four different feeding regimes from 6 days post‐hatching (dph): A, Artemia (10 individuals mL?1); B, Artemia (5 individuals mL?1); C, mixed diet (10 Artemia individuals mL?1 and 12 mg L?1 inert diet); and D, mixed diet (5 Artemia individuals mL?1 and 12 mg L?1 inert diet). Rotifers were also supplied in all cases during the first days of feeding. Mixed diets of commercial formulated feed and live prey (rotifers and Artemia) allowed larvae to complete metamorphosis, achieving similar specific growth rate (SGR) (18.5 ± 1.4% and 18.7 ± 1.6%) and survival (40 ± 7.6% and 48.5 ± 6.8%) compared with larvae fed on live feed alone (SGR of 18.3 ± 1.2%, 19.3 ± 1.9% and survival of 41.2 ± 11.3%, 38 ± 4.9%). However, in metamorphosed fish, when live feed was withdrawn on 31 dph, there was significant difference (P < 0.05) in survival and growth among treatments. Metamorphosed fish, previously fed mixture diets during larval stages, had similar survival (62.1 ± 7.6% and 62.8 ± 3.9% for regimes C and D, respectively) but higher than that obtained for fish that previously fed on live feed (49.3 ± 2% and 42.1 ± 3.9% for regimes A and B, respectively) after weaning (day 60). The SGR of weaned fish previously fed live feed was similar (3.1 ± 0.6% and 2.92 ± 0.6% for regimes A and B, respectively) but lower than that recorded for fish that was fed from day 6 to day 30 on the mixed diet (4.5 ± 1.1% and 4.9 ± 0.3% for regimes C and D, respectively). It is suggested that weaning of C. semilaevis from early development would appear to be feasible and larval co‐feeding improves growth and survival.  相似文献   

12.
Successful natural spawning of Chaetodontoplus septentrionalis in captivity from 19 March to 11 May, 2008 is described for the first time. A single male dominates a harem of two females, spawning with each at dusk, from 10 min before to 20 min after sunset. Each female laid an average 119 × 103 eggs during the spawning period. Fertilized eggs were spherical, buoyant and had a diameter of 0.83 ± 0.02 mm (mean ± SD). Embryonic development lasted 15–18 h at 28.1 °C. Newly hatched larvae were 1.60 ± 0.07 mm in total length (TL) with 27 myomeres. Larvae completed yolk absorption within 3 days post hatching (ph) at 3.01 ± 0.08 mm TL. Ten days ph, the larvae had attained 3.95 ± 0.12 mm TL. Larvae were fed either 100% s‐type rotifers (Brachionus rotundiformis), 100% copepods (Microsetella sp.), a combination of the two (50%:50%) or without live feed (starved control) to determine the effect of live feed on the survival rate. The survival was significantly (P<0.001) higher in larvae fed a combination of diet than the others. These results indicate that C. septentrionalis is a potential species for captive breeding programs and the use of a combination of diet (s‐type rotifers and copepods) may be a suitable first food for the larvae.  相似文献   

13.
The effects of light intensity on feeding incidence and prey consumption at first feeding of spotted sand bass larvae (Paralabrax maculatofasciatus Steindachner), using four light intensity treatments (0, 100, 400, and 700 lx) were evaluated. Specimens were fed the rotifer Brachionus plicatilis at a density of 3 rotifers mL?1. One hour after the addition of prey, 30±3 (mean±SEM) larvae were sampled from each treatment aquarium. Feeding incidence was evaluated as the percentage of larvae with prey in the digestive tract. Feeding intensity was measured as the number of prey in the digestive tract of the larvae. Histological analysis was carried out to describe the eye structure at the time of first feeding. Larvae fed in darkness (0 lx) had a significantly lower (P<0.05) feeding incidence (1.2±2.2%) and intensity (0.4±0.7 rotifers larvae?1) than those larvae fed at 100 (28±11%, 1.8±0.2 rotifers larvae?1), 400 (48±10%, 2.4±0.3 rotifers larvae?1), and 700 lx (52±4%, 2.4±0.1 rotifers larvae?1). Feeding incidence of the spotted sand bass larvae increased with light intensity while the feeding intensity showed no significant difference (P>0.05) between light treatments. Histological analysis of the eye structure showed that first feeding larvae had well‐formed lens along with a retina composed of pure single cones as photoreceptors.  相似文献   

