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Objective—To determine the effect of vitamin E supplementation on urokinase-plasminogen activator (u-PA) receptor (u-PAR) expression by neutrophils of dairy cows.

Animals—16 healthy Holstein dairy cows.

Procedure—16 cows were assigned to 1 of 2 experimental groups: control (no vitamin E supplementation) and vitamin E supplementation. Supplementation of vitamin E started 4 weeks prior to and continued up to 4 weeks after parturition and included oral administration of vitamin E at 3,000 U/cow per day; these cows also received 1 injection of vitamin E (5,000 units), 1 week prior to the expected date of parturition. Blood samples were collected, and neutrophils were isolated weekly throughout the experimental period. The following variables were measured: u-PA (mRNA), total cell-associated u-PA activity, membrane-bound u-PA activity, and free unoccupied u-PA binding sites on the cell membrane of neutrophils.

Results—Stimulated neutrophils isolated from cows that received vitamin E supplementation had significantly higher u-PA mRNA and total cell-associated and membrane-bound u-PA activity at postpartum week 1, compared with those of stimulated neutrophils isolated from control cows. There were no differences between groups throughout the whole experimental period in u-PA binding sites of neutrophils.

Conclusions and Clinical Relevance—The increased total cell-associated and membrane-bound u-PA activity in neutrophils isolated from cows that received vitamin E may facilitate the ability of neutrophils to extravasate and reach the mammary gland at postpartum week 1. Rapid recruitment of neutrophils is critical for proper defense of the gland.(Am J Vet Res 2001;62:1934–1938)

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in American Journal of Veterinary Research


Objective—To assess the kinetic behavior of 3 preparations of α-tocopherol (vitamin E) after oral administration to heifers.

Animals—8 postpubertal Friesian heifers.

Procedure—A single oral bolus of 5,000 U of α-tocopherol in oil or encapsulated in liposomes or cyclodextrin was administered to each cow, using a 4 X 4 design with 8 days between treatments. Blood samples for kinetic analyses were obtained at various times for 168 hours after treatment.

Results—Mean (± SEM) maximal plasma concentrations of α-tocopherol were 4.86 ± 0.49 µg/ml, 5.03 ± 0.39 µg/ml, and 5.08 ± 0.56 µg/ml after administration of oil, liposomal, and cyclodextrin preparations, respectively. Plasma concentrations peaked 21 to 34 hours after administration. The disappearance rate constant (Kd) was less after administration of α-tocopherol encapsulated in liposomes, compared with the other 2 preparations. Area under the concentration versus time curve was greater after administration of either encapsulated form of α-tocopherol, compared with α-tocopherol in oil, but these differences were not significant.

Conclusions and Clinical Relevance—The lower Kd determined for α-tocopherol encapsulated in liposomes suggests that this formulation may result in longer persistance of the vitamin in plasma than the other 2 preparations. Dietary supplementation with α-tocopherol encapsulated in liposomes may enhance plasma availability of this vitamin in cattle and could be useful during periods of increased vitamin E requirements, such as parturition and early stages of life. (Am J Vet Res 2000;61:589–593)

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in American Journal of Veterinary Research