As if low hog prices and rising feed costs weren’t enough for pork producers, how about a serious bloodstream infection that strikes almost every farm in Canada? Disease caused by Streptococcus suis is one of the most important health problems in nursery pigs. It is both widespread and highly damaging, resulting in meningitis, arthritis, endocarditis - a life-threatening inflammation of the heart’s inner lining - and sudden death. Add in that it’s likely the number one reason for antibiotic use in these animals, and the threat becomes very real, very quickly.

The High Cost of High Stress

Just as stress is a threat to humans, it can be devastating for weaned pigs. In addition to separation from the sow, a change in setting and the presence of greater pig density, the diet shifts from liquid milk to solids. These stressors create the perfect environment for bacteria like Streptococcus suis to thrive. Most pigs carry different types of this bacteria in their tonsils and nasal cavity, and while some pigs suffer serious illness or death from specific types of the pathogen, others avoid sickness altogether. Researchers have looked at possible causes of those differing reactions, citing immune system variations and protection conferred on pigs by the sow. One of the promising areas to target in fighting this disease, however, may be right in front of the pig’s snout: diet.

Feeding the Need for Solutions

Given that feed is the greatest expense for producers, comprising two-thirds of their cost of production, a lower priced diet that can also fend off a deadly pathogen would be a win-win. As a means of combatting post-weaning stress, most farms use a diet that is rich in both quality and quantity of key ingredients. Like dinner at a 5-star restaurant, high-quality meals come with a higher price tag. With that in mind, scientists examined lower complexity diets, using plant-based protein sources like soybean in place of animal sources such as plasma or fishmeal.

In this project, pigs were divided into two groups. While one group received a high cost, high complexity diet similar to the standard regime on farm today, the other was fed a low cost, low complexity diet. After infecting both groups with Streptococcus suis, the study brought a surprising result: Pigs fed the lower complexity diet were more resistant to the disease.

Passing the Acid Test

At first, researchers had trouble replicating those results at the farm level. This could be due to several factors, such as pigs mixing and animals getting varying amounts of feed. Fortunately for producers, the problem was solved with an increase in the functional amino acid component of the diet. Again, pigs were broken into groups. When compared to very complex diets or ones low in amino acids, the group that received a low complexity, low-cost diet, along with a higher number of amino acids, showed greater resistance to disease caused by Streptococcus suis. Of significance to end users, this result held true both in the lab and in the barn.

A Strong Benefits Package

In a business where cash is king, any cost-saving opportunity is a welcome one, and this project offers a number of them. By using the low-complexity diet, producers stand to save $2-3 per pig in feed expense. Equally important, animals will gain the same amount of weight on both the “high” and “low” diets by the end of the nursery period, so there are no hidden costs to saving on feed. Additionally, healthy pigs mean fewer dollars spent on disease treatment and prevention, and less need for antibiotics. At a time when antimicrobial resistance is a growing concern for human health, addressing that concern builds more trust with consumers in Canadian pork products.

Teaming Up and Moving On

Like many research projects that find success, this one was the product of collaboration. Performed at the University of Guelph (U of G), it was led by Dr. Vahab Farzan (U of G), Dr. Dan Columbus (Prairie Swine Centre) and Dr. Martin Nyachoti (University of Manitoba). From here, scientists hope to follow up on another finding from this project. During their on-farm study, they noted that pigs fed the low complexity diet had a greater incidence of diarrhea than those on the “high” regime. This might be a result of more fiber in the less complex diet, but it has prompted an interest in investigating how a low complexity diet may alter the bacterial content of the gut for pigs.