Abstract

Manatees in rehabilitation centers are typically fed commercially grown lettuces with a very limited amount of native forages. Forage analysis of submerged aquatic vegetation and commercially produced romaine have been evaluated in manatee feeding,¹ but fat-soluble vitamins have not been investigated. Serum samples were collected from twenty-five wild manatees from the Crystal River (CR) during health assessments conducted in the 2017 and 2018 winter capture seasons. Standard blood collection methods were applied and all samples separated at the capture site and refrigerated until they were placed in -80°C freezer. These samples were submitted to the Michigan State University Veterinary Diagnostic lab for 25-hydroxyvitamin D and vitamin E (alpha-tocopherol). Mean, median, standard deviation, and maximum and minimum values were calculated using untransformed data. 90% confidence intervals were calculated using Box-Cox transformed data. All data are summarized in Table 1. All statistical tests were conducted with Reference Value Advisor freeware™. For both vitamin D and vitamin E, there was one individual manatee that was an outlier for each vitamin, so reference ranges were calculated without this outlier. Vitamin E values for the CR manatees overall are lower than those seen in domestic horses (<1.5 μg/ml deficient, 1.5–2 μg/mL marginal, >2 μg/mL adequate; Reference: Michigan State University Veterinary Diagnostic Laboratory). Randomly sampled long-term captive (LTC) from a single institution and rehabilitation manatees (RM) from a different facility had similar values to the CR manatees (LTC mean 1.51 μg/ml, n=4; RM mean 1.15 μg/ml, n=9).

Table 1. Descriptive statistics and 90% confidence intervals of Vitamin D and E from wild Crystal River manatees

Vitamin E is an important anti-oxidant in many species but its significance in manatees is not clear. Vitamin D has numerous roles including immune function and is essential in growing mammals. Prolonged indoor housing could be problematic during rehabilitation as has been demonstrated in rehabilitating sea turtles.² These data from selected LTC and RM manatees reveal higher vitamin D levels compared to CR manatees. (LTC mean 92.0 pmol/dl, n=4; RH mean 86.3, n=9) Several individuals had values 10x greater than the mean for wild CR manatees and these blood values approach toxicity (Reference: Michigan State University Veterinary Diagnostic Laboratory). Vitamin D2 and D3 content for romaine is negligible and the source for these higher vitamin D levels is currently unknown but warrants continued investigation.

Acknowledgements

The authors would like to thank Maggie Hunter, USGS, for permission to evaluate these manatee samples and her feedback.

* Presenting author

Literature Cited

1.  Siegal-Willott J. 2010. Proximate nutrient analyses of four species of submerged aquatic vegetation consumed by Florida Manatee (Trichechus manatus latirostris) compared to romaine lettuce (Lactuca sativa var. longifolia). J Zoo Wildl Med. 41(4):594–602.

2.  Bloodgood JCG, Norton, TM, Hoopes, LA, Hernandez, SM. 2018. Blood nutritional markers reveal effects of rehabilitation diet on Green sea turtle health. International Wildlife Disease Association 67th Annual Conference Proceedings. St. Augustine, Florida. Pp.40.