The problem in the fight against infectious diseases in the first months of life of calves is a decrease in immunity and a violation of the biological balance between micro- and microorganism. At the same time, the use of expensive drugs undermines the efficiency of animal husbandry on farms. The drug "BychkoFF" was developed taking into account the correction of the microflora of the gastrointestinal tract and the restoration of the body's immune system. The main structural elements of the complex are nitrogen-containing substances and a dry concentrate of live acidophilic and slender bacteria. It consists of Bacillus subtilis A, B, C, amino acids of whey proteins. Amino acid composition of the complex Amino acid % in dry matter Alanine 3.09 Arginine 0.56 Aspartic acid 2.80 Ornithine 5.73 Aminobutyric acid 0.71 Cysteine ​​+ Cystine 0.73 Total: 47.3. Concentrate of acidophilic bacteria - 100000 in 1 tab. In addition to amino acids, it contains the following groups of vitamins: IU/g Riboflavin B2. 50-80 Thiamin B1, 60-80 Biotin, 1.5-2 Inositol, 350 Folic acid, 20-35 Para-aminobenzoic acid, Pantothenic acid, 118-198 Pyridoxine, 25-35 Nicotinic acid, 80-120 Ascorbic acid 150 mg. 2. The doses of the drug are as follows. Drink 1 tablet per day per head for weakened calves after a course of antibiotic therapy to strengthen the immune system and restore the beneficial microflora of the pre-stomachs. 3. The drug is injected into drinking water, at the rate of one tablet per 200 ml of warm water, and the calf is fed. The course is 14 days. 4. The drug is produced in polypropylene bottles of 140 tablets. Shelf life is one year.