The relevance of the oxidative stress and monitoring options in dairy cattle herds - Literature review

SUMMARY In this review article, the authors summarize the results of several scientific research on the oxidative stress (OS), its occurrence in cattle herds and its physiological and economical effects. OS is developed, when the concentration of reactive oxygen species exceeds the capacity of the natural antioxidant defence system in the body. The production of reactive oxygen species is continuous and avoidable in aerobic organisms, but normally it is under control, while formation of these reactive materials is inhibited, or they will be eliminated by natural antioxidants immediately. When this control mechanisms are disturbed, OS can develop. As the main predisposing factors for OS are the metabolic stress, the heat stress, the up taken mycotoxin contaminated feed, inflammatory processes and some physiological events like the birth and the calving, the OS can be expected for any herd at any time, due to these factors occur frequently. The OS is associated with several diseases of dairy cows, like ketosis and insulin resistance, retained foetal membranes, metritis, mastitis, udder oedema, early embryonic mortality, ovarian disfunction etc. The OS-caused major negative consequences may generate animal discomfort and significant economic losses for farmers. These major consequences primarily originate from the damage of biologic structures like proteins, lipids and nucleotides and can cause cell-level disfunctions which may be manifested in a reduced fertility and productivity. These consequences are also overviewed in this article in detail. The practical use of currently available individual diagnostic possibilities of OS is limited in farm conditions. This is highlighting the need to develop a routine, herd-level in vivo diagnostic methods for monitoring OS. The research on OS herd monitoring methods is still in progress at the University of Veterinary Medicine, Department of Animal Hygiene, Herd-health and Mobile Clinic