title: Selenium concentration and glutathione peroxidase (GSH-Px) activity in serum of cows at different stages of lactation.
abstract: The aim of the study was to evaluate the activity of glutathione peroxidase (GSH-Px) and the concentration of selenium in Holstein-Friesian cows at different stages of lactation. Selenium was determined spectrofluorimetrically and GSH-Px activity using a Sigma CGP1 Glutathione Peroxidase Cellular Activity Assay kit. Mean serum selenium concentration was highest in early-lactation multiparous cows (0.18 μg/ml) and the lowest in dry cows (0.111 μg/ml). In early lactation, serum selenium concentration was significantly (P ≤ 0.01) higher in multiparous cows than in cows from the other groups. Mean GSH-Px activity in the serum of dry cows was over twice lower than in late-lactation cows (P ≤ 0.01) and over four times lower than in first-calving heifers and multiparous cows in early lactation (P ≤ 0.01). The coefficients of Spearman's rank correlation between GSH-Px activity and selenium concentration in the cows at different stages of lactation were not significant. A significant (P ≤ 0.01) mean positive correlation (0.46) was found between GSH-Px activity and serum selenium concentration for all the cows analysed together. The highest Se concentration and GSH-Px activity found in the serum of cows during the first stage of lactation may suggest that the generation of reactive oxygen species and their derivatives was higher during this period compared to the other stages, thus placing the cows at a greater risk of oxidative stress. It is therefore essential to give particular attention during this period to meeting the cows' requirement for selenium and other feed components that increase, directly or indirectly, the capacity of the body's antioxidant system.
authors.affiliation: Department of Animal Reproduction Biotechnology and Environmental Hygiene, West Pomeranian University of Technology in Szczecin, Szczecin, Poland. bogumila.pilarczyk@zut.edu.pl
authors.forename: Bogumiła
authors.initials: B
authors.lastname: Pilarczyk
authors.forename: Dorota
authors.initials: D
authors.lastname: Jankowiak
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Tomza-Marciniak
authors.forename: Renata
authors.initials: R
authors.lastname: Pilarczyk
authors.forename: Piotr
authors.initials: P
authors.lastname: Sablik
authors.forename: Radosław
authors.initials: R
authors.lastname: Drozd
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Tylkowska
authors.forename: Magdalena
authors.initials: M
authors.lastname: Skólmowska
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D005260:Female; D005979:Glutathione Peroxidase / Q000097:blood* / Q000378:metabolism; D007774:Lactation; D017382:Reactive Oxygen Species / Q000097:blood / Q000378:metabolism; D012643:Selenium / Q000097:blood*; D013997:Time Factors; D000094765:Glutathione Peroxidase GPX1
chemical_list: D017382:Reactive Oxygen Species; D005979:Glutathione Peroxidase; D012643:Selenium; D000094765:Glutathione Peroxidase GPX1