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1.
Morten?O.?AlverEmail author Jo?A.?Alfredsen Gunvor??ie 《Aquaculture International》2005,13(6):519-541
High and unpredictable mortality rates are observed in the larval rearing of cod (Gadus morhua). As a means of addressing this problem, we present a model-based estimator system which can be used to indirectly measure
the larval density through monitoring the live food dynamics and larval growth. The estimator has been evaluated in a conceptual
context using a preliminary model formulation, and the observability of the process has been investigated. It was found that
the two parameters, live food dynamics and larval growth, contain enough information for the larval density to be estimated
under noisy conditions, given the correct model. When the system is applied practically, the estimation error will depend
on the measurement and model accuracy; this is especially true with respect to the predictability of the feed intake rate
of the fish. 相似文献
2.
Jorunn Skjermo Trond R. Størseth Karina Hansen Gunvor Øie 《Aquaculture (Amsterdam, Netherlands)》2006,261(3):1088-1101
Stimulation of the non-specific defence enhances the disease resistance and growth, and has good potentials as a measure for increased microbial control in juvenile production of marine fish and shellfish. So far, the most commonly used immunostimulants are β-(1 → 3, 1 → 6)-glucans, and in this study the stimulatory potential of a β-(1 → 3, 1 → 6)-glucan of marine origin, the storage polysaccharide from the marine diatom Chaetoceros mülleri, was examined. The glucan (chrysolaminaran) was extracted from cultures of C. mülleri, and used as a dietary supplement in two first feeding experiments with larvae of Atlantic cod Gadus morhua L. In one experiment the microalgal glucan was compared to the commercial yeast-glucan product MacroGard®, and in the other to an alginate with a high content of mannuronic acid (High-M alginate) isolated from Durvillaea antarctica. The stimulants were given via rotifers, and weaning to formulated feed was initiated at day 17 or 18 after hatching. The survival ± SEM at day 27 after hatching was 24.5 ± 2.0%, 14.8 ± 4.5% and 13.1 ± 1.4% for the groups fed C. mülleri-glucan, yeast glucan and for the control, respectively, in the first experiment. The group fed C. mülleri-glucan group had higher survival compared to the control (P < 0.05) group, whereas the yeast glucan had no positive effect on the survival (p > 0.05). The dry weights of the groups at day 27 were low, with 203.2 ± 52.2, 165.2 ± 43.4 and 198.5 ± 58.1 μg per larva for the C. mülleri-glucan, yeast glucan and control groups, respectively. In the second experiment the survival in the period of feeding formulated feed (days 18-30) were 44.6 ± 4.3%, 44.7 ± 1.3%, and 33.8 ± 4.1% survival for the C. mülleri-glucan, High-M alginate and control group, respectively. The cod larvae fed C. mülleri-glucan reached an average weight of 531.6 ± 17.2 μg at day 30, which was significantly higher (p < 0.05) than the control group that had an average of 473.6 ± 3.5 μg. The larvae fed High-M alginate had an average weight of 470.3 ± 31.6 μg per larva at day 30, and not significantly different from the control (p > 0.05). The early weaning to formulated diet had detrimental effect on the growth of the larvae. In both experiments the C. mülleri-glucan group was the only group showing a positive growth rate in the period of weaning to dry feed. The microbial conditions in larval gut and water were monitored with respect to total colony forming units on Marine agar, and Vibrio- and Pseudomonas-like species on selective agars (TCBS and marine Pseudomonas Agar with CFC-supplement). The larvae were rapidly colonised after hatching, but no or weak effects of the stimulants were observed on the colonisation rates or the composition. The total CFU varied from 101 to 102 CFU per μg larva after initiation of the first feeding. The percentages of Pseudomonas-like bacteria increased throughout the period, whereas the levels of Vibrio-like bacteria were low and stable. The chrysolaminaran from the diatom C. mülleri was shown to be a promising candidate for use as an immunostimulatory feed additive, and which should be further explored. 相似文献
3.
