Dietary Administration of Olive Mill Wastewater Extract Reduces Campylobacter spp. Prevalence in Broiler Chickens

Food wastes are sources of compounds that can be used as natural additives in the food and feed industry. The olive oil industry produces two main wastes: aqueous waste (olive mill wastewater) and solid waste (pomace or olive cake). These by-products are rich in phenols, which are antioxidant and antimicrobial compounds able to inhibit or delay the growth of several bacteria in vitro. The dietary effect of both olive mill wastewater polyphenolic extract (OMWPE) and dehydrated olive cake (DOC) on the prevalence of Campylobacter spp. in broiler chickens was investigated. A commercial basal diet was supplemented with either OMWPE-or DOC-enriched maize at two dosages (low: 16%; high: 33%). The prevalence of Campylobacter spp. shedding was evaluated at 21, 35, and 49 days of age. The prevalence of Campylobacter spp. differed among groups only at 49 days of age. Both OMWPE groups showed a lower (p < 0.05) prevalence compared to the control group. The odds ratio evaluation showed that the higher dose of OMWPE reduced the possibility of shedding 11-fold compared to the control group (p < 0.001). These results highlight the potential use of olive by-products against Campylobacter spp. in poultry.