Growth Response Of Rainbow Trout Research Articles

Effect of Dietary Inclusion of Citric Acid with Phytase as Supplement on Growth Responses of Rainbow Trout

Rainbow trout, a salmonid species has an economic importance worldwide and contributes to the indigenous food security. The present study was conducted in complete randomized design (CRD) to evaluate the dietary inclusion of citric acid with phytase as supplement on growth responses of rainbow trout. There were four treatments of diets with 0.5% citric acid (T1), 1% citric acid (T2), 1.5% citric acid (T3) and 0% control (T4) of citric acid incorporated with 1200FYT phytase as supplement. The treatments were replicated three times. Total harvest weight of fish in T3 (5720.2±105.6g) was significantly higher and different than T2 (4595.9±434.9g), T1 (4589.8±240.2g) and T4 (4567.5±217.3g). The highest daily growth rate was seen in treatment T3 (1.1±0.0) which was significantly different than T2 (0.9±0.0), T1 (0.9±0.0) and T4 (0.8±0.0). The highest specific growth rate was seen in the treatment T3 (0.8±0.01) which was significantly different than T1 (0.7±0.0), T2 (0.7±0.1) and T4 (0.7±0.0). The lowest food conversion ratio was seen in T3 (2.2±0.1) which was significantly different with T2 (2.6±0.1), T1 (2.7±0.1) and T4 (2.8±0.1). Similarly, the highest protein efficiency ratio was seen in treatment T3 (1.0±0.1) which was not significantly different with T2 (0.8±0.0) and T1 (0.8±0.1) but was significantly different than T4 (0.7±0.0). No significant changes were observed in water temperature, dissolve oxygen and pH under different treatments. The present findings demonstrated that dietary inclusion of citric acid with phytase as supplement enhance growth by reducing the pH in the gut which increases the phytate hydrolysis, kills the pathogens, decreases the rate of gastric emptying, improves mineralization and nutrient absorption.

Effects of three beta adrenergic receptor agonists on growth performance, blood biochemical parameters, fatty acids composition and carnitine palmitoyltransferase I gene expression of rainbow trout, Oncorhynchus mykiss

Different beta 1 and 2 adrenergic receptor agonists may be various biological and physiological effects on fish species. An experiment was designed to study the effects of feeding ractopamine, terbutaline and metaproterenol; as beta1, beta2 and less selective beta 2 adrenergic receptor agonists, respectively; on body weight gain, feed conversion ratio, concentration of biochemical parameters in the serum, gene expression of carnitine palmitoyltransferase I in liver and meat and also, fatty acids profile of filet meat of the rainbow trout. One hundred ninety two of juvenile rainbow trout were randomly assigned to 16 fiber glass tanks and fed one of four dietary treatments containing control (0), ractopamine, terbutaline and metaproterenol at levels of 10 ppm in diet for 8-week feeding trials. It was found that metaproterenol and ractopamine improved final body weight, body weight gain and feed conversion ratio of fish. The serum concentrations of phosphorus and albumin were also significantly increased by all beta adrenergic agonists and ractopamine reduced triglyceride level (p<0.05). The fatty acids level of fish filet was significantly increased by the dietary supplement of various beta adrenergic agonists (p<0.05) but ractopamine had a greater effect. The gene expression of carnitine palmitoyltransferase I in liver was significantly (P<0.05) increased by all beta adrenergic agonists. The present study showed that various beta1 and beta 2 adrenergic receptor agonists had same physiological effects on rainbow trout but it seems ractopamine, as a beta 1 adrenergic receptor, had more potential on fatty acid metabolism and growth response of rainbow trout.

Growth performance, proximate and histological analysis of rainbow trout fed diets containing Camelina sativa seeds, meal (high-oil and solvent-extracted) and oil

