共查询到20条相似文献，搜索用时 265 毫秒
1.
Three 2‐factor experiments were conducted to determine the effects of background colour and synthetic carotenoids on the skin colour of Australian snapper Pagrus auratus. Initially, we evaluated the effects on skin colour of supplementing diets for 50 days with 60 mg kg?1 of either astaxanthin (LP; Lucantin® Pink), canthaxanthin (LR; Lucantin® Red), apocarotenoic acid ethyl ester (LY; Lucantin® Yellow), selected combinations of the above or no carotenoids and holding snapper (mean weight=88 g) in either white or black cages. In a second experiment, all snapper (mean weight=142 g) from Experiment 1 were transferred from black to white, or white to white cages to measure the short‐term effects of cage colour on skin L*, a* and b* colour values. Skin colour was measured after 7 and 14 days, and total carotenoid concentrations were determined after 14 days. Cage colour was the dominant factor affecting the skin lightness of snapper with fish from white cages much lighter than fish from black cages. Diets containing astaxanthin conferred greatest skin pigmentation and there were no differences in redness (a*) and yellowness (b*) values between snapper fed 30 or 60 mg astaxanthin kg?1. Snapper fed astaxanthin in white cages displayed greater skin yellowness than those in black cages. Transferring snapper from black to white cages increased skin lightness but was not as effective as growing snapper in white cages for the entire duration. Snapper fed astaxanthin diets and transferred from black to white cages were less yellow than those transferred from white to white cages despite the improvement in skin lightness (L*), and the total carotenoid concentration of the skin of fish fed astaxanthin diets was lower in white cages. Diets containing canthaxanthin led to a low level of deposition in the skin while apocarotenoic acid ethyl ester did not alter total skin carotenoid content or skin colour values in snapper. In a third experiment, we examined the effects of dietary astaxanthin (diets had 60 mg astaxanthin kg?1 or no added carotenoids) and cage colour (black, white, red or blue) on skin colour of snapper (mean weight=88 g) after 50 days. Snapper fed the astaxanthin diet were more yellow when held in red or white cages compared with fish held in black or blue cages despite similar feed intake and growth. The skin lightness (L* values) was correlated with cage L* values, with the lightest fish obtained from white cages. The results of this study suggest that snapper should be fed 30 mg astaxanthin kg?1 in white cages for 50 days to increase lightness and the red colouration prized in Australian markets. 相似文献
2.
In an attempt to improve post‐harvest skin colour in cultured Australian snapper Pagrus auratus, a two‐factor experiment was carried out to investigate the effects of a short‐term change in cage colour before harvest, followed by immersion in K+‐enriched solutions of different concentrations. Snapper supplemented with 39 mg unesterified astaxanthin kg?1 for 50 days were transferred to black (for 1 day) or white cages (for 1 or 7 days) before euthanasia by immersing fish in seawater ice slurries supplemented with 0, 150, 300, 450 or 600 mmol L?1 K+ for 1 h. Each treatment was replicated with five snapper (mean weight=838 g) held individually within 0.2 m3 cages. L*, a* and b* skin colour values of all fish were measured after removal from K+ solutions at 0, 3, 6, 12, 24 and 48 h. After immersion in K+ solutions, fish were stored on ice. Both cage colour and K+ concentration significantly affected post‐harvest skin colour (P<0.05), and there was no interaction between these factors at any of the measurement times (P>0.05). Conditioning dark‐coloured snapper in white surroundings for 1 day was sufficient to significantly improve skin lightness (L*) after death. Although there was no difference between skin lightness values for fish held for either 1 or 7 days in white cages at measurement times up to 12 h, fish held in white cages for 7 days had significantly higher L* values (i.e. they were lighter) after 24 and 48 h of storage on ice than those held only in white cages for 1 day. K+ treatment also affected (improved) skin lightness post harvest although not until 24 and 48 h after removal of fish from solutions. Before this time, K+ treatment had no effect on skin lightness. Snapper killed by seawater ice slurry darkened (lower L*) markedly during the first 3 h of storage in contrast with all K+ treatments that prevented darkening. After 24 and 48 h of storage on ice, fish exposed to 450 and 600 mmol L?1 K+ were significantly lighter than fish from seawater ice slurries. In addition, skin redness (a*) and yellowness (b*) were strongly dependent on K+ concentration. The initial decline in response to K+ was overcome by a return of a* and b* values with time, most likely instigated by a redispersal of erythrosomes in skin erythrophores. Fish killed with 0 mmol L?1 K+ maintained the highest a* and b* values after death, but were associated with darker (lower L*) skin colouration. It is concluded that a combination of conditioning snapper in white surroundings for 1 day before harvest, followed by immersion in seawater ice slurries supplemented with 300–450 mmol L?1 K+ improves skin pigmentation after >24 h of storage on ice. 相似文献
3.
