Effects of ultraviolet B radiation and cold storage on Ram sperm morphology and physiology

Ultraviolet B radiation damages DNA increases oxidative stress and impairs fertility and survival in organisms. The spermatozoa are particularly vulnerable, experiencing altered structure, function, and fertilization capacity due to UVB exposure. The objective of the present study was to evaluate the effects of ultraviolet B radiation and cold storage on the morphology and physiology of ram spermatozoa. The samples of fresh semen from seven animals, obtained during six collections, yielded 42 ejaculates. Aliquots were diluted in Tris egg yolk and were subjected to varying doses of UVB radiation, namely no radiation (0 mJ/cm²), 2.199 mJ/cm², 4.398 mJ/cm², 6.597 mJ/cm², 8.796 mJ/cm², and 10.995 mJ/cm². All evaluations were carried out in duplicate and immediately after UVB exposure; samples were also stored at 5 °C for analysis at 24 and 48 h. Sperm were evaluated for motility using a computer assisted sperm analysis system (CASA), apart from plasma membrane integrity, mitochondrial function, DNA integrity, and acrosomal fluorescence. While UVB exposure damaged the acrosome, the plasma membrane and DNA remained intact. Storage at 5 °C for 24 h and 48 h did not affect any of the structures studied, and even though certain aspects of sperm kinematics were affected, they retained motility. Thus, exposure to UVB resulted in lower sperm motility and structures without completely damaging the sperm.