Search

Abstract: An 8‐week feeding trial was conducted to investigate the effects of dietary carbohydrate to lipid ratio (CHO: L) on growth, feed utilization, body composition and digestive enzyme activities of golden pompano, Trachinotus ovatus. Five iso‐nitrogenous (450 g/kg protein) and iso‐energetic (19 MJ/kg gross energy) diets with varying CHO: L ratios of 0.68, 1.02, 1.62, 2.61 and 4.35, respectively, were fed to triplicate groups of 30 fish (average 13.8 ± 0.1 g). Results showed that dietary CHO: L ratios did not show any significant influence on survival of golden pompano (p > .05) but significantly affected its growth performance and feed utilization (p < .05). Fish fed diets with CHO: L ratios at 1.62 and 2.61 exhibited the highest final body weight, weight gain ratio, specific growth rate, feed efficiency ratio and protein efficiency ratio. Fish body lipid and liver glycogen contents were also significantly influenced by CHO: L ratio (p < .05). Hepatic amylase activity increased firstly and then decreased as the dietary CHO: L ratio increased, while lipases activity decreased with increasing dietary CHO:L level. The regression model analysis showed that the most suitable dietary CHO: L ratio (protein 450 g/kg) to reach the highest weight gain ratio is 2.38. [ABSTRACT FROM AUTHOR]

Abstract: This experiment was designed to investigate the effects of dietary valine on the growth performance, feed utilization, digestive enzymes, serum antioxidant and immune indices of juvenile Trachinotus ovatus and determine its valine requirement. Six diets with different concentrations of L‐valine (15.0, 16.6, 18.6, 20.7, 23.5 and 25.4 g/kg dry diet, defined as diet Val‐1 to Val‐6.), were formulated to contain 430 g/kg crude protein with fish meal, soybean meal, peanut meal and precoated crystalline amino acids. Each diet was randomly assigned to triplicate treatments of 20 fish (the initial body weight was 5.34 ± 0.03 g) for 8 weeks. The results indicated that the final body weight and percent weight gain (PWG) increased with increasing valine concentration up to 18.6 g/kg (diet Val‐3), whereas the diets containing higher valine concentration reduced the growth performance significantly (p < .05). Moreover, the protein efficiency ratio, body protein deposition (BPD), muscle protein content, intestinal amylase and pepsin activities, serum T‐AOC, LZM activities, IgM, complement 3 and complement 4 concentration had a similar trend with PWG, and the trend of feed conversion ratio, serum AST, ALT activities, urea and MDA content was opposite. Meanwhile, the lipid contents of whole fish and muscle in diet Val‐6 were particularly lower than other diets (p < .05). The survival rate of diet Val‐1 was lowest in this study and was significantly lower than diet Val‐2 (p < .05). The results of polynomial regression based on PWG and BPD indicated that the optimal dietary valine requirement for Trachinotus ovatus reared in seawater‐floating net cages was 19.87–20.17 g/kg valine of dry diet, correspondingly 46.22–46.91 g/kg of dietary protein. [ABSTRACT FROM AUTHOR]

The experiment was conducted to determine the effect of dietary DL-methionine addition in fish meal reduction diet for juvenile golden pompano ( Trachinotus ovatus). The trial comprises the following of 11 diet treatments. (i) D1 diet as the standard was formulated with fish meal as the main protein source. (ii) D2-D5 diets were formulated to replace fish meal with soybean meal at 60, 120, 180 and 300 g kg−1, respectively, and the amino acid profiles (including methionine and lysine) of D2-D5 were referred to the amino acid profile of D1. (iii) D6-D9 diets were the same as D2-D5, respectively, but without methionine supplementation. (iv) D10 and D11 diets were the same as D3 and D5 diets, respectively, but without lysine supplementation. Each diet was randomly fed to groups of 20 fish (initial average weight about 18 g) per net cage (1.0 × 1.0 × 1.5 m) in triplicate and the feeding experiment lasted for 56 days. Weight gain ( WG, %) and final body weight ( FBW, g) of fish fed D3 diet were significantly higher than those of fish fed D8 and D9 diets ( P < 0.05), but without significant differences with fish fed other diets ( P > 0.05). Feed conversion ratio ( FCR) of D3, D4 and D5 diet treatments were significantly lower than that of D11 diet treatment ( P < 0.05), but without significant difference with other diet treatments ( P > 0.05). Whole-body protein contents of fish fed D3-D5 were significantly higher than those of fish fed D7-D9 ( P < 0.05), but without significant differences with fish fed other diets ( P > 0.05). In conclusion, the replacement of fish meal by soybean meal could reach 300 g kg−1 without detrimental but profitable effect on growth and survival when enough methionine and lysine were supplemented in the diet; moreover, lysine is not the first-limiting amino acid relative to methionine for juvenile T. ovatus from the present growth and proximate composition results. [ABSTRACT FROM AUTHOR]

Effect of weaning time on the larval performance of golden pompano Trachinotus ovatus was studied in the experimental condition. The same weaning regime started on four different days of posthatch ( DPH): 13 DPH (W13), 16 DPH (W16), 19 DPH (W19) and 22 DPH (W22), respectively. Growth, survival, RNA/ DNA ratios and mid-gut cell height of fish were assessed in each weaning regime over time. Growth and survival rates of fish larvae weaned in the W19 and W22 regimes were significantly higher than those in the W13 and W16 regimes. No significant differences were found either between W19 and W22, or between W13 and W16 treatments. Fish showed a decrease in the RNA/ DNA ratio in W13, but a trend of increase in W16, W19 and W22. Weaning time significantly affected the mid-gut cell height in larval golden pompano. On 24 DPH, the mid-gut cell height of fish in the W13 and W16 treatments was significantly thinner than those in the W19 and W22 treatments. Based on fish growth, survival, RNA/ DNA ratio and mid-gut cell height, weaning can be started on 13 DPH in golden pompano larvae, but we recommend that the best weaning window be 16-22 DPH. These results are supported by histological and nutritional evidence and would guide the weaning process for golden pompano larvae, and offer a useful approach to explore the weaning protocol in larval fish rearing. [ABSTRACT FROM AUTHOR]

