This study analyzed the performance, antioxidant status, hepatopancreatic lipoperoxidation, and proximate composition of Macrobrachium rosenbergii juveniles fed diets supplemented with clove basil (Ocimum gratissimum) essential oil (EO-OG). A total of 360 M. rosenbergii (initial weight 0.028 g ± 0.004) were randomly divided into four experimental groups with six replications each (n = 6). The prawns were fed diets with different EO-OG inclusion levels: 0.0, 1.0, 2.0, and 3.0 g kg⁻¹ EO-OG. After a 42-day feeding trial, dietary EO-OG showed no significant effect on prawn performance or carcass proximate composition, except on final antenna length. Prawns fed 3.0 g kg⁻¹ EO-OG displayed a 1.2- to 1.3-fold longer final antenna length than prawns from all other experimental groups. Likewise, prawns fed 3.0 g kg⁻¹ EO-OG presented a 2.6- to 3.2-fold higher catalase activity than prawns from all other experimental groups. Prawns fed EO-OG, regardless of the inclusion level, showed a 1.6- to 1.7-fold decreased hepatopancreatic lipoperoxidation compared to the control group. Therefore, EO-OG has been demonstrated to be a potential management tool as a non-nutritional dietary immunostimulant and animal welfare promoter for freshwater prawn farming, without affecting animal performance. This study recommends the dietary inclusion level of 3.0 g kg⁻¹ EO-OG for M. rosenbergii juveniles.

The objective was to evaluate the effects of partial replacement of fish meal with protein hydrolysates and a commercial product in the diets of Penaeus vannamei post-larvae on zootechnical performance, proximate chemical composition, digestive enzyme activity, and total hemocyte count. The experiment was conducted in a clear water recirculation system comprising 24 experimental units, each with 30 shrimp with an average weight of 0.2 g. The treatments were control, chicken protein hydrolysate (CPH), enzymatic hydrolysate of chicken feathers, Aquabite^®, CPH + maltodextrin, and CPH + yeast, with four replicates each. The inclusion level of the different protein sources evaluated was 6%. At the end of the experiment, all shrimp were counted, weighed, and measured to determine the zootechnical performance. The body and feed chemical compositions, as well as the enzymatic activities of the hepatopancreas and the total hemocyte count in the hemolymph, were analyzed. The data obtained were subjected to ANOVA and Tukey’s test. There was no statistical difference between the treatments in any of the analyzed parameters. The results showed that all the evaluated protein hydrolysates can be used as partial substitutes for fish meal in P. vannamei diets during the nursery phase, maintaining equivalent and adequate digestive enzyme activities, health, growth, and body composition of the shrimp, in addition to being ecologically sustainable ingredients.

This study evaluated the inclusion of protein hydrolysates and a commercial product as a partial replacement for fish meals in the diet of Pacific white shrimp (Penaeus vannamei) during the grow-out phase. A recirculation system with 24 experimental units and a biological filter was used. The experimental design was completely randomized with six treatments: control; chicken protein hydrolysate (CPH); enzymatic hydrolysate of chicken feathers; Aquabite^®; CPH + maltodextrin; CPH + yeast; and four replicates. After 50 days, the zootechnical performance and animal welfare parameters, centesimal carcass composition, digestive enzyme activity, and hemocyte count were evaluated. The treatments did not affect the zootechnical performance and total hemocyte count of the animals (p > 0.05). The evaluation of the antenna length indicated that all animals were in good health. The antenna length in treatment T5 was significantly greater (p > 0.05) than that in T4 and similar to that in treatments T3 and T6, demonstrating a positive influence of dietary protein hydrolysates. Concerning animal welfare, dietary protein hydrolysates influenced the length of the antenna (p < 0.05). The antenna length associated with different treatments indicated that the animals were in good welfare conditions in the production environment. With respect to body chemical composition, dry matter, ether extract, and ash were affected by the treatments (p < 0.05). Regarding the analysis of digestive enzymes, the treatments influenced the activities of amylase and trypsin (p < 0.05). The performance of the animals was satisfactory under all treatments, including enzymatic activity, demonstrating the possibility of using hydrolysates.

