title: Seasonal variation in semen quality in Bos indicus and Bos taurus bulls raised under tropical conditions.
abstract: In the present study, we tested the hypothesis that Bos taurus taurus bulls have greater reactive oxygen species (ROS) and lower activity of antioxidant enzymes in their semen than Bos taurus indicus bulls. Sixteen Simmental bulls (B. t. taurus) and 11 Nelore bulls (B. t. indicus) were managed extensively in a tropical environment. Semen was collected twice annually (summer and winter) for 2 consecutive years. Simmental bulls had significantly higher percentages of major sperm defects during the summer than the winter (20.3+/-3.1% versus 12.2+/-2.4%, respectively; mean+/-S.E.M.). There was an interaction of breed and season for minor sperm defects (P=0.037; highest in Nelore bulls in the summer) and an effect of season on total defects (P=0.066; higher in summer). To evaluate oxidative damage, malondialdehyde (lipid-peroxidation metabolite) concentrations were indirectly measured by semen concentrations of thiobarbituric acid reactive substances (TBARS); these were higher in summer than in winter (728.1+/-79.3ng/mL versus 423.8+/-72.6ng/mL, respectively; P=0.01). Glutathione peroxidase/redutase (GPx) activity in semen was higher in Simmental versus Nelore bulls (741.6+/-62.1 versus 510.2+/-62.8; P<0.01). However, superoxide dismutase (SOD), another antioxidant enzyme, was not significantly affected by breed or season. There were correlations between TBARS and sperm primary defects during the summer for both Simmental and Nelore bulls (r=0.59, P=0.021 and r=0.40, P=0.034, respectively), and between SOD and primary defects during summer for Simmental bulls only (r=-0.51, P=0.041). In conclusion, there was a higher level of lipid peroxidation (ROS) in semen of Simmental versus Nelore bulls; apparently the higher GPx activity in Simmental bulls was insufficient to avoid damage that occurred concurrent with increased ROS production during the summer.
authors.affiliation: University of Antwerp, Faculty of Pharmaceutical, Biomedical and Veterinary Sciences, Laboratory of Veterinary Physiology, Universiteitsplein 1, Gebouw U, B-2610 Wilrijk, Belgium. Marcilio.Nichi@ua.ac.be
authors.forename: M
authors.initials: M
authors.lastname: Nichi
authors.forename: P E J
authors.initials: PE
authors.lastname: Bols
authors.forename: R M
authors.initials: RM
authors.lastname: Züge
authors.forename: V H
authors.initials: VH
authors.lastname: Barnabe
authors.forename: I G F
authors.initials: IG
authors.lastname: Goovaerts
authors.forename: R C
authors.initials: RC
authors.lastname: Barnabe
authors.forename: C N M
authors.initials: CN
authors.lastname: Cortada
mesh_terms: D000818:Animals; D000829:Animals, Domestic / Q000502:physiology; D000975:Antioxidants / Q000378:metabolism; D001947:Breeding; D002417:Cattle / Q000502:physiology*; D018882:Heat Stress Disorders / Q000473:pathology; D008297:Male; D017382:Reactive Oxygen Species / Q000378:metabolism; D012621:Seasons; D012661:Semen / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D013045:Species Specificity; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000002:abnormalities / Q000473:pathology; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014329:Tropical Climate
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances