Andressa Tellechea Rodrigues

The replacement of fishmeal with plant-based ingredients in aquafeeds, while economically and environmentally advantageous, can impair lipid metabolism and liver function in fish due to the lack of specific bioactive compounds such as bile acids (BAs). BAs are amphipathic steroid molecules that facilitate lipid digestion and act as signaling hormones, yet their optimal inclusion levels in conventional, balanced diets for Nile tilapia (Oreochromis niloticus) remain undefined. This study evaluated the effects of dietary BA inclusion on growth performance, feed efficiency, body composition, and serum biochemical parameters of juvenile Nile tilapia (GIFT strain, initial weight 18.04 ± 3.67 g) and estimated the optimal inclusion level. Six isoproteic (320 g kg⁻¹) and isoenergetic (3300 kcal kg⁻¹) plant-based diets were formulated with increasing BAs levels (0, 50, 100, 200, 400, and 600 mg kg⁻¹) and fed to quadruplicate groups for 45 days. Only the Linear Response Plateau (LRP) model converged for weight gain data, estimating the optimal BA level at 479.70 mg kg⁻¹, with a plateau weight gain of 76.60 g. Inclusion of the 50–600 mg kg⁻¹ BAs significantly improved specific growth rate (up to 4.53%), crude protein retention efficiency (up to 81.11%), and whole-body crude protein content (up to 50.52%) compared to the control (p < 0.05). Fish fed 200 mg kg⁻¹ BAs exhibited the highest protein retention and lowest ether extract deposition, indicating a protein sparing effect. Serum lipase activity increased proportionally with BAs levels, while alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were reduced at 400 mg kg⁻¹ BAs, reflecting improved liver health. No mortality was recorded. In conclusion, dietary BAs inclusion enhances growth, protein utilization, and hepatic function in juvenile Nile tilapia fed plant-based diets. The recommended optimal level is 479.70 mg kg⁻¹ (dry matter basis), although significant benefits already occur from 50 mg kg⁻¹. These findings support the strategic use of BAs to improve the sustainability and efficiency of tilapia production.

As aquaculture activity grows to meet population demand, farming systems intensify. Therefore, new research seeks to find nutritional additives that have a positive impact, reducing their breeding time and mortality. The present study addresses the effects of the inclusion of increasing levels of bioactive peptides obtained from Tenebrio molitor (BPTM) on the growth, somatic indices, body composition, circulating metabolites and digestive enzyme activity of juvenile silver catfish (Rhamdia quelen). Three isoproteic and isocaloric diets were formulated to contain levels of 0 %, 0.5 % or 1.0 % inclusion of BPTM. In a water recirculation system, 336 jundiá juveniles (initial average weight of 3.83 ± 0.69 g) were distributed in 12 experimental units (four replicates per treatment). Fish were fed the experimental diets to apparent satiety for six weeks. At the end of the trial, biometric measurements, blood samples and body tissue samples were collected. No significant differences were observed for final weight, total length, weight gain, condition factor, somatic digestive index, somatic hepatic index and intestinal quotient among the animals in the different treatments. Regarding body composition, there were differences in moisture and ash values (higher concentrations in fish in the 0.5 % and 1.0 % BPTM treatments, respectively). The activity of intestinal trypsin and chymotrypsin was not affected, as well as the plasma parameters evaluated. It is concluded that the inclusion of BPTM did not negatively affect the parameters evaluated, but further studies need to be carried out to elucidate an ideal level of peptide inclusion.

Resumo Conforme a atividade aquícola cresce para atender a demanda populacional, os sistemas de cultivo se intensificam. Assim, novas pesquisas buscam encontrar aditivos nutricionais que reflitam positivamente, reduzindo seu tempo de criação e mortalidade. O presente estudo aborda os efeitos da inclusão de níveis crescentes de peptídeos bioativos obtidos a partir de Tenebrio molitor (PBTM) sobre o crescimento, índices somáticos, composição corporal, metabólitos circulantes e atividade de enzimas digestivas de juvenis de jundiá (Rhamdia quelen). Três dietas isoprotéicas e isocalóricas foram formuladas para conter níveis de 0 %, 0,5 % ou 1,0 % de inclusão de PBTM. Em um sistema de recirculação de água foram distribuídos 336 juvenis de jundiá (peso médio inicial de 3,83 ± 0,69 g) em 12 unidades experimentais (quatro repetições por tratamento). Os peixes foram alimentados com as dietas experimentais até a saciedade aparente durante seis semanas. Ao final do ensaio, foi realizada biometria, coleta de sangue e de tecidos corporais. Não foram observadas diferenças significativas para o peso final, comprimento total, ganho de peso, fator de condição, índice digestivo somático, hepato somático e quociente intestinal, entre os animais dos diferentes tratamentos. Quanto à composição corporal, houve diferença nos valores de umidade e cinzas (maiores concentrações nos peixes dos tratamentos 0,5 % e 1,0 % de PBTM, respectivamente). A atividade de tripsina e quimotripsina intestinal não foi afetada, bem como os parâmetros plasmáticos avaliados. Conclui-se que a inclusão de PBTM não afetou negativamente os parâmetros avaliados, porém mais estudos precisam ser realizados para elucidar um nível ideal de inclusão de peptídeos.

