Location: Warmwater Aquaculture Research Unit
2016 Annual Report
Objectives
1) Evaluate alternative feedstuffs and optimize feed formulations using traditional and alternative feedstuffs for cost-effective production of catfish, and determine if nutrient requirements differ for hybrid and channel catfish.
Sub-objective 1.1 Evaluate diets using alternative feedstuffs in low-protein diets for pond-raised hybrid catfish.
Sub-objective 1.2 Evaluate fortification of alternative diets with lysine and methionine to improve processing yield of channel catfish.
Sub-objective 1.3 Complete replacement of soybean meal using a combination of lower-cost protein sources for pond-raised hybrid catfish.
Sub-objective 1.4 Evaluate 32% or 36% protein, traditional or alternative feeds for fingerling hybrid catfish.
Sub-objective 1.5 Evaluation of growth and disease resistance of fish fed diets supplemented with taurine.
2) Develop more cost effective feeding and production strategies for hybrid and catfish production.
Sub-objective 2.1 Evaluate effects of maintenance feeding on growth and processing yield of market-size hybrid catfish.
Sub-objective 2.2 Compare hybrid fry production when feeding immediately at stocking with fry fed under an alternative feeding strategy of waiting six weeks before offering commercial diets.
3) Evaluate co-culture of alternative species for effects on water quality, biological control of disease vectors, and supplemental income for catfish producers.
Sub-objective 3.1 Co-culturing redear sunfish with channel catfish under commercial conditions.
Sub-objective 3.2 Extensive production of prawn Macrobrachium rosenbergii in fallow catfish production ponds for crop diversification.
Approach
Three 24% protein diets containing 30, 20, and 15% soybean meal will be compared with a 28% protein control diet. Hybrid catfish fingerlings will be stocked in ponds at 6,000 fish/acre. Each diet will be fed to five replicate ponds. All ponds will be harvested in October/November. A partial budget analysis based on feed and fish prices will be conducted to determine the economic benefit (if any) of using low-protein alternative diets versus the traditional control diet.
This study will evaluate five 28% protein diets fortified with varoious supplements. Experimental design, diet analyses, procedures for stocking, feeding, pond management, data collection and statistical and economic analysis will be the same as described for Sub-objective 1.A.
All soybean meal in hybrid catfish feeds will be replaced with various combinations of cottonseed meal, distiller’s grains with solubles, peanut meal, and porcine meat and bone meal. Pond will be stocked with hybrid catfish fingerlings, and diet analyses, experimental design, procedures for stocking, feeding, pond management, data collection and statistical analysis, and economic analysis will be the same as described for Sub-objective 1.A.
Four thousand small hybrid catfish fingerlings will be stocked into 20 tanks with 200 fish each. Four diets of 32% or 36% protein using either soybean meal or soybean substitutes will be evaluated. Diet, statistical, and economic analysis will be the same as described for Sub-objective 1A.
Growth and disease resistance of juvenile channel catfish will be evaluated in fish fed diets with varying levels of taurine in replicated aquaria.
The proposed study will evaluate effects of no feeding, maintenance feeding, and re-feeding on growth, feed conversion ratio, and processing yield of hybrid catfish. Market-size hybrid catfish (1.5 lb) will be stocked into ponds at the end of May or early June. The experimental design, procedures for stocking, feeding, pond management, data collection and statistical analysis will be the same as described for Sub-objective 1.A.
This study will compare production of hybrid fry fed immediately at stocking in 0.4 ha ponds with that of fry not fed until 6 weeks after stocking.
Four ponds will be stocked with channel catfish (600 fish/pond) and redear sunfish (10 fish/pond); four ponds will be stocked with redear sunfish only (10 fish/pond); four ponds will be stocked with catfish only (600 fish/pond). The study will be repeated yearly with the same stocking rates but with varying fish size. Catfish will be fed and managed according to standard industry practices and cultured through one production season.
Each treatment will consist of 4 replicate ponds to evaluate using hay, planted wheat, or rice as substrates to increase freshwater prawn production. Ponds with no substrate addition will served as controls. Ponds will be stocked with 10,000 prawn/ac. All ponds will be fed range cubes. Prawns will be harvested in the fall. All prawns will be counted and collectively weighed, and production will be compared among the treatments.
