Biofloc (consortium of diverse microorganisms associated to suspending substrates) was developed from waste of shrimp Litopenaeus vannamei postlarvae culture under low salinity (5 g L−1) to provide ...an additional nutritious biomass and reduce fishmeal inclusion in feeds in a 28‐day indoor shrimp nursery trial conducted in 15 experimental containers (250 L stocked at 600 org m−3). Four experimental diets (isoproteic and isocaloric) containing different percentage of fishmeal: 0%, 10%, 20% and 30% substituted by vegetable meal mix (corn, sorghum and wheat) were formulated and elaborated. A control treatment consisted of a commercial feed. The main water quality parameters were monitored, and no significant differences were found among treatments. The growth and survival were similar among treatments. In general, digestive enzymatic activities showed differences being greater in the biofloc system compared with clear water. It was concluded that low‐salinity shrimp nursery could be successfully developed with minimum inclusion of fishmeal in feeds, without significant effect on production response. The adjustment of C : N ratio allowed the increase of microbial biomass in the bioflocs, which contributed to maintain good water quality, provide live food and enhance digestive enzymatic activity of cultured organisms.
Squid hydrolysates obtained by autolysis without addition of lactic acid at two different pH (5 and 7) and included at 25 and 50 g kg⁻¹ in a commercial shrimp feed were evaluated. Shrimp fed on such ...diets were cultured under indoor and outdoor conditions. Diets containing both hydrolysates and included at both levels caused a higher feed consumption by shrimp. In general, shrimp fed on both hydrolysates, but particularly on that prepared at pH 7, exhibited similar or better production responses (survival, biomass, feed conversion ratio, specific growth rate) compared to those fed on diets without the inclusion of hydrolysates. Shrimp cultured outdoor showed a better growth performance compared to those cultured indoor. No significant differences were found regarding the proximate composition of shrimp of any treatment. Results suggest that the free amino acids provided by squid hydrolysates contributed to improve the feed consumption and growth performance of shrimp cultured under both indoor and outdoor conditions.
The effect of promoted biota on the production parameters, water quality, nutritional and immunological condition of Litopenaeus vannamei was assessed in semi-intensive ponds. Earthen ponds were used ...as experimental units: three with formulated + natural promoted feed + shrimp (T1), three with formulated feed + shrimp (T2), and three with promoted natural feed without shrimp (Control). The dissolved oxygen (DO) levels were optimal for all treatments (≥6 mg L⁻¹) as well as the pH (8.4-8.6). Total ammonia nitrogen was greater in T2 (0.10 mg L⁻¹) than T1 (0.07 mg L⁻¹) and the Control (0.06 mg L⁻¹). Phytoplankton, zooplankton and benthos were more abundant in T1 and the Control. The promotion of natural feed had a positive effect on all the production parameters of shrimp with an increase of 19.0%, 3.5% and 23.9% in weight gain, survival, and final biomass, respectively; also it was observed a decrease of 13.9% in feed conversion ratio. No differences in haemolymph parameters were observed for nutritional indicators (glucose, cholesterol, proteins, and triglycerides) nor for immunological response (phenoloxidase and prophenoloxidase). The results indicate that the promotion of biotic communities enhances the production parameters of farmed shrimp, without affecting the nutritional and immunological status. Also the water quality was improved by the presence of biota.
A 7‐week study was performed to evaluate the partial and total replacement of formulated feed (FF) by live insects (Trichocorixa sp.), during intensive culture of Litopenaeus vannamei. Production ...response, physiological status and postharvest quality were evaluated. Five treatments consisting of 0%, 25%, 50%, 75% and 100% of FF replacement (T‐0, T‐25, T‐50, T‐75 and T‐100) were performed. Better production responses were observed in T‐50, followed by T‐0 and T‐75 respectively. Also, no negative effect of insect supplying was detected on the physiological status of shrimp (evaluated by haemolymph parameters). However, shrimp fed exclusively on insects (T‐100) had poor growth and physiological performances, and lower postharvest quality compared with the rest of treatments. Regarding organoleptic characteristics, no effect of treatments was detected on the colour, odour and taste of shrimp muscle. In conclusion, the insect Trichocorixa sp. can contribute to the nutritional requirements of shrimp and could be used as complementary natural food, improving productive responses, without affecting the physiological status or the post mortem quality of shrimp; however the total substitution of FF by insects is not recommendable.