The unnaturally dark pigmentation of cultured Australian snapper Pagrus auratus can be improved through dietary astaxanthin supplementation and by holding fish in tanks with a white background. The practical application of these laboratory‐based findings was examined with two experiments to establish if the advantages of transferring fish to light coloured tanks before harvest could be achieved on‐farm using white cages and to determine the effects of fish density on skin colour. For the first experiment, snapper (mean TL=29.7 cm) were transferred from a commercial snapper sea cage to black or white netted cages and fed diets supplemented with unesterified astaxanthin (supplied as Lucantin® Pink, BASF) at 0 or 39 mg kg?1 for 42 days. Skin colour was measured using the CIE (black–white), (green–red), (blue–yellow) colour scale. Snapper held in white netting cages became significantly lighter (higher ) than snapper held in black cages; however, values were not as high as previous laboratory‐based studies in which snapper were held in white plastic‐lined cages. Snapper fed astaxanthin displayed significantly greater and values, and total carotenoid concentrations after 42 days. In addition, total carotenoids were higher in fish from black than white cages. The second experiment was designed to investigate whether density reduced the improvements in skin colour achieved by holding fish in white coloured cages and whether cage colour affected stress. Snapper (mean weight=435 g) were acclimated to black cages and fed 39 mg kg?1 astaxanthin for 44 days before transferring to black or white plastic‐lined cages at 14 (low), 29 (mid) or 45 (high) kg m?3 for 7 days after which time skin colour, plasma cortisol and plasma glucose concentrations were measured. Skin lightness () was greater in snapper transferred to white plastic‐lined cages with the lightest coloured fish obtained from the lowest density after 7 days. Density had no effect on plasma cortisol or glucose levels after 7 days, although plasma cortisol was elevated in snapper from black cages. For improved skin colouration we recommend feeding unesterified astaxanthin at 39 mg kg?1 for approximately 6 weeks and transferring snapper to white plastic‐lined cages or similar at low densities for short periods before harvest rather than producing fish in white netting sea cages subject to biofouling. 相似文献
4.
Mark A Booth Rebecca J Warner-Smith Geoff L Allan & Brett D Glencross 《Aquaculture Research》2004,35(5):458-464
Two experiments were conducted with Australian snapper Pagrus auratus (Bloch and Schneider, 1801). The first was aimed at determining the dietary level of astaxanthin that improved skin redness (CIE a*values) of farm‐reared snapper. Farmed snapper (ca. 600 g) fed a commercial diet without carotenoids were moved to indoor tanks and fed the same diet supplemented with 0, 36 or 72 mg astaxanthin kg?1 (unesterified form as Carophyll Pink?) for nine weeks. Skin redness (CIE a* values) continued to decrease over time in fish fed the diet without astaxanthin. Snapper fed the diet containing 72 mg astaxanthin kg?1 were significantly more red than fish fed the diet with 36 mg astaxanthin kg?1 three weeks after feeding, but skin redness was similar in both groups of fish after 6 and 9 weeks. The second experiment was designed to investigate the interactive effects of dietary astaxanthin source (unesterified form as Carophyll Pink? or esterified form as NatuRose?; 60 mg astaxanthin kg?1) and degree of shading (0%, 50% and 95% shading from incident radiation) on skin colour (CIE L*a*b*) and skin and fillet astaxanthin content of farmed snapper (ca. 800 g) held in 1 m3 floating cages. After 116 days, there were no significant interactions between dietary treatment and degree of shading for L*, a* or b* skin colour values or the concentration of astaxanthin in the skin. Negligible amounts of astaxanthin were recovered from fillet samples. The addition of shade covers significantly increased skin lightness (L*), possibly by reducing the effect of melanism in the skin, but there was no difference between the lightness of fish held under either 50% or 95% shade cover (P>0.05). 相似文献
5.