Two 7-week feeding trials were conducted to evaluate the capacity of golden pompano (Trachinotus ovatus) to use soy protein concentrate (SPC) as a dietary fish meal substitute. In trial I, fish were fed with a control diet (C) containing 400 g kg -1 fish meal and other four diets in which the fish meal in diet C was replaced by SPC at 20 (R20), 40 (R40), 60 (R60) and 80% (R80). In trial II, a 3 X 2 design was used, and 40 and 80% of the fish meal in diet C were replaced by SPC, with or without 5 g kg-1 taurine supplementation (six diets, C + T, R40 + T, R80 + T, C, R40 and R80, were formulated). In trial I, no significant difference was found in the feed intake between feeding treatments. The weight gain and nitrogen retention efficiency (NRE) decreased, whereas the feed conversion ratio (FCR) and phosphorus retention efficiency (PRE) increased, with decreasing dietary levels of fish meal. No significant differences were found in the weight gain, FCR and NRE between fish fed diets C and R20, whereas fish fed diets C and R20 had higher weight gain than those fed diets R40, R60 and R80. In trial II, no significant differences were found in the feed intake, weight gain, FCR, NRE and PRE between fish fed diets C + T and C. No significant differences were found in the feed intake, weight gain and NRE between fish fed diets R40 and R40 + T or between fish fed diets R80 and R80 + T. At the end of trial II, no significant differences were found in the condition factor, hepatosomatic index and body composition between fish fed diets C and C + T, or between fish diets R40 and R40 + T, or between fish fed diets R80 and R80 + T, except that fish fed diet R40 had lower body protein content than that of fish fed diet R40 + T. The present study reveals that taurine supplementation can elevate fish meal replacement level by SPC in the golden pompano diets. Fish meal can be reduced from 400 to 320 g kg-1, if fish meal is substituted by SPC without taurine supplementation, and can be further reduced to 240 g kg-1, if fish meal is substituted by SPC with 5 g kg -1 taurine supplementation. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the dietary methionine requirement of juvenile golden pompano (initial body weight 12.40 ± 0.02 g). Six diets were formulated with six graded levels of methionine (8.6, 9.2, 10.4, 11.5, 13.2 and 14.5 g kg−1). Each diet was randomly assigned to triplicate groups of 20 juvenile fish in seawater floating net cages (1.0 m × 1.0 m × 1.5 m). Fish were fed twice daily (08:30 and 16:30) to apparent satiation for 56 days. Weight gain ( WG), specific growth rate ( SGR), feed conversion ratio ( FCR), feed efficiency ( FE), nitrogen retention efficiency ( NRE), proximate body composition, morphometry and haematology were significantly ( P < 0.05) affected by the dietary methionine levels. WG, SGR and FE increased with increasing levels of methionine up to 13.2 g kg−1 diet ( P < 0.05) and remained nearly the same thereafter. NRE also increased with increasing levels of methionine up to 13.2 g kg−1 diet ( P < 0.05) and remained nearly the same thereafter. Linear regression analysis on WG and NRE indicated that the recommended optimum dietary methionine levels for optimal growth of juvenile pompano were 10.6 and 12.7 g kg−1 diet, respectively, corresponding to 24.6 and 29.5 g kg−1 dietary protein, respectively, so the level of dietary methionine should be between 10.6 and 12.7 g kg−1 diet, corresponding to 24.6-29.5 g kg−1 dietary protein. Additionally, the estimated requirements for the other essential amino acids were calculated from A/E ratios of whole-body amino acid profile based on the methionine requirement determined from the present experiment. [ABSTRACT FROM AUTHOR]

A feeding trial was conducted to determine the suitable dietary protein and lipid levels for juvenile golden pompano Trachinotus ovatus reared in net pens. Ten test diets were formulated at five levels of crude protein (330, 370, 410, 450 or 490 g kg−1) and two levels of crude lipid (65 or 125 g kg−1). Golden pompano fingerlings (initial body weight 4.7 g ind−1) were fed the test diets for 8 weeks. Weight gain ( WG), specific growth rate ( SGR), feed conversion ratio ( FCR), nitrogen retention efficiency ( NRE), energy retention efficiency ( ERE), condition factor ( CF), hepatosomatic index ( HSI), body protein content and total nitrogen waste ( TNW) were dependent on both dietary protein and lipid levels. Feed intake ( FI) and viscersomatic index ( VSI) were dependent on dietary protein level, while body lipid content was dependent on dietary lipid level. Weight gain increased with increasing the dietary protein level (at the same lipid level) but was lower at the dietary lipid level of 65 g kg−1 than at 125 g kg−1 (at the same protein level). Fish fed at the dietary protein levels of 460-490 g kg−1 had higher WG and lower FCR than at 330-410 g kg−1. Energy retention efficiency tended to increase with increasing the dietary protein level from 330 to 410 g kg−1, while no significant difference was found in nitrogen retention efficiency between the dietary protein levels (at the same lipid level). Results of this study suggest increasing the dietary lipid level from 65 to 125 g kg−1 could not induce protein-sparing action in golden pompano, and the suitable dietary protein and lipid levels for juvenile golden pompano reared in net pens should be 450-490 and 65 g kg−1. [ABSTRACT FROM AUTHOR]