The effects of different levels of Aloe vera gel on ileum microflora population and immune response in broilers: a comparison to antibiotic effects

The purpose of the present research is to study the effects of different levels of Aloe vera gel on microflora population, humoral and cellular immune response, and relative weight of lymphoid organs compared to the effects brought about by antibiotic. The groups included the control group (basal diet) as well as three groups with different levels of Aloe vera gel (added to basal diet at 1.5%, 2% and 2.5%), and finally a group with basal diet supplemented by 15 ppm virginiamycin antibiotic. Regarding ileum microflora, the increase in Aloe vera gel in the feed resulted in significant reduction in the number of E. coli colonies and significant increase in the number of Lactobacillus colonies compared to the control and antibiotic groups. As far as humoral immunity is concerned, Newcastle disease virus antibody titre on the 24th and 38th day was the highest in 2.5% and 2% Aloe vera gel groups, respectively. In addition, sheep red blood cells antibody titre reached its highest level in the 2.5% Aloe vera gel group on the days 24, 28, 34 and 38. The differences among the groups regarding sheep red blood cells antibody titre were significant on the days 24, 28 and 34, while no significant differences were observed on the 38th day. Regarding the cellular immunity, the highest response was obtained by injecting phytohemagglutinin-P and the highest relative weight of spleen and bursa of Fabricius was found in the 2.5% Aloe vera gel group. The findings of the study suggest reduction in number of E. coli colonies and increase in number of Lactobacillus colonies as a result of increased Aloe vera gel in the feed. Furthermore, the 2.5% Aloe vera gel group resulted in significantly higher levels of humoral and cellular immunity, as well as relatively greater weight of lymphoid organs, which suggests that Aloe vera gel can be a proper replacement for the virginiamycin antibiotic.