Ann L. Gannam

Use of hempseed meal, poultry by-product meal, and canola meal in practical diets without fish meal for sunshine bass (Morone chrysops×M. saxatilis)

In an effort to reduce fish meal FM use in diets for sunshine bass, a feeding trial was conducted. Four practical floating diets were formulated to contain 40% protein, similar energy levels, and without FM. A fifth diet was formulated to contain 30% FM and served as the control diet. Ten fish were stocked into each of 20 110-l aquaria and were fed twice daily 0730 and 1600 . h amounts of diet similar to that of the aquarium consuming the most diet at that feeding. Diets .

Comparison and Validation of Nonlethal Techniques for Estimating Condition in Juvenile Salmonids

Abstract Fish proximate composition influences growth, reproduction, and survival and is commonly used to determine physiological condition; however, proximate composition is time-consuming to measure and typically requires a lethal sample that cannot be analyzed in situ. As a result, researchers are increasingly interested in using nonlethal techniques that are quicker and less expensive to estimate proximate body components in fish. Bioelectrical impedance analysis (BIA) and microwave energy meters have been used with success on large-bodied fishes, although no evaluation on small-bodied Pacific salmon Oncorhynchus spp. has been conducted. We evaluated three nonlethal techniques (BIA, energy meter, and condition factor) as predictors of individual body composition (determined through lethal whole-body proximate analysis) in juvenile hatchery steelhead O. mykiss (minimum fork length = 138 mm; minimum wet mass = 24.5 g). The BIA values were positively correlated with measured total body water (R 2 = 0.77)...

Use of Size for Early Detection of Juvenile Hatchery Steelhead Destined to Be Precocious Males

Abstract At two Washington State hatcheries in August 1999–2002, juvenile steelhead Oncorhynchus mykiss were size-graded and the largest fish (4.8–9.2% of the population) were coded-wire-tagged and mixed with small fish to determine whether the large fish were those that became precocious males. The results showed that the large fish in August at Merwin Hatchery tended to become precocious, although the mean lengths of the precocious and nonprecocious fish were similar at their time of release in April. At Abernathy Fish Technology Center (FTC), the large fish in August did not disproportionately become precocious, and the nonprecocious fish were significantly larger than the precocious fish at release. We suggest that precocious fish at Abernathy FTC may have committed to precocity before August whereas fish at Merwin Hatchery committed to precocity in August. Because only 0.82% of the large fish became precocious, removing the 5–10% largest fish in August at the Merwin Hatchery would be marginally succe...

Appetite of chinook salmon (Oncorhynchus tshawytscha) naturally infected with bacterial kidney disease

We evaluated the use of feed restriction to decrease mortality and infection rates in yearling chinook salmon (Oncorhynchus tshawytscha) naturally infected with Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD). Fish were purposely stressed and then fed either full ration, half ration, or fasted. At the termination of the 6-week experiment, feed intake of the fish was evaluated by X-radiography after feeding all groups in excess and the amount of BKD p57 antigen in the kidneys was measured by enzyme linked immonosorbent assay (ELISA) to assess effects of infection on feeding rates. Only a few individuals in each treatment died during the experiment, but the proportion of fish with detectable antigen concentration increased as ration level decreased. Within each treatment, fish with undetectable concentrations of p57 antigen ate significantly more than fish with elevated antigen levels. Exponential regressions were fitted for each ration level describing the decrease of appetite as levels of antigen concentrations increased. The data indicate that even fish that were quite sick as judged from their relatively high antigen concentrations can still feed and that previous food shortage can increase the feed intake to some extent in the sick fish.

