Covariation between diploid and triploid progenies from common breeders in rainbow trout, Oncorhynchus mykiss (Walbaum)

The covariation between diploid and triploid progenies from common breeders was investigated in various progeny-testing experiments where either dams or sires were sampled from rainbow trout, Oncorhynchus mykiss (Walbaum), stocks. Triploidiza tion was found to frequently reduce the performance in the traits studied: body length and weight, growth, coefficient of condition and pyloric caeca number. Triploidization also generated significant interactions with the parental breeding value. These interactions were caused in part by the familial variance not being the same in triploids as in diploids, but also by actual ranking differences between diploid and triploid familial performances. However, the effect of these interactions was minor as compared with the amount of variation common to both ploidy levels (genetic correlations averaged 0.7–0.9). Therefore, selection of diploid breeders appeared efficient enough for improving triploid progeny, unless family selection methods including triploid progeny testing were preferred for other reasons. Lastly, it was observed that variances from maternal origin tended to be larger in triploids, whereas variances from paternal origin tended to be smaller, as compared with diploids. This point was discussed referring to the genetic make-up of triploids and in the scope of dams and sires for selective breeding.     

The effectiveness of adenoviral vectors to deliver and express genes in rainbow trout,Oncorhynchus mykiss (Walbaum)

The efficacy of adenoviral vectors for gene delivery into fish cells, both in vitro and in vivo, was evaluated. Vectors utilized were of human adenovirus serotype 5 (Ad), which are commonly used in human clinical trials, but have not been assessed for gene delivery to fish. Because nothing is known about Ad receptors in fish, both an Ad (Ad5Luc1) with natural tropism for the coxsackie and adenovirus receptor (CAR), as well as an infectivity enhanced Ad (Ad5LucRGD) were included within this study. Gene expression was detected in cell lines using either vector. The levels seen with Ad5LucRGD were much higher than for Ad5Luc1 in most lines except CHSE-214. Transduction of CHSE-214 cells with Ad5Luc1 could be blocked with an excess of a competitive inhibitor, suggesting that these cells possess a CAR homologue thatmediates attachment of Ad, similar to that seen in mammalian cells. In vivo gene delivery was attempted by several methods, with significant expression seen only via intramuscular injection, although infection efficiency was low. Thus it was observed that several teleost cell lines are capable of being infected and one cell line expressed a human serotype adenoviral receptor homologue that aids in Ad infection. Additionally, in vivo studies indicated that muscle tissue of rainbow trout could be infected with Ad vectors, suggesting an alternative gene delivery strategy for this animal.     

Strain differences in feed efficiency measured as residual feed intake in individually reared rainbow trout, Oncorhynchus mykiss (Walbaum)

The efficient use of feed for growth and meat production is important for all animal production industries including aquaculture. Residual feed intake (RFI) is an alternative measure of feed efficiency that has been widely used in livestock production. Residual feed intake was calculated as the difference between intake observed and intake predicted on the basis of a bioenergetics model; a low RFI indicates greater efficiency. Residual feed intake offers some advantages as a selection criterion for improving production efficiency over traditional feed efficiency statistics because it is not a ratio and it typically has a larger coefficient of variation. The RFI of individually reared rainbow trout progeny from six different genetic cross‐types was examined for genetic variation. Proximate analysis and nitrogen retention were also evaluated to determine if differences in RFI correlate to differences in body composition and nutrient retention and varied by cross‐type. Differences between cross‐types indicated a genetic component for RFI, with the most efficient fish of approximately 160 g consuming 0.99 g less and inefficient fish consuming 0.05 g more feed per day than expected. Lower RFI was associated with higher growth rates (r=?0.38, P<0.05) and greater nitrogen retention (r=?0.82 P<0.001).     

A test of a feed budget model for rainbow trout, Oncorhynchus mykiss (Walbaum)

A feed budget model, which enables farmers to adapt a general model to local conditions, was tested on rainbow trout, Oncorhynchus mykiss (Walbaum). The model has two major components; component 1 is used to calculate the energy required for one unit of biomass gain (g or kg) and component 2 estimates the daily growth increment (g or kg). Both components can be adjusted in relation to prevailing environmental conditions and, together, they express the daily energetic requirement of the specific species or strain. Fish fed using the model as a guide had a high rate of growth and good feed conversion. The model accurately predicted growth over the experiment, and is presented as a means of calculating the daily feed budget in fish farming. Growth of fish fed using self-feeders is presented for comparison with the results obtained using the model.     

