A model was developed for total parenteral nutrition (TPN) in neonatal piglets, with ingredients typical of those in clinical use. Our goal was to characterize the model and to compare growth and body composition of TPN-fed piglets with a reference sow-fed group. Forty piglets (1 to 3 d of age) received TPN (1040 kJ.-1.d-1, 14.6 g.kg-1.d-1 of amino acids, with nonprotein energy supplied equally by glucose and fat) for 8 d. Weight gain, linear growth, serum biochemistry, hematology and body composition were compared with the reference group of 20 sow-raised piglets. Piglets receiving TPN gained 63 +/- 12 g.kg-1.d-1, less than the mean (79 +/- 21 g.kg-1.d-1, P < 0.01), but within the range (49-118 g.kg-1.d-1), of sow-raised piglets. The TPN-fed piglets used the amino acids in TPN effectively, retaining 80% of infused nitrogen. At postmortem, dry-matter analysis of the bodies yielded similar findings in both groups. Wet-tissue protein concentration was lower in TPN-fed animals (12.5 +/- 0.8 vs 13.8 +/- 1.8 g.100 g body wt) because TPN-fed piglets were more hydrated. Ash concentration was lower in TPN-fed piglets, reflecting limitations in calcium and phosphorous supply.