Geology topics
H. A. Poston
Publications and source records attributed to H. A. Poston.
Factors affecting dietary requirement and deficiency signs of L-tryptophan in rainbow trout
Two experiments were conducted to determine the concentration of dietary tryptophan needed for optimal growth and survival of fingerling rainbow trout ( Salmo gairdneri ), to characterize signs of tryptophan deficiency, and to ascertain the effects of niacin on deficiency signs. Test diets containing either hydrolyzed or intact casein were fed with graded levels of added L-tryptophan (0.0, 0.25, 0.50, 0.75 and 1.0 g/100 g protein). Maximum growth occurred at 0.75 and 0.50 g tryptophan in fish fed hydrolyzed and intact casein, respectively. Changes in mineral and amino acid mixtures in the intact casein diet yielded a cation-anion (Na + K - Cl) balance of + 15.3 meq/100 g diet and pH of 6.44, compared with a balance of -21.3 and -25 meq, and pH 5.8 and 4.4 for unmodified hydrolyzed and intact casein diets, respectively. Analysis of growth by the polynomial regression function; Y = 0.16 + 0.429 X - 0.26 X 2 , where Y = mean daily gain in grams, and X = grams of added tryptophan/100 g protein, predicted that at least 0.58 g of tryptophan was needed for maximum weight gain. Analysis of apparent pathology-free fish by the function; Y = 34.33 + 147.33 X = 83.87 X 2 , where Y = percentage with no signs of deficiency, and X = grams of added tryptophan, predicted that 0.63 g tryptophan/100 g protein was needed for optimum health scores. Deletion of supplemental niacin did not affect fish response to tryptophan.
Effect of population density of lake trout in cylindrical jars on growth and oxygen consumption
Lake trout (Salvelinus namaycush), initial weight 2.25 g, were reared at population densities of 25, 50, 75, 100, and 125 fish in 6.55‐L cylindrical jars for 20 weeks with a mean water flow of 2.45 L/min. All fish survived the experiment. A significant (P < 0.05) reduction in growth occurred between population densities of 25 fish and those of 50 fish or more per jar, but differences among further increases beyond 50 fish were not significant. Total fish weight at the end of 20 weeks ranged progressively upward from 51.5 to 233.9 kg fish/m³ rearing space for fish at population densities of 25 to 125 per jar. Loading values were light at all densities, ranging upward from 0.14 to 0.62 kg fish/L per min flow. Total consumption of oxygen by fish in each jar increased with time (weeks) and population density. Oxygen consumption per unit weight of fish decreased significantly, however, with each successive 25‐fish increase in number of fish per jar. Mean specific gravity of the 25‐fish groups was less than that of fish of the other groups. Differences in population density did not significantly affect water flow rates, feed conversion, or condition factor (K) of the fish. The number of water exchanges per hour, ranging from 23.8 to 29.3 for the 25‐ to 125‐fish densities, tended to increase with each increase in population density.
Biological effects of dietary T-2 toxin on rainbow trout, Salmo gairdneri
A 16-wk feeding study was conducted to evaluate the chronic toxicity of graded levels (0, 1.0, 2.5.5, 10 and 15 mg/kg of chemically pure dietary T-2 toxin (4,15-diacetoxy-8-(3-methylbutyryloxy)-12,13-epoxy-Δ 9 -tricothecen-3-ol) in 1-g rainbow trout, Salmo gairdneri , held in 9°C single-passage well water. Levels of T-2 toxin > 2.5 mg/kg depressed growth, efficiency of feed use, hematocrit, blood hemoglobin concentration and feed acceptance, and caused a transitory edema in a dose-dependent manner. Growth of trout fed a semipurified diet containing the toxin was described by the function: Y = 0.265 + 142.075 e (0.029 X 1 − 1.554x 2 3.7 ), where Y = gain as percentage starting weight per wk; X 1 is time in wk and 0 ⩽ X 1 ⩽16; and X 2 is T-2 content of diet in mg/kgand 0⩽ X 2 ⩽15. Exposure of fish to T-2 toxin did not affect activity of intestinal lumen chymoirypsin or trypsin, nitrogen digestibility or metabolizabte energy. Feeding of 15 mg/kg T-2 toxin to adult trout caused hemorrhaging in the intestines and regurgitation of subsequently intubated feed regardless of T-2 loxin content.
Differentiation of soluble proteins in cataracts caused by deficiencies of methionine, riboflavin or zinc in diets fed to Atlantic salmon, Salmo salar, rainbow trout, Salmo gairdneri, and lake trout, Salvelinus namaycush
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Gross and histological signs of dietary deficiencies of biotin and pantothenic acid in lake trout, Salvelinus namaycush
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Interrelationships between requirements for dietary selenium, vitamin E, and L-ascorbic acid by Atlantic salmon (Salmo salar) fed a semipurified diet
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Cataractous and digestive protease responses of rainbow trout fed autoclaved isolated soybean protein and added methionine
No abstract available at this time.
