Todd D. Sink

Preliminary Observations of Mortality Reduction in Stressed, Flavobacterium columnare–Challenged Golden Shiners after Treatment with a Dairy-Yeast Prebiotic

Abstract We conducted preliminary studies to evaluate the effects of including dairy-yeast prebiotics in the diets of golden shiners Notemigonus crysoleucas with access to natural foods on their resistance to challenge with Flavobacterium columnare. In trial 1, fish were fed either a control diet or a 2% dairy-yeast prebiotic diet for 10 weeks in outdoor pools before challenge. In trial 2, fish fed the experimental diets were either subjected to confinement stress or left unmolested before challenge. Mortality (mean ± SE) was not significantly different in the control diet (23.4 ± 3.4%), the prebiotic diet (10.0 ± 3.3%), and the prebiotic diet with stress (16.7 ± 3.4%) treatments. However, mortality was significantly greater in the control diet with stress treatment (50.0 ± 3.3%) than in the other treatments. This preliminary investigation suggests that prebiotic supplementation in golden shiner feeds before a stressful event would significantly reduce the mortality from F. columnare.

Mortality Rates in Golden Shiners Fed High-Fat Diets with or without a Dairy-Yeast Prebiotic before Challenge with Flavobacterium columnare

Abstract Columnaris, caused by Flavobacterium columnare, is a major bacterial disease of the golden shiner Notemigonus crysoleucas, especially when fish become stressed during handling and transport. Feed additives, such as a dairy-yeast prebiotic, can decrease disease susceptibility in some fish species. Previous studies have indicated that diets with higher fat concentrations have improved the growth and survival of golden shiners. We conducted a study to determine whether a high-fat diet alone or supplemented with a dairy-yeast prebiotic could decrease mortality rates of golden shiners subjected to columnaris challenge. Golden shiners were assigned one of three diets with four replicate aquaria per diet and fed to apparent satiation twice daily for 16 weeks before the challenge. Diets (30.3 ± 0.31% crude protein; mean ± SE) were similar to a commercial formula and contained (1) 4% poultry fat (control), (2) 10% poultry fat, or (3) 10% poultry fat and 2% dairy-yeast prebiotic. After the 16-week feeding ...

Effects of Dietary Lipid Concentration, a Dairy–Yeast Prebiotic, and Fish and Nonfish Protein Sources on Growth, Survival, and Nonspecific Immune Response of Golden Shiners in Indoor Tanks and Outdoor Pools

Abstract We conducted two feeding trials in which golden shiners Notemigonus crysoleucas were given six practical diets: Two basal diets with 5% fish meal and either 4% or 10% supplemental lipid (poultry fat [PF]); two prebiotic diets with 2% dairy–yeast prebiotic, 5% fish meal, and 4% or 10% PF; and two 4% or 10% PF diets that contained no fish meal or prebiotic. To compare diet effects in the presence or absence of natural foods, one trial was conducted in indoor aquaria and one was conducted in outdoor pools. Diet effects were assessed by measuring growth, survival, feed efficiency, and body composition in both trials and Fultons condition factor K in the outdoor pool trial. A subset of fish from the outdoor trial was grown to a larger size for analysis of alternative complement activity (ACH50). The prebiotic enhanced growth and feed conversion ratio (FCR) slightly in the indoor aquarium trial. Weight gain and FCR did not differ among diet groups in the outdoor trial, reflecting the influence of natu...

