SHORT-TERM INGESTION OF A HIGH-PROTEIN DIET INCREASES LIVER AND KIDNEY MASS AND PROTEIN ACCRETION BUT NOT CELLULARITY IN YOUNG-PIGS

Increased visceral organ mass raises the energy cost of maintenance in animals. To determine the nutritional factors that affect organ size during growth and development, we studied 12 genetically obese 4-week- old pigs for 14 days. The piglets had free access to either a control (17% protein) or a high protein (34%) diet. They were sacrificed after 14 days and their empty gastrointestinal tracts, livers, and kidneys were weighed and samples were analyzed for protein and DNA concentrati ons. The absolute and relative (percentage of body weight) weights of liver and kidneys were greater in high protein than control piglets: l iver (313 vs 246 g, SD = 24, P < 0.09; 3.61% vs 3.18%, SD = 0.04, P < 0.01); kidneys (57 vs 41 g, SD = 4, P < 0.04; 0.66% vs 0.55%, SD = 0.0 2, P < 0.01). Protein content was greater in high protein than control pigs in both liver (48.2 vs 34.0 g, SD = 3.4, P < 0.03) and kidneys ( 6.0 vs 4.6 g, SD = 0.5, P < 0.06). Liver and kidney total DNA were una ffected by diet in both groups. The protein to DNA ratio was greater i n high protein than control pigs in both liver (45.4 vs 39.0, SD = 0.6 , P < 0.01) and kidneys (26.6 vs 24.9, SD = 0.4, P < 0.02). We conclud e that when weaned pigs have free access to a high protein diet (2 x r equirement) for 2 weeks, liver and kidney protein accretion increases, suggesting cell hypertrophy, with no clear evidence of cell hyperplas ia.