There are nutritionists and there are veterinarians. Nutritionists deal with feeds; veterinarians deal with health. Are the two connected?

Yes, they are. Each needs to understand the effects of the other’s work within the pork production system. Maybe the second most obvious connection is through recognition that overt malnutrition (although rare today) reduces the immune system’s power and makes pigs more susceptible to disease.

However, the thesis offered here is that factors other than nutrient deficiencies impact pig health, and they may be exploited to support health. This is yet another connection between nutritionists and veterinarians.

Clearly, the most important components of a herd-health program are those that veterinarians and production managers design and manage. Progress in improving such practices has been impressive. Among the more important practices are all-in/all-out pig flow, multiple-site production, age-segregated rearing, strong biosecurity programs, enhanced sanitation and vaccination. In the aggregate, these practices are remarkably effective in protecting pigs from disease challenges. However, they are not enough — as recent experiences with porcine circovirus associated disease, the industry’s on-going battle with porcine reproductive and respiratory syndrome and other diseases illustrate.

Today, a substantial body of evidence shows that specific dietary factors may provide health benefits to the animal. While they are not likely to be as powerful as all-in/all-out pig flow or a vaccine, they are nonetheless important. Most involve feed ingredients or additives, but some relate to nutrient levels, feed processing or animal feeding methods.

Why do we use expensive ingredients such as spray-dried animal plasma and dried whey in newly weaned pig diets when cheaper ingredients could meet the nutrient needs?

We use them because we perceive that they improve the pig’s gut health. In most cases, we do not yet clearly understand the physiological mechanisms through which a feed ingredient or additive may improve health, although we believe that several of them affect the digestive tract’s microbial populations or immunity, or both. This research area is still in its infancy.

The accompanying table shows a list, although admittedly incomplete, of dietary factors that may influence pig health. Its length emphasizes the richness of our supply of potentially useful technologies. All of them deserve attention; the following describes only a few examples.


  • Antibiotics added to pig diets are effective health-management tools. There are widely held concerns about using antibiotics in food-animal production as it relates to antibiotic resistance that complicates human medicine. Those concerns deserve the pork industry’s consideration.

    As a former World Health Organization panel member charged with evaluating Denmark’s ban on antibiotic growth promoters, the contribution of antibiotics used in food animals, relative to antibiotic resistance, is small but not zero.

    As an industry, we should try to minimize antibiotic use. I believe that antibiotics’ prophylactic power is often needed in newly weaned pigs, but that routine continuous feeding to finishing pigs is difficult to justify. I suggest embracing the National Pork Board’s excellent program — “Take Care: Use Antibiotics Responsibly.”

    As we strive to reduce antibiotic use, we need to consider the other options presented in the table.

  • Spray-dried animal plasma is widely accepted because it dramatically increases the newly weaned pigs’ growth rate — by an average of 23 percent to 27 percent, according to three scientific data summaries. Several pork industry technologies can increase growth rate, but such a large response is rare.

    It is now clear that dietary plasma also protects pigs from disease. A review of experiments in which young pigs were exposed to pathogenic E. coli showed that plasma reduced piglet mortality in six of seven cases.

  • Chicken eggs contain lots of antibodies to antigens that the hens experienced. It is now possible to vaccinate hens against a pig pathogen, such as F18 E. coli, and get them to produce antibodies in eggs. With an appropriate antigen and vaccination program, the antibody titer in the eggs can be quite high. Then the eggs (or the antibodies purified from the eggs) can be fed to pigs to protect them against the target pathogen.

    Experimental evidence shows strong protection in most cases, with occasional failures. Some researchers have suggested that immune-egg products may be effective in preventing disease but not in curing existing disease. In my judgment, immune-egg products are likely to become important health-management tools as we learn more about how to produce and use them.

  • A high dietary zinc oxide level protects pigs from enteric disease, but that is based almost completely on practical experience without strong experimental support. We have now demonstrated that effect in the face of an E. coli diarrhea outbreak during a controlled experiment conducted in a commercial nursery. The mortality and removal rates were substantially lower among pigs receiving zinc oxide than among those not.

Several other dietary items in the table appear to impact health, the immune system or the digestive tract’s microbial populations. We now have a solid beginning in the daunting task of evaluating these technologies for effectiveness and practicality as herd-health components. Stay tuned for progress in the coming years, as nutritionists and veterinarians work together on these challenges.

There are alternatives

Here’s an incomplete list of potential dietary technologies that can improve pig health and production performance. This approach is in beginning stages, and as it progresses, it will unlock more knowledge.

Energy & protein sources




Feeding management


Spray-dried plasma




Low-protein diets


Milk-protein products


Immune-egg products


Restricted feeding


Egg products, conventional


Mannan oligosaccharides


Fermented liquid feed


Alternate cereals







Other oligosaccharides




Direct-fed microbials   (bacteria)




Essential oils








Zinc oxide




Copper sources




Yeasts and yeast products