Azimul Haque, Saravanan Sankaran, Gulam Murshed and Srilatha Atmakuri, Kemin Industries South Asia Pvt Ltd
:Animal feed can serve as a carrier for a range of microbial contaminants such as bacteria, yeast and molds. Such contaminants have been shown to influence animal performance adversely and it compromise the safety of animal products. Feed raw materials and final feed may suffer from serious deterioration in quality because of various microbiological and chemical processes. Indeed, feed raw materials and final feed are susceptible to microbiological contamination with molds and Enterobacteriaceae. The total Enterobacteriaceae contamination of feed can be used as a marker for the general microbiological quality of the feed. The family of Enterobacteriaceae comprises several genera, including Salmonella species, Escherichia species, Shigella species and Yersinia species. Feed contaminated with Enterobacteriaceae and more in particular Salmonella species can lead to a subsequent contamination of the animal carcasses and human food-borne infections.
However, sometimes Salmonella is difficult to isolate, as these bacteria are not always distributed evenly in the feed raw materials and final feeds. This can lead to the finding of Salmonella negative analysis from feed, that is actually contaminated with Salmonella. There is a recognized association between the risk of Salmonella contamination and the degree of Enterobacteriaceae contamination. Therefore, the total Enterobacteriaceae contamination can be used as a tool to evaluate the probability of Salmonella contamination.
The principle approach to reduce and eliminate Salmonella in animal feedstuff is by monitoring and control of contamination in ingredients and process. For this reason, manufacturers and users of animal feeds typically employ a range of tactics by including chemical treatments, in an attempt to suppress, eliminate or prevent Salmonella contamination. The principle chemical agents used are organic acids and formaldehyde, although blended products may additionally employ surfactants, bacterial membrane-disrupting compounds and other elements.
Chemical treatment of feed may exert its effect before it is consumed, and/or upon ingestion, the feed is moistened by the animal’s alimentary secretions and encounters the pH conditions and endogenous acids in the crop, rumen, stomach and intestines, according to species. The antimicrobial effects may be rapid or slow and the progressive and particular advantage of chemical treatment is that the antimicrobial capability may persist during storage, thereby helping to protect the feed against re contamination.
Organic acids and their salts are relatively stable in feed and some of them are occurring naturally in living organisms, especially in the alimentary tract. They are selected for use in animal feeds because they are generally metabolized by recipient animals or if stabilized, they may pass through unabsorbed and therefore leaves no residues in foods of animal origin. Individual acids are varying in their effects on Salmonella but in general, medium chain fatty acids are more effective than short chain fatty acids. While acid decontamination may not be as effective as heat decontamination, it does provide a level of residual protection against post-production contamination/ recontamination of the feed.
Formaldehyde is included in several acid blends to improve the efficacy of the product. It is generally accepted that formaldehyde is one of the most effective products to kill Salmonella. The main difference between the effects of acids and formaldehyde is that formaldehyde kills Salmonella immediately, while the effect of acids takes some time.
SalCURB® liquid is designed as a balanced blend of formaldehyde, organic acids, its salts and a surfactant. Besides an excellent antimicrobial activity, the handling characteristics, ease of application and safety of antimicrobial product were also taken into account. The objective of the present study was to demonstrate the efficacy of SalCURB® liquid in controlling microorganisms in the feed, against a competitor feed acidifier product based on formic acid, propionic acid, ammonium formate and ammonium propionate.
In present study, we conducted a feed mixing trial in a commercial feed mill with the capacity of 1MT. The control group was treated at a dosage of 4Kg of competitor feed acidifier, whereas the treatment group was treated with 2Kg of SalCURB® liquid. Both these samples were stored at room temperature (25° – 30° C) for one hour. Later control and treated samples were collected at the rate of 250 g in a plastic cover in zip lock method and analyzed for total Enterobacteriaceae, mold count, water activity and moisture from reputed lab in Bangladesh.
The trial results were observed as follows:
• Treated group with SalCURB® liquid showed higher inhibitory concentration activity in Enterobacteriaceae count when compared to competitor feed acidifier.
• Mold count was also reduced by 4 times in treatment group when compared to control group.
• There was no significant difference observed in terms of water activity and moisture analysis in both treatment and control group.
• Based on the trial results, SalCURB® liquid was observed as a better acidifier when compared with competitor feed acidifier product.
• Hence feed hygiene is one of the important tool for effective Salmonella control in poultry.