Vitamin D status in growing dairy goats and sheep: Influence of ultraviolet B radiation on bone metabolism and calcium homeostasis

Abstract

The aim of this study was to investigate how controlled UVB irradiation in combination with reduced nutritional vitamin D (vitD) supply affects vitD status and Ca metabolism of growing goats and sheep. The hypothesis was that, like dairy cows, goats and sheep are able to compensate for the missing nutritional supply of vitD through endogenous production in the skin, with the consequence of a high vitD status and a balanced Ca homeostasis. Sixteen lambs and 14 goat kids aged 3 and a half months were housed in an UVB free environment and fed hay and a vitD-free concentrate over a period of 13 wk. One group of each species was exposed to UVB lamps daily during individual feeding; the other groups served as controls. Serum, urine, and feces samples were taken at the start and at a monthly interval. Serum was analyzed for vitD metabolites, bone markers, growth hormone, insulin-like growth factor I, Ca, and P. Apparent digestibility and urinary excretion of Ca and P were determined. The left metatarsus was analyzed by peripheral quantitative computer tomography for bone mineral density before starting and at the end of the trial. In wk 13, all animals were slaughtered and samples of skin, rumen, duodenum, kidney, and bone (metatarsus) were collected. Content of sterols of vitD synthesis in the skin, Ca flux rates in rumen and duodenum, expression of vitD receptor in duodenum and kidney, renal and intestinal gene expression of Ca transport proteins, and renal enzymes related to vitD metabolism were determined. The UVB exposure led to lower 7-dehydrocholesterol content in the skin and a better vitD status (higher serum 25-hydroxyvitamin D), but no signs of vitD deficiency were seen in the control groups and no effect of irradiation was detected in the analyzed parameters of Ca homeostasis. Differences between the 2 species were detected: lambs had a higher increase of bone mineral density, lower values of bone markers, growth hormone, and insulin-like growth factor I in serum and higher tachysterol and lower lumisterol content in skin compared with goat kids. The results indicated that growing lambs and goat kids are able to compensate for a vitD-reduced diet by cutaneous vitD synthesis when exposed to UVB irradiation and therefore to keep a high vitD status. In contrast, when a reduced vitD diet is combined with missing UVB exposure, the vitD status drops, but the experimental time was probably too short to induce a vitD deficiency or an effect on Ca homeostasis.

Investigation of relationship between vitamin D status and reproductive fitness in Scottish hill sheep

“…This study has identified a clear relationship between genotype and vitamin D 3 , but not D 2 , status in a commercially operated sheep farm. Sheep obtain vitamin D 2 from their diet 8 . In this study, the sheep shared the same pastures, and thus the fact that serum 25(OH)D 2 concentration did not differ significantly amongst the 3 genotypes indicates that genotype was not a determinant of vitamin D 2 status within the flock.…”

“…The quality and the quantity of ultraviolet B radiation are affected by latitude and season, as when the sun is low in the sky, more ultraviolet B radiation is scattered and absorbed when it travels through the ozone layer, compared to when the sun is directly overhead 7 . In regions where the latitudes are above 39°N, such as the UK (from 49 to 60°N), the low level of ultraviolet B radiation results in no previtamin D 3 being synthesized from 7-Dehydrocholesterol in human skin during exposure to sunlight, from October to March 6–8 . This could also lead to low vitamin D status in sheep farmed in such high latitude locations, although literature quantifying optimal ultraviolet radiation levels for sheep is difficult to find.…”

Vitamin D Metabolism and Profiling in Veterinary Species

“…Given that D2 is solely of dietary origin, this may be reflective of the quality of pasture available to intensively farmed sheep in comparison to wild Soay sheep on the St Kilda islands. Growing lambs and kids have been shown to be able to compensate for reduced dietary vitamin D intake by cutaneous production [131]. Interestingly, 25(OH)D3 concentrations were substantially greater in the New Zealand flock [90] in comparison to both the Scottish Blackface [91] and Soay flocks [30].…”

Evaluation of serum 25-hydroxy vitamin d3 levels in goat kids naturally infected with giardia duodenalis

“…Vitamin D is synthesised in both humans and ruminant skin (Holick et al, 1979;Hymøller and Jensen, 2010), contrary to dog and cats only required with diet (How et al, 1994). Like large and small ruminants can be able to produce Vitamin D by mostly their skin and nutritional way (Hidiroglou and Karpinski, 1989;Kovács et al, 2015;Nemeth et al, 2017).…”