[Influence of protein intake on plasma and hair leachable urea in the rat (author's transl)].

Three groups of 13 adult female rats received daily for two months 23 g per rat of three synthetic isoenergetic feeds containing respectively 5, 15, 25 p. 100 casein. Plasma urea was measured weekly. Hair leachable urea and soluble dry matter were measured, at the end of the experiment, on hairs regrown after an initial clipping, in a solution obtained by washing 1 g of hair in 50 ml of HCl 0,01 N under mechanical shaking. Mean plasma urea values for the whole experiment for the three groups were 0.27, 0.38, 0.45 g per liter; differences between all groups were highly significant; however differences for the 15 and 25 p. 100 casein groups were not significant for the last three weeks. Hair leachable urea and hair soluble dry matter values were respectively 0.35, 0.80, 1.02 mg/g of hair and 20.4, 24.0, 26.0 mg/g of hair. A positive correlation links hair urea to hair dry matter (r=0.76, p less than 0.001). When hair urea is expressed in per cent of soluble dry matter, the respective values for the three groups are 1.90, 3.42, 3.95. Differences between the 5 p. 100 casein group on the one hand and the 15 and 25 p. 100 casein groups on the other are highly significant (p less than 0.001).