[Attempts at the determination of endogenous and exogenous fecal proportions in monogastric animals].

A trial was made with growing Wistar rats receivine 15N labelled tracers. The animals were fed maize grains (Opaque). Subsequently, the level of urinary and faecal N excretion was measured and the 15N frequency was determined in the urine, faeces and different blood fractions. On the basis of the model established by Czarnetzki for the nitrogen metabolism in monogastric animals the estimated values were used to calculate the proportion of endogenic faecal N in the total amount of faecal nitrogen. In agreement with previous trails it was found that increase in protein intake produced a significant increase in endogenic faecal N; similarly, a higher value was found for the true digestibility of maize protein (by 9.3 units) compared with that established by the conventional regression technique.