Recently, ecological and economic issues have affected fish meal (FM) supply, the main source of protein for shrimp. This triggered a search for alternative dietary protein sources for shrimp production. We studied the consequences of replacing FM with a defatted insect meal, ŸnMeal^TM (YM), comprised of yellow mealworm (Tenebrio molitor). Growth and immune parameters of juvenile Pacific white shrimp (Litopenaeus vannanmei) were compared after an eight-week feeding trial. Shrimp were kept in aquaria with densities of 60 and 40 shrimp/m² and fed one of five diets in which a proportion of FM was replaced by YM. All diets were isoproteic, isoenergetic, and balanced in lysine and methionine. After the feeding trial, shrimp were challenged with pathogenic bacteria (Vibrio parahaemolyticus). Growth and feed conversion parameters improved when YM was included in shrimp diets; with the highest weight gain and best food conversion ratio (FCR) achieved when 50% of FM was replaced by YM versus the control diet that contained no YM (initial weight: 1.60 g/shrimp; growth: 5.27 vs. 3.94 g/shrimp; FCR 1.20 vs. 1.59). In challenged shrimp, mortality rates were significantly less among groups that received YM, with a 76.9% lower mortality rate in the 50% FM replacement group versus the control.

The efficacy of a single cell protein (SCP) methanotroph (Methylococcus capsulatus, Bath) bacteria meal (FeedKind^®, Calysta, Menlo Park, CA, United States), in Pacific white shrimp (Penaeus vannamei) diets was studied to determine growth performance, survival rate and disease resistance against Vibrio parahaemolyticus causing Acute Hepatopancreatic Necrosis Disease (AHPND). The growth trial was assigned in a completely randomized design (CRD) with four treatments and 5 replicates of each, T1: a fishmeal-based control containing 15% fish meal and 3 diets with graded levels of methanotroph bacteria meal, namely T2: 5% methanotroph bacteria meal, T3: 10% methanotroph bacteria meal, and T4: 15% methanotroph bacteria meal. Shrimp were fed ad libitum for 6 weeks on trial diets to assess growth. Subsequent to the growth trial, three replicates of the same groups were exposed to V. parahaemolyticus by a single bath challenge and held for a further 15 days on the same diets as the growth study to assess survival and resistance. No significant differences (p > 0.05) in survival or in growth performance, including final weight, weight gain, specific growth rate, feed consumption or feed conversion ratio of white shrimp fed feeds containing methanotroph bacteria meal or control diets for 6 weeks. Immune markers such as hemocyte counts, phenoloxidase, superoxide dismutase and lysozyme activity were similar across all groups after the 6-week feeding trial. In a V. parahaemolyticus challenge, methanotroph bacteria meal in the diet significantly promoted the survival rate, and the reduction of Vibrio sp. in the hepatopancreas of white shrimp. Hemocyte count and phenoloxidase activity showed no significant differences (p > 0.05) between diet treatment groups, but hemolymph protein was significantly higher (p < 0.05) in shrimp fed diets containing 15% methanotroph bacteria meal after challenge. The Vibrio colony counts from hepatopancreas in the treatment groups were all significantly lower than the control (p < 0.05). The findings show that methanotroph bacteria meal can entirely replace fishmeal in white shrimp diets and the 15% inclusion of methanotroph bacteria meal in shrimp diet shows no adverse effects on growth performance, feed utilization and survival rate. In addition, shrimp fed methanotroph bacteria meal diets exhibited improved survival rates to an AHPND challenge.

The stability of formulated carotenoid diets during feed processing and under different storage conditions were studied. All carotenoid diets were split into two groups with one group containing BHT (acting as an antioxidant) at 250 ppm and the other without BHT. The experiment was divided into two parts. First, all diets were evaluated in total carotenoid (TC) loss during feed processing, in dry mixed feeds after being processed and dried. In the final part, the completed dietary carotenoids were stored in an aluminum foil bag, the top of which was sealed with a bag sealer and kept under different storage conditions at 26–28 °C and 4 °C. The stability of the TC was observed during an 8-week trial period. The results showed that the diet pelleting process did not affect the carotenoid content of the diets, and the best storage temperature for the formulated carotenoid diet was at 4 °C. However, an antioxidant was added to assist in energy saving before feed processing. Thus, the addition of BHT at 250 ppm can be done at normal room temperature in order to reduce oxidation that might cause a loss of TC quantities in diets.

To consider diet optimization for the growth and health of fish under intensive aquaculture systems, with a focus on the farming of Nile tilapia and red tilapia in Thailand, we conducted an experiment based on a completely randomized design (CRD), with three treatments and four replicates. Three diets, supplemented with different trace minerals, were applied to selected groups of fish: (a) a control diet, without organic trace minerals supplementation; (b) a T1 diet of chromium-L-methionine at 500 ppb, in combination with a zinc amino acid complex at 60 parts per million (ppm); and (c) a T2 diet of chromium-L-methionine at 500 ppb in combination with selenomethionine at 300 ppb. Red tilapia with an initial mean weight of 190 ± 12 g/fish were randomly distributed into cages of 2 × 2 × 2.5 m in a freshwater pond (12 cages in total), with 34 fish per cage and a density of 17 fish/m³. During the 8 week feeding trial, the fish were fed 3–4% of their body weight twice a day. The fish were weighed, then blood samples were collected to study their immune responses. The intestines were collected, measured, and analyzed at the end of the feeding trial. The results showed that the red tilapia that were fed with diets of chromium-L-methionine in combination with a zinc amino acid complex in the T1 treatment had significantly (p < 0.05) higher final weights, weight gains, average daily gains (ADGs), and better feed conversion ratios (FCRs), compared with fish that were fed with the control diet without organic trace minerals and with fish that were fed with the T2 diet (p < 0.05). The midgut and hindgut villus heights of the group fed with chromium-L-methionine in combination with a zinc amino acid complex in the T1 treatment were significantly higher than those of the other groups (p < 0.05). The levels of the antioxidative enzyme superoxide dismutase (SOD) and lysozyme activity were not significantly different from those of fish that were fed with the control diet (p > 0.05), whereas the glutathione level tended to increase (p < 0.1) in fish that were fed with chromium-L-methionine in combination with selenomethionine in the T2 treatment. Therefore, we concluded that chromium-L-methionine in combination with a zinc amino acid complex or selenomethionine clearly enhanced red tilapia’s growth performance and feed utilization through the promotion of antioxidative enzyme activity and immune response.

Introduction: Fish oil is a key component in aquatic feeds due to its high energy content, essential omega-3 fatty acids, and rich nutrient profile. However, its high cost necessitates sustainable alternatives. This study investigated the effects of dietary lysophospholipids (LPLs) on growth performance, digestive enzyme activity, and the expression of lipid metabolism-related genes in Pacific white shrimp (Litopenaeus vannamei).Methods: Juvenile shrimp (n = 400; initial weight: 1.55 ± 0.02 g) were randomly assigned to four dietary treatments in a 2 × 2 factorial design with four replicates per treatment: a positive control (PC) with 2% fish oil, a negative control (NC) with 1% fish oil, and two LPL-supplemented groups (NC+0.03% and NC+0.06% LPLs). After 8 weeks of feeding, growth performance, digestive enzyme activity, and gene expression related to lipid metabolism were evaluated.Results: LPL supplementation (0.03% and 0.06%) significantly improved almost growth parameters such as total production, weight gain rate, specific growth rate, feed conversion ratio and protein efficiency ratio compared with the NC group (P< 0.05). The PC group showed significant improvement only in specific growth rate, feed conversion ratio, and protein efficiency ratio. Lipase activity was significantly higher in both LPL groups and the PC group than in the NC group, while protease, trypsin, and chymotrypsin activities were highest in the NC+0.06% LPLs group (P&lt; 0.05). Amylase activity was significantly higher in the PC and NC+0.06% groups compared to others. LPL supplementation also significantly upregulated lipid metabolism genes, lipase (Lip) and delta fatty acid desaturase 6 (dFAD-6), along with the antioxidative stress gene superoxide dismutase (SOD) compared to NC group. In contrast, the PC group showed significant upregulation only of SOD compared to the NC group.Discussion: Dietary inclusion of 0.03%–0.06% LPLs effectively enhanced growth performance, nutrient utilization, and lipid metabolism, offering potential to reduce fish oil use by 1% in shrimp diets. These findings provide a basis for improving feed efficiency and sustainability in shrimp aquaculture.

Since Asian sea bass is one of the economically most important fish, aquaculture conditions are constantly optimized. Evidence from feeding studies combined with the current understanding of the importance of zinc for growth and immune defense suggest that zinc supplementation may be a possible approach to optimize aquacultures of Asian sea bass. To investigate the effects of zinc deficiency and zinc supplementation, cells from Asian sea bass were incubated in culture medium with different zinc contents. The expression of genes, important for zinc homeostasis, redox metabolism, and growth hormones was analyzed using RT-PCR. Zinc deficiency induced the expression of certain zinc transporters (ZIP14, ZIP10, ZIP6, ZIP4, ZnT4, ZnT9) as well as of SOD1, IGF I and IGF II, while expression of ZnT1 and metallothionein (MT) was reduced. Zinc supplementation decreased the expression of ZIP10, while expression of ZnT1 and MT were elevated. No differences in the effects of zinc supplementation with zinc sulfate compared to supplementation with zinc amino acid complexes were observed. Thus, extracellular zinc conditions may govern the cellular zinc homeostasis, the redox metabolism and growth hormone expression in cells from Asian sea bass as reported for other fish species. Our data indicate that supplementing aquacultures with zinc may be recommended to avoid detriments of zinc deficiency.