Terrence B. Kayes

Requirements for lysine and arginine by rainbow trout (Oncorhynchus mykiss)

A series of experiments was conducted to determine lysine and arginine requirements of fingerling rainbow trout. Four groups of 30 trout each were assigned per diet and fed three times daily to satiation at 15 °C. The diets contained varying levels of lysine and arginine. Weight gain of 13.7-g trout over a 6-week feeding period increased linearly with lysine level up to 1.4% of diet, but was not different at 1.4 and 1.6% lysine. Feed efficiency and nitrogen retention improved as the lysine level in the diet increased. Carcass protein content of trout fed diets containing sufficient ivsine was higher than that of trout fed diets deficient in lysine. No significant differences in weight gain were shown between 11.6-g trout fed diets containing 0.47% arginine and either 1.5 or 3.0% lysine, indicating no apparent interactions between the dietary arginine and lysine levels. Weight gain of 12.4-g trout over a 6-week feeding period significantly (P < 0.05) increased with dietary arginine level up to 1.3%, but further increases in the arginine level did not have a significant effect. A similar trend was noted in feed efficiency, nitrogen retention and carcass protein content. Analysis of weight gain versus dietary lysine or arginine level indicated that the lysine and arginine requirements of young trout are 1.30 (3.71) and 1.41 (4.03)% of diet (protein), respectively.

Purified diet development and re-evaluation of the dietary protein requirement of fingerling rainbow trout (Oncorhynchus mykiss)

Abstract Two experiments were carried out to develop a purified diet, and to examine the protein requirement of fingerling rainbow trout. Four replicate tanks (50 fish each) of trout were assigned to a commercial salmon diet or a purified diet containing 30, 35, 40 or 45% protein; and three replicate tanks (40 fish each) to a diet containing 10, 15, 20, 25 or 35% protein (not counting crystalline dispensable amino acids which replaced casein protein to vary the protein level). Trout were fed three times a day for 6 weeks, and weight gain and feed gain ratio were monitored No significant differences were found in weight gain or feed gain ratio among 10.5-g fish fed diets containing 30, 35, 40 and 45% protein. Fish fed these diets gained about 80% as much weight as fish fed a commercial salmon diet which produced gain of 19.5 g/fish per 6 weeks. Weight gain increased with the increasing levels of casein up to 25% and the breakpoint was found at 24% intact protein, indicating that the levels of indispensable amino acids (IDAA) supplied by the 24% intact protein were sufficient to meet the requirements of trout for IDAA. Results suggested that energy sources used for trout diets play an important role in the determination of the protein requirements, and that the conventionally established protein requirement (40%) includes protein required to meet IDAA requirements (24%) and that required to meet energy needs (16%).

Effects of rearing density on the stress response and growth of rainbow trout.

Abstract One-year-old rainbow trout Oncorhynchus mykiss were reared for 8 weeks at a density of either 56 or 267 g fish/L (based on the volume of net-pens), equivalent to density indexes of 2.3 and 11.1 g fish/L-cm total fish length), respectively. The fish were held in 0.6 × 0.3-m netpens submerged to a depth of 0.15 m. Two net-pens for each fish density were suspended in each of three 3,040-L circular tanks provided with sufficient flow to maintain loading rates in the tanks at less than 800 g/(L-min). The fish were then subjected to an acute handling stress by being removed from the water for 60 s. No differences in the time course of changes in serum cortisol levels or hematocrits were observed over a 12-h period between fish in the two density groups. There were also no differences between the two groups of fish in weight, length, body condition factor (weight/length3), interrenal nuclear diameter, or the percentage of the anterior stomach that was mucosa. These results indicate that if high water qu...

Validation of a microtitre plate ELISA for measuring cortisol in fish and comparison of stress responses of rainbow trout (Oncorhynchus mykiss) and lake trout (Salvelinus namaycush)

