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Atle Foss Albert K. Imsland Erik Vikingstad Sigurd O. Stefansson Birgitta Norberg Skjalg Pedersen Trond Sandvik Bjrn Roth 《Aquaculture (Amsterdam, Netherlands)》2009,290(3-4):304-310
A group of juvenile Atlantic halibut (mean, SD, 199.5 g, 44.7) was split into two experimental groups: one group was fed in excess twice a day and later five days a week (i.e. Control group), and the other group was starved for 5 weeks and then subsequently re-fed for 10 weeks (i.e. 5/10 starvation/re-fed group). This treatment was repeated for three years until the fish were harvested (mean final weight, 4.4 kg). A size +specific compensatory response was seen; partial compensation was observed in halibut weighing less than 500 g whereas full recovery growth was seen in halibut over 2 kg. Food consumption and feed conversion efficiency was measured during two full 5/10 starvation/re-fed cycles. The Control group consumed 86% more food in the measurement period, whereas the FCE 40% higher in the 5/10 starvation/re-fed group (FCE = 0.95) compared to the Control group (FCE = 0.68). In males lower gonadosomatic index (2.2 vs. 3.0) and plasma 11-ketotestosterone (0.22 vs. 1.26 ng ml− 1) levels in the 5/10 starvation/re-fed group were observed during late winter and spring of 2006 (age 3 years) indicating higher age at 1st maturity. Starvation had a significant effect for improving the quality as starved fish had higher muscle pH (6.4 vs. 6.2), less gaping (0.1 vs. 0.3) and harder texture (61.4 vs. 57.6 N). Overall, the rearing on a repeated 5/10 starvation/re-fed regime for 3 years led to full growth compensation, higher feed conversion efficiency, lower male maturation and improved flesh quality. 相似文献
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Albert K Imsland Bjørn Roth Atle Foss Erik Vikingstad Sigurd O Stefansson Skjalg Pedersen Trond Sandvik & Birgitta Norberg 《Aquaculture Research》2009,40(11):1260-1269
The aim of this study was to investigate the effect of continuous light at different stages during the production cycle of Atlantic halibut Hippoglossus hippoglossus L. on growth, age at first maturity, endocrine parameters and flesh quality. A group of juvenile halibut [mean (SD), initial weight 191.3 g (44.7)] was reared in indoor tanks under ambient temperature conditions for 38 months until harvesting (mean final weight, 4.6 kg). The entire photoperiod experiment was divided into four phases, where the fish in each phase were exposed to either natural photoperiod (62°33'N) or continuous light (L). Thus, the following five photoperiod combinations were tested: (a) Control group (NNNN), (b) Group 2A (NLNN), (c) Group 2B (NNLN), (d) Group 2C (NNNL) and (e) Production group (LNNN). Exposure to continuous light stimulated growth, and the final mean weights of Groups 2A and 2B were 23% and 11% higher than those of the Control group (NNNN). The final plasma 11-ketotestosteron levels were lower in Groups 2A (2.94 ng mL−1 ) and 2B (2.46 ng mL−1 ) compared with the Control (5.29 ng mL−1 ), Group 2C (5.09 ng mL−1 ) and the Production group (4.78 ng mL−1 ) during spring 2007 (age 4 years), indicating higher age at first maturity in Groups 2A and 2B. Photoperiod regime had only a minor, and transient, effect on flesh-quality traits of the fish, whereas a significant seasonal effect was seen with a tendency towards increased gaping, lower pH, lower hardness and lower shear force in July compared with December and March. 相似文献
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Effects of starvation,subsequent feeding and photoperiod on flesh quality in farmed cod (Gadus morhua) 
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下载免费PDF全文 M. Bjørnevik H. Hansen B. Roth A. Foss E. Vikingstad C. Solberg A.K. Imsland 《Aquaculture Nutrition》2017,23(2):285-292
The study was designed to investigate the effect of four cycles of 5 weeks starvation followed by 10‐week refeeding compared with daily feeding under either natural photoperiod or continuous light (LL) regime on body composition and flesh quality in Atlantic cod in sea cages, northern Norway. The fish were sampled for body composition and flesh quality parameters at the start of the trial, twice at the end of a 10‐week feeding period and twice at the end of a 5‐week starvation period. There was effect of both feeding and light regime on growth, the two starving groups losing weight during starvation and regaining weight during refeeding, and the group under LL being heavier. But, the mean overall growth did not vary between groups. Starvation/refeeding regime resulted in higher slaughter yield, but no overall effect was seen on hepatosomatic index, water content, water holding capacity (WHC), muscle pH, hardness or flesh colour compared with control groups. Continuous light increased gutted weight and slaughter yield, lowered WHC and depressed maturation compared with fish under natural light regime. Increased growth rate resulted in softer fillets and lower muscle pH. 相似文献
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Bjorn Roth Albert Imsland Lars Helge Stien Rian Schelvis-Smit Snorri Gunnarsson Atle Foss 《Aquaculture International》2010,18(3):461-474
In order to test seasonal, rearing, maturing and anaerobic muscle activity effect on the flesh quality of turbot (Scophthalmus maximus) a total of 80 farmed turbot from three different strains from reared under natural or continuous light were killed by a
percussive blow to the head in November (winter, Icelandic strain), March (spring, Portuguese strain) and June (summer, domesticated
strain (France turbot)). To test the effect of anaerobic muscle activity, 10 fish were on each occasion pre rigor filleted, where one fillet was used as a control, while the other fillet was electrically stimulated using a squared 5 Hz,
10 V pulsed DC for 3 min. All pre rigor fillets were measured for pH, weighed, wrapped in aluminum foil and stored in polystyrene boxes with ice. After 7 days of
storage the fillets were measured instrumentally for pH, drip loss, colour (CIE L* a* b*) and texture properties such as hardness and shear force, while fillet shrinkage and colour (RBG) were evaluated with computer
imaging on photographs from a standard lightbox. Results showed that softness of the flesh was mainly influenced by factors
