Over periods of 22 and 14 months, IgG antibody concentrations in serum samples obtained monthly from 14 mares and 19 foals, respectively, were measured by use of ELISA against antigens of the following environmental microbes: Aspergillus umbrosus, Penicillium brevicompactum, Rhodotorula glutinis, Absidia corymbifera, Aspergillus fumigatus, Humicola grisea, Micropolyspora faeni, and Thermoactinomyces vulgaris. The mares and foals were on pasture from early June until early October, then were stabled during the winter season until the following June. In the mares, increased antibody concentrations against most microbes were observed typically in midwinter and late spring when the horses were stabled; antibody concentrations against R glutinis, however, peaked in August. Concentrations differed between the summer and winter seasons and, in most instances, between 2 consecutive years and correlated with amounts of rainfall during the previous harvest season. In the foals, circulating passively acquired antibodies disappeared within 3 to 4 months after birth. During the first year of life, substantially increased autogenous antibody concentrations were observed only against R glutinis. Antibody concentrations against the other microbes increased gradually toward the end of the indoor season. In a group of foals transferred indoors in autumn, 6 weeks later than the other foals, antibody concentrations were lower when measured in December. Results supported the view that, to minimize exposure to microbial spores during the winter season, horses should be kept outdoors as much as possible and attention should be focused on improving the ventilation in stables and the quality of feeds and beddings.

Development of diarrheal diseases of newborn animals has a miltifactorial character and it is very difficult to optimize the structure of microbial population in alimentary tract and to carry out the correction of the microbe status only by means medical preparations. Therefore, for regulation of standard structure of intestine microflora in a complex of medical and preventive measures for diarrhea diseases of young poultry an important role is played by application of probiotics, prebiotics, and immunoamplifiers. In course of study there were used biologically active preparations produced on the basis of ecologically pure products of a natural origin: immunostimulant Alveozan, probiotics Bifidoflorin liquid and Dialakt, and prebiotics Biofon АIL and Biofon. Research was realized on one-day-old broiler chickens of Kobb-500 cross. The obtained data on the positive influence of the studied preparations on microbiocenosis of an alimentary tract of broilers chickens correlated with the indexes of natural resistance (autarcesis).The analyzed preparations made it possible to increase the local protection, stimulation of hematopoiesis (increasing of hematoglobulin, erythrocytes and leukocytes); to increase the blood content of whole protein, albumens and globulins, bactericidal activity of blood serum. Complex introduction of the analysed preparations stimulated the natural disease resistance factors, normalized the metabolic function of poultry, promoted the increasing of chicken livability and productivity