Research Highlights

Aquaculture/Fisheries Center Research Highlights

Nutrition

Practical diet development for largemouth bass
Rebecca Lochmann and Bobban Subhadra

Largemouth bass (LMB) currently receive trout diets that are high in fish meal and oil. These diets are costly to make and ship to Arkansas. It is likely that more economical and environmentally friendly ingredients such as plant and poultry products can be substituted in the diets of the bass without impairing their production. In the latest feeding trial diets using feed-grade poultry meal in place of fish meal (on an equal digestible protein basis) were fed to LMB for 12 weeks. The diets contained the same lipid sources as in the previous trial. Growth and immune response were notably depressed in fish fed the poultry-meal diets compared to a commercial control diet with fish meal. Differences due to lipids were not apparent, and may have been masked by the low growth rate caused by the protein sources. Poultry meal seems to be limited in some essential amino acids and is not equal in quality to fish meal despite its apparent adequacy based on amino acid composition alone. Furthermore, the amount of blood meal that can be used in diets for LMB may be lower in the absence of fish meal.
Nutrition and nutrient utilization in native Peruvian fishes
Rebecca Lochmann and Ruguang Chen

Black pacu (Colossoma macropomum) were fed diets with cooked or uncooked pijuayo, plantain or yucca for 12 weeks. Growth, survival and immune response did not differ among treatments, indicating that these feedstuffs are all suitable energy sources for pacu. There were some diet effects evident in liver glycogen, possibly due to the effects of cooking, but the differences were not reflected in whole-body weight gain or health indices.
The effects of isopropylmethylphosphonic acid on golden shiners
Rebecca Lochmann and Steve Lochmann

There were no differences in liver glycogen of golden shiners exposed to five sublethal concentrations of isopropylmethylphosphonic acid. Depletion of hepatic glycogen can be an indication of energy depletion caused by detoxification processes. This phenomenon did not occur with sublethal expsore to IMPA in golden shiners.
The effects of temperature on performance of fingerling channel catfish fed a 32%-protein diet in a recirculating system.
Rebecca Lochmann, Harold Phillips and Suja Gupta

Catfish fingerlings were fed a standard diet and maintained in water of three different temperatures (22, 27 or 32 C) until they reached ¾ pounds. Weight gain was highest and feed conversion was lowest (1.3) in fish cultured at 27 oC, while mortality was lowest in fish cultured at 32oC . Alternative complement activity was highest in fish cultured at 22oC, while lysozyme was highest in fish cultured at 32oC. Temperature had numerous effects on fish performance when diet was fixed. These effects must be accounted for in future trials where diet composition will be manipulated to establish optimal feeding strategies for different sizes of channel catfish.
The effects of feed additives on performance of fingerling channel catfish
Rebecca Lochmann, Harold Phillips, Troy Davis and Felicia Bearden

Catfish were fed commercial diets that were ground and repelleted with feed additives consisting of prebiotics and/or probiotics. There were no effects on weight gain, survival, feed conversion, water quality or immune responses of fish fed the diets for 8-12 weeks.