Clove Oil Used at Lower Concentrations is Less Effective than MS-222 at Reducing Cortisol Stress Responses in Anesthetized Rainbow Trout

Abstract Anesthetics are widely used for surgical, field sampling, and experimental procedures in fisheries sciences. Given the high cost and the U.S. Food and Drug Administrations (FDA) mandatory withdrawal time of the only FDA-approved fisheries anesthetic, tricaine methanesulfonate (MS-222), clove oil has emerged as an alternative anesthetic that is generally regarded as safe. However, studies regarding the effectiveness of clove oil in retarding the stress response of fish are contradictory. This study evaluated the effectiveness of MS-222 (60 mg/L), clove oil (30 mg/L) emulsified in ethanol, and clove oil (30 mg/L) mechanically emulsified in water in reducing the stress response of rainbow trout Oncorhynchus mykiss during a 15-min confinement. Clove oil emulsified in ethanol (mean, 56.3 ng cortisol/mL) was not as effective in reducing the cortisol response as MS-222 (mean, 33.4 ng/mL). Furthermore, clove oil emulsified in ethanol and clove oil mechanically emulsified in water (means, 49.0 and 56.2 n...

Stress Response and Posttransport Survival of Hybrid Striped Bass Transported with or without Clove Oil

Abstract A study was undertaken to determine whether stress responses and associated mortality in hybrid striped bass (white bass Morone chrysops × striped bass M. saxatilis) during and after transport could be mitigated by use of anesthesia with low concentrations of clove oil (10 μL/L of water) during transport. Stress indicators, including plasma cortisol, glucose, chloride (Cl−), sodium (Na+), potassium (K+), and calcium (Ca++) concentrations, were determined for hybrid striped bass sampled (1) initially from ponds, (2) after seining (45 min), (3) immediately after a 3-h transport, and (4) at 24 h posttransport (recovery); these values were compared with those of captive control fish. Fish anesthetized with clove oil during transport exhibited prolonged elevation of cortisol concentrations (124.3 ± 13.2 ng/mL, mean ± SE) at 24 h posttransport, while fish not exposed to anesthetic during transport recovered rapidly (to 34.1 ± 13.3 ng/mL) within 24 h. Plasma glucose concentrations in hybrid striped bass...

Evaluation of a Dietary Dairy―Yeast Prebiotic in Juvenile Golden Shiners in Ponds

Abstract We evaluated the performance in ponds of juvenile golden shiners Notemigonus crysoleucas fed a control diet or a diet with 2% dairy–yeast prebiotic. Fish weighing 0.1 ± 0.001 g (mean ± SD) were initially stocked into five 0.04-ha earthen ponds per diet at 21.9 kg/ha and fed extruded 35%-protein pellets to satiation twice daily. Subsamples of fish were weighed at 2-week intervals for 6 weeks; the fish were harvested at 7 weeks to avoid reproduction. For golden shiners fed the control and prebiotic diets, the mean individual weight gain (2.93 and 2.89 g, respectively), net yield (214.0 and 198.8 kg/ha), feed conversion ratio (1.34 and 1.47), and survival (61.5% and 64.2%) did not differ. Condition index (Fultons K) was higher in fish fed the control (1.15) rather than the prebiotic diet (1.08). After harvest, 100 fish per pond were acclimated to tanks before being subjected to a bacterial challenge with Flavobacterium columnare. Each pond replicate received one of three experimental treatments: co...

Effects of Loading Density on Golden Shiner Survival during and after Hauling

Abstract Four hauling trips of approximately 6 h each were conducted to investigate effects of loading density on survival of golden shiners Notemigonus crysoleucas. Commercially graded golden shiners (mean weight ± SE, 3.3 ± 0.04 g) were transported at densities of 120, 180, and 240 g of fish/L of water in insulated hauling tanks that were filled with fresh well water, chilled with unchlorinated block ice, and aerated with pure oxygen. The criterion for determining success or failure was golden shiner survival. Transportation at a given density was deemed successful if survival both at trips end and at 18 h postdelivery was at least 99%. At all three hauling densities evaluated, survival exceeded 99% both at trips end and at 18 h postdelivery. Furthermore, increasing loading density had no effect on whole-body cortisol concentrations, demonstrating that no significant stress response occurred. Un-ionized ammonia concentration increased with loading density (range, 0.05–0.46 mg/L) but had no effect on f...