Dietary modulation of digestive enzymes by the administration of feed additives to rainbow trout,Oncorhynchus mykiss Walbaum

The aim of this study was to assess the metabolic and digestive enzyme activities in rainbow trout, Oncorhynchus mykiss Walbaum fed dietary supplements. The biometric indices and the following enzymes activities were measured: acid protease and pepsin from the stomach homogenates, alkaline phosphatase (AP) from the small intestine and the brush border membrane, total proteolytic enzymes and trypsin from the small intestine and liver/pancreas. Dietary garlic induced a higher pepsin activity in the stomach than lipopolysaccharide (LPS) and ginger. Conversely, dietary ginger and LPS showed a significant difference (P > 0.05) in acid protease activity compared to the controls. There was not any significant difference observed between treated groups and the controls for hepato‐pancreas proteolytic enzyme activity, except for trypsin. AP activity increased significantly with dietary garlic, ginger and LPS compared to the controls.     

Interaction between diet and genetic aptitude for weight and growth in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum)

Samples of rainbow trout, Oncorhynchus mykiss (Walbaum) alevins from 17 independent families (full‐sib‐groups) were raised from the start of feeding until the age of 18 weeks post‐hatching with three diets (C, G and S) differing in protein content (fish soluble protein concentrate: 84% in C, 54% in G and 44% in S) and carbohydrates (none in C, 30% glucose in G and 40% crude corn starch in S). Fish were fed to near satiation, and their body weight and growth were measured. Diet effect was highly significant (G< C < S), as well as the familial effect. The major part of the familial variance (80–90%) was common to the three diets. However, a minor part of the familial variance was observed to be diet dependent (family × diet interaction), and was found to result mainly from relative performances with carbohydrates (G and S diets) vs. pure protein (C diet). These results indicate that genetic improvement of growth should suffer little impairment from possible changes in future feed formulations.     

Effect of GnRHa injection on milt volume in recently stripped rainbow trout Oncorhynchus mykiss

In this study, the effect of gonadotropin‐releasing hormone agonist (GnRHa) injection on milt production in spent rainbow trout was investigated. On day 0, 25 newly matured male rainbow trout (Oncorhynchus mykiss) were stripped manually, and sperm quantity (vol: mL fish^?1) and quality, spermatocrit (%), sperm count (cell mL^?1), motile sperm percentage and motility duration (s) were evaluated. After stripping, fish were randomly divided into five groups: intact; sham (injected with propylene glycol as a hormone vehicle); and groups receiving 4, 8 or 16 μg kg^?1 BW of [d ‐Ala⁶ Des‐Gly¹⁰] mGnRHa. On day 7, the fish were stripped again and the same sperm characteristics as on day 0 were measured. At the beginning of the experiment, there were no significant differences in any of the sperm quantity characteristics between groups. On day 7, expressible milt volume was significantly reduced compared with day 0 (P<0.05, t‐test) in the intact and sham groups but milt quality remained the same (P>0.05, t‐test). The present study shows that GnRHa injection with a concentration as low as 4 μg kg^?1 BW after first stripping could prevent a significant reduction in milt quantity collected 7 days later without any adverse effects on sperm quality.     

Differences in self-feeding activity between thermally selected and normal strains of rainbow trout Oncorhynchus mykiss at high temperatures

ABSTRACT:   Feeding activity was examined at high temperatures by using a demand feeder for thermally selected and normal rainbow trout Oncorhynchus mykiss strains. When the water temperature was raised in experiment 1 from 17.5 to 25.7°C at 0.3°C/day in 21 days, the average daily food consumption rate in the thermally selected strain rose to 7.1%, which was significantly higher than that of the normal strain (4.1%, P  < 0.05). The corresponding rate was also significantly higher in the thermally selected (0.8%) than in the normal strain (0.2%, P  < 0.05) of fish in experiment 2 where water temperature was raised to 24.1°C in 0.5°C/day increments. When water temperature was raised rapidly in experiment 3 from 16.7 to 21.7°C in one day and gradually to 24.4°C in 28 days at 0.1°C/day, the average daily food consumption rates were 1.0 and 0.1% for the thermally selected and normal strains, respectively, with significant difference ( P  < 0.01). These results suggest that the thermally selected strain has acquired thermal tolerance as a result of artificial selection.     

