Haematological and Biochemical Blood Parameters in Egg-Laying Hybrid Chickens Under the Influence of a Probiotic Bacillus subtilis and Enrofloxacin

Abstract

The widespread use of antimicrobial drugs, such as enrofloxacin, in poultry farming is associated with risks of residue accumulation in the products and the development of antimicrobial resistance, posing a serious threat to consumer health. Probiotics, particularly those based on Bacillus subtilis, are considered a safe alternative capable of not only maintaining bird health but also improving the nutritional characteristics of the products. The purpose of this article was to conduct a comparative assessment of the effects of enrofloxacin, probiotic B. subtilis, and their combination on the haematological and biochemical blood parameters in egg-laying hybrid chickens as key indicators of the metabolic and immune status. Materials and methods. The research was conducted on Hisex Brown cockerels from one day to three weeks old (n = 100). Four groups of chickens were formed: a control group, a group that received the probiotic B. subtilis, a group that was given enrofloxacin, and a group that received a combination of the two. Blood sampling for biochemical and haematological analysis was performed on days 1, 5, 10 and 20 of the experiment. Results. The group that received enrofloxacin demonstrated a significant decrease in total protein and bilirubin levels on day 5, indicating liver dysfunction. In the groups that were given the probiotic, an increase in total protein by day 20 and a positive dynamic in lipid metabolism were observed. On day 10, these groups showed a significant decrease in pseudo-eosinophil concentration and an increase in lymphocyte levels, indicating stimulation of specific immunity. The combined use of the probiotic with the antibiotic mitigated some of the negative effects of the latter. The use of B. subtilis helped stabilize the biochemical status, optimize lipid metabolism and activate the specific immune response in chickens, in contrast to the negative impact of enrofloxacin. The obtained data confirm the potential for using probiotics to optimize poultry farming in order to enhance product safety and quality.