Insulin Response of Largemouth Bass to Glucose, Amino Acid, and Diet Stimulation

Abstract Investigation of the dietary requirements of largemouth bass Micropterus salmoides has intensified because of the popularity of this species. To determine commercial diets containing carbohydrate concentrations that are not detrimental to the health and survival of largemouth bass, we examined the effects of carbohydrate loads on insulin response. This study was intended to characterize the insulin response of largemouth bass to diet, glucose, and amino acids. Pellet-trained largemouth bass were either orally stimulated with glucose, lysine, arginine, or methionine or fed a commercial pelleted diet or a “natural” diet of golden shiners Notemigonus crysoleucas, then bled over time to ascertain their insulin response. Insulin response was correlated with glucose response, the insulin responses lagging slightly behind increases in blood glucose concentration. Greater increases in blood glucose were accompanied by sharper, quicker insulin responses. Glucose (4.8 ± 0.3 ng insulin/mL) and arginine (5.4...

A dietary dairy/yeast prebiotic and flaxseed oil enhance growth, hematological and immunological parameters in channel catfish at a suboptimal temperature (15°C).

Channel catfish raised in the southern United States require two growing seasons to reach market size. Growing seasons are separated by a cool period of about 3 months when feed intake and growth are greatly reduced. A cool-weather feeding strategy to improve feed intake, growth or health of catfish might improve survival and reduce the time needed to achieve market size. We conducted a feeding trial with channel catfish at a suboptimal temperature (15°C) to determine the effects of supplementing diets with either a dairy/yeast prebiotic or flaxseed oil (high in 18:3n-3) compared with a control with soybean oil (high in 18:2n-6). The trial was conducted in recirculating systems with 1140-l tanks containing 100 fish each (mean initial weight 61.4 g±0.43 s.e.m.). A 28%-protein basal diet was supplemented with 20 g/kg cellulose and 20 g/kg soybean oil (SBO, control), 20 g/kg cellulose and 20 g/kg flaxseed oil (FLAX) or 20 g/kg of a dairy/yeast prebiotic and 20 g/kg soybean oil (PREB). Fish were fed once daily to satiation and weighed every 3 weeks to track growth. Hematology, non-specific immune responses, proximate and fatty acid composition of muscle were determined to assess diet effects. Catfish-fed FLAX or PREB had higher weight gain, feed consumption and lysozyme activity than fish fed SBO. Total n-3 fatty acids in muscle were higher in fish fed SBO or FLAX than those fed PREB. Total n-6 long-chain polyunsaturated acids were higher in muscle of fish fed PREB than those fed SBO. Fatty acids in the PREB and SBO diets were similar, so the PREB appeared to increase elongation and desaturation of n-6 fatty acids in muscle. Flaxseed oil and the dairy/yeast prebiotic both have potential to increase catfish performance at a low temperature.

Effect of Diets Supplemented with Soybean, Flaxseed, or Menhaden Fish Oil on the Growth, Feed Utilization, Immune Status, and Sensory Properties of Channel Catfish in a Recirculating System at 22°C

Channel catfish feed intake and growth decline with temperature, but different dietary lipids might sustain performance during cool weather. Catfish at a suboptimal temperature (22°C) were fed 32% protein commercial floating pellets supplemented with 2% soybean oil (SBO), menhaden oil (MFO), or flaxseed oil (FLX). After 12 weeks, fish were counted and weighed, then health assays and proximate and fatty acid analysis of fillets were conducted. Weight gain, feed conversion ratio, and survival were similar among treatments, indicating limited potential of different lipids to improve growth at low temperatures. However, the favorable feed conversion ratios (FCRs; ≤1.6) indicated that feeding at 22°C was worthwhile to maintain good condition of catfish. Across diets, the unsaturated fatty acids in muscle lipids increased. The FLX and MFO both increased the n-3 HUFA in the fillet, but FLX was less effective. Unfortunately, both FLX and MFO reduced sensory properties of the fillet relative to the SBO control.