Evaluation of Prebiotic and Probiotic Feed Additives as a Method of Salmonella Mitigation in Broilers and Laying Hens

For the last few decades, antibiotic usage in poultry production has been commonly implemented for increased production performance, as well as control of infectious diseases. However, changes in recent years both from legal entities and consumers have caused this usage to shrink in the last decade. These changes have resulted in food safety becoming a greater point of concern. As antibiotics continue to be phased out, alternative methods of pathogen control must be found in order to keep a growing population fed with nutritious and safe food sources. This study was conducted to evaluate the efficacy of prebiotics and probiotics as a pre-harvest method of mitigating Salmonella in broilers and laying hens. The objectives were to: 1) evaluate the effects of yeast prebiotics, Bacillus probiotics, and their combinations as a method of reducing Salmonella counts in the ceca of broilers; 2) determine the effects of yeast prebiotics, Bacillus probiotics, and their combinations as a method of reducing Salmonella counts in the ceca of early production laying hens; 3) determine the effects of yeast prebiotics and Bacillus probiotics as a method of reducing Salmonella translocation to internal organs including liver, spleen and ovaries; and 4) determine the effects of yeast prebiotics and Bacillus probiotics as a method of reducing Salmonella counts and ovary prevalence in late production laying hens. Results from the laying hen experiments (experiments 1 and 2) showed positive benefits with the supplementation of yeast cell wall (YCW) and Bacillus products in laying hens, with reductions in cecal load being seen across all three different serovars of Salmonella. In the first experiment, supplementation of YCW at 500ppm resulted in a reduction of over 1.8 logs of Salmonella enterica serovar Typhimurium (ST) and a nominal reduction of approx. 0.5 logs of Salmonella enterica serovar Braenderup (SB) in the ceca of early production laying hens. Similar reductions were seen in the second experiment. On an individual room basis, in room 3 YCW supplementation resulted in a 1.2 log reduction in Salmonella enterica serovar Enteritidis (SE), and the Bacillus product supplementation resulted in a 1-log reduction in SE in the same room. In a cumulative overview, the YCW treatment resulted in a cumulative reduction approaching 1 log. While these did not achieve statistical significance, they did achieve a biologically relevant reduction in Salmonella colonization of >1.0 Log10 when compared to the control treatment. Results from the broiler experiments (experiments 3 and 4) were mixed and varied by the Salmonella serovar the birds were challenged with. In experiment 3, small Salmonella reductions were noted in ST challenged broilers, with a biologically relevant reduction of >1.3 logs at day 14 in the YCW treated birds. Other nominal reductions were seen with the supplementation of YCW in the diet, with a 0.8 log reduction in ST colonization at day 21 when compared to the control treatment. In experiment 4, birds challenged with Salmonella enterica serovar Infantis (SI) and supplemented with the YCW treatment experienced the greatest benefit, with a 4-point reduction in feed to weight ratio (0.04), as well as a >0.6 log reduction in SI load in the ceca at both sampling time points (days 14 and 21) when compared to the control treatment. While this value was not statistically significant, YCW did achieve a slight reduction in Salmonella load in the ceca at both sampling time points. While statistically significant reductions were not achieved in in many of the aspects observed in these experiments, biologically relevant reductions of Salmonella were observed with the inclusion of YCW or Bacillus products into the diet across a wide range of Salmonella serovars. Because of these reductions, both the Safmannan YCW and MicroSaf Bacillus show promise in improving food safety as a feed additive