Theaim of this study was to determine whether it is possible to influence thespecies composition of the gut microflora in 70-days old halibut larvae(Hippoglossus hippoglossus L.) by addition of bacteriabioencapsulated in Artemia franciscana in two shortpulses.Two Vibrio strains, PB 1-11 and PB 6-1 were used. Twotreatments received each strain alone, a third treatment received the twobacterial strains in mixture, whereas in a control treatment no bacteria wereadded. Five fish tanks were included in each treatment. The bacteria werebioencapsulated in Artemia franciscana metanauplii duringashort-term incubation in bacterial suspensions of the specific strains, andwereadded in two pulses, on day 1 and day 10 of the experiment. Addition ofbacteriadid not increase the total number of colony-forming units (CFU) in the larvalgut. The total CFU in the water was lower in tanks added bioencapsulatedbacteria than in the control treatment (p < 0.05). Animmunocolony blot assay was used to measure the numbers of the specificbacteriaadded in samples of water, A. franciscana, and fishlarvae.At the end of the experiment on day 13, the strain PB 1-11 reached on average10% of the total CFU when added alone and 25% when added in mixture with PB6-1.Strain PB 6-1 reached at the end of the experiment 26.8% of the total CFU whenadded alone and 24.2% when added in mixture with PB 1-11, whereas thepercentages of PB 1-11 and PB 6-1 in the control fish were 12.7% and 10.8% ofthe total CFU, respectively. However, the differences between the experimentaltreatments compared with the control group were not significant(p > 0.05). The addition of bioencapsulated bacteria intwo pulses within a ten days period was therefore not sufficient to influencethe species composition of the microflora of the halibut larvae. 相似文献
4.
The effects of light and short-term temperature elevation on the 48-h egg hatching success (HS) of cold-stored (2 °C) Acartia tonsa Dana (Copepoda: Calanoida) eggs were examined in the present study. The eggs can be stored for up to 7.5 months and maintain their high hatching rate under optimal conditions. Intensively produced eggs from the copepod A. tonsa may be hatched and used as an inoculum for producing copepod nauplii as live feed for fish larvae. The HS for eggs that were directly exposed to LED light declined rapidly after 1 month of storage (from 91 to 25 %), and these eggs did not hatch at all after 3 months of storage. The highest HS found was for eggs stored in complete darkness. The HS for eggs stored in normoxic (≥7 mg DO L?1) and anoxic (≤0.03 mg DO L?1) seawater was not affected by short-term temperature transitions from 2 °C up to 9 or 17 °C for a period of 12 or 24 h, when hatched 1 week post-exposure. The global mean HS for eggs stored in normoxic seawater was 85.9 % and significantly lower compared to eggs stored under anoxic conditions after 3 weeks of storage (91.8 %) (P = 0.001; SNK). 相似文献
5.
François‐Joël Gatesoupe Denis Covès Aurelio Ortega Nikos Papandroulakis Olav Vadstein Fernando de la Gándara 《Aquaculture Research》2013,44(10):1511-1523
During the first 2 years of larval rearing trials with Atlantic bluefin tuna, survival was a challenging issue. As bacterial colonization of the gut has been shown to play a key role for other species, we studied the profiles of the microbiota associated with individual larvae at different stages in three distant hatcheries. The Bacterial Community Profile (BCP) was quantified based on PCR‐DGGE analyses of partial amplicons from 16S rDNA. Considerable individual variability in BCP was observed before onset of feeding, and the BCP did not show regular fluctuation during ontogenesis. Microalgae were added to the rearing tanks in two of the three hatcheries, but it was not possible to distinguish the effect of location from the effect of algal addition on BCP. In one hatchery, the larvae were reared either with algal addition or in mesocosm, but due to high individual variability, no significant difference in BCP was detected between the two groups. It was hypothesized that this variability was caused by differences in health, physiological status and developmental stage of the larvae. A practical conclusion from the study is the need to analyse a considerable number of individuals to reflect statistically significant differences between the microbial communities associated with rearing groups. 相似文献
6.
