VITAMIN AND MINERAL TRANSFER DURING FETAL DEVELOPMENT AND THE EARLY POSTNATAL-PERIOD IN PIGS

There are periods during pregnancy when sows may have a temporally hig h requirement for certain vitamins and minerals. Proteins transferring retinol and Fe to the developing pig fetus have been discovered, wher eas transport mechanisms for other vitamins and minerals are probably present but have not yet been identified. Sow body tissues can serve a s a reservoir for many micronutrients, but it is not known whether the se reserves can supply an adequate quantity during critical fetal deve lopmental periods. There is a low placental transfer of vitamin E to t he fetus even if the dietary concentration fed to a gestating animal i s high, but colostrum and milk concentrations can be increased when th e nutrient is fed to sows. If the dam's diet contains inadequate Ca or P, the concentration of these elements in the developing fetus and mi lk will not be affected. Consequently, sow bone demineralization will occur under conditions of dietary inadequacy of Ca and P. Other nutrie nts can be depleted from sow tissue reservoirs over several parities ( e.g., Se), resulting in low quantities being provided in the milk for nursing pigs. Scientific information involving adequate vitamin and mi neral nutrition for female pigs to improve conception rate and embryon al survival that will result in optimum fetal and postnatal pig develo pment can be considered to be in its infancy.