The effect of body condition in the early dry period on the oxidative status of early lactation cows
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The objective of this study was to investigate if the extent of oxidative damage in early lactation cows is related to high body condition score at the beginning of the dry period. Therefore cows were classified in realistic body condition groups. An existing dataset from a study by Bouwstra et al. (2010) was used, originally investigating the influence of vitamin E supplementation in the dry period on the development of mastitis. In that study, the cows were divided into a low and high vitamin E supplementation group. Body condition was scored and blood samples were taken at five subsequent moments. In this analysis, the cows were classified into three BCS groups: fat, normal and lean condition, using the first moment of body condition scoring at the beginning of the dry period and the sampling moment. These BCS groups were related to the sample results at 18 days post-partum: log serum MDA concentration and the antioxidants and products of oxidative stress serum-alpha tocopherol, albumin, FRAP, ceruloplasmin, uric acid, GSH-px and SOD in erythrocytes. The hypothesis is that cows with a high BCS at the beginning of the dry period will experience a more severe degree of oxidative stress at calving and in the early lactation. The analysis remarkably showed high plasma MDA concentration in the lean condition group at 18 days post-partum. The lean cows that received the high vitamin E supplementation in the original study did not have these high plasma MDA concentrations. Additionally, the analysis suggests that high dietary intake of vitamin E during the dry period might be an effective method to prevent an increase of MDA after calving, even among thin cows.