English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Dvorak, M.: Effects of Starvation and Zinc Intake on Vitamin A and E Levels in the Blood Plasma of Piglets. Acta vet. Brno, 52,1983: 49-57. Blood plasma vitamin A and E levels of piglets were followed in four experiments for changes produced by weaning in the 4th week after birth, 5-day starvation, short-term food deprivation and by intake of zinc sulphate. The increase found in circulating vitamin A levels after weaning may have been promoted by lard supplements to the feed. Its decrease by 41 % and 34 % in two experiments during the starvation culminated on the 2nd to 5th day and was almost rectified after two days of refeeding. If piglets received an average of 480 mg zinc per animal during the 5-day starvation, the decrease in blood plasma vitamin A level did not occur during the first two days and then was relatively low. In individual animals no consistent relation was found between the changes in blood plasma vitamin A levels and the vitamin A hepatic content that suggested a satisfactory vitamin A status. In fed piglets blood plasma vitamin A concentration increased after the mean daily intake of344 mg zinc added to the feed, but not after the intake of 144 mg zinc. The effects are explained by the disappearance of postabsorption retinol esters from the blood during starvation and by increased retinol release from the liver due to high zinc supplements. Six-hour food deprivation did not affect the circulating vitamin A level, 18-hour food deprivation did so to a relatively small extent. Blood plasma vitamin E concentration decreased by more than 50 % during l3 days after weaning and then changed only little under the subsequent experimental conditions. The five-day starvation produced a decrease in vitamin E in the liver. Retinol, tc cJpherol, blood, liver, zinc. An assessment of the vitamin A status of pigs and other animals involves certain problems if it is not possible to determine the size of the vitamin stores by examination of the liver. The determination of vitamin A concentration in the blood plasma or serum is regarded as less useful (Pitt 1981), but it has been widely used in both human and veterinary medicine and seems helpful also in pigs. Circulating in the blood are retinol esters of alimentary origin, which are stored in the liver, and retinol released from the liver in combination with a specific transport protein, retinol-binding protein (RBP). Its secretion is blocked when vitamin A in the liver is deficient (Smith and Goodman 1979). It is generally believed that between extreme situations of depletion and saturation, plasma retinol level is constant even at considerable variations in the hepatic stores. Inadequate intake of vitamin A is compensated for by an internal regulatory mechanism which maintains its plasma level from endogenous reserves at a height presumably required for optimum provision to the tissues. This homeostatic mechanism, however, may be affected by factors other than the vitamin A status of the body (Underwood et al. 1979). A number of them have been identified (Pitt 1981). One of these factors may also be zinc (Smith et al. 1976; Solomons and Russell 1980). In pigs, however, blood plasma vitamin A concentration is not constant during the rearing period. It decreased when pigs were changed to a feed of a lower vitamin A content even if their hepatic reserves were adequate. A considerable decrease was found in pigs at slaughter after food deprivation for one day (Dvorak and Herzig 1982).