A two-factor experiment was carried out to investigate the change in skin colour and plasma cortisol response of cultured Australian snapper Pagrus auratus to a change in background colour. Snapper (mean weight=437 g) were held in black or white tanks and fed diets containing 39 mg unesterified astaxanthin kg−1 for 49 days before being transferred from white tanks to black cages (WB) or black tanks to white cages (BW). Skin colour values [ L * (lightness), a * (redness) and b * (yellowness)] of all snapper were measured at stocking ( t =0 days) and from cages of fish randomly assigned to each sampling time at 0.25, 0.5, 1, 2, 3, 5 and 7 days. Plasma cortisol was measured in anaesthetized snapper following colour measurements at 0, 1 and 7 days. Fish from additional black-to-black (BB) and white-to-white (WW) control treatments were also sampled for colour and cortisol at those times. Rapid changes occurred in skin lightness ( L * values) after altering background colour with maximum change in L * values for BW and WB treatments occurring within 1 day. Skin redness ( a * ) of BW snapper continued to steadily decrease over the 7 days ( a * =7.93 × e−0.051 × time ). Plasma cortisol concentrations were highest at stocking when fish were held at greater densities and were not affected by cage colour. The results of this study suggest that transferring dark coloured snapper to white cages for 1 day is sufficient to affect the greatest benefit in terms of producing light coloured fish while minimizing the reduction in favourable red skin colouration. 相似文献
6.
A single‐factor experiment was conducted to investigate the effects of dietary astaxanthin concentration on the skin colour of snapper. Snapper (mean weight=129 g) were held in white cages and fed one of seven dietary levels of unesterified astaxanthin (0, 13, 26, 39, 52, 65 or 78 mg astaxanthin kg?1) for 63 days. Treatments comprised four replicate cages, each containing five fish. The skin colour of all fish was quantified using the CIE L*, a*, b* colour scale after 21, 42 and 63 days. In addition, total carotenoid concentrations of the skin of two fish cage?1 were determined after 63 days. Supplementing diets with astaxanthin strongly affected redness (a*) and yellowness (b*) values of the skin at all sampling times. After 21 days, the a* values increased linearly as the dietary astaxanthin concentration was increased before a plateau was attained between 39 and 78 mg kg?1. The b* values similarly increased above basal levels in all astaxanthin diets. By 42 days, a* and b* values increased in magnitude while a plateau remained between 39 and 78 mg kg?1. After 63 days, there were no further increases in measured colour values, suggesting that maximum pigmentation was imparted in the skin of snapper fed diets >39 mg kg?1 after 42 days. Similarly, there were no differences in total carotenoid concentrations of the skin of snapper fed diets >39 mg kg?1 after 63 days. The plateaus that occurred in a* and b* values, while still increasing in magnitude between 21 and 42 days, indicate that the rate of astaxanthin deposition in snapper is limited and astaxanthin in diets containing >39 mg astaxanthin kg?1 is not efficiently utilized. Astaxanthin retention after 63 days was greatest from the 13 mg kg?1 diet; however, skin pigmentation was not adequate. An astaxanthin concentration of 39 mg kg?1 provided the second greatest retention in the skin while obtaining maximum pigmentation. To efficiently maximize skin pigmentation, snapper growers should commence feeding diets containing a minimum of 39 mg unesterified astaxanthin kg?1 at least 42 days before sale. 相似文献
7.
