Hugh A. Poston

Effect of body size on growth, survival and chemical composition of Atlantic salmon fed soy lecithin and choline

Abstract A nutritional study consisting of four feeding experiments was conducted in which Atlantic salmon (Salmo salar) were first fed experimental diets at swim-up (0. 18 g) and at weights of 1.0, 1.7, and 7.5 g. The objectives of the study were to (1) determine if the size at which Atlantic salmon are first fed lecithin affects their growth, survival, and body composition, and (2) compare the responses of Atlantic salmon to different sources of dietary lecithin. Fish fed 4% commercial food-grade lecithin (i.e., 100% soy lecithin) or 8% feed-grade lecithin (i.e., a corn–soy lecithin mixture containing over 50% corn lecithin and 5% insoluble impurities) from swim-up grew faster than fish fed no lecithin but fed sufficient choline. Although fish fed supplemental lecithin from swim-up grew equally well regardless of source and level of lecithin, they grew almost 50% faster than fish fed the basal diet with no supplemental lecithin or choline. Fish started on the experimental diets at 1.0 and 1.7 g grew fas...

Response of Rainbow Trout to Soy Lecithin, Choline, and Autoclaved Isolated Soy Protein

Abstract Fry of rainbow trout (Oncorhynchus mykiss) were fed, from first feeding (mean weight, 0.12 g), basal diets containing either a nonautoclaved (raw) sodium proteinate form of isolated soy protein (ISP) or the same ISP autoclaved at 0.56 kg/cm2 and l 10°C for 30 min. In the three-way factorial, 16-week study, I measured the effects of autoclaving ISP on the growth, survival, and chemical composition of rainbow trout at three levels of soy lecithin (0, 4, and 8%) and two levels of choline (0 and 0.3%). Fish fed raw ISP grew no faster with or without choline than did those fed the basal diet, but those fed heated ISP with choline showed a quantitatively small but significant advantage in weight gain. Whereas fish fed 4% lecithin with raw ISP more than tripled weight gain compared with fish fed the basal diets, fish fed 4% lecithin with heated ISP grew seven times as fast as those fed no lecithin or choline. Rainbow trout fed choline and 4% lecithin with heated ISP (but not raw ISP) grew significantly ...

Performance of Rainbow Trout Fry Fed Supplemental Soy Lecithin and Choline

Abstract Three feeding experiments were conducted with early-feeding fry of rainbow trout (Oncorhynchus mykiss; initial mean weight, 0.10–0.12 g) to determine their need for lecithin contained in soy lecithin (SL), with and without supplemental choline. The source of assay protein was an isoelectric form (RP 100) of isolated soy protein (ISP) in experiment 1, a sodium protein ISP (RP 101) in experiment 2, and an ether-extracted herring meal in expenment 3. Duration of the feeding trials was 20 weeks for experiment 1 and 16 weeks for experiments 2 and 3. Analysis of variance showed that supplemental SL and choline each increased body weight gain, survival, and body fat, and improved feed conversion (amount fed/weight gain). The extent of beneficial effects varied with type of diet fed. Fish fed either of the ISPs needed at least 4% supplemental SL, either with or without 0.3% choline, for highest survival, but survival of all fish fed extracted herring meal was high. Although choline alone enhanced growth,...

Response of Atlantic Salmon Fry to Feed-Grade Lecithin and Choline

Abstract First-feeding Atlantic salmon (Salmo salar) were fed different levels (0, 2, 4, 6, and 8% of diet) of feed-grade lecithin with and without 0.3% supplemental choline in a diet containing a sodium proteinate form of autoclaved isolated soybean protein. After 14 weeks at 9.2°C, Atlantic salmon fed 6% lecithin with or without added choline had gained the most weight. Fish fed supplemental choline without lecithin gained significantly more weight (P ≤ 0.05) than did fish fed the basal diet, but choline did not increase weight gain at any level of lecithin. Feed conversion (weight fed/weight gain) improved with increasing lecithin up to 4% and improved even more for fish fed 6% lecithin and 0.3% choline. Only 4% lecithin with or without choline was needed to yield the highest concentration of body fat, but carcass dry matter was highest and ash and protein were lowest in fry fed 8% lecithin alone or 6% lecithin and 0.3% choline. Neither lecithin nor choline influenced mortality, which was low in all gr...

Response of rainbow trout to source and level of supplemental dietary methionine

1. 1. Methionine and total sulfur amino acid (TSAA) requirements of rainbow trout (Salmo gairdneri) were investigated by feeding graded isosulfurous levels of l- and dl-methionine, l-cystine, and the free acid and calcium forms of methionine hydroxy analog (MHA). 2. 2. Added cystine did not promote growth, survival or prevent cataracts. 3. 3. l-methionine produced fastest growth, followed by dl-methionine, CaMHA and free acid MHA. 4. 4. Trout fed CaMHA gained 85.7 and 92.3% as much as those fed l-methionine and dl-methionine. 5. 5. Within each experiment, the level of L-methionine isomer that prevented cataracts was constant (1.86 g/100g protein in experiment (1), 1.45 in experiment (2) and was lower than for maximum growth (2.89 and 2.15 g) regardless of methionine source.

