Fish meal (FM) is considered as an important ingredient in aquafeed production due to its high-quality protein with well-balanced essential amino acids and many other nutrients (Hertrampf & Piedad-Pascual, 2000). Over time, researchers have focused on finding suitable FM alternatives and found some successful plant protein sources that function up to some extent in feed formula-
The objective of this study was to examine the effect of dietary supplementation of taurine for juvenile olive flounder (Paralichthys olivaceus) at low water temperature (16.4 ± 0.36°C). Fish meal (FM)-based diet was used as the control diet. Four other experimental diets were prepared by adding taurine to FM-based diet at 0.25, 0.50, 1.00, and 1. 50% (T1, T2, T3, and T4, respectively). Each experimental diet was fed to triplicate groups of fish (initial mean body weight, 19.5 g) for 10 weeks. At the end of the feeding trial, growth performance and feed utilization, hematological parameters, non-specific immune responses, whole-body proximate composition, and liver mRNA expression of insulin-like growth factor-1 (IGF-1) were investigated. Feed conversion ratio was significantly reduced while protein efficiency ratio was significantly increased in taurine-supplemented groups. Hematocrit and hemoglobin were also significantly increased while plasma cholesterol levels were decreased in taurine-supplemented groups than those in the control group. Nitroblue-tetrazolium, myeloperoxidase and lysozyme activities, and plasma immunoglobulin level were significantly increased by taurine supplementation. These results suggest that dietary taurine supplementation is effective in improving growth performances, feed utilization, and innate immunity of olive flounder in low water temperature season.
This study was conducted to evaluate the supplemental effects of esterified monobutyrin (MB) and tributyrin (TB) on growth performance, feed efficiency, digestibility, innate immunity, antioxidant status and disease resistance of Pacific white shrimp, Litopenaeus vannamei. A basal (control) experimental diet was formulated without MB or TB, and four other diets were prepared by supplementing powder forms of MB at 2 and 4 g/kg (0.2% and 0.4%) or TB at 1 and 2 g/kg (0.1% and 0.2%) (designated as MB0.2, MB0.4, TB0.1 and TB0.2, respectively). Quadruplicate groups of shrimps were hand‐fed with one of the diets four times daily for 53 days. Shrimp fed MB or TB diets showed significantly higher growth performance, feed utilization, phagocytosis and glutathione peroxidase activity than shrimp fed the control diet. Increased digestibility of dietary protein, lipid and dry matter was found in shrimp fed MB‐ or TB‐supplemented diets. Relative mRNA expression levels of IGF‐binding protein and prophenoloxidase gene were significantly increased in shrimp fed MB‐ or TB‐supplemented diets than in shrimp fed the control diet. The results of a challenge test with Vibrio harveyi showed that the disease resistance of shrimp can be significantly enhanced against V. harveyi when they were fed TB0.2 diet. The results of this study indicate that dietary supplementation of 2 g/kg MB or 1–2 g/kg TB can improve growth and feed efficiency, innate immunity, antioxidant activity, digestibility and disease resistance of L. vannamei.
A study was carried out to examine and optimize the inclusion levels of shrimp hydrolysate (SH) or tilapia hydrolysate (TH) in low fishmeal diets for olive flounder (Paralichthys olivaceus). A fishmeal (FM)‐based diet was considered as a high FM (HFM) diet, and a diet containing soy protein concentrate (SPC) as a FM replacer at 50% substitution level was regarded as a low FM (LFM) diet. Six other experimental diets were prepared by dietary supplementation of SH or TH to LFM diet at different inclusion levels of 15 g/kg, 30 or 45 g/kg in the expense of FM (designated as SH‐1.5, SH‐3.0, SH‐4.5, TH‐1.5, TH‐3.0 and TH‐4.5, respectively). After 10 weeks of a feeding trial, growth performance and feed utilization efficiency of fish were significantly higher in fish fed HFM, SH‐3.0, SH‐4.5, TH‐1.5 and TH‐3.0 diets compared to those of fish fed LFM diet. Intestine diameter, villus height and goblet cell counts of fish were significantly increased by dietary inclusion of SH or TH into LFM diet. Dry matter and protein digestibility of diets were significantly improved by SH or TH incorporation. Innate immunity of fish was significantly enhanced by dietary SH or TH supplementation into LFM diet. Disease resistance of fish was significantly increased against Edwardsiella tarda by dietary inclusion of SH and TH at the highest inclusion level (45 g/kg). The optimum inclusion level of SH or TH in a SPC‐based LFM diet could be ~30 g/kg and 15–30 g/kg, for olive flounder.
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