COMPARISON OF INTAKE OF PROTEIN IN FATTEN ING BULLS IN SYSTEM PDI ANDTRADITIONAL UNITS

The PDI system of evaluation of protein in the fattening bulls was tes ted and compared with the results expressed in crude protein and diges tible crude protein units. The results of 158 balance determinations o f digestibility made on the fattening bulls in the Research Institute for Animal Nutrition Pohorelice in the years 1984 - 1992 were evaluate d. Feed rations were based on maize silage and supplemental mixture. A t average gain 1.123 kg (s(x) = 0.016) and average weight 382.97 kg (s (x) = 7.66) the daily intake PDIE in our set was 579 g (s(x) = 8.41). This value corresponded with the data of V e n c l (1991) (difference -2.04 %) and INRA (1988) (difference -1.15 %). The value of intake PDI N 677 g (s(x) = 6.70) has shown its surplus in the feed ration. Daily intake of crude protein 1097 g was higher than a value of V e n c 1 (1 991) by 20.04 % and N.R.C. (1984) by 15.65 %, which confirmed the surp lus of crude nitrogen in feed ration of experimental animals. The agre ement of the determined intake of digestible crude protein with the da ta presented in CSN 46 7070 (difference -2.6 %) revealed some overesti mation of digestible crude protein requirement given in this norm. The maintenance PDI in our set 4.27 . H-0.75 was calculated.