Metabolism traits of 'all-fish' growth hormone transgenic common carp (Cyprinus carpio L.)

Transgenic animals with improved qualities have the potential to upset the ecological balance of a natural environment. We investigated metabolic rates of 'all-fish' growth hormone (GH) transgenic common carp under routine conditions and during starvation periods to determine whether energy stores in transgenic fish would deplete faster than controls during natural periods of starvation. Before the oxygen uptake was measured, the mean daily feed intake of transgenic carp was 2.12 times greater than control fish during 4 days of feeding. The average oxygen uptake of GH transgenic fish was 1.32 times greater than control fish within 96 h of starvation, but was not significantly different from controls between 96 and 144 h of starvation. At the same time, GH transgenic fish did not deplete energy reserves at a faster rate than did the controls, as the carcass energy contents of the two groups following a 60-d starvation period were not significantly different. Consequently, we suggest that increased routine oxygen uptake in GH transgenic common carp over that of control fish may be mainly due to the effects of feeding, and not to an increase in basal metabolism. GH transgenic fish are similar to controls in the regulation of metabolism to normally distribute energy reserves during starvation. (c) 2008 Published by Elsevier B.V.

In situ studies on the distribution patterns and dynamics of microcystins in a biomanipulation fish - bighead carp (Aristichthys nobilis)

The distribution and dynamics of microcystins in various organs of the phytoplanktivorous bighead carp were studied monthly in Lake Taihu, which is dominated by toxic cyanobacteria. There was a good agreement between LC-MS and HPLC-UV determinations. Average recoveries of spiked fish samples were 63% for MC-RR and 71% for MC-LR. The highest MC contents in intestine, liver, kidney and spleen were 85.67, 2.83, 1.70 and 1.57 mu g g(-1) DW, respectively. MCs were much higher in mid-gut walls (1.22 mu g g(-1) DW) than in hind- and fore-gut walls (0.31 and 0.18 mu g g(-1) DW, respectively), suggesting the importance of mid-gut wall as major site for MC absorption. A cysteine conjugate of MC-LR was detected frequently in kidney. Among the muscle samples analyzed, 25% were above the provisional tolerable daily intake level by WHO. Bighead is strongly resistant to microcystins and can be used as biomanipulation fish to counteract cyanotoxin contamination in eutrophic waters. (c) 2006 Elsevier Ltd. All rights reserved.

Growth and energy budget of F-2 'all-fish' growth hormone gene transgenic common carp

The growth and energy budget for F-2 'all-fish' growth hormone gene transgenic common carp Cyprinus carpio of two body sizes were investigated at 29.2 degrees C for 21 days. Specific growth rate, feed intake, feed efficiency, digestibility coefficients of dry matter and protein, gross energy intake (I-E), and the proportion of I-E utilized for heat production (H-E) were significantly higher in the transgenics than in the controls. The proportion of I-E directed to waste products [faecal energy (F-E) and excretory energy loss (Z(E) + U-E) where Z(E) is through the gills and U-E through the kidney], and the proportion of metabolizable energy (M-E) for recovered energy (R-E) were significantly lower in the transgenics than in the controls. The average energy budget equation of transgenic fish was as follows: 100 I-E = 19.3 F-E + 6.0 (Z(E) + U-E) + 45.2 H-E + 29.5 R-E or 100 M-E = 60.5 H-E + 39.5 R-E. The average energy budget equation of the controls was: 100 I-E = 25.2 F-E + 7.4 (Z(E) + U-E) + 35.5 H-E + 31.9 R-E or 100 M-E = 52.7 H-E + 47.3 R-E. These findings indicate that the high growth rate of 'all-fish' transgenic common carp relative to their non-transgenic counterparts was due to their increased feed intake, reduced lose of waste productions and improved feed efficiency. The benefit of the increased energy intake by transgenic fish, however, was diminished by their increased metabolism.

Investigation on intake, accumulation and toxicity of microcystins to silver carp

Daily intake and accumulation of microcystins (MCYSTs, MCs) in silver carp (Hypophthalmichthys molitrix) were investigated under lab conditions by feeding the fish exclusively with fresh toxic Microcystis bloom at a density of 6 x 10(9) algal cells L-1. The medial lethal dose (LD50) of microcystin-LR to silver carp was estimated to be 270 mu g kg(-1) body-weight, underlining its strong resistance to toxic Microcystis bloom. It can survive after being ingested with high doses of microcystins (about 10 mg kg(-1)) during the 28-days feeding experiment. Enzyme-linked immuno-sorbent assay results show that microcystin concentrations in muscle and liver are 1.57 +/- 0.31 mu g kg(-1) and 4.28 +/- 1.64 mg kg(-1) fresh weight. The former is much lower than the World Health Organization limit recommended for human consumption. These results suggest that silver carps can be widely used in cyanobacterial bloom control, and consumption of fish muscles is safe for human beings.