Zooplankton communities were studied in shrimp ponds using different strategies to enhance natural productivity. The traditional treatment consisted of performing the strategy of simple fertilization ...(TT); for the alternative treatment (AT), fertilization was combined with the use of organic substrates enriched with nutrients; both treatments were stocked with shrimp post-larvae (
Litopenaeus vannamei
). Additionally, ponds with substrates but without shrimp were also studied (C). Total zooplankton concentration was greater in C ponds (1,002 org L
−1
) followed by AT (309 org L
−1
) and TT (124 org L
−1
), respectively. Copepods were the most abundant organisms in all treatments (≥65 %), but their concentration decreased when shrimp were present in ponds. Such decline of copepods enhanced the proliferation of other zooplankton organisms such as polychaetes, protozoans, barnacles, ciliatea and others. Contents of shrimp stomachs exhibited a shrimp preference for copepods, polychaetes and protozoans; in addition, stomach contents of shrimp revealed their higher consumption of zooplankton when these organisms are abundant in the culture. Finally, shrimp reared in AT had a better growth performance than those from TT. It is concluded that enriched substrates are useful to improve and maintain high concentrations of zooplankton; copepods seem to suppress the proliferation of other zooplankton populations; however, they are preferred preys by shrimp.
Se realizó un experimento durante siete semanas para evaluar el efecto del suministro de copépodos (Acartia sp. y Calanus pacificus), como alimento exógeno durante la preengorda intensiva de camarón ...blanco (Litopenaeus vannamei), en los parámetros de producción y la calidad del agua. Se probaron cinco tratamientos en los que el camarón fue alimentado con dieta formulada más la adición de 0 (control), 1, 2, 4 u 8 copépodos mL-1. En los tratamientos con 1 y 4 copépodos mL-1 se observaron niveles de nitrógeno amoniacal total superiores al resto de los tratamientos (>4 mg L-1). El nivel de nitritos fue significativamente más alto en el tratamiento con 8 copépodos mL-1, mientras que el de nitratos fue más elevado en todos los tratamientos en comparación con el control. La concentración de fosfatos fue superior en los tratamientos con 4 y 8 copépodos mL-1. Los camarones en los tratamientos con 2, 4 y 8 copépodos mL-1 presentaron mayor supervivencia (>93%), peso (>3.1 g) y biomasa final (>77 g). El tratamiento con 2 copépodos mL-1 presentó el mejor factor de conversión alimenticia (1.19) en comparación con el resto (>1.7). Los resultados sugieren que la adición de copépodos como alimento natural exógeno durante la preengorda intensiva del camarón puede tener un efecto negativo sobre la calidad del agua, aunque esto no afectó la supervivencia; sin embargo, el efecto en los parámetros de producción fue positivo y se considera viable el uso de copépodos como alimento vivo para la etapa de preengorda en el cultivo de camarón blanco.
Carbohydrate and lipid digestibility of three vegetal and four animal ingredients, and diets in which they were included, were evaluated for juvenile Australian redclaw crayfish, Cherax ...quadricarinatus. The ingredients were: soy paste, textured wheat, sorghum meal, sardine meals (67% and 58% crude protein), squid meal and red crab meal. A basal diet was formulated, and then seven experimental diets were created, including 150 g kgsuperscript -1 of each ingredient in the reference diet. Digestibility was measured in vivo, using chromic oxide as marker. A single-factor, completely randomized experimental design with three replicates per treatment was performed. Mean carbohydrate digestibility of vegetal ingredients and the corresponding diets was better than carbohydrate digestibility of animal ingredients. Sorghum meal had a carbohydrate digestibility over 94%, and the diet in which it was included over 92%. Soy paste and wheat meals also presented excellent carbohydrate digestibility (around 88% for ingredients and over 90% for diets). Mean carbohydrate digestibility of animal ingredients and their corresponding diets were very poor (from 18% to 32%) and this affected the carbohydrate digestibility of diets in which they were included (87-89%). Lipid digestibility was also better for vegetal ingredients. Soy paste and wheat meal recorded values over 93% and their diets over 94%. Sorghum lipid presented slightly lower digestibility. Some of the animal ingredients, especially red crab, had an excellent lipid digestibility (92.1%).
Bacterial diversity of phototrophic (PAb) and heterotrophic (Hb) biofilms was studied over time (0, 15 and 30 days of culture) using high throughput sequencing and considering the V3 and V4 ...hypervariable regions of the 16S rRNA gene. Bacterial composition in terms of relative abundance and diversity showed slight changes during the trial. Proteobacteria was the most abundant phylum in both biofilms during the experimental period. Chlamidiae-Verrucomicrobia, Bacteriodetes, and Planctomycetes were also abundant phyla in the PAb, whereas Planctomycetes, Bacteriodetes, Actinobacteria, and Chlamydiae were the abundant phyla in the Hb. Of the reads assigned up to species level, a total of 27 heterotrophic and autotrophic species were detected in both biofilms, most of them associated with the metabolism of nitrogenous and sulfurous metabolites and organic matter, and the rest with the structural functions in the biofilm. This is the first time some of these species have been reportedly detected in these biofilms or in the marine environment. Results suggest complex interaction networks in microbial conglomerates formed in biofilms, in which bacterial populations seem to play important metabolic and physiological roles.
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