14.
We estimated recent growth of Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) larvae collected on the southern flank of Georges Bank in May 1992–94 from the ratio of RNA to DNA (R/D) and water temperature. Growth of both species increased with water temperature to about 7°C and then decreased. The highest growth rates were observed in May 1993 at water temperatures around 7°C. These data confirm an earlier observation of comparable temperature optima for growth of Atlantic cod and haddock larvae in the north‐west Atlantic. Comparisons of field growth rates and temperature optima with data for larvae cultured at high temperatures and prey densities in the laboratory suggest that growth may have been food‐limited at higher temperatures on Georges Bank. Given that 7°C is the long‐term mean water temperature on the southern flank in May and that climate models predict a possible 2–4°C rise in water temperatures for the western North Atlantic, our findings point to a possible adverse effect of global warming on Atlantic cod and haddock.  相似文献   

15.
Atlantic halibut, Hippoglossus hippoglossus L., larvae were reared under four different Artemia feeding regimes for 40 days from day 20 post first feeding. Three Artemia enrichments were used: Super Selco? (SS), AlgaMac 2000? (AM) and a particulate mix of AlgaMac 2000? with tuna orbital oil (TOO/AM). The SS and AM Artemia were tested in three different combinations: (1) a 1:1 ratio continuously to day 60 (AM/SS); (2) a 1:1 ratio to day 41, then AM only (AM/SS-41): and (3) AM only to day 41, then a 1:1 ratio (AM-41). The fourth treatment comprised TOO/AM Artemia, which was fed continuously. At day 60 post first feeding, measurements were made of survival and growth rates, postmetamorphic characteristics (i.e. eye migration and pigment distribution), and lipid composition. The mean survival rates ranged from 65.1% to 84.5%. Specific growth rates varied from 7.64 to 8.13. The eye migration indices were between 2.3 and 2.6. These parameters did not differ significantly among treatments (P 0.05). A significantly greater proportion of fry (P<0.05) exhibited‘perfect metamorphosis’(correct pigment distribution and complete eye migration) in the AM/ SS-41 and AM-41 treatments (59.8 ± 3.03% and 54.6 ± 1.08%, respectively) compared to the AM/SS and TOO/AM treatments (35.9 ± 4.02% and 39.9 ± 6.43%, respectively). The fatty acid compositions of livers and eyes varied according to feeding regime, but did not correspond to the metamorphosis characteristics of the fry.  相似文献   

16.
We evaluated the effect of four densities (940, 1880, 3760, 7520 eggs cm?2 and 0.5, 1, 2, 4 ind mL?1 of embryos and larvae, respectively) and four temperatures (8, 11, 14, 17°C) on early growth and survival of the sea urchin Strongylocentrotus purpuratus. Prism‐stage length was significantly greater in embryos initially held at 940 and 1880 eggs cm?2 than in those held at 3760 and 7520 eggs cm?2. Larvae grew significantly faster and had significantly greater survival when reared at 0.5 or 1 ind mL?1 than when held at 2 or 4 ind mL?1. Embryos had greater survival at 11 and 14°C than at 8 and 17°C, whereas embryo length was significantly smaller at 8°C than at 11, 14 or 17°C. Larvae grew significantly slower at 8°C than at 11, 14 or 17°C, whereas survival was significantly reduced at 8 and 17°C compared with 11 and 14°C. Per cent survival from prism to metamorphic competency in the best treatments was 48.9 ± 2.2% and 50.0 ± 3.6% (mean ± SE) for the 1 ind mL?1 and 11°C treatments, respectively. On the basis of these results, for rearing of S. purpuratus under static conditions, we recommend that fertilized eggs and larvae be held at ≤1880 eggs cm?2 and ≤1 ind mL?1, respectively, and at 11–14°C.  相似文献   

17.
The effects of two weaning diets and different weaning protocols on growth, survival, skeletal deformity and gut morphology of Atlantic cod larvae were studied in four groups from 16 to 45 days posthatch (dph). Cod larvae in groups 1 (early weaning with control diet) and 2 (early weaning with experimental diet) were used to evaluate the effects of different polar lipid content of weaning diets on larval and juvenile performance. Cod larvae in groups 2, 3 (early weaning with experimental diet + cofeeding with Artemia) and 4 (earlier weaning with experimental diet and earlier cofeeding with Artemia) were used to evaluate the effects of early introduction of dry diet and Artemia. From 45 to 170 dph, cod juveniles from all four groups were reared using a standard feeding protocol. No significant differences in growth, survival, deformities and gut morphology were found between cod larvae and juveniles from groups 1 and 2. Cod larvae fed on cofeeding regime with Artemia nauplii (groups 3 and 4) were bigger and had lower frequencies of jaw and neck deformities and higher foregut microvillus circumference than cod larvae from group 2. Our results demonstrate the importance of proper weaning protocols in producing better quality cod juveniles.  相似文献   