A 61‐day experiment was carried out to investigate the effect of dietary oxidized fish oil on growth performance and skin colour of Chinese longsnout catfish (Leiocassis longirostris Günther). Seven diets (Diet 1–7) containing different levels of oxidized fish oil (0, 10, 20, 30, 40, 50 and 60 g kg?1 dry diet) were evaluated at same dietary lipid level (60 g kg?1 diet). Fish skin colour (CIE L*a*b*) and melanin content was measured at three zones of fish body: back (Zone I), belly (Zone II) and tail (Zone III). The results showed that there were no significant differences in growth or feed utilization. Apparent digestibility coefficient of energy (ADCe) decreased while those of dry matter (ADCd), protein (ADCp) or lipid (ADCl) were not affected. Lightness (L*) of Zone I or II were not influenced while L* of Zone III decreased. Oxidized oil increased melanin content of Zone III. No apparent effects on the thiobarbituric acid reactive substances (TBARS) values of blood serum, liver and muscle were observed. In conclusion, dietary oil oxidation did not affect fish growth performance. Fish tail skin lightness was lower in the fish fed with high dietary oxidized fish oil and was positively correlated to melanin content. 相似文献
8.
Daniel D. Benetti Jaime A. Matera Owen M. Stevens Jorge F. Alarcon Michael W. Feeley Federico J. Rotman Yoichi Minemoto Gill Banner-Stevens Janice Fanke Scott Zimmerman Loyal Eldridge 《Journal of the World Aquaculture Society》2002,33(3):349-357
Abstract.— The aquaculture performance of mutton snapper Lutjanus analis raised in floating net cages was assessed by measuring their growth, survival, and feed conversion rates during a growout trial conducted in a 3.2‐ha saltwater lake in the Florida Keys, Florida, USA. Approximately 10,500 hatchery‐reared finger‐lings were stocked in two circular, high‐density polyethylene (HDPE) net cages of 7‐m diameter × 7‐m deep (300 m2) and 10‐m diameter × 7‐m deep (600 m3) dimensions. Cages were stocked at 25 fish/m3 (3.2 kg/m3) and 5 fish/m3 (0.72 kg/m3), respectively. Fish grew from a mean of 16.5 g to 302.8 g (25.6 cm TL) in 246 days in the former cage and from a mean of 42.3 g to 245.6 g (23.8 cm TL) in 178 d in the latter cage. Growth rates in weight were best expressed by the following exponential equations: cage 1 (high stocking density): W = 20.716 e0.0112x (r2= 0.83); cage 2 (low stocking density): W = 38.848 e0.0118x (r2= 0.81). Length‐weight data indicate that hatcheryraised, cage‐cultured mutton snapper are heavier per unit length than their wild counterparts. There was no significant difference (P < 0.05) between the slopes of the two lines, indicating that fish in the two cages grew at the same rate. The length‐weight relationships for mutton snapper stocked in cages 1 and 2 are expressed, respectively, by the equations W = 0.000009 L 3.11 (r2= 0.99) and W = 0.000005 L 3.22 (r2= 0.97). Overall feed conversion rate for both cages combined was 1.4. Approximately 10% of the fish sampled exhibited some degree of deformity, particularly scoliosis. Overall survival rate was 70%. Results suggest that L. analis has potential for aquaculture development in net cage systems. 相似文献
9.
