Research Highlights

Aquaculture/Fisheries Center Research Highlights

Nutrition

Effect of different lipid supplements in practical diets on performance of channel catfish
Rebecca Lochmann

A commercial 32% - protein catfish feed was ground and repelleted with different lipid supplements:

1.) arachidonic acid (ARA), 2.) docosahexaenoic acid (DHA), 3.) a mixture of ARA and DHA (50/50%), or 4.) conjugated linoleic acid (CLA). One additional diet was not supplemented (control). A feeding trial (10 weeks) was conducted in 110-L aquaria in a flow-through system. Each diet was fed to four tanks of eight fish averaging 5.7g initially at a rate of 4-5% divided into two feedings. Fish were weighed every two weeks. At the end of the trial final weights were obtained. Lysosome and alternative complement activity were each measured in four fish per tank (16 individual fish per assay per treatment). Bled fish carcasses were frozen prior to analysis of proximate composition. Average individual weight gain was lower in fish fed the CLA diet than in those fed the control diet or the ARA diet (P=0.08). Fish on the ARA+DHA and DHA diets had intermediate weight gain. Survival ranged from 97-100% and did not differ by treatment. Lysozyme was higher in fish fed diets with DHA or ARA+DHA than in fish fed the ARA diet (P=0.02). Complement activity was not affected by diet. Hepatosomatic index (Liver weight/whole fish weight) was not affected by diet.
Development of larval feeds for golden shiners in ponds
Rebecca Lochmann

We tested diets containing poultry meal versus fish meal+ blood meal (Year 1), and fish meal+poultry meal versus an all plant-protein diet (Year 2) in separate pond studies. Water quality confounded results in Year 1 but production was not reduced by poultry meal compared to fish meal+blood meal. Fry production was similar on an all-plant-protein diet compared to a commercial diet with fish meal+poultry meal. This study ran from 2002-2003.
High-fat feeds for golden shiners in ponds
Rebecca Lochmann

A series of trials has been conducted in ponds and pools looking at regular versus high fat levels and different types of fat (menhaden fish oil or poultry fat). Growth tends to be higher on the regular-fat diet with 28-29% protein, but survival is better on the high-fat diets. Fish fed different types of fat had the same response to a low-temperature stress test (high survival across diets), but fish fed the diet with a high level of menhaden oil survived better than fish fed poultry fat (regular or high level) when exposed to high temperatures. Diets with high fat and protein levels reduced the time needed to achieve 0.5-gram fish by about two weeks.
Nutrition, immunity, economics, and field demonstrations of sunshine bass
Rebecca Lochmann

A series of feeding trials has been conducted in tanks under controlled conditions at the Stuttgart National Aquaculture Research Facility. The fish have received diets with different amylose:amylopectin ratios to try and improve carbohydrate utilization. Growth, survival and body composition data as well as data addressing the cellular impact of these diets was collected. Fish fed glucose had the greatest number of responses that were different from fish fed diets with different ratios of amylose and amylopectin. So far, there is no evidence that manipulating the ratio of amylose to amylopectin will improve carbohydrate utilization in fish, in contrast to mammals.
Practical diet development for largemouth bass lipid components
Rebecca Lochmann

A feeding trial was conducted in tanks under controlled conditions at UAPB. The fish were fed diets with different lipids including fish, poultry and plant sources for 10 weeks. Growth and survival of the fish was the same on all diets regardless of lipid source.
Digestibility of native Peruvian feedstuffs by paco, Piaractus brachypomus
Rebecca Lochmann

Native feedstuffs were obtained from Iquitos, Peru, and processed and incorporated into diets. A new system was built to accommodate the fish, which weigh 2-4 kg each. The fish required a lengthy acclimation period to the new system. We determined that the white tanks were stressful to them but we needed the large tank volume so the fish are being reared in the dark. We also determined that fecal stripping was not an appropriate technique for these fishes. Their digestive tracts are very long and it is not practical to remove large quantities of feces without stressing the fish. They are eating normally now and feces are being collected daily by siphoning. The first in a series of three sequential feeding trials is underway.