Available online at www.scholarsresearchlibrary.com Scholars Research Library Annals of Biological Research, 2011, 2 (5) :113-119 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-1233 CODEN (USA): ABRNBW 113 Scholars Research Library Glutamine andGlutathione peroxidase activity (GPX) and Total Antioxidant Capacity (TAS) inPrepartum in Holstein Dry Cows T. Tanha 1 , H. Amanlou 2 , M. Chamani 3 , Y. Ebrahimnezhad 4 , R.Salamatdost 4 ,N .Maheri 4 , M.Fathi 4 1 Department of AnimalScience,Payam Noor University , Iran 2 Department of Animal Science, Zanjan University, Zanjan, Iran 3 Department of Animal Science, Islamic Azad University,Science and Reaserch Branch, Tehran, Iran Department of Animal Science, Islamic Azad University,Shabestar Branch,Shabestar, Iran _____________________________________________________________________________ ABSTRACT The objectives of this study was to investigate whether consuming of protected glutamine (PG) before parturition in close up period would affect dry matter intake (DMI kg/d ), blood urea nitrogen (BUN mg/dl ), body condition score (BCS) and biomarkers of oxidative stress, glutathione peroxidase activity (GPX units/ml PCV ) and Total Antioxidant Status (TAS mmol/L ). Thirty six pregnant Holstein dairy cows were assigned into two treatment groups based on their BCS and expected calving date in t student examination. Treatment groups consisted of 1)glutamine supplementat - ion100 g/d per cow from 21d before calving until parturition (F), 2) glutamine unsupplementation from 21d before calving until parturition (N). There weren’t any significant differences among treatments in DMI and BCS on d -21,-14 ,-7 and calving day before parturition. There weren’t significant differences in The total antioxidant status(TAS) but plasma glutathione Peroxidase activity (GPX) was significant difference between two group and was greater for (F) group at -7d before calving (57.44 vs 47.94 and p≤0.05 respectively) and -14 (45.87 vs 41.72 and p≤0.04 respectively) before parturition. It seems that supplementation diets with glutamine on the close up period can enhance plasma glutathione Peroxides activity (GPX) and the best level of formaldehyde for protection of glutamine is 1%. Key words:Holstein Cow, Glutamine, Glutathione Peroxides Activity, Total Antioxidant Status. _____________________________________________________________________________