| As world experience shows, of particular importance in the prevention and treatment of gastrointestinal diseases of young animals is replacement therapy, aimed at restoring intestinal biocenosis through the regulatory injection of live bacteria representing the normal intestinal microflora. Currently, the veterinary service has a sufficient number of domestic and imported probiotic products of various species composition, intended for the prevention of gastrointestinal diseases of young animals and birds. However, monitoring of the probiotic market shows that the vast majority of developments are not in demand by practice. This circumstance gives grounds to assume that the approach to the development of probiotics should be based on the study of many parameters, including, first of all, a comprehensive assessment of the properties of microorganisms -probionts. The article presents the results of studying the effect of "Enterocol" from the strain E.coli 64G on the total amount of protein, quantitative and qualitative content of immunoglobulins in the blood serum of newborn calves. It was found that feeding off of the newborn calves with "Enterocol" helped to increase the concentration of total protein and immunoglobulins of all classes in the blood. The authors of the study came to the conclusion that the degree of the above increase depends on the dose of the drug given. Citation | Bulegenova M, Biyashev K, Kirkimbaeva Z, Biyashev B, Ermagambetova S, Oryntayev K, Altenov A (2019). The effect of the drug "enterocol" on the humoral factors of calf body resistance. Adv. Anim. Vet. Sci. 7(8): 674-680.

At present, it is relevant to preserve and raise healthy, well-developed newborn animals adapted to new conditions, which form the basis for increasing the yield of animal husbandry. Gastrointestinal diseases cause the main losses of young animals. Acute gastrointestinal diseases of calves, lambs, piglets, and chickens are widespread in Kazakhstan. The study aims to develop a competitive treatment and prophylactic drug composition based on probiotic bacterial strains. Modern certified and standardized biochemical, microbiological, molecular biological studies were considered during the research. The morphological, cultural, and biochemical properties of the cultures were studied according to generally accepted schemes. Standard methods of finding averages and their mean errors were used for the mathematical processing of results. Antibiotics, sulfonamide, and nitrofuran drugs are the most common methods to combat diseases in young animals. However, the use of antibacterial agents often leads to the death of normal microflora, disrupting the microbiocenosis of the gastrointestinal tract, the appearance of microorganisms with resistance to drugs, and a decrease in product quality. In this regard, the direction of biotechnology involved in the development and creation of environmentally friendly microbial preparations with prophylactic effectiveness is very relevant. Data on the prophylactic and therapeutic efficacy of the probiotic strain of Escherichia coli 39-SN are presented.