Minimal Erythema Dose Determination in Holstein Friesian Cattle.

Jaka Jakob Hodnik,Jožica Ježek,Žiga Krušič,Jože Starič,Marko Jankovec,Stefan Mitterhofer

doi:10.3389/fvets.2021.757452

Jaka Jakob Hodnik, Jožica Ježek + Show 4 more

Open Access

https://doi.org/10.3389/fvets.2021.757452

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Abstract

Cattle on pasture are continuously exposed to solar UV radiation, which has been associated with biological effects such as sunburn, photosensitization, squamous cell carcinoma, and cutaneous vitamin D3 production. The minimal erythema dose (MED) required to produce first-degree sunburn (erythema) is poorly researched in cattle. Since cattle are naturally covered with dense hair coats, the MED is influenced by the UV protection offered by the hair. The objective of this study was to determine the MED on intact-hair-covered (MED-H) and shaved white skin (MED-S) of Holstein Friesian cattle. Twenty-one Holstein Friesian cows and heifers were MED tested using a narrowband UV-B LED light (peak irradiance at 292 nm) on eight hair-covered and eight shaved areas over white skin previously unexposed to direct sunlight. Erythema was visually assessed after 24 h. The mean MED-H and MED-S were 5,595 and 329 J/m2, respectively. Heifers had a higher MED-H compared to cows, 7,600 and 4,969 J/m2, respectively. The mean UV transmittance of white cattle hair was 6.7%. MED-H was correlated with hair length (Spearman's rho = 0.76). A linear regression model showed that each millimeter of hair coat length increased the MED-H by 316 J/m2. In conclusion, this study provides a MED testing protocol for cattle and reports standardized values of MED for cattle on intact-hair-covered and shaved areas.

Highlights

Minimal erythema dose (MED) is defined as the ultraviolet (UV) dose that produces perceptible erythema or erythema with defined boundaries on an individual’s skin [1,2,3]
The difference between cows and heifers for minimal erythema dose (MED)-S was close to statistical significance (p = 0.053), averaging 344 and 280 J/m2, respectively
For each millimeter increase in hair length, the MED on intact-hair-covered (MED-H) increased by 316 J/m2 (p = 3.4∗10−8) (Figure 5)

Summary

Introduction

Minimal erythema dose (MED) is defined as the ultraviolet (UV) dose that produces perceptible erythema or erythema with defined boundaries on an individual’s skin [1,2,3]. MED is dependent on constitutive skin color, skin thickness, prior UV exposure (thickening of skin and facultative pigmentation), and immune status [4]. The dose is usually reported using the International Commission on Illumination (La Commission Internationale de l’Eclairage—CIE) human erythema action spectrum weighting [5], which allows the direct comparison of different UV light sources. MED testing is performed by exposing a skin surface to a range of UV doses and reading the results after 24 h. The lowest dose that produces erythema is the MED for that individual [1,2,3]. Like most animals, produce vitamin D3 in their skin under the influence of UV irradiation, the MED could be used to determine safe UV exposure dose guidelines, as has been done for humans [6]

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