Effect of Density at Harvest on the Growth Performance and Profitability of Hatchery‐reared Spotted Rose Snapper,Lutjanus guttatus,Cultured in Floating Net Cages 
下载免费PDF全文
下载免费PDF全文 Carlos Humberto Hernández Crisantema Hernández Francisco Javier Martínez‐Cordero Nicolás Castañeda‐Lomas Guillermo Rodríguez‐Domínguez Albert G. J. Tacon Eugenio Alberto Aragón‐Noriega 《Journal of the World Aquaculture Society》2016,47(1):51-60
This study evaluated the effect of the density at harvest on the performance and profitability of hatchery‐reared spotted rose snapper cultured in cages. The fish were stocked at harvest densities of 15, 20, and 22 kg/m3 in cages of 222 and 286 m3. More than 39,000 snapper fingerlings with an initial weight of 14 g were stocked. The fish were fed an extruded diet and cultured over a 360 d period. The thermal growth coefficient ranged from 0.04 to 0.05 and survival was 95% for all treatments, with the highest final weight (436.8 g) observed for fish reared at a density of 20 kg/m3. The allometric value b indicated that hatchery‐raised, cage‐cultured snapper were heavier than their wild counterparts. The major costs were feed (ranging from 44.7–45.9%), labor (22.4–32.6%), and seed costs (20.2–26.1%). The total production cost ranged from US$ 6.5 to US$ 7.5/kg. The baseline scenario was not economically feasible. However, a 10% increase in the sales price resulted in increases in the internal rate of return (183%) and net present value (US$ 97,628.9). These results suggest that L. guttatus has the potential for commercial production in cages. 相似文献
10.
Effects of background colour on growth performance,skin pigmentation,physiological condition and innate immune responses of goldfish,Carassius auratus 下载免费PDF全文
下载免费PDF全文 Khalil Eslamloo Sobhan R Akhavan Ahmad Eslamifar Morgane A Henry 《Aquaculture Research》2015,46(1):202-215
A study was carried out to investigate the effects of background colour on the growth performance, skin colour, haematology, physiological condition and non‐specific immune responses of goldfish, Carassius auratus. Goldfish were reared in tanks with four different background colours (white, black, blue and red) for 8 weeks. Fish growth performance markedly rose in white background compared with the other treatments. There was no significant difference in haematological parameters or plasma proteins concentrations between treatments. Plasma cortisol of fish reared in red background was significantly higher than that in black and white backgrounds. Plasma antiprotease and lysozyme activities were more than doubled in white and black treatments compared with the red and blue groups. The other immune parameters tested (plasma peroxidase, complement and bactericidal activities) did not significantly change between treatments. Skin carotenoid content and the intensity of fish skin colour extremely diminished in white background. This study revealed that red and blue backgrounds are chronically stressful and immunosuppressive in goldfish. White backgrounds will preferably be used for the culture of goldfish for best fish growth. However, a way to revert the colour loss of goldfish skin reared in white backgrounds remains to be investigated. 相似文献
11.
Bjorn Roth Mads Dorenfeld Jenssen Thor Magne Jonassen Atle Foss & Albert Imsland 《Aquaculture Research》2007,38(7):757-763
To determine the effect of maturation on flesh quality, 20 Atlantic halibut (Hippoglossus hippoglossus) consisting of mature and immature fish of both sexes were killed on site, exsanguinated and stored on ice. After 6 days of storage, the fish was gutted and filleted before colour, texture hardness and shear force were evaluated to determine the effect of maturation. Results show that mature males excreted black mucus from the skin during ice storage, while a greyish mucus was observed from immature fish. Mature fish had approximately 2% lower slaughter yield and 6% lower fillet yield compared with immature fish. The fillets from mature males were significantly harder compared with fillets from immature fish and the muscle structure proved to be stronger as an increased fracturability was observed in mature fish. In colour, fillets from mature fish proved to have a whiter appearance (L*) than immature fish, while no difference was seen in a* and b* values. We conclude that the physiological changes associated with maturation affects the end quality, and may be related to slower growth. 相似文献
12.
