The need to develop standardized diets to support zebrafish (Danio rerio) research is supported by the knowledge that specific dietary ingredients, nutrients, or antinutritional factors in diets have been shown to affect development and growth of adult D. rerio and their offspring. In this study, there were seven dietary treatments consisting of five commercially available diets and two laboratory-prepared diets, three replicates per treatment. Fish were fed ad libitum twice daily for 9 weeks. At 9 weeks, both weight and length were recorded to determine condition indices. D. rerio fed one of the laboratory-prepared diets had significantly higher weights than individuals fed any of the other diets and exhibited significantly higher lengths than those fed five of the six remaining diets. Although there were significant differences in general growth demographics (length=weight) after the 9-week feeding trial, no significant differences in overall health of D. rerio were observed for the different dietary treatments as determined by statistical analysis of condition factor indices (K ¼ [weightÂ100]=length 3 ). The success achieved with the laboratory-prepared diets represents the foundation for establishing an open-formulation nutritional standard to ensure that the D. rerio model for research does not generate confounding research results caused by nutritional vagaries.

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Zebrafish (Danio rerio) skeletal bone possesses properties similar to human bone, which suggests that they may be used as a model to study mineralization characteristics of the human Haversian system, as well as human bone diseases. One prerequisite for the use of zebrafish as an alternative osteoporotic bone model is to determine whether their bone displays functional plasticity similar to that observed in other bone models. Strontium citrate was supplemented into a laboratory-prepared diet (45% crude protein) to produce dietary strontium levels of 0%, 0.63%, 1.26%, 1.89%, and 2.43% and fed ad libitum twice daily for 12 weeks to 28-day-old intact zebrafish. Length was determined at 4-week intervals, and both weight and length were recorded at 12 weeks. At 12 weeks, seven zebrafish from each dietary level were analyzed for total bone mineral density by microcomputed tomography. Dietary strontium citrate supplementation significantly (p < 0.05) increased zebrafish whole-body and spinal column bone mineral density. In addition, trace amounts of strontium were incorporated into the scale matrix in those zebrafish that consumed strontium-supplemented diets. These findings suggest that zebrafish bone displays plasticity similar to that reported for other bone models (i.e., rat, mouse, and monkey) that received supplements of strontium compounds and zebrafish should be viewed as an increasingly valuable bone model.

The suitability of crude and purified struvite (MgNH4PO4), a major precipitate in wastewater streams, was investigated for renewable replacement of conventional nitrogen and phosphate resources for cultivation of microalgae. Bovine effluent wastewater stone, the source of crude struvite, was characterized for soluble N/P, trace metals, and biochemical components and compared to the purified mineral. Cultivation trials using struvite as a major nutrient source were conducted using two microalgae production strains, Nannochloropsis salina and Phaeodactylum tricornutum, in both lab and outdoor pilot-scale raceways in a variety of seasonal conditions. Both crude and purified struvite-based media were found to result in biomass productivities at least as high as established media formulations (maximum outdoor co-culture yield ∼20±4gAFDW/m(2)/day). Analysis of nutrient uptake by the alga suggest that struvite provides increased nutrient utilization efficiency, and that crude struvite satisfies the trace metals requirement and results in increased pigment productivity for both microalgae strains.

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Accurate digestibility coefficients for protein, energy, and lipid are needed by feed formulators to optimize diets to meet nutritional requirements and to substitute ingredients cost‐effectively. Of particular interest is protein, which accounts for the majority of shrimp feed content and expense. The current study evaluated seven cottonseed meal and protein products. Most of the samples were derived from a glandless cotton variety that lacks significant levels of the antinutritive compound, gossypol. The various protein fractions were evaluated for apparent crude protein, crude lipid, and energy digestibility when fed to juvenile Pacific White Shrimp, Litopenaeus vannamei. Apparent energy digestibility for the protein fractions derived from the glandless seed ranged from 76.7% for ground kernels to 94.6% for protein isolate, and these values were greater than the value obtained for the commercial meal that contained gossypol (64%). Apparent protein digestibility for the six glandless‐cotton‐based samples varied from 72.3% for the ground full‐fat kernels to 94.1% for the protein isolate, and these values were mostly higher than the value obtained for the commercial meal (82.3%). The high apparent digestibility values demonstrate that low‐gossypol cottonseed protein products may be useful as a cost‐effective replacement for more expensive protein sources in L. vannamei diets.

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