Geology topics

S. G. Hughes

Publications and source records attributed to S. G. Hughes.

22 records · Page 2Linked to original sources

USGS1984

Effect of excess dietary riboflavin on growth of rainbow trout

Fingerling rainbow trout were fed semipurified diets containing graded levels of supplemental riboflavin (3, 35, 42, 49, 56, 63, 70, 100 and 600 mg/kg of diet) to determine if dietary riboflavin in excess of requirements decreases growth. In three trials with three sizes of fish (mean initial weights, 0.5, 3.2 and 4.3 g) and two water temperatures (8.3° and 15°C), no significant diet-related growth inhibition was detected. The results suggest that rainbow trout, like other animals, are insensitive to excesses of dietary riboflavin and that the growth depression reported by other workers was the result of some other dietary influence or of faulty experimental design.

Journal of Nutrition↗

USGS1983

Dietary requirements for essential branched-chain amino acids by lake trout

In a 12‐week growth study of the dietary requirements of young lake trout Salvelinus namaycush for essential branched‐chain amino acids, the leucine requirement was between 2.74 and 3.66%, and the isoleucine requirement between 1.54 and 2.06%, of dietary protein (as‐fed basis). These ranges are substantially lower than those published and widely used in formulation of salmonid feeds. On the basis of both growth criteria and concentration of free amino acids in blood plasma, the valine requirement was within the range of 1.77 to 2.23% of dietary protein. The upper value of this range is substantially lower than the requirement reported for chinook salmon Oncorhynchus tshawytscha. Plasma valine concentrations in lake trout responded to dietary supplements of valine above the requirement level; the concentrations increased sharply once the requirement was exceeded. This finding is similar to observations recorded in other animals.

Transactions of the American Fisheries Society↗

USGS1982

Use of ozone in a water reuse system for salmonids

A water reuse system is described in which ozone is used in addition to biological filters to remove toxic metabolic wastes from the water. The system functions at a higher rate of efficiency than has been reported for other reuse systems and supports excellent growth of rainbow trout (Salmo gairdneri).

Progressive Fish-Culturist↗

USGS1981

Riboflavin requirement of fingerling rainbow trout

Fingerling rainbow trout (Salmo gairdneri) were fed purified diets containing graded levels (0, 3, 6, 12, 18, 24, and 54 mg/kg) of supplemental riboflavin for 20 weeks. The cellular riboflavin supply of the fingerlings was estimated on the basis of the activity of the FAD‐dependent enzyme, erythrocyte glutathione reductase (EGR). The dietary riboflavin level that produced the fastest growth, an efficient feed: gain ratio, and normal values for the EGR activity coefficient was about 3 mg of supplemental riboflavin per kilogram of diet.

Progressive Fish-Culturist↗