Effect of Housing Type on 25 OH Vitamin D in Serum of Rhesus Monkeys

Abstract

Objective: Vitamin D status is primarily dependent upon sun exposure and dietary sources, however genetic, cultural, and environmental factors can have a modulating role in the measured amount. One under-reported factor is the effect of regular living quarters on the degree of sun exposure. Herein, we assess vitamin D status in the blood of Rhesus monkeys (Macaca mulatta) housed in high amounts of sunlight (corn-cribs), medium sunlight (corrals with shaded areas), and minimal sunlight (quarantine cages). Methods: Fifty-five male Rhesus monkeys, aged 1 to 31 years were housed in varying amounts of sun exposure at the Caribbean Primate Research Center. Serum was collected and analyzed for 25 OH Vitamin D which is the preferred metabolite for determination of Vitamin D using High Performance Liquid Chromatography (HPLC). Results: 25 OH Vitamin D levels in blood were significantly greater in corn-cribhoused monkeys than in corral or quarantine-housed animals (p > 0.01 and p >0.001 respectively). Significant differences of serum levels were not found when ages of animals housed in the same environment were compared. Conclusion: Monkeys housed in a tropical environment with the greatest amount of exposure to sunlight maintain the highest serum levels of 25 OH vitamin D independent of age. These findings emphasize the importance of documenting the environment in which subjects typically spend their time when Vitamin D results are interpreted.