Calves fed with milk from cows receiving plant extracts improved redox status

The objective of this study was to evaluate the biomarkers of the redox state of pre-weaned Jersey dairy calves that consumed milk from cows supplemented with green tea (Camellia sinensis) or oregano extracts (Origanum vulgare). A completely randomized design was used with repeated measures in time. From their birth to 60 days of life, 8, 8 and 7 calves received milk from cows fed on a basal diet without addition of plant extracts (CON), with addition of 10.0 g of oregano extract (OE) per day and with 5.0 g of green tea extract (GT) per day, respectively. On days 1, 30, and 60 after birth redox state biomarkers were evaluated. Body weight was evaluated every two weeks, rectal temperature and fecal score were accessed every two days and concentrate intake was measured every day. Statistical analyses for body weight, body weight gain, concentrate intake, rectal temperature, variables of redox status were performed using the procedure Mixed, evaluating the fixed effects of treatment, day of measurement and their interaction. Statistical analyses for the mean fecal score and the number of days to the first diarrhea occurrence were performed using the procedure Mixed, evaluating the fixed effect of treatment. On day 1, calves fed with milk from GT group had higher plasma glutathione peroxidase activity (GPx) than CON. However, the reverse occurred on day 60. On the day 1, calves in the CON group presented higher concentrations of thiol groups (also known as sulfhydryl groups) than those in GT and OE groups, with reverse occurring on day 30. Calves in the OE group had lower oxidation of dichlorofluorescein in the erythrocytes compared to the others; while calves in the GT group presented higher concentration of GSH and higher activity of the catalase enzyme compared to CON and OE, respectively. Pre-weaned calves fed with milk of cows supplemented with extracts of green tea and oregano did not change physiological and productive variables but they showed improvement in some antioxidant biomarkers.