DETERMINATION OF ENERGY REQUIREMENT FOR B ULL PRODUCTION

Determination of apparent digestibility of organic nutrients was asses sed in 196 fattened bulls of the Czech Pied breed from the Research In stitute of Animal Nutrition at Pohorelice. The average weight of bulls was 379.69 kg (S(x) = 98.09), average daily weight gain was 1.137 kg (S(x) = 0.198). The feed ration contained com silage and supplementary mix in 168 bulls, and beet-top silage and supplementary mix in 28 bul ls. The average content of gross energy (GE) of the feed ration made 1 7.55 MJ/kg dry matter (S(x) = 0.86), average value of metabolizable en ergy (ME) was 9.28 MJ/kg dry matter (S(x), 0. 69) and average content of net energy (NE) amounted to 5.34 MJ/kg (S(x) = 0.58). The above-nie ntioned concentrations of energy indicate the bulk type of feed ration s used in the trials. This equation was calculated by means of regress ion analysis from the data on individual NE uptake: NE uptake = -1.84 + 0.076 x weight + 13.59 x weight gain (R = 0.798).The calculated valu es were compared with literary data (Van Es, 1978; INRA 1988). The sha pe of the equation proposed for practical conditions: NE requirement = -9.39 + 0.095 x weight + 17.40 x weight gain.