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The safety and effectiveness of four aluminosilicate-based products (Novasil Plus, Zeolex Extra, Mycofix Select, and Fixat) were tested for 42 days on juvenile Pacific white shrimp, Litopenaeus vannamei, fed diets containing corn grains that had been previously inoculated with Aspergillus parasiticus and then sterilized. Two control diets, one uncontaminated and another contaminated with the contaminated corn grain, were elaborated to contain a final concentration of 0 and 75 μg kg–1 total aflatoxins. Both diets were formulated to contain 38% crude protein and 8% lipids. Eight more diets were manufactured from the previous two to contain each of the test products at inclusion levels of 2.5 to 5.0 g kg–1, in accordance with the inclusion level recommended by the manufacturer. Mycofix Select and Fixat inclusion improved diet stability (12–16%). Water absorption capacity in the diets increased (from 2% to 17%) due to the supplementation of aluminosilicates. Feeding aflatoxin-contaminated diets to Pacific white shrimp resulted in lower feed intake and weight gain without affecting the feed conversion ratio, nitrogen retention, and survival. Feeding the uncontaminated diets supplemented with Zeolex Extra, Mycofix Select, and Fixat resulted in a slight reduction in feed intake without affecting growth rate, nitrogen retention, or survival. Conversely, the inclusion of Novasil Plus in the uncontaminated diet did not affect feed intake and an 8% growth rate improval was observed. Three of the tested products failed to provide complete restoration of feed consumption and shrimp growth rate when added to the aflatoxin-contaminated diet.

Carbon and nitrogen stable isotope values were determined in Pacific white shrimp (Litopenaeus vannamei) with the objective of discriminating animals produced through aquaculture practices from those extracted from the wild. Farmed animals were collected at semi-intensive shrimp farms in Mexico and Ecuador. Fisheries-derived shrimps were caught in different fishing areas representing two estuarine systems and four open sea locations in Mexico and Ecuador. Carbon and nitrogen stable isotope values (␦ 13 C VPDB and ␦ 15 N AIR ) allowed clear differentiation of wild from farmed animals. ␦ 13 C VPDB and ␦ 15 N AIR values in shrimps collected in the open sea were isotopically enriched (−16.99‰ and 11.57‰), indicating that these organisms belong to higher trophic levels than farmed animals. ␦ 13 C VPDB and ␦ 15 N AIR values of farmed animals (−19.72‰ and 7.85‰, respectively) partially overlapped with values measured in animals collected in estuaries (−18.46‰ and 5.38‰, respectively). Canonical discriminant analysis showed that when used separately and in conjunction, ␦ 13 C VPDB and ␦ 15 N AIR values were powerful discriminatory variables and demonstrate the viability of isotopic evaluations to distinguish wild-caught shrimps from aquaculture shrimps. Methodological improvements will define a verification tool to support shrimp traceability protocols.