Effects on growth performance and body composition in Nile tilapia, Oreochromis niloticus, fry fed organic diets containing yeast extract and soyabean meal as a total replacement of fish meal without amino acid supplementation

Fish meal (FM) is the main protein source in aquaculture diets owing to its palatability and quality. Available quantities of FM have remained constant for the past several decades; however, demand has dramatically increased due to its inclusion in diets used for the global aquaculture industry. There are various alternative protein sources that can be used in aquaculture diets, with soyabean meal (SBM) being the most widely used plant protein ingredient; however, use of SBM as the sole protein source has often resulted in reduced fish growth. There is a growing segment of consumers who desire organically grown foods, and since Nile tilapia is one of the most-cultured fish in the world and has herbivorous/omnivorous feeding habits, Nile tilapia fed an organic diet may allow producers to enter this rapidly developing market. A feeding experiment was conducted to evaluate the combination of organic SBM and an organic yeast extract (YE) as complete replacements for FM. Five isonitrogenous, isocaloric diets were fed to small (0.1 g) Nile tilapia, Oreochromis niloticus, for 6 weeks. Diets contained various percentages (0%, 10%, 20%, 30% and 40%) of YE, with Diet 1 formulated to be similar to a high-quality commercial diet containing 0% YE and 20% FM. At the conclusion of the feeding trial, fish fed Diet 1 had statistically significantly (p < 0.05) higher mean final weight (3.99 g) and specific growth rate (8.48% day− 1), and a lower feed conversion ratio (1.40) than fish fed all other diets. Based upon the data, an organic diet which replaces FM with a combination of SBM and YE appears promising but further research is needed to refine formulation so as to have similar growth performance with a FM-based diet.

Inability to Control Ceratomyxosis in Rainbow Trout and Steelhead with Oral Treatments of Glucan Immunostimulant or the Fumagillin Analog TNP-470

Abstract Two oral treatments were tested for their ability to protect migratory hatchery salmonids against infection by the myxozoan parasite Ceratomyxa shasta. Rainbow trout Oncorhynchus mykiss and steelhead (anadromous rainbow trout) were fed a diet containing either the immunomodulatory compound MacroGard (a glucan from yeast) or the antiparasitic drug fumagillin (from Aspergillus fumigatus). MacroGard was administered in the feed at 2% and 4% of the diet. At the 2% level, the fish were either fed for 14 d before the exposure to the parasite or for 14 d before and after exposure; at the 4% level, the drug was administered for 14 d before the challenge. Fumagillin analog TNP-470 was top-coated on the feed to achieve a dose of 3 or 10 mg × kg fish–1 × d–1. The lower dose was administered for 14 d before exposure or for 14 d before and after exposure; fish given the higher dose were fed the drug only prior to exposure. When administered at 2%, MacroGard significantly increased the mean time to death; howe...

Inhibitory Effects of Rosemary Oil on the In Vitro Growth of Six Common Finfish Pathogens

Abstract Additives are commonly used in feed to enhance fish performance, health, and well-being. In recent years, antibiotics have received increased scrutiny owing to concerns about overuse and their environmental impact. These concerns have generated a desire for naturally derived alternatives for the aquafeed industry. For screening purposes, we examined the in vitro effects of an essential oil on bacteria commonly associated with fish diseases. Six concentrations of rosemary Rosmarinus officinalis oil (0.1, 0.3, 0.5, 0.7, and 0.9 μL/μL of 1% Tween-20 and pure rosemary oil [1.0]) were used against Flavobacterium psychrophilum, Yersinia ruckeri, Aeromonas salmonicida, and three warmwater bacterial pathogens, A. hydrophila, Edwardsiella ictaluri, and E. tarda, along with a control treatment (1% Tween-20 only). After incubation, the mean zone of inhibition around the disks was measured. While most concentrations were found to inhibit pathogen growth, a concentration of 50% or more was found to have signi...

