Effects of stress on cortisol secretion and vitamin metabolism in cattle

At the transition from pregnancy to lactation in cows with high milk produc tion the consumption of O-2 increases from about 3,200-3,500 to 6,500-6,800 l per cow and day. With that a high increase in the formation of reactive O-2-radicals (= oxidative stress) and in the consumption of ascorbic acid a nd vitamin E in the mammary gland is combined; the importance of the Se-con taining glutathione-peroxidase in the removal of H2O2 increases. For the st imulation of the activity of the immune system in the perinatal period an i njection of 3.000 I. E. vitamin E and of 50 mg Se on the 10(th) as well as a further of 3.000 I. E. on the 5(th) day before parturition is recommended . As stress in cattle especially infections, operations, long lasting heat and cold as well as transports are effective. For the stimulation of the im mune system under stress conditions an injection of combination-preparation s of the vitamins A, D-3 and E and of ascorbic acid is recommended. Also th e supplementation of 1.000 I. E. of vitamin E and of 3 mg Se per cow and da y during the dry period as well as of 1.000 I. E. and of 5 mg Se per day fo r four weeks after parturition is effective.