Effect of intraperitoneally injected tocopherol on vitamin E status of dairy cow.
The effect of intraperitoneal (IP) administration of vitamin E on the concentration of tocopherol in the blood and milk of cows was studied. Two trials were carried out using a total of twenty-four Holstein cows. In the first trial, two doses of dl-alpha-tocopherol (1 g and 5 g) were given to six cows in each treatment. Administration of 1 g caused a small increase in blood and milk concentrations; dosing with 5 g IP caused appreciable increases in both plasma and milk concentrations. Plasma and milk concentrations peaked 1 d after dosing with a maximum value of 10.7 micrograms/ml plasma and 1.39 micrograms/ml milk. Then there was a continuous decline during the 14 d experimental period. In the 2nd trial, twelve cows were dosed IP with the acetate form of vitamin E. Six cows were given 5 g and six others 10 g of dl-alpha-tocopherol acetate. Maximum plasma vitamin E concentrations occurred at d 2 (7.4 micrograms/ml) and d 1 (10.9 micrograms/ml) for the cows dosed with 5 and 10 g of the ester form, respectively. Milk vitamin E concentrations were significantly higher (P less than .05) during the first 4 d for cows dosed with 10 compared to those given 5 g. During the 14 d experimental period, maximum milk vitamin E concentration for the 10 g group was 141 micrograms vitamin E/g fat 2 d after dosing and for the 5 g group 62 micrograms vitamin E/mg fat also at 2 d after dosing. The technique of dosing cows with vitamin E by IP proved to be an effective way for increasing vitamin E status. These treatments had no effect on cholesterol content of milk fat. However, it was noted that cholesterol level was lower in PM milking as compared to AM milking.