Nutritional considerations for supplemental gruel feeding of elasmobranchs

Citation

Williams SM, Mylniczenko ND, Sullivan KE, and Bissell H. 2023. Nutritional considerations for supplemental gruel feeding of elasmobranchs. In Brooks M, Fidgett A, Kendrick E, Treiber K Eds. Proceedings of the Fifteenth Conference on Zoo and Wildlife Nutrition, Zoo and Wildlife Nutrition Foundation and AZA Nutrition Advisory Group, Hybrid.

Abstract

Depending on the species, life stage, and energy expenditure, dietary caloric requirements can vary greatly. Designing an appropriate gruel feeding regimen should consider caloric targets based on the individual’s daily base diet. The fat and protein ratio of the animal’s diet also directs the inclusion of gruel components, including additional supplements. The addition of water is often necessary to create appropriate texture to pass through a feeding tube which dilutes the gruel caloric density. In cases of high caloric demand, multiple feedings per day may be required to administer adequate calories, while individuals with lower caloric needs may be met in a single bolus. The animal’s stomach capacity limits the volume that can be delivered. Generally, two percent of body weight for initial volume, with ultrasound assessment aiding in visualizing stomach fill to avoid overfeeding. Use body weights collected during handling to assess the success of a feeding regimen. Observing fecal quality illustrates how gruel is digested. Poorly digested fecals could indicate over-feeding (pushing gruel into the distal gut) or rapid transit time. Floating, oily fecals may indicate fat content which is too high.

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