Evaluation of Advanced Soy Products in Diets Fed to Florida Pompano

Abstract

It has been suggested that soybean meal could be utilized to substitute the use of animal meal in the development of practical diets for majority of aquaculture species. However, the presence of anti-nutritional factors may limit the wider use of conventional soybean meal (SBM) and play a role in decreasing the growth performance of fish, alter the serum and enzyme activities, and induce the inflammation in the distal intestine and the liver of the fish. Currently, different advanced processing technique, such as fermentation, combination of non-alcohol and enzymatic treatment, and alcohol extraction technique, have been reported to be an effective method to denature and lowering the level of anti-nutritional factors, improve the nutritional value, and reduce the molecular weight of soy-protein. Therefore, this study was conducted to explore the potential use of this advanced soy products, especially fermented soybean meal (FSBM) and enzyme-treated soy (ESBM), as the protein sources in formulating the practical diets for Florida pompano Trachinotus carolinus. In this study, the potential use of squid products as an attractant as well as the protein source for pompano also becomes the main parameter of interest to be included in pompano diet. The first study was designed to evaluate the efficacy of commercially produced FSBM known as PepSoyGenTM to replace conventional SBM in the development of plant-based diet for Florida pompano. In this study, the utilization of FSBM as much as 0, 206, 309 and 410 g kg-1 to approximately replace 0, 50, 75 and 100% of SBM had no effects in growth parameters of pompano. The gradual replacement also did not have significant differences in total protein, albumin, glucose, cholesterol, bile acids, plasma alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase activities in all treatments of pompano. However, glycogen granulation, inflammation and nuclear change condition in the liver of pompano were better as the inclusion of fermented product increased. Based on the results, further research regarding the optimum inclusion level of FSBM to satisfy the nutrient requirement of pompano might be needed to improve the efficacy of fermented soy products. The second study investigated the potential use of commercial ESBM (NutriVanceTM) to reduce the inclusion level of fish meal (FM) in the development of practical diet for Florida pompano. There are two series of trials conducted in this study and the decreasing growth of pompano as the inclusion level of FM was further replaced by soy-protein were confirmed. The results also indicate that the gradual replacement of dietary FM with ESBM had no effect to the majority of serum and enzyme activities of pompano across all trials. The histomorphological structure of liver and distal intestine were slightly affected by lower inclusion level of FM. Overall, the results showed that ESBM could be used as a potential dietary protein sources to replace FM in the development of practical diet for pompano. The third study was designed to investigate and compare the effects of diets containing high inclusion level of advanced soy products (ESBM and FSBM) in combination with porcine meal (PM) to completely replace poultry by-product meal (PBM) on growth performance, body composition and distal intestine histology of Florida pompano Trachinotus carolinus. Under the experimental conditions, fish fed ESBM performed equally well in terms of growth parameters in comparison to fish fed PBM. Meanwhile, fish fed FSBM had significantly lower feed intake, indicating a palatability issue with the high use of FSBM. Interestingly, the results indicate that the dietary treatments had no effect in whole-body proximate and mineral composition. Moreover, the high inclusion of advanced soy products had no significant effect to the histomorphological conditions of distal intestine of the fish. Based on these results, 451 g kg-1 ESBM supplemented with 38 g kg-1 PM can be utilized to develop a practical diet for juvenile Florida pompano without impacting growth, nutritive parameters and several distal intestine health parameters. The fourth study investigated the inclusion effects of squid products, namely squid hydrolysates (SH) and squid meal (SM) to improve the palatability and nutritional value of soy-based diet. The squid products were added to the basal diets, to produce diets containing 1, 2 and 4% of SH and SM. Under the experimental conditions, the addition of 4% SH improved the response of basal diet and did not show any significant difference in terms of growth performance as compared to the reference diet (15% PBM). Meanwhile, the inclusion of SM into the basal diet were not able to induce better growth of pompano. At the end of growth trial, there were no significant effect to the whole body proximate, amino acids composition, enzyme and serum biochemistry activities of the fish. Regarding to the histology analysis, fish fed with basal diet showed disordered vacuolization in the liver and decreased the lamina propria thickness in the intestine. The inclusion of 4% SH partly prevented the alteration of liver and distal intestine of Florida pompano and findings were similar to fish fed with PBM. Based on these results, combination of ESBM and 4% SH has the potential to serve as an alternative protein source and attractant to improve the efficacy of plant-based diet for pompano. The fifth study aimed to conduct a quantitative review on the effect of various inclusion size of FSBM as a potential ingredient to replace dietary FM on the growth and food conversion ratio (FCR) of several aquaculture species. The effect size of 53 comparisons data between FSBM inclusion level in diet formulation and a control condition was -3.75 [95 % CI -4.49 to -3.01] for final weight and 1.26 [95 % CI 0.58 to 1.94] for FCR. According to meta-regression analysis, FSBM inclusion level of 8–40 % improves the final weight of fish. Meanwhile, inclusion level of FSBM higher than 40 % will likely decrease the final weight of fish compared to fish that received high percentage of FM. On the other hand, the inclusion of FSBM is more effective at the level of 15–44 % to improve the FCR of the diet and inclusion levels out of this range would produce various effects to the FCR. This study provides a useful information on the optimum inclusion level of FSBM to replace dietary FM in formulating practical diets based on the selected study. We showed that for future aquaculture, the development of sustainable and economically sound practical diet will depend on the reduction of animal meal and the increased inclusion of sustainable protein sources. Further treatment of SBM could produce better nutrition profile in the resulted meal and growth performance of the fish. Therefore, it is important for researcher and stake holders to properly evaluate the utilization of advanced soy products and determine the optimum inclusion level of these advanced soy products to replace the use of conventional SBM and animal meal that still support the optimum growth and health status of fish.