Modulatory Effects of Dietary β-Carotene on Blood and Mammary Leukocyte Function in Periparturient Dairy Cows

Abstract

Beginning 4 wk prior to predicted calving, 14 Holstein cows per treatment were fed diets 1) unsupplemented (control) or supplemented daily with 2) 300 mg of beta-carotene, 3) 600 mg of beta-carotene, or 4) 120,000 IU of vitamin A. Blood was collected around calving on wk -4, -2, -1, 0 (within 24 h postcalving), 1, 2, and 4 for isolation of lymphocytes and neutrophils and for the analysis of plasma vitamins. Lacteal secretions were collected on wk 0, 1, 2, and 4 for the isolation of phagocytes. Cows supplemented with 600 mg of beta-carotene had higher concentrations of plasma beta-carotene and retinol than did unsupplemented cows. Supplemental vitamin A increased plasma retinol on wk 4 and decreased plasma beta-carotene on wk -1 and 0. Treatment did not affect concentrations of plasma alpha-tocopherol. Blood lymphocyte proliferation in response to concanavalin A, phytohemagglutinin, and pokeweed mitogen during the peripartum period was higher in cows supplemented with beta-carotene than in unsupplemented controls. Phagocytic activity of blood neutrophils was enhanced on wk 1 in cows fed 300 mg of beta-carotene. Intracellular killing by blood neutrophils was enhanced in cows supplemented with beta-carotene (wk 0) and vitamin A (wk 0 and 1). Iodine uptake and nitroblue tetrazolium reduction by blood neutrophils was stimulated in cows supplemented with beta-carotene. Phagocytic activity, iodine uptake, and nitroblue tetrazolium reduction by mammary phagocytes from all cows generally were lower postpartum than on the day of calving. The incidence of retained placenta and metritis was higher for unsupplemented cows than for cows supplemented with beta-carotene. Therefore, dietary beta-carotene can elevate peripartum concentrations of blood beta-carotene, enhance host defense mechanisms by potentiating lymphocyte and phagocyte function, and decrease the incidence of certain reproductive disorders.

The influence of selected techniques of bovine leukocyte isolation on their viability and metabolism

“…The results indicate that the most useful method, with highest % of cells are Ficoll and Histopaque. The results are similar to those obtained by Michal et al (1994). The experiments showed that the isolation methods had an influence on the viability of leukocytes.…”

The effect of β-carotene and nucleotide base supplementation on haematological, biochemical and certain immunological parameters in weaned pigs

“…The two T-cell mitogens reflect the general cellular immune responsiveness of the organism. The results of this experiment correspond to data given in a number of reports in the literature, according to which both nucleotide and P-carotene supplementation result in an increase in T-cell immune responsiveness (Bendich and Shapiro, 1986;Barankiewicz and Cohen, 1987;Perignon et al, 1987;Hoskinson et al, 1989;Daniel et al, 1991 a,b;Michal et al, 1994). P-carotene is deposited in the lymphocytes, and acts as an immunostimulator partly by virtue of its effect on membrane protection and partly via promoting blastogenesis (Chew et al, 1993).…”

Micronutrients and immune function in cattle

“…The addition of low concentrations of β-carotene to bovine lymphocyte cultures also stimulated mitogen-induced blastogenesis (Daniel et al 1991). Supplementation of β-carotene did not consistently affect neutrophil bactericidal activity (Michal et al 1994).…”