Immune Parameters in Chickens Treated with Antibiotics and Probiotics during Early Life

SIMPLE SUMMARY: The effect of using antibiotics in animal production is resulting in an increase in drug resistance among bacteria, often to multiple substances with different mechanisms of action. In the future, this could lead to an increase in mortality in human and animal populations. In consequence, there is enormous and fully justified public pressure to limit the amount of antibiotics used in livestock production. The study aimed to compare the effect of administration of antibiotics or probiotics on chickens in their first week of life, on selected parameters of humoral and cellular immunity, and on the bursa of Fabricius and spleen indices. Administration of the antibiotic enrofloxacin or a probiotic containing Enterococcus faecium and Bacillus amyloliquefaciens strains to chickens in their first week of life exerts pronounced immunomodulatory effects on humoral and cellular defence mechanisms in these birds. Early administration of a probiotic has a positive effect on the immune system, however, early administration of enrofloxacin can pose a risk of suppression of humoral immunity of the chickens. ABSTRACT: The aim of the study was to compare the effect of the administration of antibiotics or probiotics on chickens in their first week of life, on selected parameters of humoral and cellular immunity, and on the bursa of Fabricius and spleen indices. The experiment was carried out on 90 one-day-old male broilers. The control group received no additive in the drinking water; the group GP received a probiotic providing Enterococcus faecium and Bacillus amyloliquefaciens; and the group GA received 10% enrofloxacin in the drinking water on the first five days of life. Administration of the antibiotic enrofloxacin or a probiotic containing E. faecium and B. amyloliquefaciens strains to chickens in their first week of life exerts pronounced immunomodulatory effects on humoral and cellular defense mechanisms in these birds. The changes in the subpopulations of B and T cells immediately following early administration of enrofloxacin or the probiotic were not observed at the age of 35 days. Early administration of enrofloxacin can pose a risk of suppression of humoral immunity, as indicated by the significant decrease in the total IgY concentration in the plasma of the chickens.