Gary Reinitz

Relative effect of age, diet, and feeding rate on the body composition of young rainbow trout (Salmo gairdneri)

Abstract Rainbow trout with an initial weight of 2.1 g were fed two experimental diets at three feeding rates for 308 days, or starved for 140 days. Previous nutritional history (diet and feeding rate) and fish size (individual weight) were observed to be the primary determinants of percent protein, fat, ash, or moisture in the carcasses of nonstarving fish. Age could not be identified as a primary factor in determing body composition. Both protein and fat were catabolized for energy by starving fish but the depletion of body fat was much more rapid and severe. Increasing the rate of feeding increased protein and fat (%) and decreased moisture and ash (%) in fish carcasses. Diet affected the percent of fat and moisture but not protein or ash in fish carcasses. An increase in dietary fat and protein (%) resulted in a decrease in moisture (%) and an increase in fat (%) in fish carcasses.

Formulation of practical diets for rainbow trout based on desired performance and body composition

Abstract Rainbow trout ( Salmo gairdneri ) with an initial average weight of 1.8 g were fed eight experimental diets with 26 and 35% protein and varying amounts of lipid for 112 days. All experimental diets contained 10% fish meal (the only source of animal protein), as compared to a control diet with 35% fish meal. The energy content of the diet was the most important factor in determining growth rate. The percentage of dietary lipid was the dominant factor in determining the body composition of rainbow trout. Increased amounts of dietary lipid resulted in fish with increased amounts of whole-body fat and reduced amounts of whole-body protein and moisture. Body composition was more closely a function of nutritional history than of fish size. Protein retention and energy retention were negatively associated with the percentage of digestible protein in the diet. Mortality rates did not differ significantly among the groups tested; the general health of all fish examined was good.

Influence of Varying Lipid Concentrations with Two Protein Concentrations in Diets for Rainbow Trout (Salmo gairdneri)

Abstract The sparing action of dietary lipids on protein observed in rainbow trout was demonstrated in practical trout diets. The digestible energy content of a diet in relation to the percent of dietary protein (DE/P ratio) can be a determining factor in the protein requirements of rainbow trout. The DE/P ratio of the diet was positively correlated with protein retained (%) by the fish but with no other factors measured in this study. Growth, feed conversion, and daily length increment were all correlated with the energy content of the diet. Increased amounts of digestible energy in the diet also enhanced the efficient use of that energy. Diets containing high percentages of fat produced fatter fish with lower percentages of protein.

Effects of dietary lipids on growth and fatty acid composition of rainbow trout (Salmo gairdneri)

Abstract No adverse effects resulted from the partial replacement of either soy oil or fish oil with animal fat in diets fed to rainbow trout held for 182 days at 11°C. The influence of fatty acid composition of dietary lipids on growth in rainbow trout appears to be secondary to other dietary factors, providing the diet contains the required amounts of essential fatty acids. The fatty acid composition of carcass lipids reflects that of dietary lipids.

Soybean Meal as a Substitute for Herring Meal in Practical Diets for Rainbow Trout

Abstract Juvenile rainbow trout (Salmo gairdneri) were fed six diets containing different percentages of soybean meal as a replacement for herring meal for a 168-day period. Fish fed a diet with 65% soybean meal and no herring meal grew at an acceptable rate and remained in good health. Weight gain offish fed a diet with 5% herring meal and 56% soybean meal was not significantly different from that of fish fed a diet with 20% herring meal and 31% soybean meal. Protein retention, energy retention, percentage mortality, and whole-body composition (crude fat excepted) did not vary significantly among fish fed the various diets.

Variations of Body Composition and Growth among Strains of Rainbow Trout

Abstract Fish from six strains of rainbow trout (Salmo gairdneri) were fed the starter diet SD7 until reaching an average weight of 1.5 g. In the second segment of this trial, 1.5-g fish from the six strains were fed the experimental diet X263 for 180 days. At the end of both trial segments, body composition varied significantly among strains of fish. After 180 days of diet X263, growth and feed conversion also differed significantly among strains. Changes in body composition averaged for all strains combined after 180 days of the diet X263 were as follows: crude protein decreased 8.2%; moisture decreased 5.7%; ash increased 6.2%. Data from the first segment of this trial give the strongest support to the hypothesis that variations of body composition of rainbow trout are influenced by genotype.

Differential Performance of Four Strains of Rainbow Trout Reared under Standardized Conditions

Abstract Four strains of rainbow trout were evaluated for average weight gain, feed conversion, daily length increment, and percent mortality. Significant differences were found to exist between certain strains for all characteristics measured. The rank of the four strains in rate of growth was the same whether the fish were fed a diet high in plant protein or high in animal protein, suggesting that genetically distinct strains of rainbow trout may exhibit the same relative growth rates, irrespective of diet.

Influence of Diet and Feeding Rate on the Performance and Production Cost of Rainbow Trout

Abstract Rainbow trout Salmo gairdneri with an initial weight of 2.1 g were fed a high-protein, high-fat diet or a low-protein, low-fat diet at three feeding rates (based on hatchery constants of 10, 20, or 30) for 308 days. The high-protein, high-fat diet fed at the intermediate rate yielded the optimum combination of fish growth, condition, and dress-out weight with feed efficiency and unit cost. Diet affected the composition of fish carcasses: As the percent of dietary fat and protein increased, the percent of moisture decreased and the percent of fat increased; as feeding rate increased, the percent of protein and fat increased and the percent of moisture and ash decreased. Received January 3, 1983 Accepted August 2, 1983

Effect on tricaine methanesulfonate (MS-222) on hematocrit values in rainbow trout (Salmo gairdneri)

1. Anesthesia of rainbow trout (Salmo gairdneri) with 70 ppm tricaine methanesulfonate (MS-222) for 3–9 min resulted in a linear increase in hematocrit. 2. Handling of unanesthetized trout caused a higher and more variable hematocrit reading than did exposure to MS-222 for up to 3 min. 3. The range and standard error of hematocrit readings was smallest in trout treated with MS-222 for 1 min.

The Effect of Nutrient Dilution with Sodium Bentonite in Practical Diets for Rainbow Trout

Abstract Rainbow trout (Salmo gairdneri) with a mean initial weight of 18.8 g (0.041 lb) were fed one of two experimental diets (29.2% protein or 38.5% protein), or the 38.5% protein diet plus 5%, 10%, or 15% sodium bentonite, for 196 days. The addition of sodium bentonite to the 38.5% protein diet reduced weight gain and increased the unit cost of fish produced. Metabolizable energy content of the diet was a primary factor in determining growth rate. As the percent of dietary lipid increased, the percent of fat in fish carcasses increased and the percent of moisture decreased. Kidney tubules from 5 of 10 fish fed the diet with 15% sodium bentonite showed extreme epithelial swelling and dialation along with cytoplasmic degeneration and renal casts apparent in some tubule lumens.