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Öğe Dietary carbohydrate level influencing feed intake, nutrient utilisation and plasma glucose concentration in the rainbow trout, Oncorhynchus mykiss(Tubitak Scientific & Technological Research Council Turkey, 2001) Tekinay, AA; Davies, SJA twelve-week nutrition trial was carried out to evaluate the efficacy of different carbohydrate levels on digestibility, feed intake, growth performance, carcass and muscle composition and plasma glucose level in the rainbow trout, Oncorhynchus mykiss. Three test diets were formulated using extruded wheat meal (15.3, 32.2 and 43.5%) as the carbohydrate source and fed rainbow trout (Initial Body Weight: 33.8 +/-0.46 g.). These were either restricted: LCR (Low Carbohydrate Restricted), MCR (Medium-Carbohydrate-Restricted) and HCR (High-Carbohydrate Restricted); or satiation: LCS (Low-Carbohydrate Satiation), MCS (Medium-Carbohydrate Satiation) and HCS (High-Carbohydrate Satiation) respectively. The aim of applying different feeding regimes was to quantify the protein sparing effect of carbohydrate and to determine the response of rainbow trout to different levels of carbohydrates. The results showed that protein, energy and carbohydrate digestibility was reduced with increasing dietary carbohydrate levels, whilst lipid digestibility was similar all the groups. There was a significant energy substitution from the carbohydrate source in the restricted groups. However, since the maximum feeding rate was reached in the restricted regimes (MCR and HCR), a similar sparing action of carbohydrate was observed in the satiation groups (MCS and HCS). All the groups displayed good growth performance. and exhibited growth that was LCS exhibited the highest (P<0.05) growth rate. MCR and MCS trout exhibited growth that was superior (P<0.05) to that of the LCR, HCR and HCS treatments. The feed efficiency of all the treatments was close to 100%. The quantities of carcass and muscle protein, lipid and ash were not found to be different (P>0.05). Transient hyperglycaemia was observed in trout fed a high carbohydrate diet. These results are discussed with respect to the protein sparing action of dietary carbohydrate in practical trout diets and the possible physiological effects of carbohydrates on feed intake regulation.Öğe Growth, feed utilization and carcass composition in rainbow trout fed diets with a similar digestible energy content and different carbohydrate levels(Aquaculturehub Inc, 2003) Tekinay, AA; Davies, SJ; Güner, YThree diets including 13.2%, 22% or 30.5% carbohydrates as extruded wheat meal were fed to rainbow trout, Oncorhynchus mykiss (initial weight 34.8 g), for twelve weeks to investigate their influence on growth, protein and energy utilization and carcass composition. Daily feeding rates were 1.76, 2.05 or 2.17 g feed per 100 g body weight for the three diets, respectively, so as to reach a daily allowance of about 35.5 kJ digestible energy per 100 g body weight. No significant differences (p>0.05) in final mean weight or specific growth rate were observed between the treatments. Feed efficiency was negatively correlated to the dietary carbohydrate level. Utilized digestible protein and energy per kg growth were 365, 348, 358 g and 15.4, 15.9, 17.0 MJ, respectively, for the three diets. Apparent net protein and energy utilization of the groups fed a medium or high carbohydrate level were higher than those of the low carbohydrate group. Analysis of fish carcasses at the end of the trial revealed no significant (p>0.05) variations attributable to the carbohydrate level.Öğe Influence of dietary energy level on stomach emptying and appetite revival rates in rainbow trout, Oncorhynchus mykiss(Scientific Technical Research Council Turkey, 2003) Tekinay, AA; Güner, Y; Davies, SJD1, D2 and D3 diets containing 15.5, 12.5 and 9.0 MJ kg(-1) digestible energy concentrations were offered to rainbow trout (Oncorhynchus mykiss Walbaum, 1792), and the rates of gastric evacuation and feed intake were determined. Gastric evacuation determinations were achieved by slaughtering eight fish every 6 h until no residue was found in the cardiac stomach. Return of appetite experiments were conducted by re-feeding groups of trout every 6 h following the first feeding. The data provided from each process was modelled by regression analysis and compared statistically. Square root equations best explained the gastric evacuation data, whereas first-order models were used for the description of return of appetite. The gastric emptying slope of D1 was found to be different (P < 0.05) to the other two treatments, whilst no significance (P > 0.05) was apparent between the slopes of D2 and D3. Similarly, the return of appetite slope of D I was significantly different (P < 0.05) to the slopes of D2 and D3, although no noticeable difference (P > 0.05) was evident between the return of appetite slopes of D2 and D3. A close relationship between appetite revival and gastric evacuation rates in rainbow trout was established.Öğe The influence of multiple meals on the gastric evacuation rate in rainbow trout (Oncorhynchus mykiss)(Aquaculturehub Inc, 2003) Tekinay, AA; Güner, Y; Akbas, I; Baysal, HRainbow trout, Oncorhynchus mykiss (mean weight 70.8+/-1.0 g SEM) raised in the Sea of Marmara (Turkey), were used for a preliminary gastric evacuation study. After being starved 72 hours, three groups of 110 fish, each, were fed ad libitum once, twice or three times in a single day. Ten fish from each group were withdrawn and killed in an anesthetic solution during each sampling at 0, 3, 6, 9, 12, 15, 18, 21, 24, 27 and 30 hours following the last feeding. Gastric material was removed from the fish and dried for gastric evacuation modelling. Gompertz and logistic models (with fixed asymptotes) best explained the data. The gastric emptying rate of the trout offered a single meal (Group A) was faster than those fed two (Group B) or three (Group C) meals while the emptying patterns of Groups B and C were similar to each other. The time required to evacuate 95% of the gastric material from the first meal was estimated as 54.3, 68.0 and 67.8 h for Groups A, B and C, respectively, according to the Gompertz equations (with a fixed asymptote).