Progress Report
Studies were conducted evaluating feeds and feeding practices for hybrid catfish production. Production variables between hybrid catfish (Ictalurus punctatus x I. furcatus) nursery ponds fed immediately after stocking (industry standard) versus delayed feeding after stocking were compared. Nine 0.04 ha ponds were fertilized and stocked with swim-up fry at 10,000/pond (250,000/hectare). Ponds were randomly assigned to the standard feeding protocol or the delayed feeding protocol. At 2 weeks (wk) post-stocking, fish in the delayed feeding treatment were significantly smaller than fish in the standard feeding protocol. Therefore, all ponds began receiving commercial diets after 2 wk. At 2 wk post-stocking and continuing through 5 wk post-stocking, average individual fish length and weight was greater in the standard feeding protocol compared to the delayed feeding protocol. At harvest, there were no differences in production variables between the two feeding protocols. Unlike a previous study with channel catfish fry, where feed was withheld for 6 wk without compromising production, noticeable deficiencies in hybrid fry growth were observed after only 2 wk of feed restriction. However, compensatory growth was observed, and restricting feed did not result in differences in production variables observed 6 wk post-stocking. At the feeding rate and prices during this study, we observed feed savings of $38.75/hectare by delaying feeding for 2 wk.
A pond study was initiated to evaluate effects of no feeding, maintenance feeding, and refeeding on production and processing characteristics of market-size hybrid catfish (Ictalurus punctatus × I. furcatus). Fish with an average weight of 644 grams were stocked into 20 earthen ponds (0.04 hectare) at 14,826 fish/hectare at the end of May. They were either not fed, fed once weekly to satiation for two months to simulate a long-term harvest delay, or fed daily to satiation. After two months fish in half the ponds in each of the feed restricted treatments were harvested and those in the remaining ponds were fed daily for an additional month. Fish not fed for two months lost 14.3% weight, compared with a weight gain of 6.7% for fish fed once weekly. Fish not fed or fed once weekly for two months had reduced visceral fat and fillet yield compared with fish fed daily. There were no significant differences in visceral fat percentage and fillet yield between fish not fed and fed once weekly. At the end of three months, there were no significant differences in weight gain, net yield, fillet yield, or visceral fat whether fish were previously not fed or fed once weekly for two months. Fish fed daily for three months had significantly higher visceral fat and marginally higher fillet yield (Probability= 0.08). Feeding once weekly for two months followed by one-month full feeding resulted in significantly higher feed conversion ratio than fish fed daily for three months. Results demonstrate feeding once weekly can generally maintain body weight of hybrid catfish. No feeding or feeding once weekly for two months does not affect survival, but significantly reduces fillet yield. One month of full feeding following no feeding or maintenance feeding improves fillet yield relative to values before refeeding.
Accomplishments
1. Development of cost-effective feeding strategies for hybrid catfish fry. In contrast to channel catfish, hybrid catfish appear to be more aggressive feeders, and fry typically begin consuming a pelleted floating around 2 weeks post stocking. At the time of this study, cost of the 35% protein fry/fingerling dust and minipellets used for the study was $0.62/kilogram. Feed savings by restricting feed during the first 2 weeks came to $1.55/pond or $38.75/hectare. No differences in growth between treatments were observed up to 2 weeks. As a result, it is recommended hybrid fry producers begin offering commercial diets no later than 2 weeks post stocking, to take advantage of the aggressive feeding behavior of these fish and maximize growth. Size difference of both channel catfish fry and hybrid fry begin to occur between restricted feeding ponds and traditional ponds shortly after fish are observed accepting commercial pellets. A possible strategy to mitigate risk involved with yearly variations in zooplankton abundance may be to feed a few randomly selected ponds in the traditional manner. As soon as fry are observed feeding in those ponds, the producer could then begin feeding all ponds.
2. Development of cost-effective feeding strategies to maintain body weight of market-size hybrid catfish during harvest delays. Several circumstances, such as off-flavor, oversupply of fish in the market, or low fish prices, can cause delays in harvesting market-size fish in catfish production. Delays in harvest increases the risk of fish losses and restricts cash flow resulting in diminished production efficiency. Harvest delays can become a serious issue, especially for hybrid catfish, since they feed more aggressively and grow faster than channel catfish. To address this issue, scientists at Mississippi State University at Stoneville, Mississippi examined effects of no feeding, maintenance feeding (feeding once weekly) and refeeding on production and processing characteristics, and fillet proximate composition of market-size hybrid catfish. Results show feeding once weekly can generally maintain fish body weight, and no feeding or feeding once weekly for two months does not affect survival but significantly reduces fillet yield. These data provide catfish producers with information that can be used to minimize production losses in events of long-term harvest delays.
None.
Review Publications
Li, M.H., Robinson, E.H. 2015. Complete feeds-intensive systems. Book Chapter. P. 111-126.
Menghe, L.H., Wise, D.J., Bosworth, B.G., Lucas, P.M., Kingery, K. 2016. Effects of no feeding, maintenance feeding, and refeeding on production and processing characteristics of market-size hybrid catfish. North American Journal of Aquaculture. 78:(3)224-228.
