Evaluation of the net energy value of glucose (cerelose) and maize starch in diets for rainbow trout (Salmo gairdneri).

1. Quadruplicate groups of rainbow trout (Salmo gairdneri) (mean body-weight 24.9 g) were reared on six dietary treatments (practical-type diets) in a modified paired-feeding experiment for 12 weeks at 15 degrees to determine the net energy (NE) value of starch and glucose to rainbow trout.

Effects of thyroid hormone supplementation of canola meal-based diets on growth, and interrenal and thyroid gland physiology of rainbow trout (Salmo gairdneri).

Rainbow trout fed a 26% canola meal-based (CM) diet for 12 weeks at 15°C exhibited reduced growth, lower feed conversion, enlarged thyroid glands and lower plasma thyroid hormone (TH) levels than comparable fish fed equinitrogenous, equicaloric soybean meal-based (SB) diets. Supplementation of the SB diets with either T4 (20 mg/kg) or T3 (10 or 20 mg/kg) had no effect on the growth rate, feed conversion and thyroid histology of the trout. However, plasma T4 levels weredepressed in trout fed the T4- and high T3-supplemented SB diets.

Accumulation of waterborne selenium by rainbow trout (Salmo gairdneri), eggs, fry and juveniles.

The effect of waterborne selenite levels on selenium accumulated by different developmental stages of rainbow trout (Salmo gairdneri) was studied using(75)SeO 3 (=) as a tracer. All stages readily accumulated selenium at both high and low concentrations, but the rate of accumulation increased as the trout developed from the egg to the juvenile feeding stage. The low rate of selenium accumulation by embryos seemed to be related more to a lack of gills than to the presence of a chorion.

Dietary carbohydrate and growth, body composition and heat increment in rainbow trout (Salmo gairdneri).

A study was conducted to determine growth, body composition and heat increment (HI) of rainbow trout reared on isonitrogenous high digestible carbohydrate (HC) and high fat (HL) diets at 15°C. Trout reared on the HC diet had a significantly lower final body weight and carcass lipid content and a significantly higher feed:gain ratio and carcass protein content than trout reared on the HL diet after 12 weeks on the test diets. The lower carcass lipid composition indicates that trout do not readily convert dietary carbohydrates into fat.

The biological activity of 25-hydroxycholecalciferol and 1,25--dihydroxycholecalciferol for rainbow trout (Salmo gairdneri).

Dietary 25-hydroxycholecalciferol (25-hydroxycholecalciferol (25-OH-D3) and 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] showed vitamin D activity in rainbow trout. However, inclusion of dietary cholecalciferol (vitamin D3 or D3), ergocalciferol (vitamin D2 or D2), 25-OH-D3 or 1,25-(OH)2D3 did not result in the presence of detectable levels of vitamin D or 25-OH-D in the blood plasma of the fish. Fish fed the diet devoid of vitamin D over an extended period of time showed symptoms of a droopy-tail or "lordosis-like" syndrome that appeared to be related to muscle weakness since x-ray examination indicated no abnormality in vertebral development.