Utilization of (3S,3'S)-astaxanthin acyl esters in pigmentation of rainbow trout (Oncorhynchus mykiss)

The deposition of natural, optically active, astaxanthin fatty acid esters in rainbow trout ( Oncorhynchus mykiss ) was studied. Mono-esterified and di-esterified (3 S ,3' S ) astaxanthin were purified from the green microalga Haematococcus pluvialis and incorporated into extruded diets and compared with diets containing synthetic racemic astaxanthin (Carophyll Pink) and a total carotenoid extract from the alga. All sources of astaxanthin achieved >4 mg kg⁻¹ in the white muscle after 6 weeks feeding. No significant difference ( P  > 0.05) between the deposition of astaxanthin or total carotenoid for the different diets was observed. Other xanthophylls, namely lutein, zeaxanthin and idoxanthin were found in the white muscle of rainbow trout fed all diets and together accounted for 10–14% of total carotenoid. Astaxanthin was deposited in the white muscle in the stereochemical form administered in the diet, i.e. racemic astaxanthin for Carophyll Pink and ˜100% (3 S ,3' S )-astaxanthin for the algal sources. In contrast, epimerization of (3 S ,3' S ) astaxanthin from the alga was observed for the astaxanthin esters deposited in the skin of rainbow trout, with a ratio close to 1.0:2.0:1.0 (3 S ,3' S :3 R ,3' S :3 R ,3' R ).     

The use of AquaMats® to enhance growth and improve fin condition among raceway cultured rainbow trout Oncorhynchus mykiss (Walbaum)

AquaMats® are a type of artificial seaweed designed to provide structure in ponds used for fish culture and as a substrate for the growth of aquatic plants and invertebrates which in turn are a source of nutrition to cultured species. In two separate tests AquaMats® were placed into raceways used to rear rainbow trout Oncorhynchus mykiss (Walbaum) to evaluate their effect on fish growth and fin condition. In the first test, the AquaMats® were placed perpendicular to the raceway length similar to a baffle design. One treatment consisted of AquaMats® that were cleaned on a regular basis, and the other treatment consisted of AquaMats® that were not cleaned throughout the test. By the end of the test no differences were found between treatments with respect to final fish weight, specific growth rate, or feed conversion ratio. The use of AquaMats® did not improve fin condition, in fact several fins measured were significantly better among control fish. In the second test AquaMats® were placed on the raceway bottom parallel to their length and to the water flow. AquaMats® were also hung from the side of the raceway to provide cover. At the conclusion of this test no differences were found between treatments with respect to final fish weight, specific growth rate, or feed conversion ratio. The placement of AquaMats® did have a transitory impact on fin condition. Mid‐way through the test, treatment fish generally exhibited longer fins compared with the controls. However, by the end of the test, these differences were no longer detectable. The results from both tests indicate that fish were not provided with additional nutrition to the extent it improved growth. However, the use of AquaMats® did make a significant, albeit transitory, impact on fin condition.     

5个虹鳟群体的生化遗传分析

虹鳟(Oncorhynchus mykiss)系山河流中的冷水性鱼类,属鲑形目、鲑科、大麻哈鱼属。从20世纪90年代起,黑龙江水产研究所陆续从国外引种芬兰虹鳟、道氏虹鳟、挪威虹鳟、丹麦虹鳟和美国加州虹鳟,经多年选育养殖成功,为我国冷水鲑鳟增养殖及游钓业增加了新品种。目前,关于虹鳟生殖[     

Apparent digestibility coefficients of nutrients in brewer's and rendered animal by-products for rainbow trout (Oncorhynchus mykiss (Walbaum))

Two experiments were conducted to measure the apparent digestibility coefficients (ADCs) of nutrients, dry matter, and energy in by‐products of the brewing industry and in selected animal protein ingredients for rainbow trout. In experiment 1, 500 rainbow trout (average body weight 170.8±5.5 g) were stocked in ten 140‐L digestibility tanks with 50 fish per tank and two tanks per diet. Yttrium oxide was used as an inert marker in the diets. The high fibre content of brewer's dried grains (BDG) affected the ADCs of dry matter but not of protein or amino acids. Brewer's dried yeast had a higher protein content than BDG, but ADC values for protein and amino acids were significantly lower. The ADCs of phosphorus were similar among brewer's dried products. The BDG high‐protein, fraction had marginally higher ADC values for dry matter, protein and amino acids than regular BDG. Conditions in experiment 2 were similar to those in experiment 1. ADC values for spray‐dried porcine plasma were over 98% for dry matter, crude protein, crude fat, and gross energy. ADC values for spent hen meal were higher than those of poultry by‐product meal or feather meal, with the exception of gross energy. However, spent hen meal was unpalatable. The ADCs in these ingredients were variable, and this variability must be taken into account when these ingredients are formulated into feeds for fish.     

