Revista de la Facultad de Agronomía de la Universidad del Zulia

Integration of zootechnical and ecological factors to evaluate the physiological well-being of Penaeus vannamei on farms connected to Lake Maracaibo, Venezuela

Mon, 15 Jun 2026 00:00:00 +0000

The semi-intensive commercial shrimp farming in Lake Maracaibo, Venezuela, is affected by eutrophication processes resulting from excess nutrients, which favor the proliferation of microalgae and the deterioration of water quality. There is limited information on the relationship between production variables, fluctuations in planktonic communities, and their impact on the physiological state of the shrimp. Therefore, the objective of this study was to analyze the relationship between production and ecological variables with the Relative Condition Index (RCI) as a physiological indicator of Penaeus vannamei during a ten-week grow-out cycle. Production and ecological variables were monitored weekly, including qualitative and quantitative analyses of phytoplankton and zooplankton. Data were evaluated using Pearson correlation, variable selection with VIF and AIC, logistic regression with Firth's bias reduction, and deviance analysis. Shrimp exhibited a final average CRI of 1.36 ± 0.92 and an average ICA of 1.81 ± 0.89. The phytoplankton community was dominated by Cyanobacteria (57.8%), followed by Chlorophyta (32.4 %) and Heterokontophyta (9.1 %), while zooplankton was primarily represented by copepods (69.9 %). However, the model showed a positive association between CRI and the abundance of Chlorella sp. and barnacle nauplii, and a negative relationship with Mesocyclops sp. These results suggest that the nutritional and functional quality of plankton may be more relevant than its total abundance, constituting a bioindicator of physiological well-being and a potential supplementary food source.

Chemical composition and antioxidant activity of the silverskin of three varieties of Coffea arabica L.

Mon, 15 Jun 2026 00:00:00 +0000

The silverskin (SS) of Coffea arabica L., a byproduct of coffee processing, represents a potential source of bioactive compounds with nutraceutical properties. The chemical composition (residual moisture, ash, fats, proteins, and minerals) and antioxidant capacity of the SS from three varieties of C. arabica (Acauã [AW], Sarchimor Rojo [CR], and Catucaí Amarillo [CA]) from the province of El Oro, Ecuador, were evaluated. The extraction of secondary metabolites (total phenols and caffeine) was performed for 60 min using ultrasound (US: 30 °C, 40 Hz) and dynamic digestion (D: 60 °C, 60 rpm), employing an ethanol:water mixture of (70:30 % v/v) and a plant material:solvent ratio of 20:80 % w/v. Total phenols were quantified using the Folin-Ciocalteu method, and caffeine analysis was performed through high-performance liquid chromatography (HPLC) with DAD detection. The evaluated samples met the residual moisture (RM) and total ash content requirements according to the NTE INEN standards, also exhibiting low percentages of fat and protein. The CR variety stood out with 44.8 mg.g⁻¹ of K and 24.9 mg.g⁻¹ of N. Method D extracted the highest amount of phenolic compounds, with CR recording the highest content at 85.0 mg GAE.g⁻¹ of dry extract (DE), which positively correlated with a higher Trolox equivalent antioxidant capacity (DPPH: 108.61 mg TEAC.g⁻¹ DE; FRAP: 122.96 mg TEAC.g⁻¹ DE). In contrast, caffeine levels were higher for the AW variety extracted by US (128.44 mg.g⁻¹ DE), being statistically different from the rest. The three varieties meet regulatory standards and demonstrate that SS is a raw material of great interest to the food and pharmaceutical industries.