In experiments with broiler chickens Ross I was BVK (protein-lucerne concentrate) in the portion of 0,5% added to feed mixtures - in experimental groups 1, 2 and 3 during the first age period (1-21 days of age) and in experimental groups 4, 5 and 6 during the second age period (22-45 days of age). Experimental groups 7, 8 and 9 received BVK during the whole experimental period (1-45 days of life). Control groups 10, 11 and 12 received no portions of BVK. The BVK contains 38% of nitrogen in dry matter and some other biological components and is produced by a simple and cheap separation (sedimentation and drying). The positive stimulatory influences were estimated especially during the first experimental period (1-21 days of age). The addition of BVK to feed mixtures only during the second experimental period exercised light inhibitory effects (1 801.79 +/- 19.231 x 1 863.11 +/- 24.472 g). The best feed conversion efficiency was estimated in the first three experimental groups of chickens - 1.960 kg. In experimental groups 7, 8 and 9 we estimated 2.085 kg, in experimental groups 4, 5 and 6 - 2.193 kg and in control groups 10, 11 and 12 - 2.300 kg.