Minimal Erythema Dose Determination in Holstein Friesian Cattle

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.

Bovine heat stress management: current amelioration approaches and the case for a novel mitogenomic strategy

“…Both coat strategies generate a desirable HT benefit by prolonging hyperthermia onset and consequent HS indicators for modified calves. However, the practical drawback left undiscussed is that lighter and/or shorter coats are conversely more susceptible to sunburn (Hodnik et al, 2021). The impacts of this trade-off, especially in high-thermal areas with minimal shade, should be investigated before implementing this genetic strategy.…”