20.500.12556/RUL-166711 Effects of UV-B light exposure during automatic milking on vitamin D levels in Holstein Friesian cows Vitamin D is essential for cattle and can be synthesized in the skin under ultraviolet irradiation. This study investigated the effects of narrow-band UV-B irradiation during automatic milking on blood vitamin D concentration and the influence of hair and black skin areas on cutaneous vitamin D synthesis in Holstein Friesian cows. Fifty-one cows were stratified by milk yield, days after calving, and percentage of black skin, then divided into three groups: shaved and irradiated (80 J/m2), unshaved and irradiated (129–305 J/m2), and a control group. A custom UV-B light (peak radiation at 295 nm) was installed in the milking robot. Blood 25-hydroxyvitamin D (25(OH)D) levels were measured at baseline, and 7, 30, and 60 days postexposure using an enzyme-linked fluorescent assay. UV-B exposure significantly (p < 0.001) increased 25(OH)D levels in shaved (13.4 ng/mL), unshaved (10 ng/mL), and control groups (5.1 ng/mL). Despite receiving less than half the UV-B dose, the shaved group had superior 25(OH)D synthesis compared to the unshaved group (p < 0.05), highlighting hair’s role in reducing UV-B absorption. Cutaneous synthesis correlated with black skin area in shaved cows but not in unshaved cows. UV-B irradiation also increased daily milk production by 2.2 kg (shaved) and 2.9 kg (unshaved) compared to controls (p < 0.001). UV-B exposure during automatic milking offers a novel, non-disruptive method for enhancing vitamin D levels in dairy cows. ultraviolet-B light cattle 25-hydroxyvitamin D milk yield skin skin hair color blood true false true Angleški jezik Angleški jezik Članek v reviji 2025-01-22 14:25:04 2025-01-22 14:25:09 2025-01-23 03:54:06 0000-00-00 00:00:00 2025 0 0 8 str. Vol. 11, [article no.] 1433230 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 2025-01-01 636.2.09:616 2297-1769 10.3389/fvets.2024.1433230 223240707 effects_of_UV-B-Jezek.pdf effects_of_UV-B-Jezek.pdf 1 7EE857DFFC265572FB9AF9A5BC70F30A a2ab4fd6e090e91dc374adac429d9eb69a89218eebf6be129ddc6f1fc3602117 05676a1d-d8c4-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=198526 https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2024.1433230/full 1 84344073-d8c3-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=198525 Veterinarska fakulteta 0 0 0