Effect of dietary inclusion of lysozyme on growth performance and plasma biochemical parameters of rainbow trout (Oncorhynchus mykiss)

This study was conducted to evaluate the effect of dietary lysozyme supplementation on growth performance and plasma biochemical parameters of rainbow trout (Oncorhynchus mykiss). Graded levels of lysozyme [0 (control), 150, 300, 450 and 600 mg kg^?1 diet] were fed to fish (initial average weight 7.76 g) for 10 weeks. Dietary lysozyme supplementation regardless of inclusion level generally improved the growth, feed utilization and nutrient retention, but significant differences were mainly observed between the 450 or 600 mg kg^?1 lysozyme group and the control group. Lysozyme supplementation generally decreased the plasma aspartate aminotransferase and alanine aminotransferase (ALT) activities, but significant difference was only observed in the ALT activity between the 450 mg kg^?1 lysozyme group and the control group. In contrast, lysozyme supplementation generally increased the plasma alkaline phosphatase and lysozyme activities, but significant difference was only observed in the lysozyme activity between the 600 mg kg^?1 lysozyme group and the control group. Lysozyme supplementation generally increased the plasma antioxidant activities of enzymes (including superoxide dismutase, glutathione peroxidase and catalase) and total antioxidant capacity, but decreased the plasma malondialdehyde level. These results suggest that dietary 450–600 mg kg^?1 lysozyme inclusion may improve the growth and non‐specific immune response of rainbow trout.     

Coastal movement and growth of domesticated rainbow trout (Oncorhynchus mykiss (Walbaum)) in Norway

Between 1979 and 1991, hatchery-reared 1+ and 2+ rainbow trout were released in May and June in the Boknafjord at the mouth of the River Imsa, and from April to June in the Oslofjord, southern Norway. The fish were recaptured in the fjords of release, in rivers emptying there and from rivers and sea further along the Norwegian coast. Of the total recaptures, 35.6% ascended rivers in the year of release. Some fish released at the River Imsa returned to the area of release after spending 1 to 3 years at sea. Among those that were recaptured in rivers, 11.9% were recaptured in other rivers than the Imsa. The growth rate of the fish varied inversely with size at release. The growth rate was higher in the Oslofjord than in the Boknafjord, and in both areas the growth rate decreased with time after release. Rainbow trout that had escaped from local fish farms entered the River Imsa between March and December. Adults ascending in spring remained a shorter time in the river (37 days) than those ascending in autumn (200 days). Fish entering in autumn decreased more in weight during their river stay than those ascending in spring, and females more than males. Spawning took place in April-May. The monthly mean river stay of juvenile entrants ranged from 2 weeks to 6 months. In total, 27.8% of the rainbow trout escaped from fish farms and captured in the Imsa strayed to other rivers for repeat spawning. There is no evidence for continuing survival of escaped Norwegian rainbow trout in the wild.     

Dietary microbial phytase supplementation and the utilization of phosphorus, trace minerals and protein by rainbow trout [Oncorhynchus mykiss (Walbaum)] fed soybean meal-based diets

Effects of thermal and enzymatic treatments of soybean meal on apparent absorption of total phosphorus, phytate phosphorus, nitrogen (protein), ash, calcium, magnesium, copper, iron, manganese, strontium and zinc were examined using rainbow trout, Oncorhynchus mykiss (Walbaum), as the test species. Absorption of the test nutrients was estimated using yttrium as an inert non-absorbable indicator. Thermal treatments (microwaving, dry roasting, steam heating, cooking) had no measurable effect on the apparent absorption of phosphorus and other minerals. Phytase supplementation increased the apparent absorption of phosphorus, nitrogen (protein), ash, calcium, magnesium, copper, iron, strontium and zinc in low-ash diets containing soybean meal, but had little effect in high-ash diets containing both soybean and fish meal. In low-ash diets, the apparent absorption of phosphorus increased in accord with the level of phytase added to the diet, from 27% (no phytase added) up to 90% (phytase added, 4000 units kg⁻¹ diet) or 93% (predigested with phytase, 200 units kg⁻¹ soybean meal). In high-ash diets, dietary acidification with citric acid decreased the effect of phytase, whereas in low-ash diets, acidification markedly increased the effect of the enzyme. Excretion of phosphorus in the faeces of fish fed a low-ash diet containing phytase-treated soybean meal was 0.32 g per kg diet consumed, a 95%−98% reduction compared with phosphorus excretion by fish consuming commercial trout feeds.