This study evaluated the anaesthetic potential of clove basil (Ocimum gratissimum) essential oil (EO-OG) in the post-larvae (PLs) of M. rosenbergii. The PLs were individually transferred to aquariums (500 mL) containing 50, 100, 150, 200, or 300 μL L⁻¹ EO-OG. A sixth group of PLs was exposed to freshwater only, and a seventh group was exposed to the highest concentration of ethanol used to dilute EO-OG. Upon reaching the anaesthesia stage, the PLs were transferred to aquariums (500 mL) with freshwater only to evaluate the recovery time. The shortest sedation times were observed at 200 (15.98 s) and 300 μL L⁻¹ (25.85 s). The shortest anaesthesia time was observed at 200 μL L⁻¹ (22.52 s). The longest recovery time was observed at 100 μL L⁻¹ (1367.10 s); the shortest recovery time was observed at 150 μL L⁻¹ (630.10 s). No mortality or adverse effects were observed in any experimental group. The concentration of 150 μL L⁻¹ resulted in sedation (49.24 s), anaesthesia (80.10 s), and recovery (630.10 s) times within those suggested as adequate for freshwater prawn farming. This research demonstrated the sedative and anaesthetic properties of EO-OG and its potential application in prawn farming. This study recommends using 150 μL L⁻¹ of EO-OG in M. rosenbergii PLs.

We evaluated the inclusion of hydrolyzed feather meal (HFM) as a partial replacement for fishmeal in diets for Macrobrachium rosenbergii post-larvae (PL) over a 32-day nursery feeding trial. Five experimental diets with increasing HFM levels (control, 1.5%, 3.0%, 4.5%, and 6.0%) were tested. Survival rates ranged from 73.3 ± 5.44% to 83.3 ± 3.84% without significant differences among groups. Dietary HFM inclusion levels above 3.0% significantly improved prawn performance, including final weight (up to 2.18-fold higher than control), length (1.13-fold), antenna length (1.18-fold), biomass gain (2.14-fold), and feed conversion ratio (1.59-fold lower). Prawn-fed diets at 6.0% HFM showed the highest performance among all experimental groups. No significant effects were observed on antioxidant biomarkers or digestive enzymes in prawns hepatopancreas, which suggests no imbalance in the antioxidant system or impairment of digestive function. Likewise, carcass proximate composition remained stable across experimental groups. These findings suggest that HFM at 3.0–6.0% dietary inclusion levels is a potential alternative to fishmeal in nursery-phase diets for M. rosernbergii PL, promoting prawn growth and welfare and maintaining health and carcass quality. Notably, to the best of our knowledge, this is the first study demonstrating the potential effective use of HFM in feeding the nursery phase of M. rosernbergii.

<!--Galleys --> <!--Full Text:--> PDF <!--END GALLEYS---> Abstract The objective of this study was to identify morphological characteristics of different populations of Penaeus schmitti Burkenroad, 1936 to contribute to its biology and conservation. In order to compare geographically isolated populations, between 2014 and 2016, selected biological variables were analyzed in six populations dispersed along the Brazilian coast and one from the Cuban coast. Specimens with eight upper rostral teeth predominated. The ordination of shrimp measurements by non-metric multidimensional scaling showed the greatest dispersion on data from Cuba, Rio Grande do Norte, and Espirito Santo, which are also the localities that presented the highest coefficient of variation. On the other hand, the values corresponding to Sergipe, Rio de Janeiro, Paraná, and Santa Catarina showed a greater similarity or clustering of the data of each location. Tail weight was estimated using length and depth of the sixth abdominal segment. The populations of Santa Catarina, Brazil (28°S), had the longest and heavier abdomens proportionally among all the compared populations, while the organisms of Manzanillo, Cuba (20°N), had proportionally shorter abdomens and the narrowest cephalothorax. The regression equation indicated a positive allometric growth for P. schmitti, and the largest total length reported for genus Penaeus in the natural environment corresponded to a P. schmitti specimen. This information could be useful in future taxonomic studies to correctly identify the species and its morphological variability. Color differences were also observed, with white ventral spots in the sternite XIV of some females from Brazilian populations, which was not previously reported in the literature. Extending these studies is recommended to contribute to the conservation and culture of P. schmitti.