Influence ofUVBexposure on the vitamin D status and calcium homoeostasis of growing sheep and goats

Abstract

SummaryThe purpose of this study was to investigate the influence of exposure to ultraviolet radiation (UVB) on vitamin D status, intestinal calcium absorption and bone metabolism in growing sheep and goats. The hypothesis was that growing sheep and goats are able to synthesise vitamin D within their skin as a result of UVB exposure and that respective consequences for their vitamin D blood levels and the associated parameters can be shown. Fourteen 18-week-old lambs and goat kids were kept in an UVB-free environment and randomly assigned to two groups. One group was daily exposed to UVB (300 watt) for 12 weeks, and the other served as a control group. Except for the exposure to UVB, all animals were kept under the same conditions and fed according to their requirements. Before the start of the experiment and every second week, blood samples were taken. Also the left metatarsus of each animal was analysed by quantitative computer tomography to test for bone mineral status before the start, in week 7 and at the end of the experiment. After 12 weeks, the animals were slaughtered and samples were taken from skin, gastrointestinal tract and kidney for further analyses. In this study, exposure to UVB led to increased serum 1,25-dihydroxyvitamin D (1,25VitD) levels in goat kids, whereas in lambs, serum 25-hydroxyvitamin D (25VitD) levels were increased. In both species UVB-exposed animals showed lower 7-dehydrocholesterol (7DHC) values in skin than their respective control groups. These results indicate that growing goat kids and lambs are able to synthesise vitamin D in the skin when being exposed to UVB.

Physiological limit of the daily endogenous cholecalciferol synthesis from UV light in cattle

“…This is probably because the cows in the study by Hymøller and Jensen (2012) were not deprived of D 3 prior their study. This is supported by the negative correlation between the initial plasma 25OHD 3 concentration and the effect of UV-light exposure on plasma concentrations of 25OHD 3 in humans reported by Bogh et al (2010) lambs, which only increased their plasma 25OHD 3 concentration from 43 ng/ml to 50 ng/ml during 11 weeks of daily UV-light exposure (Kov acs et al, 2015).…”

“…This is supported by the negative correlation between the initial plasma 25OHD 3 concentration and the effect of UV‐light exposure on plasma concentrations of 25OHD 3 in humans reported by Bogh et al. () and the relatively limited effect of 30‐min daily UV‐light exposure in D 3 ‐supplemented lambs, which only increased their plasma 25OHD 3 concentration from 43 ng/ml to 50 ng/ml during 11 weeks of daily UV‐light exposure (Kovács et al., ).…”

“…Sheep and goats also respond to UV‐light exposure by increasing their plasma concentration of 25OHD 3 (Kohler et al., ; Kovács et al., ). Sheep, however, show higher plasma 25OHD 3 concentrations after being exposed to UV light when shorn than when unshorn (Hidiroglou and Karpinski, ; Kohler et al., ) and can therefore utilise D 3 from sunlight during summer when their wool is thin (Kohler et al., ).…”

Vitamin D and its role in psoriasis: An overview of the dermatologist and nutritionist

“…The epidermis is the natural source of vitamin D synthesis by the action of ultraviolet light (UV) B of the sun or other UVB source [8]. On the other hand, evidence is accumulating that vitamin D might represent a key modulator of immune and inflammation mechanisms [9] .…”

Zeolite A effect on calcium homeostasis in growing goats1

“…Protein extraction and Western blot analysis of VDR and CaBP-28k were carried out as described by Kovács et al (2015). As primary antibody, monoclonal antibodies against VDR (Abcam, Cambridge, UK, diluted 1:200 in TBST) or CaBP-28k (Swant, Bellinzona, Switzerland, diluted 1:500 in TBST), respectively, were used.…”