Vitamin A concentration in bovine liver and milk does not only depend on characteristics of the farming system.

The study examined the vitamin A status in commercially managed suckler cows and lactating dairy cows and identified primary influencing factors. Liver retinyl ester concentrations were higher in multiparous than primiparous cows (p < 0.01). Pasture availability was associated with higher β-carotene concentrations (p < 0.001). In dairy cows, pasture access during the dry period did not affect any of the parameters assayed. β-Carotene and retinol in milk increased with parity. No vitamin A deficiency or hypervitaminosis A was detected. Liver and milk retinol and retinyl ester concentrations that were analysed in the present study and data from a recent German total diet study were used to estimate the exposure to preformed vitamin A in vulnerable groups (children, 0.5-5 years). 95th percentiles of preformed vitamin A intake do not exceed tolerable upper intake levels in individuals between 1 year and 5 years, but in infants 6 to 12 months of age.