A microtitre plate enzyme-linked immunoassay (ELISA) was validated for measuring serum cortisol in rainbow trout (Oncorhynchus mykiss) and lake trout (Salvelinus namaycush). The ELISA uses a highly specific rabbit antibody raised against cortisol-3-carboxymethyloxime (CMO)/bovine serum albumin (BSA), and a conjugate of horseradish peroxidase (HRP) also linked to cortisol in the 3-position by a CMO bridge. The chromatogenic substrate is 3,3′,5,5′-tetramethylbenzidine (TMB). The standard curve was linear (logit/log) from the lower limit of sensitivity of the assay (2 pg/well = approx. 100 pg/ml serum) to approximately 1000 pg/well. The ELISA satisfied the strictest criteria of specificity, reproducibility (interassay coefficient of variation 98%). Changes in serum cortisol, glucose and chloride were measured in rainbow trout and lake trout following an acute 1-min handling stressor. In both species, cortisol levels rose rapidly to peaks of approximately 300 ng/ml by 1 h post-stress, and slowly returned to baseline over the next 48 h. Glucose levels rose faster in rainbow trout than in lake trout but reached similar peak levels of approximately 135 mg/dl at 6 h post-stress in both species. Chloride levels declined between 1 and 3 h in both species, although rainbow trout showed a greater and more prolonged hypochloremia than lake trout. Within 1 week following administration of the stressors, 19 rainbow trout ( ∼ 17% of the fish in the experiment) and 2 lake trout ( ∼ 2%) died. Most of the fish which died had been sampled when their serum chloride levels were low, suggesting that the survival rates of stocked trout may be increased if they are rehandled and stocked before or after this period of hypochloremia.

Requirements for sulfur amino acids and utilization of D-methionine by rainbow trout (Oncorhynchus mykiss)

Abstract The methionine (Met) requirement and replacement values of cystine (Cys) and D-Met for L-Met were estimated at 15 °C for fingerling rainbow trout ( Oncorhynchus mykiss ) by feeding diets containing various levels of L-Met, D-Met and L-Cys. Four tanks, each containing 28 (Experiment 1) or 30 (Experiment 2) trout (11–15 g initial weight), were assigned to each diet. Weight gain and nitrogen retention during a 6-week period increased with increasing levels of L-Met up to 0.5% of diet, when the diets contained excess L-Cys (0.5%). Feed efficiency increased as L-Met increased, but no significant ( P > 0.05) differences were detected at levels above 0.4%. With diets containing 0.5% L-Met, the Cys requirement was found to be 0.3% of the diet. Increasing D-Met level above 0.27% in a diet containing 0.23% L-Met did not significantly ( P

Effect of fasting or feeding diets containing different levels of protein or amino acids on the activities of the liver amino acid-degrading enzymes and amino acid oxidation in rainbow trout (Oncorhynchus mykiss)

Abstract Experiments were done on fingerling rainbow trout at 15 ± 1 °C to determine the effect of: (1) fasting or feeding diets containing different levels of protein on liver glutamate dehydrogenase (GDH), alanine aminotransferase (AAT) and histidase activities; (2) dietary protein level on the oxidation rates of glutamate and phenylalanine in vivo; and ( 3 ) dietary phenylalanine level on the phenylalanine oxidation rate in vivo. Activities of GDH and AAT per g liver or per g protein were higher (P The oxidation rates of dietary glutamate and phenylalanine in trout that had previously been fed the 35% protein diet, were about three and five times those found in fish previously fed the 10% protein diet, respectively. This difference was found when fish that had been fed the 10 or 35% protein diet were subsequently fed the 35% protein diet containing14C-labeled glutamate or phenylalanine, indicating that trout previously fed a high protein diet have a greater capacity to catabolize these amino acids. The oxidation rate of dietary glutamate was approximately five or nine times that of phenylalanine in trout fed diets containing 35 or 10% protein, respectively. The rate of phenylalanine oxidation increased with increasing phenylalanine levels in the diet; no break point or plateau in the dose-response curve was observed. Our studies demonstrated that fasting or feeding a high protein diet increases the amino acid catabolism in trout, and suggested that the amino acid oxidation technique cannot be used to determine the amino acid requirements of trout.

The influence of triploidy and heat and hydrostatic pressure shocks on the growth and reproductive development of juvenile yellow perch (Perca jlavescens)

Abstract We evaluated triploidy induction as a means to sterilize yellow perch (Perca flavescens) and reduce the diminution of growth associated with the onset of sexual maturation. Treatment of perch eggs with heat shocks (28–30°C, for durations of 10–25 min, beginning at 2–5 min post-fertilization) or hydrostatic pressure shocks (9000 or 11 000 psi, for durations of 8 or 12 min, beginning at 5 min post-fertilization) resulted in triploidy induction rates of 30–70%. In one experiment, juvenile heatshocked triploid perch grew faster than heat-shocked diploids. In a second experiment, heat-shocked triploid perch grew slower than unshocked diploids up to 25 g, but subsequent growth of fish from the two groups was not different. In a third experiment, unshocked diploids grew faster than fish subjected to either heat or pressure shocks, and among shocked fish, triploids outgrew diploids. Histological inspections revealed that gonadal development of juvenile triploid perch of both sexes was retarded compared to that of diploids. These findings show that heat and pressure shocks exert a negative influence on growth that is independent of changes in ploidy, and that triploid perch may have the potential to outgrow diploids if the negative effects of such shocks can be avoided.