The effect of supplemental dietary amino acids, minerals and vitamins on salmonids fed cataractogenic diets
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Supplemental dietary methionine prevents cataracts in lake trout fed isolated soybean protein
No abstract available at this time.
Relative effect of two dietary water-soluble analogues of menaquinone on coagulation and packed cell volume of blood of lake trout (Salvelinus namaycush)
Triplicate lots of fingerling lake trout ( Salvelinus namaycush ) (initial mean weight, 5.3 g) were fed a basal, semipurified diet, or this basal diet supplemented with either 1.0 or 2.0 ppm of either menadione sodium bisulfite (MSB) or menadione dimethylpyrimidinol bisulfite (MPB) for 18 wk at 14 C. Neither form of vitamin K had a significant effect on the growth, food conversion, or body composition of the fish.Fish fed 1 ppm of MSB had a significantly higher mean packed cell volume (PCV) than those fed 2 ppm of either analogue. Trout fed 2 ppm of MPB had an intermediate PCV which was not significantly different from that of trout fed either 1 ppm MPB or 2 ppm MSB. A dietary level of 1 ppm MPB (providing an equivalent menaquinone concentration of about 0.5 mg/kg of diet) is sufficient to insure normal coagulation of lake trout blood and a satisfactory PCV.
Optimum level of dietary biotin for growth, feed utilization, and swimming stamina of fingerling lake trout (Salvelinus namaycush)
Triplicate lots of fingerling lake trout ( Salvelinus namaycush ) held at 9 C for 20 wk were fed a semipurified basal diet supplemented with 1% spray-dried egg white or d-biotin at concentrations of 0.1, 0.5, 1.0, or 5.0 ppm. Trout fed the basal diet, either alone or with egg white, grew more slowly and converted feed less efficiently ( P < 0.05) than those fed supplemental biotin. Neither the growth rate nor feed conversion differed significantly among the four groups fed supplemental biotin. However, when forced to swim to exhaustion against controlled water currents, trout fed either basal diet, with or without egg white, or 0.1 ppm supplemental biotin, swam a shorter distance ( P < 0.05) than those fed more biotin. Fish fed 0.5 ppm biotin swam as far as those fed 1.0 ppm, but not as far as those fed 5.0 ppm. These results indicate that young lake trout probably need no more than 0.1 ppm biotin for optimum growth and feed conversion, but require from 0.5 to 1.0 ppm for optimum swimming stamina.
Level of dietary biotin required for optimum growth, feed utilization and swimming stamina by juvenile lake trout
No abstract available at this time.
Effect of dietary biotin and lipid on growth, stamina, lipid metabolism and biotin-containing enzymes in brook trout (Salvelinus fontinalis)
Simultaneous dietary fat and biotin deficiencies in brook trout suppressed weight gain, feed/gain efficiency, swimming stamina, and total liver lipids. Dietary fat alone reduced body water, increased body fat and ash, reversed the elevating effect of biotin plus fat on liver palmitic and stearic acids, and widened the 16:0 to 16:1, 18:0 to 18:1, 18:2 to 20:4 and 18:3 to 22:5 liver fatty acid ratios. Fat also accentuated the accumulation of liver oleic and linoleic acids caused by biotin deprivation and apparently prevented docosapentaenoic acid biosynthesis in biotin-deprived trout. Fish fed fat with no biotin had the least, and those fed biotin with no fat the most, liver acetyl CoA carboxylase (ACC) and pyruvate carboxylase (PC) activities. Those fed neither supplemental biotin nor fat and those fed both showed equal liver ACC activity.
Effect of feeding brown trout (Salmo trutta) a diet pelleted in dry and moist forms
Growth rate, body composition, and intake of either dry matter or energy did not differ significantly ( P > 0.05) between two groups of juvenile brown trout ( Salmo trutta ) fed either a low- or high-moisture semipurified diet at different rates to compensate for a diet energy density gradient. Feed/gain efficiency, on an as-fed basis, was significantly greater ( P < 0.01) in fish fed the low-moisture diet, but did not differ ( P > 0.05) when compared on the basis of dry matter or energy intake.
Changes in the visual pigments of trout
The proportions of two visual pigments (rhodopsin and porphyropsin) were examined in four species of trout under experimental and natural conditions. Brook trout ( Salvelinus fontinalis ), rainbow trout ( Salmo gairdneri ), and brown trout ( Salmo trutta ) have different relative proportions of visual pigments in their retinae. The visual pigment balance in wild cutthroat trout ( Salmo clarki ) is related to forest canopy (access to light) and season. The brown trout have a more red-sensitive and less labile pair of visual pigments than brook or rainbow trout, which respond to photic conditions by increasing the proportion of porphyropsin (in light) and increasing rhodopsin (in darkness). The brown trout have a high percentage of porphyropsin, regardless of experimental conditions. This result does not reflect an inability to form rhodopsin but rather may relate to a consistently high proportion of 3-dehydroretinol in the pigment epithelium. The possible advantages and mechanisms of environmental control of trout visual pigment absorbance, as currently understood, are discussed.