PROTEIN RESTRICTION DURING PREGNANCY AFFECTS POSTNATAL-GROWTH IN SWINE PROGENY

Protein deficiency during pregnancy affects fetal development. The cri tical period, when the fetus is most susceptible to maternal protein d eficiency and its effect on neonatal growth, is unknown. Therefore, we studied the effect of a protein-restricted diet during early and late pregnancy and throughout pregnancy on growth of pigs from birth to ma rket weight. Sows were fed a control (13% protein) or protein-restrict ed (0.5% protein) diet throughout pregnancy or protein-restricted diet from d 1 to 44, then control diet to term or control diet from d 1 to 81, then the protein-restricted diet to term. In Experiment 1, birth weights were measured, and 12 pigs/diet group were weaned at 4 wk and raised to market weight. Feeding the protein-restricted diet throughou t pregnancy reduced birth and slaughter weights, whereas the control f ollowed by protein-restricted and protein-restricted followed by contr ol diets reduced only birth weight relative to controls. Indices of ca rcass lean were reduced in the protein-restricted piglets, with carcas s fat not affected. In Experiment 2, control and control-protein-restr icted litters were reduced to six piglets and 3/litter cross-fostered to a sow of the other treatment group. After weaning at 4 wk, 4 piglet s/group were individually fed to 8 wk. The control and control followe d by protein-restricted diet fed piglets had similar weights at birth, but piglets raised by a control-protein-restricted sow tended to weig h less at weaning than their littermates raised by a control sow. Afte r weaning, these piglets had greater feed intakes relative to other gr oups and there were no weight differences by 8 wk. These results demon strated that maternal protein restriction throughout pregnancy stunted the postnatal development of the swine progeny. Protein restriction d uring the first or last trimester, however, did not have a permanent e ffect upon postnatal growth of pigs, once any restriction of intake wa s removed.