Feb 14, 2023

The case for storing feed samples six months or more

A nutritionist’s tale of defending a formula’s safety with saved samples.

I just read the Kansas State University guidelines from the Grain Sciences department regarding sampling and sample management of raw materials and finished, mixed products. That information is freely available on the internet, and in truth, this was the trigger for an unpleasant memory that made me realize how lucky I was to have been a student of the above department while studying for my master’s degree.

Not long ago, one of my clients was taken to court for having sold an off product. That product was designed by me and manufactured under my guidelines in a toll-mill feed plant.

So, naturally, I was called to advise on what might have gone wrong. The claim was substantial and, of course, someone had to pay for the damage. This was one of the rare occasions when the veterinarians blamed the feed, and they were right — but that is another story for another time.

As it happens, I am loath to changing formulas for minor issues and especially when prices fluctuate slightly up or down. I prefer to either pass the savings to my customer or absorb the increase.

This was a formula for a piglets line, and I learned early in my career that these formulas are not as forgiving to least-cost formulation as formulas for older animals. I had production records that showed my original design was indeed what was produced — and such records are something feed mills of substance keep for some time as part of the quality assurance program. If not, they should think about it.

Lab analysis points to conclusion

Both my own client (a distributor) and the end-user (a farmer) analyzed the feed for all possible matters. The laboratory results came back as expected with no blame to be placed upon the raw materials and mixing at the feed mill.

Then, I was told that the actual problem was the animals refused to eat the feed. That information combined with the hot and humid climate of the location where the end user had his farm made me ask for a lipid oxidation test.

As it happened, my formula contained plenty of lipids, both from extruded soybeans and from added soybean oil. Most would agree that this was a logical conclusion.

Indeed, both the farmer and the distributor ran independent laboratory analyses and they both came to the same conclusion. The product was super oxidized. Immediately, the blame was shifted back to the feed plant.

Here comes the good part — the feed plant kept samples of all finished products and all raw materials upon receiving them. They also kept it in a normal room without any refrigeration or special cooling system.

The samples were kept over a year, despite the usual six-month expiration date for most finished product. Apparently, this was not the first time the feed plant had to address such complaints long after the feed had seen the end of its useful life.

Here’s the end of the story. The samples kept at the feed mill, at room temperature, were all fine.

Indeed, the numbers were as good as fresh product. No oxidation. I use quite a bit of antioxidants for several reasons, and under normal conditions these help keep free radicals in check avoiding the unpleasant results of lipid rancidity.

I must also mention the feed plant was in northern Europe while the end-customer was at the opposite end. In my defense, I never expected my distributor to send products that far south, or I would have reduced the amount of lipids added, which I did after the incident. On further investigation, the products arrived at the end user near their expiration date, and they were used just prior to the expiration date.

So, all these factors caused a big commotion and some lost business with a good lesson learned by the distributor.

How to properly keep feed samples

Long story short, keep samples. If you are in a warm and humid environment, invest in a large refrigerator or install a cooling system where you can keep samples. Ideally, freeze samples. But that is something we did only for university trials. For commercial purposes a cool, dry, dark room should suffice. Many feed mills run out of sample storage space very fast, so they tend to discard samples after six months. That might cost them as claims could take some time before they get resolved.

To keep storage capacity maximized, one may reduce the amount of sample retained. To obtain a representative sample requires a bit of extra effort. Some feed plants just pick a handful of products and place it in a plastic bag. That is not a representative sample, and believe me, in six months that sample will turn blue or green if the hands have some moisture or dirt on them.

It is advisable to use clean utensils and sterilized bags for sensitive samples. Procedures for proper sampling abound, and I strongly recommend locating the KSU guidelines for consultation. Sampling is a serious business that can save a feed plant serious money.

Editor’s note: Here is a relevant link from the KSU Animal Sciences department.

Ioannis Mavromichalis, Ph.D., is an animal nutrition industry consultant. He may be contacted at [email protected]

Ioannis Mavromichalis, PhD

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