Nutritional implications of tryptophan catabolizing enzymes in several species of trout and salmon.

Summary and conclusions Data obtained from assays from activity of 3HAA and PC in livers of five species of trout and salmon indicate that, in general, dietary tryptophan is not an effective precursor of niacin, for which a dietary requirement exists. Intergeneric differences in this relationship may or may not suggest differences in the quantitative requirements for dietary niacin by these individual species of salmonids.

Interrelations of oxygen concentration, fish density, and performance of Atlantic salmon in an ozonated water reuse system.

Abstract In a 16-week study, we stocked duplicate groups of 3.3-g Atlantic salmon (Salmo salar) in 25-fish increments (25 to 100 fish/6.5-L jar) and in 250-fish increments (250 to 1,000 fish/144-L trough), in an ozonated, 100% closed water reuse system, to examine changes in fish performance in response to rearing at different densities and loadings within the system. Maximum rearing density (kg!m3) reached 219 in jars and 125 in troughs. Maximum loading (ratio of fish weight to water flow) reached 0.45 kg/(L/min) in jars, and 0.79 kg/(L/min) in troughs. A rise in water temperature from 18.9 to 21°C during weeks 11 and 12 was accompanied by a drop in effluent dissolved oxygen (DO), followed by an increase in mortality and a decline in biweekly weight gain. Later declines in water temperature to 18.4°C, and reductions in biomass, were followed by reduced mortality and increased weight gain. In both jars and troughs, mortality increased when dissolved oxygen dropped to 6.5 mg/L or lower, water temperature r...

Choline requirement of swim-up rainbow trout fry

Abstract Triplicate 150-fish lots of first-feeding fry of rainbow trout (Oncorhynchus mykiss; initial mean weight, 0. 12 g) were fed casein–gelatin-based diets containing 0, 200, 400, 800, 1,000, 2,000, 4,000, or 8,000 mg choline/kg of feed for 12 weeks to determine their need for dietary choline. Although the growth rates of fry were suboptimal, results showed that fry needed no more than 4,000 mg choline/kg casein–gelatin diet for maximum growth and 2,000 mg/kg for maximum body fat and minimum protein. Survival was significantly lower for fish fed 800 mg choline/kg of diet than for those fed greater amounts of the nutrient. These results suggest that the dietary choline requirement of early feeding salmonids is greater than that previously reported for older salmonids. The amount of choline needed by fishes apparently decreases with age or size.

Tryptophan conversion to niacin in the brook trout (Salvelinus fontinalis).

Summary and conclusionsData on growth, body composition and liver 3HAA and PC assays indicate that L-tryptophan is an inefficient precursor of dietary niacin for the brook trout.The brook trout has a high liver PC activity. While this enzyme activity, alone, indicates a high requirement for dietary niacin, the 3HAA/PC ratio is a more meaningful indicator of the efficiency of the tryptophanto-niacin conversion in the brook trout and other species.An investigation of the PC and 3HAA activities of other salmonids should help elucidate interspecies and intergeneric variations in niacin requirements.Summary and conclusions Data on growth, body composition and liver 3HAA and PC assays indicate that L-tryptophan is an inefficient precursor of dietary niacin for the brook trout. The brook trout has a high liver PC activity. While this enzyme activity, alone, indicates a high requirement for dietary niacin, the 3HAA/PC ratio is a more meaningful indicator of the efficiency of the tryptophanto-niacin conversion in the brook trout and other species. An investigation of the PC and 3HAA activities of other salmonids should help elucidate interspecies and intergeneric variations in niacin requirements.

Effects of dietary aluminum on growth and composition of young Atlantic salmon

Abstract A 16-week feeding experiment was conducted to measure the effects of supplemental dietary aluminum (0, 25, 50, 100, 500, 1,000, 1,500, and 2,000 mg/kg diet) on growth, survival, feed conversion, and proximate composition of Atlantic salmon (Salmo salar), mean weight 4.8 g. No significant differences (P > 0.05) in growth, survival, or feed conversion were found among fish fed the different levels of aluminum. Body fat increased significantly in fish fed aluminum at the rate of 2,000 mg/kg of diet. Total ash was significantly lower in fish fed 1,000–2,000 mg aluminum/kg of diet than in those fed smaller amounts. Differences in concentration of individually measured minerals (aluminum, copper, iron, manganese, and magnesium) were not significant in either carcass or vertebrae of experimental fish. Supplemental dietary aluminum (up to 2,000 mg/ kg of diet) had no measurable beneficial or obvious adverse effect on fingerling Atlantic salmon.