Effect of Protein Deprivation of Swine During All or Part of Gestation on Birth Weight, Postnatal Growth Rate and Nucleic Acid Content of Brain and Muscle of Progeny

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Abstract
It was previously shown that gilts deprived of dietary protein during gestation are capable of producing grossly normal, viable young. The present experiment was designed to study the effect of dietary protein deprivation during various intervals of gestation in the gilt on subsequent growth of the progeny and on nucleic acid content of the brain and muscle of the progeny during young adulthood. Eighteen pregnant gilts were divided at 3 to 4 days after breeding into four groups as follows: 1) protein-free diet to parturition; 2) protein-free diet to day 16, then control diet days 16 to 20 (period of implantation of blastocyst), then protein-free diet to parturition; 3) control diet to day 24, then protein-free diet to parturition; and 4) control diet to parturition. All gilts fed the protein-free diet during any part of gestation lost weight; all control gilts gained weight. Litter size (number of live plus stillborn pigs) was not significantly affected by treatment. Birth weight and postnatal growth rate were significantly reduced in progeny of gilts fed the protein-free diet to parturition (group 1) but not in those of gilts deprived from day 24 to parturition (group 3). The birth weight and postnatal growth rate of progeny of gilts given transitory protein at implantation (group 2) were greater than those of gilts deprived of protein throughout (group 1), supporting the concept of a beneficial effect of transitory protein at implantation on the development of the fetus. Fresh weights of cerebrum and cerebellum plus medulla of the progeny at a slaughter weights of approximately 90 kg were not affected by prenatal treatment but percentage dry matter was greater in brains of control progeny than in those of progeny of protein-deprived gilts. Neither DNA concentration nor total DNA content of either organ were affected by treatment. RNA per gram of protein or total RNA per organ was greater in progeny of controls than in those of protein-deprived gilts, suggesting greater protein synthetic activity in the brains of the former. No treatment differences were noted in dry matter, protein, DNA or RNA concentration of skeletal muscle (longissimus dorsi) of progeny. It is concluded that dietary protein deprivation of the gilt throughout pregnancy results in reduced birth weight and postnatal weight gain of the progeny but does not permanently affect DNA content (cell number) of the cerebrum or cerebellum. RNA concentration and total RNA in these organs in the young adult progeny may be decreased by maternal dietary protein deprivation during gestation, suggesting an effect on brain protein synthetic activity. DNA concentration of skeletal muscle at 90 kg body weight was not affected by treatment but RNA/DNA was significantly reduced in progeny of protein-deprived gilts. The depressed postnatal weight gain in progeny of protein-deprived gilts suggests an effect on metabolism not clearly reflected by these parameters.