The efficacy of an organic acid based antimicrobial product Sal CURB on the total enterobacteriaceae contamination of mash feed.

Introduction

Animal feed stands at the beginning of the food safety chain. Feed raw materials and final feed are susceptible to microbiological contamination with Enterobacteriaceae and Salmonella species. Feed contaminated with Enterobacteriaceae and Salmonella can lead to a subsequent contamination of the animal carcasses which may cause human food-borne infections. With stringent regulations on feed and food hygiene the contamination of feed and food with Salmonella must be controlled.

A combination of heat and pressure in the pelleting process with organic acids will accelerate the reduction of Enterobacteriaceae in the feed. When no organic acids are present in the feed, there is no residual effect against subsequent recontamination.

The application of a mixture of organic acids as in Sal CURB is a solution to avoid the recontamination of the feed with Salmonella and Enterobacteriaceae.

The total Enterobacteriaceae contamination of feed can be used as a marker for the microbiological quality of the feed. Salmonella belongs to the group Enterobacteriaceae, and analysis of the total Enterobacteriaceae contamination of feed will give information on the susceptibility of the feed to be contaminated with Salmonella.

The aim is therefore to investigate the effect of the antimicrobial product Sal CURB to control the total Enterobacteriaceae contamination in mash feed.

Materials and Methods

Mash feed samples were collected from all over Europe and analysed for their microbiological quality in the Kemin Animal Health and Nutrition Customer Service Laboratory in Europe. A distinction between mash feed samples not treated with an antimicrobial (Control) and mash feed samples treated with Sal CURB was noted. Sal CURB was applied under field conditions in accordance with the recommended application level.

In this study more than 850 samples were analysed, of this, approximately 330 were control samples and more than 530 samples were treated with Sal CURB.

The total Enterobacteriaceae contamination of the samples was expressed as colony forming units per gram (cfu/g). The lowest to highest bacterial count determined was from 100 (2 log) to 10,000,000 cfu/g (7 log).

For interpretation of the degree of Enterobacteriaceae contamination the samples were distributed into different classes according to their log cycles contamination. A percentile distribution of the number of samples present in each log class is presented.

Results and Discussion

The total Enterobacteriaceae distribution of the control and treated Sal CURB mash feed is shown in Figure 1.

Distribution of the total Enterobacteriaceae contamination between Sal CURB and untreated mash feed samples

Figure 1. Distribution of the total Enterobacteriaceae contamination between Sal CURB and untreated mash feed samples

The control group has a higher total Enterobacteriaceae contamination compared to the Sal CURB treated mash feed, and represents a normal distribution of the curve. The largest fraction of mash feed samples analysed had a total Enterobacteriaceae contamination of 3-5 log. Approximately 20 to 25% had less than 3 log (1 000 cfu/g) and 20% above log 5.

Sal CURB treated feed had a lower total Enterobacteriaceae contamination, with 65% of the samples less than 1 000 cfu/g (log 3). Only a small fraction of the mash feed samples treated with Sal CURB had a total Enterobacteriaceae contamination above log 4.

The total average Enterobacteriaceae contamination is shown in Figure 2. Sal CURB treated feed samples had an average Enterobacteriaceae contamination of 2.5 log compared to the control of 3.8 log. This indicates that, on average, Sal CURB lowers the total Enterobacteriaceae contamination with 1.3 logs or by more than 95%. The balanced mixture of organic acids in Sal CURB is effective to reduce the total Enterobacteriaceae contamination of mash feed. Enterobacteriaceae contamination is correlated to the risk of Salmonella, reducing the Enterobacteriaceae counts, the incidence of a Salmonella contamination is reduced as well.

Average total Enterobacteriaceae contamination between Sal CURB® and untreated mash feed samples

Figure 2. Average total Enterobacteriaceae contamination between Sal CURB and untreated mash feed samples.

Conclusion

Sal CURB lowered the total Enterobacteriaceae level in mash feed from 6 310 to 316 cfu/g. Application of Sal CURB in mash feed reduces 95% of the total Enterobacteriaceae count. Sal CURB plays an essential role to control the microbiological contamination of feed and to guarantee optimal feed and food safety.

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