Abstract #T99

# T99
Characterization of metabolic and oxidative status in Italian Mediterranean water buffalos during the peripartum period.
H. Sauerwein*1, B. Heitkönig1, U. Müller1, S. Dänicke2, J. Frahm2, A. Caffi3, F. Ceciliani4, 1Institute of Animal Science, Physiology and Hygiene Unit, University of Bonn, Bonn, Germany, 2Institute of Animal Nutrition, Friedrich-Loeffler-Institute (FLI), Federal Research Institute for Animal Health, Braunschweig, Germany, 3L'azienda Caffi S.r.l. Societa' Agricola, Grumello Cremonese Ed Uniti, Italy, 4Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Milan, Italy.

During the transition from pregnancy to lactation, markers of oxidative stress in blood commonly increase and peak in the first weeks of lactation in dairy cows. Our objective was to characterize the oxidative status in water buffalos, in context with indicators for metabolic stress during that phase. Blood samples were collected weekly from 10 buffalo cows (lactation number 4.6 ± 1.6; daily milk yield 9.0 ± 1.9 kg; means ± SD) from 6 weeks (wk) ante partum (ap) until 8 wk postpartum (pp). Beside nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHB), the following variables were determined in serum using photometric assays: derivatives of reactive oxygen metabolites (dROM), ferric reducing ability (FRAP), thiobarbituric acid reactive substances (TBARS), and advanced oxidation protein products (AOPP). Linear mixed models with time (wk) as repeated effect considering the nested periods ap and pp and cow as random effect were used to evaluate the time courses using SPSS. The dROM values declined with time (P = 0.02) from peak values in wk 2 and 1 ap toward lowest values from wk 3 to 8 pp. FRAP was not affected by time. The oxidative stress index (OSi), i.e., the calculated ratio (dROM/FRAP), also decreased with time showing greater values ap than pp (P = 0.001). The TBARS values did not change with time, whereas AOPP concentrations were greater ap than pp (<0.001); BHB concentrations were not affected by time. Greater NEFA values were observed ap than pp (P < 0.001). Both BHB and NEFA values remained below the thresholds applied for dairy cows to define subclinical or clinical ketosis, thus indicating that the buffaloes studied herein were not under particular metabolic stress. The greater OSi values before calving resulted from increased concentrations of pro-oxidants rather than from decreased anti-oxidants. The profiles of indicators for oxidative status reported in the literature for dairy cows indicate that oxidative stress occurs in early lactation; in contrast, the most oxidative stress in water buffaloes was observed in late pregnancy rather than lactation in our study.

Key Words: oxidative stress, water buffalo, transition period