By Laura Greiner and Sarah Elefson
Greiner is an assistant professor in animal science at Iowa State University. Elefson is a research graduate assistant.
From time to time, producers may experience an issue within their barns and suspect that feed may be playing a role. These types of issues can range from unexpected mycotoxin levels and feed mill scale malfunction to long storage of vitamins and the incorrect diet being placed within a bin. Careful review of the diets and step-by-step evaluations should be made to determine if feed may be the root cause.
Here are a few key points to remember when gathering information to assess diets.
1. Consult with a nutritionist.
Your nutritionist should be able to provide you with current diets and work with the feed mill and potential ingredient suppliers to assist you whenever a nutritional issue is being considered in a diagnostic case.
2. Gather a dietary sample.
Vitamin or mineral inclusion challenges can occur in a variety of places during the feed manufacturing process. The best ingredient to sample to ascertain what levels are being added to the diets would be the premix. Heat, humidity and storage time could negatively impact vitamin levels. A complete feed sample could also be beneficial if there was a suspected issue with mixing the feed, particularly if the feed mill inventory values are different from expected values.
3. Gather tissue samples.
It is imperative to understand what tissue/fluid will best provide you with the actual level of a nutrient within the body as some systems in the body will tightly regulate nutrient levels. Not all vitamin, mineral and other nutritional parameters can be best assessed from serum samples. For example, vitamin A is tightly regulated within the blood. Therefore, the liver will provide a better understanding of actual vitamin A status. Furthermore, if the issue at hand is unknown to be disease or nutritionally related, sampling animals that are not clinical may provide valuable information. When pigs are not eating, certain blood measurements such as calcium and phosphorus may not test within the normal range and could mislead investigators.
4. Select appropriate sampling technique.
Certain serum collection tubes (such as those with the gel fraction) may bind nutrients and cause a false analytical value. This may also be true in terms of the use of serum or plasma and even when sample is collected post-feed consumption. The diagnostic laboratory and your nutritionist can provide guidance on the appropriate sample.
5. Understand parameters.
Different ages of swine will have different thresholds of tolerance relative to others. For example, sows can tolerate a higher level of vomitoxin compared to a newly weaned pig. Vitamin and mineral status can also change based on phase of production. Your nutritionist should be able to provide you with appropriate reference value ranges when reviewing the diagnostic findings.
Additional information on sampling techniques and vitamin and mineral levels will soon be available through Iowa State’s Iowa Pork Industry Center and extension materials.
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