title: Effects of vitamin E supplementation on and the association of body condition score with changes in peroxidative biomarkers and antioxidants around calving in dairy heifers.
abstract: The objective of this study was to investigate the effect of vitamin E supplementation on oxidative status in blood, liver, milk, and ovarian follicular fluid in periparturient heifers. Vitamin E supplementation started 8 wk before calving and continued until 8 wk postpartum. Grass silage was the main forage fed during the experiment. In addition, supplemented heifers (n=9) received 3,000I U of vitamin E daily on a carrier food; control heifers (n=9) consumed only the carrier food. Blood samples and liver biopsies were taken frequently throughout the study and ovarian follicular fluid was sampled at 8 wk postpartum. Body condition score was scored weekly and milk yield was measured daily. A marker of oxidative damage, determinable reactive oxygen metabolites (d-ROM), and a set of antioxidants were measured in blood, liver, milk, and ovarian follicular fluid. Control heifers had a low vitamin E status, and selenium status was marginal in control and supplemented heifers. Vitamin E supplementation increased vitamin E concentrations in blood, liver, and ovarian follicular fluid and increased triacylglycerol in liver. Serum d-ROM were not reduced by vitamin E supplementation. Superoxide dismutase and glutathione peroxidase activity in red blood cells and liver and glutathione peroxidase activity in ovarian follicular fluid were not affected by vitamin E supplementation and they were not increased around calving. Protein thiol groups and ratio of reduced glutathione to oxidized glutathione were also not increased around calving. These results suggest that heifers around calving experience a low level of oxidative processes. This might be caused by lower than expected milk production attributed to a low forage intake. Serum d-ROM were negatively correlated with protein thiol groups and positively correlated with the activity of glutathione peroxidase in red blood cells, oxidized glutathione, and the ratio of reduced glutathione and oxidized glutathione in serum. The lack of treatment effects allowed estimation of the effects of body condition 4 wk before calving and the loss of body condition on markers of lipid peroxidation and antioxidants. A trend that a body condition of >or=3 might result in more oxidative damage measured by serum d-ROM was observed, but fatter heifers had a significantly higher ratio of reduced glutathione to oxidized glutathione.
authors.affiliation: Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, PO Box 80.151, 3508 TD, Utrecht, the Netherlands. p.dobbelaar@uu.nl
authors.forename: P
authors.initials: P
authors.lastname: Dobbelaar
authors.forename: R J
authors.initials: RJ
authors.lastname: Bouwstra
authors.forename: R M A
authors.initials: RM
authors.lastname: Goselink
authors.forename: R
authors.initials: R
authors.lastname: Jorritsma
authors.forename: J J G C
authors.initials: JJ
authors.lastname: van den Borne
authors.forename: E H J M
authors.initials: EH
authors.lastname: Jansen
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000032:analysis*; D015415:Biomarkers / Q000032:analysis* / Q000097:blood; D001824:Body Constitution / Q000502:physiology*; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D003612:Dairying; D019587:Dietary Supplements; D005260:Female; D007774:Lactation; D015227:Lipid Peroxidation / Q000502:physiology; D008099:Liver / Q000378:metabolism; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D006080:Ovarian Follicle / Q000378:metabolism; D036801:Parturition / Q000502:physiology*; D011247:Pregnancy; D012643:Selenium / Q000378:metabolism; D014810:Vitamin E / Q000008:administration & dosage* / Q000378:metabolism
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D014810:Vitamin E; D012643:Selenium