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Shrimp (Litopenaeus vannamei) were provided access to sea urchin (Lytechinus variegatus) egesta to investigate whether fresh egesta (containing an active microbiome) consumed alone or in combination with a commercial shrimp feed could influence growth, feed conversion, body composition, and survival of L. vannamei in co-culture. In an initial experiment conducted for 8 wk, shrimp were proffered a full or reduced ration (100%, 60%, and 20%) of commercial shrimp feed with or without access to sea urchin egesta serving as a source of supplemental nutrients and presumptive probiotics. Individual weight gain of shrimp provided sea urchin egesta only (10.37 [+ or -] 0.35 g) did not differ significantly from that of shrimp proffered a full ration of feed (9.46 [+ or -] 0.39 g) despite significant compositional differences. Consumption of sea urchin egesta combined with commercial shrimp feed resulted in significantly greater weight gain of shrimp when compared with shrimp proffered the same level of commercial shrimp feed only. The largest weight gains of shrimp were found for those groups fed rations of 60% and 100% and had access to egesta (14.09 [+ or -] 0.75 g and 14.72 [+ or -] 0.68 g, respectively). In the next experiment, shrimp were stocked at different densities (approximately 23, 45, 68, and 90 individuals [m.sup.-2]) and were not proffered feed directly. All replicates were provided access to fresh sea urchin egesta produced by four urchins that were fed at a daily rate of 3% of the total initial group weight (140.4 [+ or -] 0.7 g) for 8 wk. The largest individual weight gain was found in the lowest density treatment (6.55 [+ or -] 0.38 g). Harvested biomass significantly increased as density increased, except for the highest density treatment. These results indicate that sea urchin egesta may provide some growth enhancement factor(s) to shrimp when proffered in conjunction with a commercial diet, and at a certain density of shrimp sea urchin egesta may actually serve as a nutritionally complete diet. KEY WORDS: Lytechinus variegatus, Litopenaeus vannamei, co-culture, egesta, integrated aquaculture, sea urchin, shrimp, INTRODUCTION A previous study (Jensen et al. 2018) suggested that fresh egesta (fecal pellets) produced by sea urchins (Lytechinus variegatus) served as a sufficient source of nutrition for cocultured Litopenaeus [...]

Previously, dietary humic substances (HSs) or protease complexes (PCs) in fingerling channel catfish Ictalurus punctatus (Rafinesque) have demonstrated potential for health enhancement. Two trials were conducted to elucidate an optimal HS or PC administration plan for growth and health promotion. The first feeding trial was conducted within a recirculating aquaculture system. Catfish fingerlings were fed a commercial control (28% protein) or supplemented diet (control + PC or HS). Diets were administered through four feeding regimens of either HS, or PC‐supplemented diet. After 60 days, continuous feeding of diets with HS or PC contributed to improved feed efficiency and weight gain of the fish. Similarly, catfish growth was enhanced following the application of HS or PC for the final 4 weeks. Serum lysozyme activity was relatively improved in catfish when a PC or HS diets were offered for 60 days. Feeding either of the supplements for the final 4 weeks improved skin lysozyme activity compared to the control group. In the second trial, catfish were fed either the commercial control diet, PC‐supplemented diet, or HS‐supplemented diet in an outdoor production environment for 60 days. Both HS and PC catfish groups had higher survival rates than the control group. Furthermore, growth performance was superior in additive‐fed groups. After HS or PC application, gut microbiota analysis from catfish fecal at two time points revealed significant variation in alpha diversity, community abundance, and beta diversity. However, the association of dietary HS or PC on improved survival, immunity, and gut microbiota modulations presents their importance as functional immunostimulants in catfish aquaculture. [ABSTRACT FROM AUTHOR]