associated with growth, such as season, photoperiod and maturation. Anaerobic muscle activity simulated with electrical stimulation
caused an increase in drip loss (<1%) and loss of shear force (<4%), but had no effect on hardness or fillet shrinkage. Computer
imaging revealed that muscle contractions related to the electrical stimulus forced out blood from the fillet causing less
reddishness for the entire storage period. We conclude that a pH drop upon slaughter associated with anaerobic muscle activity
has a minor effect on the flesh quality in the short run, while seasonal/alternatively genetic effects are predominant. 相似文献
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Albert K. Imsland Snorri Gunnarsson A. Foss Benedikt Sigur?sson Sindri Sigur?sson 《Journal of the World Aquaculture Society》2009,40(6):762-770
We compared growth properties of spotted wolffish with initial mean weight (± SE) 3.65 (± 0.15) kg reared in shallow raceways at three different densities (50, 70, and 90 kg/m2, corresponding to approx. 170, 240, and 310 kg/m3) in a 447‐day‐long growth trial at ambient temperature (mean (± SD), 4.2 C ± 1.9). Growth in all three groups was comparable, but there was a trend toward higher growth at the highest density. Final mean weights (kg ± SE) were 4.90 (± 0.15), 4.80 (± 0.16), and 5.05 (± 0.11), at the 50, 70, and 90 kg/m2 density, respectively. Initially, growth rates were higher at the 90 kg/m2 density group compared to the two other densities, but overall growth rates were similar in all three groups. Feed conversion efficiency differed and was higher at the two highest densities compared to lowest density. The acid–base balance was influenced by the density treatment as there was a general trend toward higher partial pressure of CO2 and HCO in the 90 kg/m2 group. Calculated productivity increased almost linearly with increasing stocking density and was found to be 24, 42, and 66 g/m2/day at 50, 70, and 90 kg/m2, respectively. The results show that the optimum density conditions for farming large spotted wolffish, both with respect to growth rate, feed conversion, and productivity are at densities equal to or higher than 90 kg/m2. 相似文献
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S. O. Handeland A. K. Imsland B. Th. Björnsson S. O. Stefansson M. Porter 《Fish physiology and biochemistry》2013,39(5):1079-1088
Melatonin implants were used to override natural melatonin rhythm in groups of juvenile Atlantic salmon, Salmo salar, raised at simulated natural photoperiod (SNP) and constant light (LL) from mid-March until end of August. The experiment contained also both sham control (with non-melatonin implants) and control (no implants). No differences were found in the experimental variables between these two control groups. Growth and food intake were negatively affected by melatonin implantation. Overall, higher GH levels were observed in the SNP melatonin-implanted group, whereas no differences in GH levels were seen between the SNP control, LL control, or the LL melatonin-implanted groups. Highest food intake was seen in the LL control group. No differences in food intake were recorded between the LL melatonin-implanted and SNP control groups. Gill Na+, K+, ATPase (NKA) activity was influenced by time as well as the interaction between photoperiod and time. No differences in gill NKA activity or plasma chloride levels following transfer to seawater were seen between the groups with melatonin implants and their controls. Based on the present results, it seems apparent that melatonin does play a role in regulating food intake and growth in Atlantic salmon smolts. 相似文献
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Albert K. D. Imsland Trine Haugen Susanne Håvardstun Anders Mangor-Jensen 《Journal Of Applied Aquaculture》2013,25(3):252-262
Different levels of pressure were investigated to see if it was possible to induce triploidy at a lower pressure than previously used (600 bar) for Atlantic cod (Gadus morhua). Newly fertilized eggs were exposed to different levels of pressure: 400, 500, and 600 bar, and one control group (no pressure). Induction of triploidy occurred at each pressure level used in this experiment. Mean weight and length at the termination of the trial period was significantly lower, in the 400 bar group, compared to the other treatment groups. Microsatellite loci analysis revealed over 90% triploid outcome in each experimental group. Lower incidence of deformities was seen in the 400 bar group compared to the 500 and 600 bar groups. Overall this study demonstrated successful triploid induction at both low (400 bar) and medium (500 bar) pressures. 相似文献
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The effects of chronic and periodic peaks of un-ionised ammonia (UIA-N) exposure on eye health and cataract formation in juvenile
Atlantic halibut, Hippoglossus hippoglossus, were examined. Fish with mean initial weight 51.7 g (SD 13.2) were exposed to five treatments consisting of control group
and three groups (ChronicLow, ChronicMedium and ChronicHigh,) chronically exposed with UIA-N of 0.06, 0.12 to 0.17 mg/l, respectively,
for 62 days at 11.9°C, pH 8.0 and salinity 34‰. Furthermore, a fifth group (HighPulse) was exposed to the same high levels
as ChronicHigh for a short daily period (peak of 15 mg/l 30 min after exposure, 10 mg/l 1 h after exposure and 1.2 mg/l 3 h
after exposure). In the subsequent period of the experimental study (from day 63 until day 100), no ammonia was added to the
water. Mean weights were significantly lower in groups exposed to chronically high ambient ammonia concentrations compared
to corresponding control group throughout the experimental period. The sampled fish exhibited signs of mild cataract formation,
although the results showed no clear evidence that the ammonia treatments contributed to differences. Minor differences were
found in measured muscle free amino acids, which could be used to explain potential changes in buffering capacity. The eye
histidine status differed significantly at day 62, and osmotic differences in the eye lenses (measured as differences in N-acetyl
histidine) were found in all group exposed to chronic levels of ammonia. 相似文献