Aflatoxin is a mycotoxin produced by fungi of the genus Aspergillus that is present in various foods. Probiotics are well-established products in aquaculture, and due to their effective contribution to the intestine, they can be used as an aflatoxin adsorbent. This study evaluated the effects of aflatoxin B1 (AFB1) on enzymatic activity and intestinal function in Piaractus mesopotamicus (pacu) fingerlings fed diets containing a probiotic-based adsorbent (PBA). Seventy-two fish with an average weight of 12 ± 1.30 g were used in the study. The experiment was conducted over 15 days using a completely randomized design with six diet treatments (AFB1 per kg of formulated diet) and two replicates. These treatments were: control without AFB1; 25.0 µg of AFB1; 400.0 µg of AFB1; control diet without AFB1 + PBA; 25.0 µg of AFB1 + PBA; and 400.0 µg of AFB1 + PBA. After the experimental period, the digestive enzymes protease, amylase, and lipase from the stomach, pyloric caeca, and intestine were quantified. The height and width of the intestinal villi, pyloric caeca, and stomach wall were measured. Fish fed the 400.0 µg of AFB1 diet showed reduced feed consumption, even though they ingested higher amounts of AFB1 compared to those fed the other experimental diets. The best zootechnical performance parameters were observed in fish fed the control diet without AFB1 + PBA. Changes (p < 0.05) were observed in the amount of protease in the stomach, pyloric caeca, and intestine; in the amount of amylase in the intestine; and the amount of lipase in the pyloric caeca and intestine. Changes were observed (p < 0.05) in the length of the stomach wall and the anterior and posterior intestines. Changes in the width of the stomach and anterior intestine walls were observed as a result of diet. Our results suggest that the use of probiotics as an aflatoxin adsorbent in pacu diets is beneficial from a physiological perspective and may also enhance growth.

Objetivou-se caracterizar o perfil fermentativo, valor nutricional e microbiológico da silagem da raiz de mandioca in natura com e sem aditivos. Foi utilizado delineamento inteiramente casualizado em esquema de parcelas subdivididas no tempo 4x3, com cinco repetições. Nas parcelas foram alocados os materiais de estudo: Raiz de mandioca triturada in natura ou adicionado dos farelos de milho, soja ou arroz. Nas subparcelas foram alocados os tempos: material fresco: antes da ensilagem, abertura: aos 45 dias de fermentação e estabilidade após a silagem ser exposta ao ar durante sete dias. Foram realizadas as amostragens para determinação das análises bromatológicas, nutrientes digestíveis totais, digestibilidade, pH, temperatura, nitrogênio amoniacal, o perfil microbiológico por meio da determinação das populações de fungos e leveduras, Clostridium, bactérias ácido láticas e enterobactérias. A adição de farelos alterou os parâmetros avaliados. A matéria seca aumentou ao longo da fermentação e da exposição ao ar e em todos os tempos e materiais o pH foi adequado. A proteína bruta diminuiu até a abertura dos silos devido as fermentações indesejadas, apresentando-se mais elevada na silagem adicionada de farelo de soja. Os baixos conteúdos de compostos fibrosos e NDT, e a elevada digestibilidade sugerem silagens obtidas como alimentos energéticos em dietas de ruminantes e/ou monogástricos. Em conclusão, a raiz de mandioca in natura ou com inclusão de aditivos pode ser conservada na forma de silagem para uso nas dietas de ruminantes.

Dietary protein quality and proper protein to energy ratios: a bioeconomic approach in aquaculture feeding practices

In the present study, juvenile (live body weight, 54.3 ± 8.2 g), preadult (live body weight, 822.5 ± 33.9 g), and adult (live body weight, 1,562.8 ± 41.8 g) pacu, Piaractus mesopotamicus, were used to estimate their dietary essential amino acid (EAA) requirements using the whole‐body amino acid (AA) pattern. The results showed that whole‐body moisture, crude protein, total lipid, and ash contents expressed on a wet weight basis (%) were significantly different among the studied growth phases. No significant differences were observed in the dietary EAA requirements estimated for the three growth phases of pacu. These dietary EAA requirements were found to be different than those previously estimated for the same fish through its muscle AA pattern. Based on whole‐body EAA to total EAA ratios {A/E ratios; [(each EAA/total EAA) × 1,000]}, EAA requirements were estimated to be histidine (0.42%), arginine (1.36%), threonine (0.82%), valine (0.90%), methionine (0.45%), isoleucine (0.83%), leucine (1.29%), phenylalanine (0.74%), lysine (1.64%), and tryptophan (0.14%) for pacu. These estimated requirements may serve as a reference line in the formulation of practical and experimental diets until dose–response‐based optimum EAA requirements are available for pacu.