Nutritional Diagnostics – Here Are 7 Tips

Disease breaks. Mortality. Less-than-ideal production metrics. Looking for answers to challenges in your herd? Josh Flohr, technical and production support manager at Seaboard Foods, says nutritional diagnostics – analyzing feed, tissue, or serum samples to determine the exact level of a nutrient or the corresponding metabolite of a nutrient in the animal – may be what you need to better understand the issues your herd is facing. Flohr offered a few tips for diagnostic sampling during the Allen D. Leman Swine Conference in Minneapolis this week.

1. Sample from both the general population and challenge population.
Producers often collect samples from the challenged population to determine their nutritional status, but Flohr says it’s important to also sample your general population to obtain a “control” or baseline. For example, if you sample from a fall-behind pig that likely has not eaten in multiple days, it makes sense that the pig’s nutritional status is below a normal threshold.

2. Does the clinical pathology fit the clinical symptoms?
Imagine your herd is showing classical signs of mulberry heart disease, Flohr says. Serum samples are sent in. The diagnostics show low circulating Vitamin E levels. This is logical. However, in a second example, imagine your herd is experiencing high rates of scours in 25- to 50-pound pigs. Serum results suggest Vitamin D levels are low. In this case, Flohr says he would not conclude these issues are related because they have never been proven to be related before. 

3. Understand the metabolic marker being analyzed.
Sometimes the marker of nutrient status is not the same as the active metabolite in the body, he adds. Understanding the relationship and metabolism of the nutrient may help draw inference from the analytical results.

4. If results are accompanied by reference ranges, understand the source of the reference range.
If the lab provides a reference range, find out how the reference range was established. If you are sampling tissues from a neonatal pig and the reference range was established in adult animals, or another species, it would not be surprising that the results are different, Flohr says.

5. Understand analytical procedures and variation associated with them.
It’s important to understand the basic analytical procedures and understand variations that can occur. For example, many people send in bones to determine bone ash values which can be used to assess the Calcium and Phosphorus status of the animal. He says results typically come back lower than the reference range because the reference ranges use “defatted bones.” Most labs do not defat the bones prior to ashing, which lowers the ash content. In addition, the type of bone analyzed could greatly affect what a normal ash content would be.

6. Identify the expected analytical error associated with testing.
There is always error associated with analytical techniques, but some nutrients and procedures introduce more error than others, he says. A good example of this is analysis of vitamins in complete feed. It’s tough to do, and for some vitamins, you can see up to 40% error. However, if you analyze a vitamin premix (less complex matrix), then the analytical error is much less. When Flohr analyzes for vitamins, he typically tests premix for quantification purposes and evaluates feed mill batching records to determine whether the right amount of premix went into the feed. Finally, he uses the complete feed analysis mainly as a “yes” or “no” answer to whether the vitamin is present in the diet, rather than rely on the quantitative result.

7. Communicate with your nutritionist.
Don’t be afraid to communicate with a nutritionist to review results and provide some perspective on their experiences in testing.