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Influence of dietary arginine and glycine content on thyroid function and growth of juvenile rainbow trout, Oncorhynchus mykiss (Walbaum) (1996)

RILEY, W. W. ; HIGGS, D.A. ; DOSANJH, B.S. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Aquaculture nutrition 2 (1996), S. 0

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ISSN: 1365-2095

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Juvenile rainbow trout, held at 12°C on a 12 h light :12 h dark photocycle, were fed a constant ration (1 % of body wt day −1) of isonitrogenous and isoenergetic diets that varied in either arginine content (3.6-56.1 g kg−1 dry matter; experiment 1), or glycine (3.3–118 g kg−1 dry matter) and alanine (5.0-42.3 g kg−1 dry matter) content (experiment 2).In experiment 1, the lowest dietary level of arginine depressed growth, feed efficiency, plasma l-thyroxine (T4) and 3,5,3′-triiodo-l-thyronine (T3) levels and hepatic T4 5’monodeiodinase (5'D) activity responsible for T4-to-T3 conversion. Over the dietary range of 7.1–56.1 g arginine kg−1, there was no change in 5'D activity, despite an arginine stimulation of growth. The optimum level of arginine for growth was within the range of 14.1–28.1 g kg−1 of the diet or 32–63 g kg−1 of dietary protein.In experiment 2, an increase in dietary glycine level, at the expense of glutamic acid, increased 5'D activity without attendant elevation of the plasma T3 level. The latter finding suggests that glycine also induced a compensatory increase in T3 degradation rate. This may explain why the glycine-induced increase in 5'D activity was unaccompanied by any changes in growth indices. Alteration of dietary alanine content did not affect growth or thyroid function.We conclude that of the various dietary amino acids tested, only glycine led to a progressive stimulation of hepatic T4 5'D activity. However, because glycine likely enhanced T3 degradation, no increases in plasma T3 or growth indices were found. Glycine may serve as an advance signal that activates thyroid function immediately preceding or coincident with energy and nutrient (especially protein) intake. This, in turn, may improve the efficiency of nutrient absorption and/or post-absorptive anabolic events.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2095.1996.tb00065.x

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Influence of dietary blends of menhaden oil and canola oil on growth, muscle lipid composition, and thyroidal status of Atlantic salmon (Salmo salar) in sea water (1998)

Dosanjh, B.S. ; Higgs, D.A. ; McKenzie, D.J. ; [et al.]

Springer

Fish physiology and biochemistry 19 (1998), S. 123-134

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ISSN: 1573-5168

Keywords: Atlantic salmon ; canola oil ; growth ; lipid composition ; thyroidal status

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The effects of various dietary blends of menhaden oil (MO) with canola oil (CO) on the growth performance, whole body proximate composition, flesh quality (muscle proximate and lipid composition) and thyroidal status of immature Atlantic salmon in sea water were studied. Atlantic salmon (initial weight, 145.2–181.3 g), held on a natural photoperiod and in 1100 L fibreglass tanks that were supplied with running, aerated (D.O., 9–10.5 p.p.m.), ambient temperature (8–10.5 °C) sea water (salinity, 28–30‰), were fed twice daily to satiation one of four isonitrogenous (∼36% digestible protein) and isoenergetic (∼18.8 MJ of digestible energy kg-1) extruded high-energy diets for 112 days. All diets contained omega –3 (n-3) fatty acids in excess of requirements and differed only with respect to the source of the supplemental lipid which was either, 25% MO; 20.75% MO and 4.25% CO; 16.5% MO and 8.5% CO; or 12.25% MO and 12.75% CO. Thus, CO comprised, respectively, 0, 15.5, 31.2, or 47.0% of the total dietary lipid content (∼28% on an air-dry basis). Dissimilar percentages of saturated fatty acids in the dietary lipids were not found to be consistently related to the apparent gross energy digestibility coefficients of the diets. Atlantic salmon growth, dry feed intake, feed and protein utilization, percent survival, thyroidal status, and whole body and muscle proximate compositions were generally not influenced by the different sources of supplemental lipid. Therefore, our results suggest that canola oil may comprise as much as 47% of the lipid in high-energy grower diets for Atlantic salmon without compromising performance. The muscle lipid compositions generally mirrored those of the dietary lipids which, in turn, were influenced strongly by the concentrations and compositions of the CO and MO in the diet. Hence, as the dietary CO level was increased there were attendant increases in percentages of oleic acid (18:1(n-9)), linoleic acid (18:2(n-6)), total omega-6 (n-6) fatty acid content, and ratios of (n-6) to (n-3) and decreases of eicosapentaenoic acid (EPA; 20:5(n-3)), docosahexaenoic acid (DHA; 22:6(n-3)) and n-3 HUFAs (EPA & DHA) in the flesh lipids. The ranges for percentages of saturated and unsaturated fatty acids in the flesh lipids were, however, much less than those noted respectively in the dietary lipids probably because of selective metabolism of many of the former acids and some of the 18 carbon unsaturates for energy purposes.