Three different experiments were carried out on growing male Sprague-D
awley rats. In the first experiment, dietary nitrogen was given in cas
ein at four different protein values ranging from 5 to 16%. Rats were
fed ad libitum for 21 days. In the second experiment, which lasted 17
days, animals were given three diets that differed in the molecular fo
rm of the nitrogen supply - that is, proteins or peptides. The protein
value (NX6.25) was 10% in each diet. In the third experiment, malnour
ished rats were refed diets with a protein value of 15% (NX6.25) for e
ight days. The dietary nitrogen was either in the form of protein, pep
tide, or amino acid. Body weight was recorded daily. At the end of eac
h experiment the intestinal villus height was measured by light micros
copy. Data were statistically analysed by Exner's coefficient. The res
ults assessed the validity of the correlation between villus height an
d gain in body weight.