TDK conference 2022

The growing antimicrobial resistance could lead to up to 10 million deaths per year by mid-century on current trends, and so alternatives to antibiotics are needed to treat bacterial diseases. Antibiotic alternatives include propolis, which has a proven immunomodulatory and bacteriostatic or bactericidal effect, depending on the bacterium. Salmonella enterica, known as the most common foodborne pathogen, is usually transmitted by eggs and contaminated or inadequately heat-treated poultry meat. From a human and animal health perspective, there is a large body of research defining its in vitro efficacy, but the in vivo efficacy of propolis is a less researched area.

In our studies, doses of propolis dried after alcoholic extraction were administered 1x, 3x and 5x in feed and aqueous extract in drinking water. During rearing, daily weight gain was measured individually and feed consumption was measured in groups. In addition, Salmonella enterica strains were infected in the treated groups.

It was shown that although there was no significant difference in weight gain between control and treated groups, the weight gain of the treated groups was professionally relevantly higher than that of the control group during the first two weeks. Until day 12 of life, the groups treated with each dried propolis extract consumed much less feed than the control group and their weight gain exceeded that of the control group. This trend decreased until day 24, when the indicators improved again. The feed conversion of the aqueous extract group was better than that of the control group for most of the study period. The feeding of propolis did not result in an earlier cessation of Salmonella shedding but did reduce the likelihood of clinical signs of infection. In the infected groups, Salmonella shedding was detectable by day 3 for the group fed 1x dose of dried propolis extract, day 6 for the 3x dose, day 14 for the 5x dose, and day 6 for the group fed the aqueous extract, whereas in the positive control it was detectable only by day 3.

Based on our results, we can conclude that propolis can be safely used as a supplementary treatment for broiler chickens, significantly improving economic indicators during certain periods of the rearing period. In the future, it is worthwhile to conduct more studies with larger numbers of animals to investigate the efficacy and pharmacokinetic properties of propolis.