Olimpia Carrillo

The Pacific fat sleeper, Dormitator latifrons, is an omnivorous freshwater fish that primarily feeds on detritus. Our understanding of the digestive physiology of this species still needs to be completed, particularly concerning the characterization of its digestive enzymes. This information is crucial in guiding the design of diets that promote optimal digestion of this species, which has the potential for aquaculture. Thus, this study aimed to optimize enzymatic methods and characterize the digestive enzymes of the digestive tract regions: anterior region (AR), middle region (MR), posterior region (PR), and hepatopancreas (HP). Total acid protease, total alkaline protease, amylase, and lipase activities were measured. The enzymatic methods were optimized at an eco-physiological temperature of 25 degrees C based on extract volume, extract dilution, incubation time, pH, and CaCl2 concentration to determine specific activity (U/mg of protein). The optimal pH for acid protease (AR) was pH 2.0; while for alkaline protease, the optimal pH was between 7.5 and 11.0. For AR, chymotrypsin was pH 7.0; for the remaining digestive regions, it was pH 9.0-11.0. The optimal pH for amylase was 6.0 to 7.5 (all regions), and for lipase, it was between 7.0 and 11.0, with two apparent in vitro activity peaks (PR). HP experimental samples showed low or no chymotrypsin, amylase, and lipase activity. CaCl2 did not affect enzyme activity except for amylase and lipase (only in PR and HP, respectively). The acid proteolytic activity (pH 2.0) found in AR and the proteolytic inhibition by pepstatin suggest the presence of a stomach.

PDF Abstract The development of feeding protocols and the study of gastric evacuation or passage of food through the digestive tract is essential to generate information on the digestive physiology of organisms, as they help to quantify the daily ration to avoid any poor diet. In this sense, the present work aims to demonstrate some basic aspects of the fish Dormitator latifrons digestive physiology by evaluating the transit of food through the intestinal tract as a function of time. In a completely randomized standard design, juveniles of D. latifrons were fed ad libitum with commercial pellets. Five conditioned organisms were sacrificed every hour after a single feeding. The food bolus was collected at each sampling point, using polynomial regression models to analyze the passage of food through time in the digestive tract. The passage of food showed a nonlinear behavior in time, being the simple exponential decay model of two parameters (R² = 0.630; P < 0.0001) the best to explain the evacuation of food through the digestive tract. This knowledge will generate better feeding protocols for this species with commercial importance and aquaculture potential.

Objective: To evaluate some reproductive aspects of D. latifrons and the nutritional quality of its eggs. Design/methods/approach: Eighty-two fish were randomly collected (August 2021), and their sex, length, weight, somatic indices, Fulton condition index (K), proximate composition, and amino acid and lipid composition (fatty acids) of the gonads were determined. Results: Of the total specimens collected, 62% were females; length and weight values were higher in males, but their gonadosomatic index (GSI) was lower than in females. Somatic indices did not show differences between different weight ranges. In the roe of D. latifrons, the average proximate composition was 24.3% protein and 8.5% lipids. The most abundant essential amino acids were leucine and lysine. Linoleic acid (C18:2n6) was the fatty acid with the highest concentration. Limitations/implications: It is necessary to complement the analysis of the amino acid and fatty acid profile of the roe in wild organisms to relate the changes caused by balanced feed. Findings/conclusions: This study shows that the D. latifrons roe is a good source of amino acids and PUFA. Keywords: proximate composition, fatty acids, essential amino acids Objective: To evaluate some reproductive aspects of D. latifrons and the nutritional quality of its eggs. Design/methods/approach: Eighty-two fish were randomly collected (August 2021), and their sex, length, weight, somatic indices, Fulton condition index (K), proximate composition, and amino acid and lipid composition (fatty acids) of the gonads were determined. Results: Of the total specimens collected, 62% were females; length and weight values were higher in males, but their gonadosomatic index (GSI) was lower than in females. Somatic indices did not show differences between different weight ranges. In the roe of D. latifrons, the average proximate composition was 24.3% protein and 8.5% lipids. The most abundant essential amino acids were leucine and lysine. Linoleic acid (C18:2n6) was the fatty acid with the highest concentration. Limitations/implications: It is necessary to complement the analysis of the amino acid and fatty acid profile of the roe in wild organisms to relate the changes caused by balanced feed. Findings/conclusions: This study shows that the D. latifrons roe is a good source of amino acids and PUFA.

Dormitator latifrons is an excellent candidate to be cultured in Mexico. In this research work four experimental treatments were carried out to evaluate the effect of stock density on growth: D3 (three organisms/m3), D5 (five organisms/m3), D6 (six organisms/m3) and D7 (seven organisms/m3), during 90 days. No significant differences were observed between the evaluated densities, although the highest increase in weight in percentage is observed with higher stock density (7 org/m3). Density did not have a negative effect on survival.

Investigación cuasiexperimental, modalidad intervención acción participación, con el objetivo de determinar la influencia de una estrategia de intervención educativa en el estado nutricional de 31 adolescentes de la comunidad Cerro Guayabal, Ecuador implementada durante tres meses. Se precisaron necesidades cognitivas sobre alimentación y nutrición a través de un cuestionario de conocimientos; el estado nutricional según evaluación de ingesta alimentaria y composición corporal mediante un cuestionario de frecuencia semi-cuantitativo y técnica antropométrica. Se logró satisfacer las necesidades cognitivas, alimentarias y nutricionales, valoradas por los resultados del cuestionario de conocimiento aplicado al finalizar la intervención. La ingesta media de energía y macronutrientes mejoró favorablemente, los % de adecuación de energía y carbohidratos aumentaron, los de grasas calcio, potasio, hierro y cinc disminuyeron, mientras que la piridoxina, folato y retinol mejoraron; la riboflavina se mantuvo normal y la tiamina, niacina, vitamina C y E aumentaron; la proporción de adolescentes masculinos que antes estaban en la categoría de reserva proteica baja según el AMB, disminuyó en 50%, ambos sexos se distribuyeron mayoritariamente en las categorías de reserva calórica muy alta. La aplicación de la estrategia permitió modificar el estado nutricional y logró la satisfacción de necesidades cognitivas sobre alimentación y nutrición de adolescentes del estudio.