Two 112-day feeding trials were conducted to examine the effects of including camelina (Camelina sativa) products in rainbow trout diets. In the first experiment, 20 tanks (40L) of rainbow trout (Oncorhynchus mykiss; 2.36±0.18g, 30 fish/tank) were fed one of five diets containing solvent-extracted camelina meal (SECM) at dietary inclusion levels of 0, 50, 100, 150 or 200g/kg. Weight gain and specific growth rate (SGR) of fish fed 200g/kg SECM were significantly lower than those fed 0 and 50g/kg SECM. The protein efficiency ratio (PER) of fish fed 50g/kg SECM (2.4) was significantly higher than fish fed 0, 150 and 200g/kg SECM (all 2.1). There were no significant differences among treatments for total feed consumption or FCR, although during earlier periods of the trial, fish fed 150 and 200g/kg SECM had higher FCR than fish fed 0 and 50g/kg SECM (P<0.05). In the second experiment, 24 tanks (40L) of rainbow trout (1.0±0.1g, 30 fish/tank) were fed one of eight diets: a control diet; six diets containing full-fat camelina seed or high oil residue camelina meal (HORM), at dietary inclusion levels of 100, 200 and 300g/kg; or a diet that contained 100g/kg SECM and 151g/kg camelina oil (SECM+CO), with no added fish oil. After 112days on feed, fish fed diet containing 300g/kg camelina seed and 300g/kg HORM gained less weight than fish fed the control diet (P<0.05). Fish that consumed 300g/kg camelina seed also gained significantly less weight than fish fed 100g/kg camelina seed and 100g/kg HORM. Feed consumption was not affected by diet. FCR was higher in fish fed 300g/kg HORM than in fish fed 100g/kg camelina seed and the PER of the fish fed 300g/kg HORM was lower than that of fish fed 100g/kg camelina seed and HORM (P<0.05). There was no treatment effect on the intestinal histology of fish fed these diets (P<0.05). Fish fed up to 100g/kg SECM, camelina seed and HORM, as well as the SECM+CO diet did not perform any differently than fish fed the control diet (P>0.05). Although there were a few negative effects on performance in fish fed 200g/kg camelina seed and HORM early in the trial, this did not remain consistent for the entire trial. The maximum dietary inclusion threshold of these camelina products in juvenile rainbow trout diets is likely between 100 and 200g/kg, although further research will be required to determine more definite values. Statement of relevanceThis study determines the feed intake and growth response of rainbow trout fed camelina seed (dietary inclusion levels of 0, 100, 200 and 300g/kg), high oil residue camelina meal (dietary inclusion levels of 0, 100, 200 and 300g/kg) and solvent-extracted camelina meal (dietary inclusion levels of 0, 50, 100, 150 and 200g/kg) and a combination of 100g/kg solvent-extracted camelina meal and 151g/kg camelina oil, as well as information regarding the carcass composition and intestinal morphology of fish fed the first two ingredients. This research provides data that will enable the formulation of practical diets using these feed ingredients.

Effects of restricted ration, time-restricted access and reward level on voluntary food intake, growth and growth heterogeneity of rainbow trout ( Oncorhynchus mykiss) fed on demand with self-feeders

Growth responses of rainbow trout fed on demand using self-feeders were tested over an 8 week period when triplicate groups were exposed to two feeding levels (unlimited and fixed ration), at two feeding frequencies (time-restricted and free access) and three reward levels (0.17 g, 0.30 g and 0.43 g per trigger actuation). Triplicate groups were also hand fed as control of maximum growth. Each fish was marked according to its weight-class, and each group of 26 fish comprised a predetermined number of fish per weight-class: two fish of 13–16 g, six fish of 16–19 g, 10 fish of 19–22 g, six fish of 22–25 g and two fish of 25–28 g. There was no significant effect of feeding regime on feed efficiency. Voluntary feed intake and specific growth rates were significantly decreased as fish were exposed to reduced reward levels, even though there was a negative relationship between reward level and daily demand. Time-restricted access to self-feeders led to a decrease in feed intake, and an increase in growth heterogeneity in comparison with free access to self-feeders. Voluntary feed intake and specific growth rates were always lower in self-fed groups than in groups fed to apparent satiation by hand. Individual growth heterogeneity was greater within tanks allowed time-restricted access to self-feeders and within tanks fed by hand to visual satiation than within those given continuous access to self feeders. It is suggested that rainbow trout fed on demand with self feeders may not ingest as much food as they would be able to, and may not be satiated, but do express their hunger in relation with the level of effort that has to be done to obtain food.

Nutrient digestibility and growth responses of rainbow trout (Salmo gairdneri) fed different levels of cassava and rice

Seven groups of fingerling rainbow trout (Salmo gairdneri) were fed for 10 weeks on 0%, 10%, 20% and 30% of cassava or rice in isonitrogenous diets.

Cellular growth responses of rainbow trout ( Salmo gairdneri) fed different levels of dietary protein, and an anabolic steroid ethylestrenol

Cellular growth responses of rainbow trout ( Salmo gairdneri) fed different levels of dietary protein (35, 45, and 55%), with and without the anabolic steroid ethylestrenol, have been studied over a 60-day period. With an increase in dietary protein, total liver proteins increased in fish fed the steroid-free (control) diets, whereas no change occurred in the other tissues. Muscle and spleen RNA was unchanged, but RNA increased in liver, kidney, and brain. The DNA content increased in muscle, decreased in brain, but remained constant in liver, kidney, and spleen. Feeding the ethylestrenol-supplemented (experimental) diets resulted in an increase in total proteins, RNA, and DNA of kidney over the respective control value at each level of dietary protein. In the other tissues, total proteins and DNA were essentially unchanged, but total RNA content decreased in liver and increased in muscle in the experimental groups. It is concluded that in trout, the dietary protein level exerts marked differential effects on cellular growth parameters ( RNA DNA , RNA/protein, protein/DNA), which are further modified by steroid treatment. Evidence that cellular growth responses in muscle keep pace with total body growth was also indicated.

Growth response of rainbow trout ( Salmo gairdneri) to dietary ω3 and ω6 fatty acids

Different levels of trilinolenin (ω3) and trilinolein (ω6) fatty acids were incorporated in 16 trout diets. Results from feeding experiments showed inferior fish growth on diets (a) deficient in ω3 fatty acid (FA), (b) high in ω6 and low in ω3 FAs, and (c) high in both ω3 and ω6 FAs. Diets supporting rapid fish growth were those containing (a) high levels of ω3 FA and (b) high ω3 and low ω6 FAs. Fish lipid fatty acid composition, feed conversion efficiency and fish mortality are discussed.