Experimental protein deficiency in adult rats.

Male adult rats of the Wistar strain were fed "ad libitum" either a protein-free or a 20% casein diet for a period of 28 to 32 days. At the end of the experimental procedure, the animals given the protein-free diet presented a marked loss of body weight plus low levels of plasma protein and albumin concentration. Their livers showed diffuse fatty changes; most of the animals had moderate to severe fatty liver infiltration. They had a negative cumulative nitrogen balance; on the contrary, rats fed the 20% casein diet showed nitrogen retention. The animals of one of the two protein-deficient groups had a significant lower food intake than its control group. However, when food intake was related to animal body weight (g/100 g), the rates of rats on the 20% casein diet and those on protein-free diet were not significantly different.