Feed Efficiency Of Fish Research Articles

Influence of low dietary cholecalciferol intake on phosphorus and trace element metabolism by rainbow trout ( Oncorhynchus mykiss, Walbaum)

A study was conducted to investigate the relationship between dietary cholecalciferol and phosphorus (P) metabolism in rainbow trout ( Oncorhynchus mykiss). Triplicate groups of rainbow trout fingerlings, initial weight 12.4±0.7 g, were fed to satiation one of four semipurified diets containing either 3.2 or 5.6 g kg −1 P and either 100 or 2600 IU kg −1 cholecalciferol in a 2×2 factorial design. The fish were reared in freshwater for 20 weeks on a 12 h photoperiod regime without exposure to UV-radiation. Growth and feed efficiency of fish were not influenced by dietary cholecalciferol and P levels. Fish fed the diet containing 3.2 g P kg −1 exhibited poor bone mineralization, low plasma phosphate level and reduced carcass P concentration. The low level of dietary vitamin D 3 (100 IU kg −1) significantly improved bone mineralization. Liver cholecalciferol concentration was higher (4.9 vs 9 ng g −1) at 2600 IU kg −1 cholecalciferol but dietary P had no effect on the liver content of this vitamin. Higher dietary P significantly increased urine P concentration whereas dietary cholecalciferol level had no effect. Dietary P supplementation increased body ash, Ca and P but Mg and Mn levels decreased significantly. Although cholecalciferol supplementation increased Mn deposition, carcass Zn content decreased. While tripling in weight during the trial, rainbow trout reared in freshwater effectively utilized phosphorus from a low-cholecalciferol diet.

Utilization of Malt Protein Flour in Fingerling Rainbow Trout Diets

Two feeding experiments were conducted to evaluate malt protein flour (MPF) as an alternative protein source for the diet of rainbow trout Oncorhynchus mykiss fingerlings. MPF is a new protein rich by-product from brewer's spent grain. Experiment 1 was conducted to clarify the suitable substitution level of MPF for white fish meal (WFM) in the diet. The control diet, containing WFM as the sole protein source, and isonitrogenous (40% crude protein) experimental diets, containing MPF substituted for 20 to 80% of WFM protein, were fed to fish with an average initial weight of 10g for 6 weeks. Weight gain and feed efficiency in fish fed the diet substituting MPF up to the 60% level were not different (p>0.05) from those in fish fed the control diet. There were no significant differences in protein and energy retention between 0 to 40% substitution level. In Experiment 2, crystalline essential amino acids (EAA) were supplemented in the diets containing MPF to simulate the EAA composition in the control diet. Consequently, no significant differences were detected in protein and energy retention between 0 to 60% substitution level. Thus, these results suggest that MPF is a promising alternative protein source for the diet of fingerling rainbow trout.

Total sulfur amino acid requirement of juvenile hybrid striped bass ( Morone chrysops×M. saxatilis)

Two separate feeding trials were conducted to determine the total sulfur amino acid requirement of hybrid striped bass. Semipurified diets containing 35% crude protein from fish muscle and crystalline amino acids were supplemented with graded levels of methionine. Each diet was fed to juvenile fish in triplicate aquaria receiving freshwater for 8 weeks. Fish fed the basal diet which contained 0.38% methionine and 0.13% cystine experienced complete mortality within 1 week. Prior to death, some fish fed inadequate methionine were observed to have bilateral cataracts. Weight gain and feed efficiency of fish were significantly ( P<0.01) affected by supplemental methionine. Regression analysis of weight gain data using the broken-line model indicated a total sulfur amino acid requirement (±s.e.) of 1.0% (±0.02%) of dry diet or 2.9% of dietary protein.

Three Types of Catfish Offal Meals for Channel Catfish Fingerlings

Abstract The use of three different types of catfish offal meals by fingerling channel catfish (Ictalurus punctatus) was investigated. These included: an experimentally produced formic acid catfish offal silage; a commercially produced catfish offal meal prepared by the conventional rendering process; and a commercially produced catfish offal protein hydrolysate. There was no significant difference in growth rate, protein efficiency ratio, or feed efficiency of fish fed either the catfish offal meal produced by rendering or menhaden fish meal. Fish fed either the formic acid catfish offal silage or the catfish offal protein hydrolysate had a significantly lower growth rate, protein efficiency ratio, and feed efficiency than fish fed menhaden fish meal. The decreased performance of the catfish offal protein hydrolysate could be attributed to a marginal or slightly deficient presence of certain amino acids. It is unclear what factors in the formic acid catfish offal silage may have inhibited its use; the re...