FETAL ORGAN RESPONSE TO MATERNAL PROTEIN-DEPRIVATION DURING PREGNANCY IN SWINE

To test the hypothesis that maternal protein deprivation in early pregnancy retards body and organ growth of 63-d (midterm) pig fetuses, 16 primiparous domestic four-way crossbred swine were fed a diet adequate in protein (13% protein) (A) or a protein-restricted (0.7% protein) diet (PR) from d 1 to 63 of pregnancy or to parturition. Maternal body weight, plasma protein, hematocrit, and heart and spleen weights were reduced, and indices of body fatness were increased by the PR diet. Fetal body weights were reduced and fetal placental weights were increased at d 63 by protein restriction. Length from crown to rump and weights of liver, kidney, gastrointestinal tract, and cerebrum were lower in PR than in A fetuses. Concentrations of protein, RNA and DNA in liver, cerebrum and longissimus muscle were unaffected by maternal diet, but total amounts of all three constituents in liver and cerebrum were lower in PR than in A. Relative organ weights were similar in A and PR fetuses except that kidneys and gastrointestinal tract were greater in A fetuses. Newborn body weights and absolute organ weights were generally lower in PR than in A, but relative weights were similar. The observed reduction in body and organ weights and amounts of protein, RNA and DNA in 63-d fetuses and newborn progeny of PR swine establishes that the stunting effect of maternal protein restriction can be initiated by midterm, preceding the period of most rapid accretion of body tissues during prenatal life in the pig.