Effect of a feeding stimulant on feeding adaptation of gibel carp Carassius auratus gibelio (Bloch), fed diets with replacement of fish meal by meat and bone meal

The objectives of the study were to investigate the effect of a feeding stimulant on feeding adaptation of gibel carp (Carassius auratus gibelio Bloch) fed diets with replacement of fish meal by meat and bone meal (MBM), and whether or not the juvenile gibel carp could adapt to higher MBM level in the diet. Juvenile and adult gibel carp were tested. Two and one replacement levels were used for juvenile and adult fish respectively. Each group of diets was set as two types with or without a unique rare earth oxide: Y2O3, Yb2O3, La2O3, Sm2O3, Nd2O3 or Gd2O3 (only the first four rare earth oxides were used in adult diets) for four adaptation periods of 3, 7, 14 and 28 days respectively. After mixing, an equal mixture of all six diets for juvenile or four diets for adult was offered in excess for 2 days. During the last 2 days of each experiment, no feed was offered and faeces from each tank were collected. Feeding preference was expressed as relative feed intake of each diet, which was estimated based on the relative concentration of each marker in the faeces. Given some adaptation period, such as 3-28 days, the effects of MBM and squid extract inclusion on the preference to each diet were reduced. After 28 days adaptation, the preferences between groups were not significantly different.

Growth and feed utilization in two strains of gibel carp, Carassius auratus gibelio: paternal effects in a gynogenetic fish

Gibel carp (Carassius auratus gibelio Bloch) is a natural gynogenetic fish which requires sperm of the same or related species to activate egg development. The eggs of one gibel carp were divided into two batches. One batch was 'fertilized' with sperm from gibel carp (strain DD), and the other 'fertilized' with sperm from red common carp (Cyprinus carpio red variety) (strain DR). The juveniles were transferred to the laboratory 36 days post-hatch. Triplicate groups of each strain were fed a formulated diet at either 3% or satiation ration for 8 weeks. At both the restricted and satiation rations, specific growth rate was significantly higher in strain DR than in strain DD. At the 3% ration, there was no significant difference in feeding rate or feed conversion efficiency between the two strains. At the satiation ration, strain DR had a significantly lower feeding rate but higher feed conversion efficiency than strain DD. At the satiation ration, strain DR had a significantly lower intake protein, but higher recovered protein than strain DD. There was no significant difference in faecal protein loss between the two strains. At the 3% ration, strain had no significant effects on intake protein, faecal protein or recovered protein. Neither faecal energy loss nor recovered energy was affected by strain or ration. At both the 3% and satiation ration, final body contents of dry matter and lipid were significantly lower in strain DR than strain DD, while there was no significant difference in protein and energy content between the two strains at either ration level. The results suggested that gibel carp 'fertilized' with sperm of common carp grew faster than those 'fertilized' with sperm of gibel carp through increased feed conversion efficiency and protein retention.

Effect of several feeding stimulants on diet preference by juvenile gibel carp (Carassius auratus gibelio), fed diets with or without partial replacement of fish meal by meat and bone meal

The objectives of this work were to study the effects of several feeding stimulants on gibel carp fed diets with or without replacement of fish meal by meat and bone meal (MBM). The feeding stimulants tested were betaine, glycine, L-lysine, L-methionine, L-phenylalanine, and a commercial squid extract. Three inclusion levels were tested for each stimulant (0.18, 0.5%, and 1% for betaine and 0.1, 0.25 and 0.5% for the other stimulants). Two basal diets (40% crude protein) were used. one with 26% fish meal (FM), and the other with 21% fish meal and 6% MBM, Betaine at 0.1% in the fish meal group and at 0.5% in the meat and bone meal group was used in all experiments for comparison among stimulants. In the experiment on each stimulant, six tanks of fish were equally divided into two groups, one fed the FM diet, and the other fed the MBM diet. After 7 days' adaptation to the basal diet, in which the fish were fed to satiation twice a day, the fish were fed for another 7 days an equal mixture of diets containing varying levels of stimulants. Each diet contained a unique rare earth oxide as inert marker (Y2O3, Yb2O3, La2O3, Sm2O3 or Nd2O3). During the last 3 days of the experiment, faeces from each tank were collected. Preference for each diet was estimated based on the relative concentration of each marker in the faeces. Gibel carp fed the FM diet had higher intake than those fed the MBM diet, but the difference was significant only in the experiments on betaine, glycine and L-methionine. None of the feeding stimulants tested showed feeding enhancing effects in FM diets. All feeding stimulants showed feeding enhancing effects in MBM diets. and the optimum inclusion level was 0.5% for betaine, 0.1% for glycine, 0.25% for L-lysine, 0.1% for L-methionine. 0.25% For L-phenylalanine. and 0.1% for squid extract. The squid extract had the strongest stimulating effect among all the stimulants tested. (C) 2001 Elsevier Science B.V. All rights reserved.