The effects of aquarium background colour and feed colour on survival, growth rates and feed utilization efficiency of thinlip mullet (Liza ramada) larvae (0.035 g) were investigated in two experiments. In the aquarium background colour trial, 50 larvae were stocked in duplicates in 120 L glass aquaria filled with dechlorinated tap water. The outside walls and bottoms of each pair of the aquaria were covered with coloured paper sheets to achieve one of six colours (white, black, red, green, yellow and blue), while noncoloured aquaria served as a control. The fish were fed an experimental diet (35% crude protein) at a daily rate of 5% of their body weight (BW), twice a day for 8 weeks. The best growth rates, feed efficiency and survival were achieved in larvae reared in light‐coloured aquaria (white, noncoloured and yellow). Fish performance was significantly retarded in larvae reared in dark‐coloured aquaria (red, green, black and blue). Body composition was not significantly affected by aquarium colour. In a feed colour trial, duplicate groups of larvae (0.035 g) were stocked at 50 fish per 120 L aquarium and fed a test diet (35% crude protein) with six different colours [dark blue, red, yellow, light brown (control), light green and dark brown] at a daily rate of 5% BW, twice a day for 8 weeks. The best performance and survival were achieved in fish fed on dark‐coloured diets (red, dark blue and dark brown). Light‐coloured diets (yellow, light green and light brown) resulted in inferior performance. Body composition was not significantly affected by feed colour. These results suggest that light‐coloured tanks should be used for rearing thinlip mullet, L. ramada larvae, while dark‐coloured diets are more preferable to light‐coloured diets. 相似文献
13.
Effects of background colour on growth indices and stress of young sterlet (Acipenser ruthenus) in a closed circulated system 下载免费PDF全文
下载免费PDF全文 In this study, the physiological response and growth performances of Acipenser ruthenus were investigated after a long‐term background colour adaptation (12 weeks). Twelve groups of 10 individuals with initial mean body weight of 183 g were reared in black, dark blue, grey and white tanks (three replicates for each colour). At the end of the experiments, growth (initial body weight, final body weight, weight gain per cent, food efficiency ratio, protein efficiency ratio, specific growth rate), blood (cortisol, glucose, pO2, pCO2, pH, haematocrit, osmolality, triglycerides, cholesterol, total lipids) and liver (hepatosomatic index, total lipids, glycogen) parameters were analyzed. Plasma cortisol in the dark‐adapted sterlet (21.95 ± 3.9 ng mL?1) was significantly lower than those in white‐adapted fish (39.44 ± 6.5 ng mL?1), whereas there were no significant differences in cortisol levels between the grey‐adapted fish (23.05 ± 4.1 ng mL?1) and dark blue‐adapted fish (24.2 ± 3.6 ng mL?1). A remarkable increase in mean of body weight (%) was detected in dark‐adapted sterlet (45.2 ± 3.2) being 27.67%, 12.1% and 11.8% higher than the white, grey and dark blue‐adapted fish respectively. The obtained results verified that different background colours lead to different growth performances and physiological responses of starlet, depending on rearing conditions. 相似文献
14.
Nafsika Karakatsouli Sofronios E Papoutsoglou & Georgios Manolessos 《Aquaculture Research》2007,38(11):1152-1160
Appropriate rearing conditions for successful farming of white sea bream Diplodus sargus L. have not yet been studied in depth, while one of the major problems is the species increased aggressiveness. Given the known effect of density and background colour on fish growth, welfare and social behaviour, the present study aimed to investigate whether the two factors combined could favour D. sargus performance. Juveniles (17.37±0.06 g) were reared in white, light blue and black tanks under low (7 fish tank−1 or 1.96 kg m−3) and high (28 fish tank−1 or 7.79 kg m−3) density for 87 days. Water quality was not affected by experimental treatments. The best overall performance (growth, food utilization, body protein content, liver fatty acids) was achieved under low density and white or light blue tanks. Increased incidence of social interactions was indicated in fish under high density or when reared in light blue and black tanks. The present results clearly suggested that the use of black tanks should be avoided. On the other hand, stocking D. sargus at a density of up to 7.79 kg m−3 may be feasible because productivity was greater even if growth was slower. In this case, however, the use of white tanks is highly recommended. 相似文献
15.
