This study was to investigate the time course of changes to the antioxidant activity of milk from cows fed a trehalose-supplemented diet, and to determine possible underlying mechanisms for observed changes. Six Holstein cows were used, and subjected to two experimental feeding periods consisting of a 1% trehalose-supplemented diet for 10days, followed by a basal diet only (no trehalose) for 10days. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities in milk were gradually increased during the trehalose supplementation period and were highest at the end of the second period. However, trehalose was not detected in the milk and plasma of dairy cows fed a diet supplemented with trehalose for 10days, indicating that the increased antioxidant activity in the milk of trehalose-fed cows is not due to the direct transfer of trehalose to the milk. Plasma DPPH activities exhibited a similar time course to that seen for milk. Relative superoxide dismutase (SOD) activities in the rumen were higher 3days after the end of trehalose supplementation than at any other time during the experimental periods. These results suggested that the improved antioxidant activity in milk and plasma of cows fed a trehalose-supplemented diet was due to improved ruminal relative SOD activity.
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