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INTRODUCCIÓNEl objetivo final de los fabricantes y proveedores de alimento acuícola es asegurar que los alimentos producidos sean seguros y saludables (Tacon y Metian 2008 ABSTRACT. Two feeding trials were carried out to evaluate the effect of diets containing corn or peanut grains naturally contaminated with aflatoxins on the growth, feed intake, survival, and histological response of the white shrimp Litopenaeus vannamei. In trial 1, four experimental diets were formulated to contain 0, 500, 1000, and 2000 g kg -1 of total aflatoxins (TA) and fed to L. vannamei juveniles for 28 days. In trial 2, six experimental diets were formulated to contain 0, 10, 20, 40, 60, and 120 g kg -1 TA and fed to L. vannamei juveniles for 64 days. Feed intake and weight gain were significantly affected by the presence of aflatoxins from naturally contaminated grains. Feed conversion rate increased significantly from a level of inclusion of 60 g kg -1 . Survival was significantly reduced only for shrimp fed diets supplemented with 1000 and 2000 g kg -1 TA. Shrimp exposed to higher aflatoxin inclusion levels presented significantly lower lipid vacuole levels in R-cells (12-28%), lower B-cell activity, and lower mitotic E-cell activity. Tubular epithelial atrophy increased from the inclusion level of 20 g kg -1 . Hepatopancreatocyte sloughing was significantly higher in shrimp fed diets supplemented with 1000 and 2000 g kg -1 TA. It is worth noting that shrimp fed 40 g kg -1 TA presented a high hepatopancreatocyte sloughing coefficient. Based on these results we conclude that the presence of aflatoxins, even at low levels, reduces feed intake and weight gain, and alters the cells of the hepatopancreas.Key words: aflatoxin, shrimp, growth, Litopenaeus vannamei. RESUMEN.Se llevaron a cabo dos bioensayos para evaluar el efecto de granos de maíz y maní contaminados naturalmente con aflatoxinas sobre el crecimiento, consumo de alimento, supervivencia y daños histológicos de juveniles del camarón blanco Litopenaeus vannamei. Para el bioensayo 1, se formularon cuatro dietas con 0, 500, 1000 y 2000 g kg -1 de aflatoxinas totales (AT) y se proporcionaron a juveniles de L. vannamei durante 28 días. Para el bioensayo 2, se formularon seis dietas con 0, 10, 20, 40, 60 y 120 g kg -1 AT y se proporcionaron a juveniles de L. vannamei durante 64 días. El consumo de alimento fue significativamente afectado por la presencia de aflatoxinas. La tasa de conversión alimenticia incrementó significativamente a partir de un nivel de inclusión de 60 g kg -1 . La supervivencia fue significativamente reducida solamente en los camarones que fueron alimentados con las dietas suplementadas con 1000 y 2000 g kg -1 AT. Los camarones expuestos a los niveles de inclusión altos presentaron un menor nivel de vacuolas lipídicas en las células R (12-28%), y una menor actividad de las células B y de la actividad mitótica de las células E. La atrofia de los túbulos del epitelio se incrementó a partir de un nivel de inclusión de 20 g kg -1 . La descamación de las ...

Dry matter, energy, crude protein and amino acid apparent digestibility coefficients (ADCs) were determined in white shrimp juveniles for six wheat products: hard red winter whole grain meal (HWG), Rayon whole grain meal (RWG), Durum whole grain meal (DWG), hard red winter clear flour (HCF), mixed wheat 2nd clear flour (MCF) and semolina (S). The test diets included 30% of the test ingredients and 70% of a ground commercial diet supplemented with 1% chromic oxide and 1% sodium alginate. Amino acid contents in the ingredients, diets and feces were analyzed, and digestibility was determined by difference in order to minimize the impact of endogenous amino acid losses; crude protein and amino acids ADCs were adjusted for dietary preprandial losses in seawater. In general, nutrients digestibility was far higher in the wheat products than in the fish meal-based reference diet. Dry matter and crude protein ADCs were not statistically different among wheat products (from 84 to 96% and from 88 to 107% respectively). Energy ADCs were significantly higher for clear flours (96% for HCF and MCF) than for whole grain meals and S (from 83 to 86%). Total amino acids (TAA) and essential amino acids (EAA) ADCs, once adjusted for preprandial leaching from the experimental diets, ranged from 81 to 89% and from 58 to 81% respectively, and were statistically comparable among wheat products. Low Thr ADCs appear as a common feature of the amino acids digestibility profiles for whole grain meals, clear flours, or semolina.

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The relative contribution of the dietary nitrogen supplied by fish meal and a biofloc meal to the growth of Pacific white shrimp was evaluated using stable isotope analysis. Biofloculated material was obtained from an experimental tilapia culture system. Five formulated diets were supplied. Two of them consisted in isotopic controls having only fish meal or biofloc meal as protein source. Three mixed diets were formulated with varying proportions of these ingredients on a dietary nitrogen basis (75:25, 50:50 and 25:75). At the end of the trial, survival rates were similar (92-100%) but significant differences in mean final weight were observed and a negative correlation between the inclusion of biofloc meal and weight gain was evidenced. Mean final weight in shrimp fed on diet containing only fish meal was 2.8 g, while mean final weight of animals fed on diet containing 50% biofloc was 1.9 g. Isotopic mixing models indicated that all diets contributed higher proportions of dietary nitrogen from fish meal than from biofloc meal. Dietary nitrogen available in diets containing 25%, 50% and 75% of biofloc meal was incorporated in muscle tissue as 5%, 41% and 64% respectively. Diet supplying 25% of nitrogen from biofloc was the only mixed diet eliciting growth comparable to diet containing only fish meal. Lower growth and nitrogen deposition in shrimp fed on diets containing high proportions of biofloc meal were possibly associated to the use of only two protein sources and a restriction of essential amino acids.