Plasma retinol concentration in grazing heifers: First data obtained from a dairy herd in the south of Chile

Abstract

There is no information available about plasma retinol concentration in grazing heifers in Chile, for this reason the plasma retinol concentration was measured in dairy heifers grazing during the winter and spring seasons on paddocks in the south of Chile. Fifteen clinically healthy Friesian heifers from a dairy farm located in the Valdivia Province, Chile, aged between 16 and 18 months, were used. The animals were grazing on fertilized natural pastures from July to December. Blood samples were taken monthly from each animal and plasma retinol concentrations were determined using reverse-phase high performance liquid chromatography. Mean (± SD) plasma retinol concentration was 0.46 ± 0.09 µg/ml with values fluctuating between 0.18 - 0.69 µg/ml. Plasma retinol concentration was lower in winter (0.42 ± 0.09 µg/ml, with values fluctuating between 0.18 to 0.57 Hg/ml) and higher in spring (0.50 ± 0.09 µg/ml; with values fluctuating between 0.29 to 0.69 µg/ml). The average values obtained in this study constitute the first data currently available in Chile regarding plasma retinol concentration in grazing cattle.