Noemí Tejera Juana Rosa Cejas Covadonga Rodríguez Salvador Jerez José Antonio Pérez Beatriz Concepción Felipe Antonio Lorenzo 《Aquaculture Research》2010,41(7):1043-1053
Pigmentation capability of red porgy (Pagrus pagrus) skin reared under open sea‐cage conditions and fed an astaxanthin‐enriched diet was studied. Skin lipid peroxide levels and lipid composition were also evaluated to establish the antioxidant role of astaxanthin under these sunlight‐exposure conditions. Fish placed either in an offshore sea cage system (SC) or in an inland tank facility (T) housed inside a ‘shade‐house’ enclosure were fed a commercial diet supplemented with 22 mg kg?1 astaxanthin. No differences in growth or survival were found. Both groups displayed a red skin, but SC fish presented a darker pigmentation, which externally reflected the higher deposition of melanin, astaxanthin and tunaxanthin found in its skin. The lower level of lipid peroxides found in SC fish might be related with the higher level of astaxanthin mentioned above. Nevertheless, lipid and fatty acid profiles did not show significant differences between groups. Our results indicate that sustainable production of red porgy with a natural red hue is possible on the basis of proper adjustment of two factors illumination and dietary astaxanthin. 相似文献
16.
Scale matters: performance of European sea bass,Dicentrarchus labrax,L. (1758), reared in cages of different volumes 下载免费PDF全文
下载免费PDF全文 Athanasios Samaras Michael Pavlidis Konstadia Lika Antonia Theodoridi Nikos Papandroulakis 《Aquaculture Research》2017,48(3):990-1005
The effects of rearing volume on on‐growing European sea bass performance and stress parameters were investigated for the first time in a pilot aquaculture farm. Fish were held under the same initial stocking densities in triplicate net‐pen cages of different sizes (1.4, 45 and 252 m3) for a period of 8 months. Results showed significant differences among the experimental groups in most parameters tested, with better performance in the two larger rearing volumes. In particular, growth rate showed a linear association with rearing volume, being 0.68 g day?1 for the large cage group, 0.56 g day?1 and 0.32 g day?1 for the medium and the small groups respectively. The feed conversion ratio and per cent survival (%) were also better in the large cage group. Fish reared in the small and medium‐sized cages showed higher plasma cortisol concentrations than those reared in large cages, which showed low basal cortisol concentrations. Additionally, after an acute chasing stress challenge, fish in the large and small groups, but not the medium group, showed increased cortisol concentrations. Differences also occurred in the ratio of the expression of cortisol receptors, namely the mineralocorticoid (mr) and glucocorticoid receptors (gr). In specific, the ratio of mr to grmRNA expression in the liver was higher in fish reared in the small cages. These findings verify that experimental scale significantly affects experimental results and is a critical factor for the interpretation of results. 相似文献
17.
Anne Mokoro Elijah Oyoo‐Okoth Charles C. Ngugi James Njiru Joseph Rasowo Victoria Chepkirui‐Boit David Manguya‐Lusega 《Aquaculture Research》2014,45(10):1672-1684
We evaluated the effect of varying cage stocking density (60, 90 and 120 fish m?3) and feeding duration (10, 30 and 60 min) in a cage‐cum‐pond‐integrated system on growth performance, water quality and economic benefits in Labeo victorianus culture. Interactions between stocking density and feeding duration significantly (P < 0.05) affected the fish growth performance and yields in the cages‐cum‐pond system. Stocking density of 60 fish m?3 resulted in the highest growth in cages and in ponds regardless of the feeding duration, but produced lower yields than at stocking density 90 fish m?3. The lowest Apparent Food Conversion Ratio (AFCR) in cages occurred at stocking density of 60 fish m?3 and feeding duration of 30 min. Growth performance in the open ponds declined with increased feeding duration of the caged fish. Survival in cages and in the open ponds decreased with increased cage density, but was not affected by feeding duration. Low dissolved oxygen were recorded, at stocking density of 120 fish m?3, the lowest DO occurred when feeding of caged fish lasted 60 min. Growth performance, water quality and economic benefits in Labeo victorianus culture positively respond to interaction between stocking density and feeding durations. 相似文献
18.
