Henryka Dabrowska

Digestion of protein by rainbow trout (Salmo gairdneri Rich.) and absorption of amino acids within the alimentary tract

Abstract 1. 1. The alimentary tract content has been divided into the stomach, pyloric caeca region, the middle intestine and the posterior intestine which was parted into two equal segments. 2. 2. Protein and free amino acids were analysed in digesta of subsequent parts of digestive tract in fish fed three different diets. 3. 3. An indirect method of apparent digestibility was employed to ascertain the absorption site of particular amino acids. 4. 4. A separate trial was performed to determine the metabolic amino acids excretion with the use of non-protein diet. Assuming that traces of amino acids supplied in non-protein diet should be subtracted from the metabolic ones, the metabolic amino acid excretion was calculated for subsequent parts of digestive tract. 5. 5. On the basis of the knowledge of metabolic amino acid excretion, the true digestibility of examined diets was calculated in the parts of digestive tract.

The effect of large doses of vitamin C AND magnesium on stress responses in common carp, Cyprinus carpio

1. Plasma magnesium, cortisol, lactate and ascorbic acid were examined in common carp subjected to various dietary treatments and following handling stress. 2. Under conditions of satisfied dietary magnesium and ascorbate requirements, plasma cortisol concentration after stress increased less pronouncedly than in fish fed large doses of ascorbate and/or magnesium. 3. Plasma lactate increased significantly in all groups after stress, although the increase seemed to be more severe (detrimental) in fish on large doses of ascorbate, either as ascorbic acid (AA) or ascorbic monophosphate Mg salt (AP). 4. Large doses of dietary ascorbate, both AA and AP, resulted in a significant increase of total ascorbate concentration in kidney and hepatopancreas of carp in comparison to pre-experimental level. 5. Kidney total ascorbate concentration decreased by 10-23% in all groups but one in which fish fed diet supplemented with AA displayed a significant increase (30%) of tissue ascorbate. The opposite trend was found in hepatopancreas of AA group with 21.5% ascorbate depletion. 6. The present results suggest that plasma cortisol and kidney (steroidogenesis site) and hepatopancreas ascorbate concentration responses to stress may not be related. Our results also do not support the hypothesis of the primary role of the high concentration of ascorbate in the kidney inhibiting steroidogenesis.

Artificial Diets for Common Carp: Effect of the Addition of Enzyme Extracts

Abstract An experiment on feeding the larvae of carp (Cyprinus carpio) with an artificial diet is described, and 3 previous years of study are briefly summarized. When extracts offish digestive enzymes from hepatopancreas and intestine were added to the diet processed by freeze-drying, growth and survival of the larvae were better than in our previous experiments, but not as good as when the larvae were fed natural food. After 16 days, an increase of 7-10 mg in individual body weight offish was observed and survival was 22-44%.

Prevention of zebra mussel infestation and dispersal during aquaculture operations

Abstract The zebra mussel Dreissena polymorpha, an exotic invasive species, poses a major threat to North American fish management programs and the aquaculture industry. Fish hatcheries may become infected with zebra mussels from a variety of sources, including the water supply, fish shipments, boats, and equipment. The hatcheries could then serve as agents for the overland dispersal of zebra mussels into stocked waters and to other fish hatcheries. We evaluated the effectiveness and safety of aquaculture chemicals for use in controlling zebra mussels in fish hatcheries and preventing dispersal of veligers during fish transport. Chemicals were evaluated for use in fish transport and as disinfectants for ponds and equipment. Standardized static toxicity tests were conducted with representative species of warmwater, coolwater, and coldwater fishes and with larval (3-d-old veligers), early juvenile (settling larvae), and adult zebra mussels. Chemical concentrations and exposure durations were based on recomm...

A study of the feeding of common carp larvae with artificial food

Abstract Common carp larvae were reared on artificial diets from hatching to 25 days old. The main components used in the diets were freeze-dried spleen, fish protein and chicken egg yolk. Free amino acids and bovine trypsin were added and the diet was made alkaline. All diets were gelatinized with agar to give a final dry matter content (15–20%) similar to that of zooplankton. Growth of larvae was negligible but survival was from 11 to 40%. Feeding on days 1, 2 and 3 with zooplankton and subsequently on an artificial diet (40% lyophilised egg yolk, 40% blood meal) showed some improvement both in growth and survival.

Effect of dietary proteins on the free amino acid content in rainbow trout (Salmo gairdneri rich.) muscles

Abstract 1. 1. Groups of rainbow trout were fed for 12 weeks on diets containing different levels of the poultry-by-product meal. Concentration of free amino acids was measured in the latero-dorsal muscle. 2. 2. Despite similar levels of nutritive substances and exogenous amino acids, the diets were characterized by different nutritive values for trout. 3. 3. Patterns of free amino acids in the muscle tissue were different in particular fish groups.

Environmental factors affecting the accumulation of sediment-sorbed hexachlorobiphenyls by channel catfish

Abstract Channel catfish ( Ictalurus punctatus ) fingerlings were used to determine kinetically the accumulation of two symmetrical hexachlorobiphenyl (HCBP) isomers as a function of environmental temperature and sediment organic carbon (OC) content (0.9% and 3.1%). Groups of fish were exposed to each contaminated sediment, spiked with 14 C radiolabelled (2,4,5) 2 or (2,3,5) 2 HCBP (IUPAC No. 153 and 133) for up to 10 days at 13°C or 20°C. The uptake clearance rates ( k 1 ) and elimination rate constants ( k 2 ) were estimated using first-order uptake and elimination models. Temperature was the more influential parameter tested. Both uptake clearance rates and bioaccumulation factors were affected by changing temperature. Increasing temperature from 13°C to 20°C resulted in a 2–4-fold increase of the k 1 , for both isomers. Sediment OC content also affected the k 1 , although to a lesser extent than temperature and not in a consistent way. Bioaccumulation factors estimated for the (2,4,5) 2 isomer of HCBP were generally lower than those for the (2,3,5) 2 HCBP isomer. Increasing temperature and/or sediment OC content resulted in a decrease of the BCFs for (2,3,5) 2 isomer but not for (2,4,5) 2 . These results indicate that environmental hazard may be difficult to predict even when chemicals with similar K ow values are considered.