Channel catfish (Ictalurus punctatus) and Nile tilapia (Oreochromis niloticus) are two aquaculture species of great importance. Intensive production is often hindered by poor growth performance and disease mortality. The aim of this study was to evaluate the potential of a commercial fermented yeast product, DVAQUA, on channel catfish and Nile tilapia growth performance metrics and disease resistance. Channel catfish and Nile tilapia were fed practical diets supplemented with 0%, 0.1% or 0.4% of DVAQUA over approximately 2‐month feeding periods in recirculation aquaculture systems. To assess the potential of the postbiotic against common aquaculture pathogens, juvenile catfish were subsequently challenged by immersion with Edwardsiella ictaluri S97‐773 or virulent Aeromonas hydrophila ML09‐119. Nile tilapia juveniles were challenged by injection with Streptococcus iniae ARS‐98‐60. Serum lysozyme activity, blood chemistry and growth metrics were measured at the end of the feeding period, but no differences were observed across the different metrics, except for survival. For the pathogen challenges, there were no differences in endpoint mortality for channel catfish with either pathogen (p >.05). In contrast, Nile tilapia survivability to S. iniae infection increased proportionally to the inclusion of DVAQUA (p =.005). Changes to sera lysozyme activity were also noted in the tilapia trial, with a reduction of activity in the fish fed the 0.4% DVAQUA diet compared to the control diet (p =.031). Expression profiles of proinflammatory genes and antibodies were also found to be modulated in channel catfish fed the postbiotic, indicating some degree of protective response. These results suggest that this postbiotic may be beneficial in protecting Nile tilapia against S. iniae infection by influencing immune parameters and additional research is needed to evaluate the potential of this DVAQUA for improving catfish health and disease control. [ABSTRACT FROM AUTHOR]

Florida pompano, Trachinotus carolinus, can be fed soy‐based, low‐animal protein diets. However, anti‐nutritional factors and carbohydrates limit digestibility. Dietary carbohydrase enzymes have been used to improve carbohydrate digestibility in several species and may be beneficial for Florida pompano. The present study was designed to evaluate the effects of using a carbohydrase enzyme complex (Natugrain® TS L, BASF Corporation, Ludwigshafen, Germany) composed of endo‐1,4‐ß‐xylanase and endo‐1,4‐ß‐glucanase (Xyl + Glu) on growth performance, feed utilization, and digestibility in diets fed to juvenile Florida pompano. A growth trial was conducted with iso‐nitrogenous (40%) and iso‐lipidic (8%) test diets containing 0, 0.015, 0.030, and 0.045% of Xyl + Glu. The trial was conducted in a recirculating system with 12, 1000‐L tanks. Twenty fish (mean weight: 23.34 g ± 1.49 g) were stocked into each tank in a randomized design. Growth results indicated that there were no significant differences (p > 0.05) in growth and feed conversion; however, thermal growth coefficient displayed significant differences (p = 0.0499) between the 0.015 and 0.030% inclusion. All enzymatic treatments displayed significant differences (p = 0.029) in apparent digestibility of crude protein compared with the basal diet. Results indicate that Xyl + Glu enzyme complex can impact protein digestibility but did not significantly affect growth performance. [ABSTRACT FROM AUTHOR]

A 56-day feeding trial was conducted to evaluate the quantitative methionine requirements in the diets of Florida pompano (Trachinotus carolinus). Eight practical diets using soybean meal, poultry meal, and red lentil meal as the primary protein sources were formulated using graded levels of methionine supplement (0 to 0.70 g/100 g diet). Groups of 15 juvenile Florida pompano (4.04 ± 0.05 g) were size-sorted and placed into one of 40 glass aquaria (132 L) with five replicates per diet. Significant differences (p ≤ 0.05) were observed in overall biomass, mean weight, weight gain, thermal growth coefficient (TGC), and feed conversion ratio (FCR). To estimate the dietary methionine requirement, a series of statistical models, including the one-slope broken line model (BLM1), two-slope broken line model (BLM2), broken quadratic model (BQM), and four-parameter saturation kinetic model (SKM-4) were used to assess mean weight, weight gain, TGC, apparent net protein retention (ANPR), and methionine retention (MR). The model selection showed that BLM1 fit the data best for MW and TGC, SKM-4 for PWG and ANPR, and BQM for MR. Based on these results, a minimum dietary methionine requirement of 0.68% of the diet or 1.70 g/100 g protein is recommended. [ABSTRACT FROM AUTHOR]