Nanthawan Santisathitkul Karun Thongprajukaew Suktianchai Saekhow Patchawadee Sandos Sasitorn Buntomnimit Hirun Kanghae 《Aquaculture Research》2020,51(4):1743-1752
Background colour influences the growth performance and feed utilization of various fish species. In the current study, the effects of different aquarium backgrounds (transparent, white, black, red, green and blue) on growth performance, feed utilization, digestive enzyme activities, flesh quality, carcass composition and haematological parameters were investigated in Asian seabass (Lates calcarifer). The fish (16.17 ± 0.02 g initial body weight) were distributed into eighteen glass aquaria (6 treatments × 3 replications) with the various background colours and reared for 10 weeks. At the end of the experiment, positive growth performance and feed utilization were observed in fish reared against transparent, white, black or green backgrounds, while negative effects were noted for fish reared on the remaining treatments (p < .05). Modulation of the main digestive enzymes was observed across the six treatments, indicating different strategies for utilizing nutrients by the fish. The activity ratio of trypsin to chymotrypsin was highest in the fish reared against a black background, followed by a white background. Flesh quality, in terms of protein synthesis capacity and protein turnover rate, indicated a significant improvement in the fish reared against white, black and green backgrounds, while the contents of myosin and actin were similar across the six colour treatments. Carcass composition and haematological parameters showed no negative effects in either of the preferred treatments. These findings indicate that the most suitable background colours for rearing Asian seabass are black, followed by white and green, while transparent, red or blue backgrounds are unsuitable. 相似文献
19.
Mario Garduño-Lugo Germán Muñoz-Córdova & Miguel Ángel Olvera-Novoa 《Aquaculture Research》2004,35(4):340-344
Mass selection in Oreochromis niloticus, Stirling strain, was used to obtain a red colour homozygous dominant population from a base population containing wild type and red fish with black blotches. Each selection generation included 28–80 breeders in a 1:1 male:female ratio and a density of 1 pair m?2.First selection for red colour was done when fry reached 3 g, discarding those exhibiting wild type colouring or with a high black blotch incidence. Second selection was done before fish began the reproduction stage. To determine if red‐coloured fish were homozygous, a progeny test was done with the fifth selection generation using eight individual crosses of red males with wild type females and wild type males with red females. Red colour proportion increased from 5.6% in the first generation to 100% in the fifth generation. All fry in the progeny test were red colour, inferring that the population was homozygous dominant (RR). Accumulated inbreeding rate in the fifth selection generation was 1.79%. The selection process did not affect fecundity as fry production in red colour females was similar to that in wild type females. Mass selection to obtain a red homozygous population in O. niloticus, Stirling strain, was appropriate and was also effective in reducing black blotch incidence in the same species. 相似文献
20.
In this study, we have investigated the effects of Porphyridium cruentum (Rodophyta) as a natural pigment source and astaxanthin and β-carotene as synthetic pigment sources on the skin colour of
cichlid fish (Cichlasoma severum sp., Heckel 1840), which are generally light orange with white patches and becomes shiny orange in the reproductive phase.
The fish were fed diets containing 50 mg kg−1 astaxanthin and β-carotene, and P. cruentum powder. The amount of both natural and synthetic pigment sources given as feed was 50 mg kg−1, and the experiment was continued for 50 days. Total carotenoid content of the fish was determined spectrophotometrically
at the end of the experiment. As a result, while a visible change of colour in the skin of the fish fed on the feed containing
astaxanthin was observed with 0.34 ± 0.2 mg g−1 of pigment accumulation, a relatively small change of colour was observed in the skin of other fish that were fed on the
feed containing P. cruentum and β-carotene with 0.22 ± 0.2 mg g−1 and 0.26 ± 0.1 mg g−1 of pigment accumulations, respectively. Therefore, it was determined that these pigment sources have an effect on the colour
of cichlid fish. 相似文献