18.
This work aimed at validating the use of two prospective probionts (Arthrobacter sp. and Enterococcus sp.) at early stages of cod (Gadus morhua L.) rearing. Ova at late post‐fertilized stage and larvae during their first 4 weeks of life were bathed with both probionts, isolated previously from the cod‐rearing environment. This treatment was compared with groups fed rotifers supplemented with a commercial probiotic (Remus®) and those untreated. Microbiological analyses (total viable counts, presumptive Vibrio and lactic acid bacteria) were performed in rearing systems and larval survival, growth and development were assessed. Larval development was evaluated by proteolytic activity of larval lysates and immunological analysis of important proteins: apolipoprotein A‐I, haemoglobin, C‐reactive protein, C3 and cod serum proteins. Bacterial bathing led to a significantly higher larval weight, length and culturable microbial load in larval gastrointestinal (GI) tract when compared with the control and Remus groups. Development occurred earlier in bathed larvae. However, their survival was negatively affected compared with the control group, but was significantly higher than for the Remus group. The non‐pathogenicity of both probionts was demonstrated by intraperitoneal injection of 13 g cod juveniles. The results suggest that Arthrobacter and Enterococcus probionts affected the larval GI microbiota and contributed to growth, development and digestion, either directly or indirectly.  相似文献   

19.
This study reported the traits values such as colour, feed conversion ratio (FCR), specific growth rate (SGR) and fluorescence capacity of F1 hybrids of Amphiprion percula (male) and A. ocellaris (female). The hybrids exhibited significant variation in FCR (3.63 ± 0.56) and SGR (3.63% ± 0.44) compared with the pure breeds, A. percula (3.12 ± 0.42; 2.80% ± 0.42) and A. ocellaris (3.17 ± 0.43; 3.02% ± 0.19). An exponential relationship was found between FCR and SGR in both the breeds. Image analysis displayed a better colour performance of hybrid than the pure breeds. Individual body parts of the hybrid and pure breeds showed significant colour variation between each other. However, colour contrast of whole body of hybrid was found closer to A. ocellaris in hue cone and towards A. percula in saturation and brightness values. Hence, hybrid displays combination colour reflexion of both the parents. The total pigment content of hybrid (65.71 μg g?1 ± 2.81) was found higher than A. ocellaris (62.01 μg g?1 ± 2.29) and A. percula (56.71 μg g?1 ± 2.56). Further, the spectroflurometric analysis revealed that the both hybrid and pure breeds having poor fluorescence on skin pigmentation. A direct positive heterosis was observed on the SGR, FCR, total pigment and spawning frequency, while negative effect was noted on total length of newly hatched larvae (TL), fertilization rate (FrR), hatching rate (HR), deformation rate (DFR) and survival rate (SR). Hence, multiple cross‐breeding programmes will help in developing high‐quality traits in successive generations.  相似文献   

20.
Culture performance beyond metamorphosis of larval loach (Misgurnus anguillicaudatus) was examined in a feeding experiment of the early development stage (20 days after hatch; DAH). Total length, dry weight, length- and weight-specific growth rate (SGR) and survival were monitored in different diet regimes. During 20 days, diet treatments included: microparticle diets (A); live daphnia (Moina micrura) (B); live daphnia plus live chlorella (Chlorella pyrenoidosa) (C); and live daphnia plus microparticle diets (D). Fish survival rates during 20 days were 21.23 ± 4.2% (A), 73.19 ± 2.8% (B), 90.76 ± 3% (C) and 91.46 ± 3.1% (D), respectively. Length- and weight-specific growth rate after 20 DAH (final mean SGR; % day−1) were 5.36 ± 0.44 and 15.75 ± 1.52 (A), 9.29 ± 1.25 and 23.47 ± 2.23 (B), 9.42 ± 1.55 and 24.88 ± 2.9 (C) and 9.55 ± 1.23 and 24.40 ± 2.75 (D), respectively. Fish in treatments B, C and D displayed higher growth rates and were significantly longer and heavier than fish in treatment A by the end of the experiment (Ρ < 0.05). Fish in treatment A had highly significant greater (Ρ < 0.001) mortalities than in treatments B, C and D. There were no significant differences in any growth parameter between fish in treatments B, C and D, but the survivals in treatments C and D (90.76% and 91.46%) were significantly higher than in treatment B (73.19%, Ρ < 0.05). The results demonstrated that enriched prey and co-feeding may serve as a potential feeding strategy for loach larvae, and the form of co-feeding reduces the costs and dependence on live foods to a certain extent. We concluded that larval loach should be reared over metamorphosis using either of the following methods: feed with live daphnia supplemented with microparticle diets or with live chlorella. However, a prolonged rearing period of loach larvae is needed to detect nutritional problems and observe remote effects of co-feeding on weaning in the future.  相似文献   

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