Altered Growth Rates, Carcass Fatty Acid Concentrations, and Tissue Histology in First-Feeding Steelhead Fed a Fish-Meal- and Fish-Oil-Free Diet

Abstract A 12-week feeding trial was conducted to evaluate a fish-meal-free, fish-oil-free diet for use with first-feeding steelhead Oncorhynchus mykiss. The marine-based control diet (marine diet) contained sardine (Sardinops spp.) meal and pollock (Pollachius virens) liver oil as the primary sources of protein and lipid, respectively. The experimental diet (terrestrial diet) contained only terrestrial sources of protein (poultry by-product meal, blood meal, canola, corn gluten, and wheat gluten) and lipid (canola oil and flaxseed oil). Each diet was administered to five replicate groups of first-feeding fry. At the conclusion of the feeding trial, fish that were fed the marine diet exhibited significantly higher weight gain and feed efficiency than fish that were given the terrestrial diet. Survival was not significantly affected by dietary treatment. However, fish that received the terrestrial diet exhibited significantly lower hemoglobin concentration and percent packed cell volume. Histological exami...

Evaluation of Commercial Diets for First-Feeding Spring Chinook Salmon

Abstract In 2006, Bio-Oregon, Inc., the only commercial producer of cold-extruded moist diets (∼20–27% moisture) formulated for salmonids, announced that it would discontinue production of this diet line. One of these diets, BioDiet starter (19.5–21.5% moisture) was the primary feed used in many hatcheries that produce Chinook salmon Oncorhynchus tshawytscha. Thus, a feeding trial was conducted to identify an alternative starter diet for spring Chinook salmon. Five commercial diets were evaluated: Skretting BioVita (<10% moisture), EWOS Micro (<10% moisture), Rangen Starter (<10% moisture), Rangen Soft-Moist (14–17% moisture), and Silver Cup Soft-Moist (<13% moisture). Each dietary treatment was fed to quadruplicate groups of 200 randomly selected first-feeding fry reared in fiberglass tanks. Initial weight of the fish averaged 0.34 g/fish. The flow-through water supply was 12°C throughout the 8-week feeding trial. At the end of the study, fish fed Skretting BioVita exhibited significantly higher (P < 0.0...

Combined effects of diets and temperature on mitochondrial function, growth and nutrient efficiency in rainbow trout (Oncorhynchus mykiss)

A 4×3 factorial experiment was conducted to evaluate the effects of two dietary protein sources (mixed fishmeal/plant protein-, and plant protein- based diet), two dietary lipid levels (10% and 20%) and three water temperatures (10°C, 14°C, and 18°C) on the growth performance, nutrient utilization efficiencies and mitochondrial enzyme complex activities in rainbow trout Oncorhynchus mykiss (average weight±SD, 39.5±5g) over a 180day rearing period. At the end of the experiment, weight gain (WG), condition factor (CF), and feed efficiency (FE) were significantly affected by diet×temperature interaction (P<0.05). Specific growth rate (SGR) was significantly affected by increasing temperature (P<0.05). The plant protein-based diets led to a higher CF than the mixed fishmeal/plant protein-based diets. The protein productive value (PPV), protein efficiency ratio (PER), lipid efficiency ratio, (LER) and lipid productive value (LPV) were all significantly affected by diet×temperature interaction (P<0.05). The diet×temperature interaction also had significant effects on mitochondrial enzyme complexes II, V and citrate synthase in the liver, complexes II and IV in the intestine, and complex IV in the muscle (P<0.05). Temperature had a significant main effect on the activity of the enzymatic complexes I and III in the liver, complex III and citrate synthase in the intestine, and complexes I, II, III, V and citrate synthase in the muscle (P<0.05). Diet had a significant main effect on complexes I and III in the liver, complexes II and III for the intestine and complexes I and II in the muscle (P<0.05). The significant temperature x diet interaction observed has practical ecological implications explicitly demonstrating how changes in temperature regimens as anticipated in the rising global temperature can influence organismal performance in relation to changes in dietary formulations (replacing fishmeal based diet with plant protein based ingredients). To illustrate the practical application of the observations from this study, the most economical and cost effective way to produce rainbow trout would be to use 40/10PP diet at 14°C because fish fed this treatment had a weight gain comparable to that of the fish fed the more expensive experimental diets (40/10 FM/PP, 40/20 FM/PP, and 40/20 PP).