Stefania Dooms Spiros Papakostas Stefan Hoffman Daan Delbare Alexander Triantafyllidis Olav Vadstein Patrick Sorgeloos 《Aquaculture (Amsterdam, Netherlands)》2007,262(1):29-40
Many zooplanktonic organisms, like the cyclic parthenogenetic rotifer Brachionus plicatilis (Rotifera: Monogononta), are actually a complex of species and biotypes with a high degree of morphological similarity (i.e. cryptic species). Various phylogenetic studies with molecular markers (e.g. ITS1 and COI) on wild Brachionus populations described the presence of at least nine genetically divergent Brachionus species and biotypes. Because different studies found evidence that these cryptic species and biotypes differ significantly in ecological preferences and thus probably behave differently in response to rearing conditions in the hatchery, questions rise on the actual identity of the rotifer strains used in aquaculture, where Brachionus discrimination is still based on morphology. This study is a part of an investigation of the genetic make-up of strains used in hatcheries, aquaculture research institutes and laboratories, and describes the rapid and sensitive PCR-DGGE method for the detection of Brachionus species and biotypes based on nucleotide sequence variation within the mitochondrial 16S rRNA gene. Considerable genetic diversity was found, albeit smaller within hatcheries than within laboratories and aquaculture research institutes. All 16S haplotypes produced an unambiguous DGGE fingerprint out of which a database was constructed. 相似文献
7.
Anna V. Eggertsdóttir DVM PhD Øyvind Stigen DVM PhD Lars Lønaas DVM PhD Marianne Langeland DVM PhD Morten Devor DVM Gunvor Vibe-Petersen DVM PhD Thomas Eriksen DVM PhD 《Veterinary surgery : VS》2001,30(6):546-551
OBJECTIVE: To compare the recurrence rate of acute gastric dilatation with or without volvulus (GDV) after circumcostal gastropexy (CCGP) or gastrocolopexy (GCP) in dogs. STUDY DESIGN: A prospective, double-blind, multicenter, randomized, controlled, clinical trial with two groups (A and B). ANIMALS: Fifty-four client-owned dogs presented for treatment of GDV. METHODS: Dogs with acute GDV that had not previously had a gastropexy performed were included. The preoperative treatment before gastropexy was standardized. A CCGP was performed on dogs in group A, and a GCP was performed on dogs in group B. Postoperative treatment was standardized, but deviation did occur according to the special needs of particular patients. A minimal follow-up time of 180 days was required for dogs not excluded from the study. The median follow-up time in group A was 700 days; in group B, it was 400 days. The occurrence of abdominal pain and gastrointestinal problems after surgery were recorded by the owners. RESULTS: There was no significant difference in the recurrence rate of GDV between the two groups. At the end of the study, the recurrence rate was 9% and 20% in group A and in group B, respectively. CONCLUSIONS: Both surgical techniques are effective in preventing recurrence of GDV. 相似文献
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9.
Anders Jón Fjellheim Karina Jane Playfoot Jorunn Skjermo Olav Vadstein 《Aquaculture Research》2012,43(10):1499-1508
The diversity of the microbiota in 15 Atlantic cod (Gadus morhua L.) larvae from three different hatcheries with variable food type and water treatment was characterized with culture dependent and independent approaches. The culture‐dependent approach was phenotypic characterization of bacterial isolates based on 16 tests, and the culture‐independent approach was terminal restriction fragment length polymorphism (T‐RFLP) of PCR amplified 16S rRNA. Both approaches revealed large inter‐individual differences in the microbiota of cod larvae. Data from real time PCR indicate substantially lower variation in bacterial number larva?1 both within and between hatcheries than the data on colony forming units, resulting in an estimated four orders of magnitude variation in culturability between larvae. Considerably higher richness and diversity were observed with T‐RFLP than with phenotypic characterization, and no correlation between the two approaches was found for diversity indexes calculated at the individual level. Dissimilarity in the composition of the microbiota between individuals from the same rearing environment was comparable to the dissimilarities between hatcheries. The large inter‐individual variation is important to consider when designing experiments, as pooling of individuals will completely mask this variability. We conclude that colonization of individual cod larvae by bacteria seems to be a stochastic and not a deterministic process, which is not well understood. 相似文献
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