Salmonella is a natural inhabitant of the lower part of intestinal tract of poultry. In case of an external stress such as diet change, boosted performance, environmental conditions, etc., Salmonella starts to overgrow and migrate from the hind-gut to the small intestine. This overgrow is also responsible for Salmonella shedding in the environment creating conditions for cross contamination between broilers reared in the same flock.
It is also well known that in case of Salmonella infection, other enterobacteriaceae, such as E. coli, will overgrow in the hind gut and migrate to the upper part of the intestine. A way to control Salmonella prevalence in broiler flocks is to limit its presence in the caeca and thus prevent its shedding.
The antimicrobial effects of essential oils (EO) have been scientifically proven (Hammer et al., 1999). Essential oils (EO) improve feed digestion and also increase the permeability of the bacterial cell membrane thus respectively reducing the substrate for bacterial overgrow in the hind-gut and enhancing the efficacy of organic acids (OA). Organic acids (OA) and essential oils can have a synergistic action and consequently can be used effectively in combination as an anti-salmonella feeding strategy.
Kemin research showed that encapsulation techniques are valid tools to increase short chain fatty acids (SCFA) and EO efficacy along the gastrointestinal tract versus the non-encapsulated ones. The aim of this trial is to evaluate the efficacy of FormaXOL™ to control Salmonella colonization in infected birds.
Experimental animals and treatments. At 1 day of age, 40 commercial broilers (females) were housed and split in 2 groups (20 broilers/group). From day 1 both groups received the experimental diets: Control [commercial diet (CD) without organic acids and/or essential oils], and FormaXOL™ 1 (CD + FormaXOL™ @ 1.0 kg/ton of feed).
Infection and analysis. At day 7 of age all birds both groups were orally inoculated with 106 cfu of a field strain of S. enteritidis.
At 1 day post infection (PI) a cloaca swab was conducted on all the birds to evaluate Salmonella colonization. A Salmonella positive/negative test was carried out. During the first week PI, the faeces produced during 12 hours were collected at day 3 and 5 PI from the floor of the isolator to investigate Salmonella shedding. The same was repeated during the second week at day 10 and 12 PI. A S. enteritidis count test was performed on faecal samples.
At the end of the first week PI, (7 days PI) 50% of birds were euthanized and cecum samples were collected for bacteriological analysis. The remaining 50% were euthanized at the end of the second week PI (14 days PI). In both sampling periods and for every cecal content collected, the count of Salmonella enteritidis, total Enterobacteriaceae and Escherichia coli was performed as cfu/g of cecal content.
For statistical analysis, data were submitted to one-way ANOVA.
After 3, 5, 10, 12 days PI a non-sticky wax paper was laid at the bottom of each isolator to collect faeces. After 12 hours papers were collected and a single pool of 50 g of faeces was obtained per each isolator/group for Salmonella enteritidis count. Results of microbiological analysis are reported in table 1. The results clearly show that after a strong Salmonella challenge, FormaXOL™ is able to significantly limit the Salmonella shedding.
Table 1. Salmonella enteritidis shedding at 3, 5, 10 and 12 days post infection (log cfu/g faeces)
Table 2 and 3 reports the Salmonella and E. coli count in the caecum content respectively, collected from birds euthanized at 7 and 14 days PI. The Salmonella count in the control was significantly higher at both 7 and 14 days PI. In the Control group, from 7 to 14 days PI, the Salmonella count increased by 1.13 log while in the FormaXOL™ treated group there was 0.41 Log reduction.
Table 2. Salmonella enteritidis count in the caecum at 7 and 14 days post infection (log cfu/g)
Considering that broilers were reared in isolators, these results could be explained by an E. coli outbreak in birds strongly contaminated by Salmonella, while in groups were FormaXOL™ controlled the Salmonella prevalence, the E. coli count was lower.
Table 3. Escherichia coli count in the caecum at 7 and 14 days post infection (log cfu/g)
This trial demonstrates the efficacy of FormaXOL™ to control Salmonella contamination in poultry. Results also demonstrate the ability of FormaXOL™’s preventative action on Salmonella along the intestinal tract, being effective until the hind gut. FormaXOL™ clearly lowered the Salmonella counts in the faeces and in the cecal contents.
1. Hammer K.A., Carson C.F., Riley T.V. (1999). Antimicrobial activity of essential oils and other plant extracts. Journal of Applied Microbiology 1999, 86, 985–990. SA-11-00314
2. Efficacy of FormaXOLTM to control Salmonella prevalence in infected broilers. TL-11-00141