Effect of Dietary Supplementation with Organic Silicon on the Growth Performance, Blood Biochemistry, Digestive Enzymes, Morphohistology, Intestinal Microbiota and Stress Resistance in Juvenile Hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus).

In recent decades, interest has been aroused worldwide in the use of silicon in nutrition; however, information on its effect on nutrition and metabolism of fish is limited. The objective of the research was to evaluate the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology and intestinal microbiota and stress resistance in hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). Methodologically, six levels of organic silicon (DOS) [control (0), 10, 20, 30, 40 and 50 mg·kg-1] were used to feed juvenile fish (initial weight 7.51 ± 0.25 g) grown for eight weeks in 18 aquariums (15 fish/aquarium). The results indicated that growth performance showed differences (p < 0.05) for specific growth rate, feed conversion and survival. Triglycerides, cholesterol and glucose, transaminases and digestive enzymes were significantly influenced by DOS levels. The histological study confirmed that the administered diets did not cause damage and induced significant morphological changes in the proximal intestine. The 16S rRNA gene sequencing analysis of the gut microbiota showed a high diversity and richness of OTU/Chao-1, with Fusobacteria, Proteobacteria, Bacteroidetes and Acidobacteria predominating in the DOS treatments compared to the control (p < 0.05). Induction of hypoxia stress after the feeding period showed a significant relative survival rate of 83.33% in fish fed 50 mg·kg-1. It is concluded that the DOS treatments performed better than the control treatment in most of the variables analysed. DOS had no negative effects on the fish. The results showed that up to 50 mg·kg-1 DOS improved digestive, metabolic and growth performance in hybrid Tilapia.

Composición química de intestinos de pollos pre-secados con harinas vegetales: proteína alternativa para la acuicultura

RESUMEN Objetivo. Caracterizar la composición química de intestinos de pollos procesados con harinas vegetales (HV), como fuente alternativa de proteína para la acuicultura. Materiales y métodos. Los intestinos de pollos, molidos, cocidos y desgrasados (IPMCD), se mezclaron de forma individual con harinas vegetales (HV): polvo de arroz (PA), salvado de trigo (ST), harinas de palmiste (HPa), maíz (HM) y soya (HS), en proporciones (p:p): 80:20, 70:30, 60:40, 50:50 y 40:60 (IPMCD:HV), con 20 tratamientos y diseño completamente aleatorizado. Se evaluó materia seca, proteína cruda, lípidos, fibra, cenizas, energía bruta (MJ kg-1) y costos. Se aplicó análisis de componentes principales (PCA) para verificar la interacción entre proporciones. Resultados. Las mayores proporciones con IPMCD, incrementaron el contenido de proteína y lípidos (p<0.05) y redujeron el costo (p<0.05). Las mezclas con 50:50 y 40:60% (IPMCD:HV) mostraron mayores niveles de fibra y cenizas (p<0.05). Además, el empleó de HS en las mezclas, incrementó el porcentaje de proteína, energía y costos (p<0.05), efecto contrario con HPa que mostró los menores costos (p<0.05). Conclusiones. Las proporciones de IPMCD:HV alcanzaron altos niveles de materia seca, que facilitó el proceso de deshidratación. El contenido nutricional y costos de las mezclas, las acredita como posibles alimentos acuícolas, para reemplazar la proteína en las dietas, según la especie, fin productivo y requerimientos del mercado. El PCA con matriz de covarianza, sugiere que los tratamientos IPMCD:HS (80:20), IPMCD:HS (70:30) y IPMCD:HS (60:40) tienen mejores características nutricionales, aunque, IPMCD:HPa (80:20) mostró altos niveles de proteína y fue la más económica.

ABSTRACT Objective. Characterizing the chemical composition of pre-dried chicken intestines with vegetable meal (VM), as an alternative source of protein for aquaculture. Materials and methods. Chicken intestines, grounded, cooked and defatted (CIGCD), were mixed individually with VM : rice powder (RP), wheat bran (WB), palm kernel cake (PKC), cornmeal (CM) and soybean meal (SBM), in proportions (w:w): 80:20, 70:30, 60:40, 50:50 and 40:60 (CIGCD:VM), for a total of 20 experimental treatments, according to a completely randomized design. Dry matter, crude protein, lipid, fiber, ashes, gross energy (MJ kg-1) and costs were evaluated. The principal component analysis (PCA) was applied to verify the interaction between proportions. Results. The proportions with higher levels of CIGCD, protein and lipid content increased (p<0.05), with reduced cost (p<0.05). Those with higher values of VM, fiber and ash showed high values (p<0.05). The mixtures with SBM, high figures of protein, energy and costs (p<0.05) and with PKC the lowest costs (p<0.05). Conclusions. The proportions of CIGCD:VM reached high levels of dry matter, which facilitated the dehydration process. The content of protein, lipid, energy and costs, obtained in the different mixtures, accredits them as possible aquaculture feed, to replace conventional protein in diets, according to the species, productive purpose and market requirements. The PCA with covariance matrix suggests that the mixtures CIGCD:VM, the treatments CIGCD:SBM (80:20), CIGCD:SBM (70:30) and CIGCD:SBM (60:40) have better nutritional characteristics, although, the CIGCD:PKC (80:20) ratio showed high protein levels and was the most economical.