Abstract: The aim of this study was to analysis the effect of Astragalus polysaccharides(APS) on antioxidant capacity of lactating Holstein cows.In trial,35 lactational Holstein cows were randomly divided into 5 group(7 per group) with similar age,calving number,and weight.0,5,10,50 and 100 g of APS were added to each group in order with concentrated feed every day and lasting for 14 days.The total antioxidant capacity(T-AOC),activity of superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px),and the content of malondialdehyde(MDA) in serum were determined at 0 day,14^th day and 24^th day after feeding APS,respectively.The results showed that T-AOC,activity of SOD and GSH-Px were significantly improved (P<0.05),and the content of MDA was significantly decreased (P<0.05) under the influence of the appropriate APS.The results indicated that addition of APS in daily ration can improve the antioxidant capacity of lactational cows and the suitable amount of APS is 10 g to 50 g per day for each cow.

Key words: astragalus polysaccharides, holstein cows, lactational period, antioxidant capacity