[Factors influencing the vitamin A concentration in the liver of cattle].

Nineteen long-term individual- and group-feeding experiments with 180 male calves, 338 growing bulls, 302 heifers, and 344 dairy cows were carried out in order to measure the influence of feeding (straw, silages or green fodder as roughages) and different vitamin-A supplies (0-40,000 IU per 100 kg body weight per day in growing cattle or 0-120,000 IU per dairy cow per day) on liver vitamin-A concentration. All together, 2,127 biopsies from livers were taken for retinol analysis. At the end of six growth experiments animals were slaughtered.

Influence of beta-carotene supplementation on carotene content of ovaries of heifers.

Carotene is stored as a tissue reserve in the corpus luteum. With different carotene supplementations in heifers (0, 100, 200 and 300 mg/animal and day) it could be clearly seen that the carotene concentration in the corpus luteum (2.3, 27, 50 and 81 micrograms/g) was directly dependent on it.