Manipulation of ploidy in yellow perch (Perca flavescens) by heat shock, hydrostatic pressure shock, and spermatozoa inactivation

Abstract Heat shocks, hydrostatic pressure shocks, and ultraviolet radiation were evaluated for their efficacy as methods of manipulating ploidy in yellow perch (Perca flavescens). The most effective methods of inducing triploidy were heat shocks of 28–30°C applied at a time of initiation (TI) of 5 min postfertilization for durations of 10 or 25 min, and hydrostatic pressure shocks of 9000 or 11 000 psi applied at a TI of 5 min for a duration of 12 min. These treatments resulted in triploidy induction rates that ranged from 54–100%, and embryonic survival rates of 16–80%. Cold shocks of 0°C had no effect on the ploidy or survival of embryos. For perch, hydrostatic pressure shock offered several advantages over heat shock as a method of manipulating ploidy. The most effective methods of inducing tetraploidy were hydrostatic pressure shocks of 9000 psi applied at a TI of 192 min for durations of 16 or 24 min. Ultraviolet radiation of perch sperm with doses of 3240–6480 ergs/mm2 resulted in 100% inactivation of paternal chromosomes, and perch eggs fertilized with inactivated sperm had survival rates of > 50%, thereby establishing methods for producing gynogenetic perch. Studies comparing the growth and performance of diploid vs. triploid perch are underway. Tetraploid perch are being reared to sexual maturity to evaluate their potential as brood fish.

Effects of dietary tryptophan levels on growth, feed/gain, carcass composition and liver glutamate dehydrogenase activity in rainbow trout (Salmo gairdneri)

1. The tryptophan requirement of rainbow trout (initial body wt, 13 g) was estimated by feeding diets containing varied levels of tryptophan from 0.06 to 0.5% of diet for 6 weeks. 2. The estimated tryptophan requirement was 0.20-0.25 (0.57-0.71)% of diet (dietary proteins). 3. Nitrogen retention increased and feed/gain decreased with dietary tryptophan levels up to 0.14%, but no further effect was observed at levels above 0.14%. 4. Carcass protein content gradually increased and lipid and ash contents decreased with increasing dietary tryptophan levels. 5. Dietary tryptophan levels did not affect hepatosomatic index or liver glutamate dehydrogenase activity.

Effects of temperature on hypophyseal (growth hormone) regulation of length, weight, and allometric growth and total lipid and water concentrations in the black bullhead (Ictalurus melas)

Abstract The effects of temperature on the somatotropic function of the pituitary gland were studied in the bullhead ( Ictalurus melas ) by comparing the 16-day length, weight, and allometric growth responses at 12, 18, 24, and 29° of hypophysectomized and sham-hypophysectomized fish versus those of hypophysectomized fish injected with beef growth hormone (bGH). In an experiment beginning 6 days after surgery, hypophysectomized, saline-injected bullheads gained small but significant length increments at 18°, but not 12, 24, or 29°: mean total weights increased 9 to 18%, regardless of temperature. Beef GH (1.0 μg/g body weight, every second day) stimulated length increases of 4.93, 7.13, and 6.51% at 18, 24, and 29°, respectively: weight gains of 49 to 53% were made at all three temperatures. Under similar conditions, sham-hypophysectomized, saline-injected fish added length increments of 3.92, 5.64, 3.42% and weight increments of 24 to 28%. Sham-operated bullheads grew little at 12°; GH-treated animals gained weight (20%) but not length. After 16 days of treatment at a given temperature, relative morphometry and total lipid and water concentrations were generally the same in hypophysectomized and sham-operated control groups. Growth hormone, especially at 18°, caused splanchnomegaly of the nonhepatic viscera and stimulated increases in ponderal condition, relative somatic muscle and skeletal mass, and morphometric indexes of body depth and width. In the same animals, tissue water concentrations, measured only at 18 and 24°, were increased: total lipids were decreased at 18° but not 24°. Growth hormone at 12, 18, and 24° slowed the allometric enlargement of the liver caused by hypophysectomy. Arguments are made that temperature may influence rates of pituitary growth-regulating hormone synthesis, secretion, and turnover, as well as alter levels of tissue responsiveness, and that the growth rates or patterns of individual tissues, organs, and body parts may be differentially influenced by variations in their thermalhormonal environment.