Compensatory growth in the gibel carp following feed deprivation: temporal patterns in growth, nutrient deposition, feed intake and body composition

To investigate the nature of compenstory growth in fish, an 8 week study at 28 degreesC was performed on juvenile gibel carp Carassius auratus gibelio weighing 6.6 g. Fish were starved for 0 (control), 1 (Sl)or 2 (S2) weeks and then re-fed to satiation For 5 weeks. Weekly changes in weight gain, feed intake and body composition were monitored during re-feeding. No significant difference was found in final body weight between the three groups, indicating complete compensation in the deprived fish, The deprived groups caught up in body weight with that of the control after 2 weeks of re-feeding. Body fat:lean body mass ratio was restored to the control level within 1 week of re-feeding. In the re-feeding period, weekly gains in body weight, protein. lipid, ash and energy in the S1 group were significantly higher than in the controls for 1 week. For the S2 group, weekly gains in body weight. lipid. ash and energy were higher than in the controls for 2 weeks, and gain in protein was higher than in the controls for 3 weeks, though gain in body energy became elevated again during the last 2 weeks of the experiment. Feed intake remained higher than the control level for 3 weeks in the S1 group and 3 weeks in the SZ group. Growth efficiency was not significantly different among the three groups in any of the weeks during re-feeding. Compensatory responses in growth and especially feed intake tended to last longer than the recovery of body composition. (C) 2001 The Fisheries Society of the British Isles.

Feeding level-scaled retention efficiency, growth and energy partitioning of a marine detritivorous fish, redlip mullet (Liza haematocheila T. & S.)

The effects of feeding level on growth, retention efficiency, faeces production and energy partitioning of redlip mullet were studied. A practical diet was used and fed at six levels from starvation, 1%, 2%, 3%, 4% of body weight (BW) to satiation for 3 weeks. The temperature was kept at 24 +/- 1 degrees C. Reducing the feeding amount resulted in significantly lower weight gain, and retention efficiency was significantly affected by feeding levels and attained the maximum at maximum feeding intake. Feeding 2% BW was the minimum required for fish to maintain growth. Fish carcass composition under different feeding levels could be divided into three groups: (1) starvation and FL1; (2) FL2 and FL3 and (3) FL4 and satiation, with significant differences among the groups but no differences in the groups except that ash content remained at constant value. Body composition of fish of group 2 was close to initial fish. The thermal-unit coefficient was 0.0381 at satiation, and significantly increased with increasing feeding levels. In order to accurately estimate basal metabolism (HeE), another trial on the relationship between HeE (kJ) and BW (g) was carried out. An exponential curve as HeE=0.1255BW(0.8386) explained this relationship. Intake energy (IE) increased from 11.30 to 63.08 kJ per fish, matching with different feeding levels. Energy allocated to growth of IE decreased with reducing feeding amount. There was a linear relationship between metabolism energy and retention energy in percentage.

Transporting nutrients from sediments: nitrogen and carbon as indicators to measure scavenging ability of a detritivorous fish, Liza haematocheila

The redlip mullet, Liza haematocheila, is a common species in polyculture as a scavenger in China. Feeding on detritus, redlip mullet transports nutrients from sediments up into the water column and converts them into forms that can be utilized by phytoplankton and affects the relative abundance of detritus and dissolved inorganic nutrients to phytoplankton, zooplankton and other fishes. We used nitrogen and carbon as the indicators in this study to measure the scavenging ability, which means intake of nitrogen or carbon by redlip mullet, and the loss of nutrients. Temperature and body weight significantly affected growth nitrogen, faecal nitrogen and faecal carbon. At a certain temperature, the proportion of growth nitrogen or growth carbon increased while the proportion of excretion nitrogen or respiration carbon decreased with increasing body weight.

Influences of the Fish-Mouth Project and the Groins on the Flow and Sediment Ratio of the Yangtze River Waterway

A depth-integrated two-dimensional numerical model of current, salinity and sediment transport was proposed and calibrated by the observation data in the Yangtze River Estuary. It was then applied to investigate the flow and sediment ratio of the navigati