Life-span of compact UVB bulbs dedicated to tropical and desert reptiles and their role in the prevention of metabolic bone diseases

SUMMARY Background: Metabolic bone disease (MBD) is considered the most prevalent disease of reptiles in captivity. The lack of cholecalciferol in the diet and/or the lack of suitable UV-B-light (natural or artificial form) are the most important causes (nutritional MBD). Objectives: The authors of this study investigated commercially available ultraviolet-B (UV-B) bulbs of three popular companies’. Bulbs were divided into two categories “tropical” and “desert”, according to the target species. Materials and Methods: The bulbs were placed individually into plastic terrariums which were covered with thick black foil. The level of UV-B irradiation of 9 different compact bulbs was measured over distance and time. Measurements were made 7 times with 7 week differences with Solartech 6.2 UV meter with a distance of 10, 20, 30 and 40 cm from the surface of the bulb. One company’s products had significantly lower irradiation − despite the same outputs − even at the beginning of the study (ANOVA test, p < 0.05). Results and Discussion: However all products had a lifespan of 1 year accord ing to the label information, two “desert” and one “tropical” bulb had a very low level of irradiation at the 4th measurement (28th week, 20 cm). According to the results all of the bulbs lost 30-35% of their irradiation level compared to starting levels at the time of the 2nd measuring (7th week), which was only 50% at the time of the 3rd measurement (14th week). Because of this – if regular control of the irradiation is not possible – changing of the bulbs in every 3−4 months is recommended. As the irradiation of the 13W bulb was low even at the beginning, this seems to be less adequate for desert species. Bulb with similar W outputs may have different level of UV-B irradiations; accordingly it is advised to regularly control the level of emission