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H. G. Ketola

Publications and source records attributed to H. G. Ketola.

32 records · Page 2Linked to original sources
USGS1979

Influence of dietary zinc on cataracts in rainbow trout (Salmo gairdneri)

The purpose of this study was to determine the cause of lens cataracts in hatchery trout fed diets containing white fish meal. After preliminary investigations, three experiments were conducted with fry of rainbow trout ( Salmo gairdneri ) that were fed practical-type diets containing either 40% herring meal (control diet) or 40% white fish meal with and without various mineral supplements. In all experiments, the trout fed herring meal grew well and had normal lenses. Those fed the diet containing white fish meal without supplement grew slowly and developed bilateral cataracts determined by using a slit-lamp biomicroscope. The severity of cataracts was increased by supplementing the diet with a mixture of minerals (phosphates and carbonates of calcium, sodium and potassium). Cataracts were prevented, however, with supplemental Na2EDTA or zinc but not by supplements of manganese, copper, iron or various other minerals. The metabolic alterations responsible for the zinc-deficiency cataract were not determined.

Journal of Nutrition↗
USGS1976

Choline metabolism and nutritional requirement of lake trout (Salvelinus namaycush)

Duplicate lots of 2-g lake trout (Salvelinus namaycush) were fed a purified diet alone and with equimolar supplements of aminoethanol, methylaminoethanol, dimethylaminoethanol, choline or betaine. Supplements of choline, methyl- and dimethylaminoethanol significantly increased growth rate and reduced liver fat content, whereas aminoethanol and betaine did not. These results suggest that trout biosyn-thesize choline from methyl- and dimethylaminoethanol but not from aminoethanol or betaine. In another experiment triplicate lots of 5-g trout were fed diets containing graded levels (0, 500, 1,000, 2,000 and 4,000 mg/kg) of choline. Growth results showed that the requirement for choline is no greater than 1,000 mg/kg of diet.

Journal of Animal Science↗
USGS1975

Amino acid supplementation of casein in diets of Atlantic salmon (Salmo salar) fry and of soybean meal for rainbow trout (Salmo gairdneri) fingerlings

Fry of Atlantic salmon ( Salmo salar ) fed a diet containing isolated fish protein grew significantly faster than those fed a diet containing casein without supplemental amino acids, and had improved feed conversion and lower mortality. Supplementing the casein diet with essential amino acids to the levels in the isolated fish protein diet significantly increased growth rate, reduced mortality, and improved feed conversion.When fingerling rainbow trout ( S . gairdneri ) were fed diets containing soybean meal as the sole source of protein, additions of amino acids to simulate those levels of essential amino acids in trout eggs and isolated fish protein significantly improved growth. Additions of methionine, lysine, histidine, and leucine individually and in several combinations had no effect.

Journal of the Fisheries Research Board of Canada↗
USGS1975

Requirement of Atlantic salmon for dietary phosphorus

Triplicate lots of young Atlantic salnon (Salmo salar) were fed a diet containing graded levels of supplemental inorganic phosphorus. The basal diet, containing mainly dehulled soybean meal and other plant materials, provided 40% crude protein, 0.7% phosphorus, 1.5% calcium, and 4,000 IU of supplemental cholecalciferol per kg of diet. Supplements of inorganic phosphorus significantly improved growth, feed utilization, and bone ash content. Inorganic phosphorus supplementation up to 0.6% of the diet increased growth rate and bone ash content; additions beyond this level had little further effect. This study suggests that when young salmon are fed diets containing 0.7% phosphorus from plant sources, the minimum requirement for supplemental inorganic phosphorus is approximately 0.6% of the diet.

Transactions of the American Fisheries Society↗