Estimating the impact of COVID-19 pandemic on alternative semi-intensive shrimp (Penaeus vannamei) production schedules in Mexico: a stochastic bioeconomic approach.

This study uses a stochastic bioeconomic approach to estimate the COVID-19 pandemic economic impact on shrimp farming in Mexico. Seeding-harvesting schedules - March-June, May-August, and August-November - were analyzed using shrimp prices and production costs corresponding to 2017-2019 (pre-pandemic) and 2020 (pandemic). The analyses estimated net revenue varied within 597.97-2758.88 USD$ ha-1 and 1262.40-1701.32 USD$ ha-1 under the pre-pandemic and pandemic scenarios, respectively. Significant decreases (38%) were estimated in net revenue values in March-June and May-August under the pandemic scenario. However, probability distributions estimated that uncertainty on the expected net revenues was not affected by the pandemic conditions, and the probability of losing was null or negligible in all the cases. Unfavorable conditions under the pandemic also required significantly higher break-even production for March-June (25.7%) and May-August (28.5%) schedules. The cost of post-larvae was the most important economic factor influencing net revenue. To conclude, although the operating conditions during the pandemic were conducive to worsening the economic outcome, no evidence still exists that uncertainty and economic risk increased compared with pre-pandemic conditions.

Bioprocessing of common beans in diets for tilapia: in vivo digestibility and antinutritional factors.

BACKGROUND: Bioprocessing of ingredients by solid-state fermentation is a low-cost technique for preparing diets. It is performed by adding microorganisms such as Rhizopus oligosporus to bean grains, achieving minimal degradation of nutrients and a significant improvement in digestibility. In particular, fermentation induces favorable changes in beans by reducing enzyme inhibitors, such as phytates and tannins. RESULTS: Fermentation significantly (P < 0.05) increased the protein content and digestibility of dry matter and protein compared with whole bean grains, and decreased the content of lipids, ash and phytic acid. Hardening did not have a significant (P > 0.05) effect on the chemical content of beans and digestibility of diets. The dehulled bean meal significantly (P < 0.05) increased protein and lipid content and digestibility of dry matter and protein of beans, and decreased fiber, ash and tannin content. The chemical content of beans and digestibility of ingredients compare favorably with those reported by other authors, indicating the benefits of fermentation and dehulling. CONCLUSION: We concluded that bean meal obtained from fermentation or dehulling represents a low-cost alternative for diets for tilapia. © 2017 Society of Chemical Industry.

Diseño, construcción y aplicabilidad del índice de evaluación ambiental de ecosistemas acuáticos (IEAEA) / Desing, development and applicability of the aquatic ecosystems environmental evaluation index (EEAEI)

Se diseño, construyó y comprobó la aplicabilidad de un Indice de Evaluación Ambiental de Ecosistemas Acuáticos (IEAEA) basado en calidad físico-química, contenido de contaminantes en agua y sedimentos. Los criterios de calidad se fundamentan en investigaciones recientes y límites permisibles, y se establece cuáles contaminantes representan problemas potenciales en salud pública o ecosistemas acuáticos. La validación incluyó análisis de Componentes Principales y Análisis de Sensibilidad. El IEAEA fue aplicado a resultados de 28 campañas de Tehuantepec, Oaxaca, México. Los análisis de sensibilidad se desarrollaron con los subíndices extremos y con la serie completa. La mayoría de los indicadores presentaron alta significación estadística. El modelo es robusto y los valores fluctúan cerca de la mediana. Se demostró que muestra sensibilidad a variaciones climáticas, número de variables y volúmen de datos, por lo que se comprobó su aplicabilidad