The role of nutritional supplementation on serum mineral concentration in managed stingray populations
Citation
Williams SM, Sullivan KE, Livingston S, Valdes EVV, and Mylniczenko. 2021. The role of nutritional supplementation on serum mineral concentration in managed stingray populations. In Brooks M, Koutsos E, and Henry B Eds. Proceedings of the Fourteenth Conference on Zoo and Wildlife Nutrition, Zoo and Wildlife Nutrition Foundation and AZA Nutrition Advisory Group, Virtual.
Abstract
Iodine is an essential nutrient for normal thyroid function in shark and ray species. In closed aquarium systems, aqueous iodine is bound by ozonation, becoming non-absorbable iodate and necessitating the supplementation of iodine (Sherrill et al., 2004). The most common supplementation method is through diet with commercial multi-nutrient tablets. Research has shown reproductive disease to be a widespread problem in aquarium-housed female southern stingray (Hypanus americanus), with 65% diagnosed as having developed moderate to advanced reproductive disease (Mylniczenko et al., 2019). The most affected females were found to have increased serum iodine levels (Mylniczenko et al., 2016). Elevated serum iodine has been documented in an aquarium managed group of southern stingrays, compared to managed and wild rays in natural sea water; while removal of supplementation returned animals to near-wild iodine levels (William et al., 2017). These findings were replicated in two additional groups (Taeniura meyeni and Himantura sp.) with elevated and subsequent reduction in serum iodine with the removal of supplementation. Other serum micro-minerals, including cobalt, also fluctuated in response to changes in supplementation. In addition, we collected paired serum samples for each of eleven blackblotch rays (Taeniura meyeni) and demonstrated that 24 hours post supplementation administration showed the greatest serum iodine concentration, with a return to initial level by the 72-hour mark. These findings have led us to a more critical review of the broad application of mineral supplementation to these species. Understanding appropriate recommendations for efficient mineral delivery is critical to maximizing animal wellness and nutrition in stingray species under human care.
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