Winter Feeding of Catfish
Carole Engle and Adam Nanninga

A second winter feeding study was conducted in 2007, with treatments of feeding or not feeding according to standard winter feeding recommendations.  Ponds were stocked at 3,512 lb/ac with fish ranging in size from 0.2 to 5.9 lb.  Fish in both treatment and control ponds lost weight over the winter.  However, ponds that were fed lost significantly less weight than those that were not fed.  Larger fish (over 1 lb) had a statistically similar average weight while smaller fish (less than 1 lb) that were fed over the winter were significantly larger than those that were not fed.  There were no differences in water quality.  A partial budget showed that feeding over the winter resulted in losing $112/acre less than not feeding.  This second winter trial confirmed that additional work on winter feeding is needed, particularly with multiple-batch fish populations to prevent losses over this 5-month period.  The winter feeding studies demonstrated a clear need for improved feeding recommendations for the months of November through March. 

The Effect of Varying Quantities of Large Carryover Catfish on Growth of Understocked Fingerlings
Carole Engle and Adam Nanninga

The majority of channel catfish production in the US is produced in multiple batch.  Southworth et. al. (2006) found that varying stocking density of fingerlings in multiple-batch systems had little effect on production efficiency and water quality.  This study was designed to evaluate the effect of varying amounts of large carryover catfish on the growth of understocked fingerlings.  Twelve 0.25 acre ponds were stocked in April of 2007 with 6,000 fingerlings per acre.  Treatments were based on carryover stocking density with ponds receiving either 650 lb/ac, 1,300 lb/ac, or 1,950 lb/ac.  Ponds were harvested completely in November 2007.  Fingerlings stocked in the lower density ponds grew to a larger average weight than in the higher density treatments.  No difference was found in net yield of fingerlings.  Survival of fingerlings was low across all treatments.  This study provides a measure of the effect on understocked fingerlings of different weights of larger fish in the pond. 

Effect of Aeration Rates on the Production and Profit of Catfish in Commercial Growout Ponds.
Steeve Pomerleau and Carole Engle

A total of 6 commercial catfish ponds with fixed electric paddlewheel aeration rates ranging from 1.5 to 3.5 hp/ac have been monitored since March 2007. The fish inventory has been assessed in March by seining each pond twice with a small mesh fingerling seine. All harvested fish were weighed back into the pond with a hydraulic boom and random samples of fish were individually weighed. Total ammonia nitrogen, nitrite, and pH were measured weekly. Temperature and dissolved oxygen levels were recorded 24 hours a day with commercial DO monitoring buoys. Before the beginning of the 2008 growing season, the total fish inventory in those ponds will be assessed to accurately estimate annual yields, survival, and feed conversion ratios. The study will continue in 2008 with a total of twelve ponds on two farms. 

Optimizing Techniques for Artificial Spawning of Catfish
Alf Haukenes

Artificial spawning and out of season spawning in catfish are techniques being explored to enhance the production of hybrid catfish (blue catfish- channel catfish) fingerlings. Experiments conducted in 2007 in indoor wet laboratory facilities at UAPB evaluated implants designed to slowly release gonadotropin releasing hormones to foster a more synchronized artificial spawning schedule.  Plasma samples were collected during the course of this experimentation and will be assayed for steroid hormones to characterize differences between ovulating female catfish versus those that did not any yield eggs to better understand the mechanisms of final maturation of eggs and lead towards the recognition of a more optimal window for scheduling hormone treatments.  Field trials were also performed on a commercial catfish hatchery comparing two hormone approaches to induce spawning.   

Effect of Soybean Oil, Menhaden Oil, and Flaxseed Oil Supplements in Finishing Diets on the Growth, Feed Utilization, Health, Liver and Ovarian Lipid Composition of Food-Size Channel Catfish Reared at 22ºC.
Rebecca Lochmann, Todd Sink, and Harold Phillips

We conducted a feeding trial to determine the effects of different supplemental lipids on performance of channel catfish grown from 0.8 lbs to market size (1.25 lbs = 0.57 kg) at 22^oC. Ten catfish were stocked into each of four 1140-L tanks in one of 3 independent recirculating systems. Fish were fed a 32%-protein commercial floating pellet top-dressed with 2% soybean oil (SBO), menhaden oil (MFO), or flaxseed oil (FLX) once daily to satiation for 8 weeks. Weight gain was highest in fish fed the FLX diet, and there were no differences in feed conversion ratio (FCR) or survival among treatments. The HSI was higher in fish fed the MFO vs the FLX diet. Alternative complement activity was higher in fish fed the SBO vs the MFO diet, but lysozyme did not differ by diet. 

Effects of Dietary Lipid Source and Concentration on Channel Catfish (Ictalurus punctatus) Egg Biochemical Composition, Egg and Fry Production, and Egg and Fry Quality
Todd Sink and Rebecca Lochmann

The objective was to determine the effects of lipid source (poultry fat or menhaden fish oil) and concentration (4 or 10% lipid supplementation) in channel catfish broodstock diets on subsequent egg biochemical composition, egg production, and egg and fry quality. Three-year-old USDA-103 strain broodfish were stocked into outdoor tanks and fed diets with 4- or 10% added fish oil or poultry fat. The diet with 10% added fish oil (10FO) produced superior results including increased spawning success, fecundity, total egg volume (matrix removed), individual egg weight, eggs·spawn-1 (volumetric), total egg lipid concentration, total n-3 fatty acids, total n-3 HUFAs, n-3: n-6 ratio, hatching success, and fry survival compared to the control (4FO) diet. 

The Effects of Grobiotic-A on the Growth and Health of Channel Catfish Fry in Aquaria
Miles Thompson, Rebecca Lochmann, and Todd Sink

We conducted a 12-week feeding trial to determine the effects of Grobiotic-A, a dairy/yeast prebiotic, on channel catfish fry (0.4 g initially). The basal diet was a commercially available 36%-protein extruded pellet with 2% cellulose (control) or prebiotic. Each diet was fed to groups of 40 channel catfish fry stocked in each of five replicate 110-L tanks per treatment in a flow-through system twice daily to satiation. All fish achieved 1900% or greater increase in growth by the end of the trial, but there were no differences in average individual weight gain, feed conversion ratio, survival, or non-specific immune responses of fish between diets. Fish exposed to E. ictaluri showed almost no mortality, and antibody titers showed prior exposure to E. ictaluri. Therefore, the trial will be repeated with naïve fry. 

Growth and Survival of Channel Catfish Ictalurus punctatus Fry Fed Diets with 36 or 45% Total Protein and All-Plant or Animal-Protein Sources
Todd Sink, Rebecca Lochmann, and Nicholas Kinsey

The objective was to compare the effects of 36 and 45% animal-protein diets and 36 and 45% all-plant-protein diets on catfish fry growth and survival. Experimental diets were formulated to contain: 36% all-plant protein (primarily from soybean meal); 36% animal and plant protein (≥ 45% of crude protein as fish meal); 45% all-plant protein (primarily from soy protein concentrate and soybean meal); and 45% animal and plant protein (≥ 60% of crude protein as fish meal). Fish were fed at 20% of body weight daily for 28 days using 24-hour automated feeders. Mean final lengths, weights and survival were not significantly different among diets. Growth is not limited in channel catfish fry fed all-plant protein diets, and that there is no apparent advantage to the inclusion of animal protein in the diet.