Disease in the early nursery period decreases a pig’s trajectory for growth and your potential for profit. Data suggests these early insults reduce the total potential gain that they can achieve later in life, says Brooke Smith, veterinary nutrition lead on the Cargill Animal Nutrition - Pork Solutions team. Not only can these challenges increase susceptibility to other mortalities, but they can also lead to secondary bacterial infections.
“Performance will come if we can keep pigs healthy,” Smith says. “When pigs are healthy, they grow phenomenally. We have genetics to thank for that in modern production systems. It’s the healthy part that the industry struggles with because of the cards that have been dealt.”
She believes much of the interest in understanding and leveraging nutrition in the health space is driven by veterinarians who need to add more tools to their belt.
“The pathogens, by and large, are getting harder and harder to treat and manage, so veterinarians need more ways to approach them,” says Smith, who completed her DVM and Ph.D. in swine nutrition at the University of Illinois.
Fight PRRS With Nutrition
Studies continue to show the benefits of various feed ingredients when it comes to dealing with health challenges such as porcine reproductive and respiratory syndrome (PRRS). Jim Pettigrew and Dean Boyd were studying the impact of soy under a PRRS challenge when Ryan Dilger joined the University of Illinois animal science faculty in 2010. Together, they set out to understand why pigs that received soybean meal fared better in the face of a PRRS challenge than pigs fed a purified lysine supplement.
When Smith became a doctoral student in Dilger’s nutrition lab, she began conducting controlled wean-to-finish studies to isolate the effects or the reason soybeans were eliciting these benefits. She studied secondary metabolites in soy – the isoflavones and the saponins.
In one of the studies of pigs supplemented with isoflavones versus not, she says they did not see any longstanding growth effects.
“There were some transient up and downs on performance and body weight, but nothing significant if you looked at the overall trend,” she explains. “We did see a difference in the last final body weight between our supplemented and our non-supplemented treatments, with the supplemented group being slightly lower. But a couple days later, at harvest, that difference was lost – whatever was there was minimal.”
But the more impactful finding was the clinical response to PRRS infection was different. They saw shifts in the dynamics of viral clearance or how long it takes pigs to become PRRS negative.
“With new PRRS strains getting more virulent, veterinarians are seeing a longer time where this virus is being shed into the environment,” Smith explains. “With the isoflavone supplementation, we saw that when PRRS-challenged pigs became negative, we had fewer pigs revert back to a positive state. This suggests their clearance was more effective. That finding was also supported by the neutralizing antibody response we saw where more pigs had protective titers earlier than the positive group.”
She says the biggest takeaway was the impact on mortality. Although the study was relatively small with 96 animals total, the result was clear.
“In our isoflavone group versus our positive control group, when we had a wave of secondary bacterial infections (common with PRRS), we saw the isoflavones mortality plateau while our positive continued to experience mortalities,” Smith says. “They had the same medical intervention and received an antibiotic to help with the secondary infection. For whatever reason, our isoflavone group responded better to that, and by the end of the study, had experienced 50% less mortality than our positive control.”
Inflammation and Healing
When a pig gets sick – when that virus takes hold in the respiratory tract – the result is a fever or inflammatory response to fight off pathogens and promote healing, Dilger explains. The pig stops eating, goes off feed, and in the case of a PRRS infection, that all happens over an approximate 14-day period before the pig starts to recover.
“Their immune system is trying to get rid of that virus and calm everything back down again,” Dilger says. “That’s exactly what the isoflavones, and we think saponins as well, are doing – reducing the viral load. Supplemented pigs got rid of the PRRS virus in a shorter amount of time, which means they had lower inflammation and got back on feed faster. If an animal cannot course correct, if they don’t have any nutritional or other support, mortality is always a possibility.”
Producers generally know seasonality when their pigs are more likely to have respiratory issues, he adds. Can we get something in these pigs before they get that pathogen, to give them a leg up when they mount an immune response?
“As a nutritionist, my technology does nothing if the animal doesn’t eat,” Dilger adds. “That’s why it has to be before the pigs encounter the pathogen. Working with a veterinarian is key – so producers can be proactive.”
How Does Health Benefit Growth?
After graduating from the University of Illinois, Smith took on a role at Cargill where she spends much of her time thinking about the nursery pig and what she can put in the diet of this at-risk population to benefit its health.
“We see a ton of bioactives in this space right now,” she says.
Smith points out that soy, a fundamental ingredient in commercial swine diets, has historically been under-emphasized or cautioned against in young pigs because of issues with digestibility and anti-nutritional factors.
“It takes that pig a while to adapt and develop its gut to be able to digest soybean meal appropriately,” Smith says. “But with improvements in further processing techniques of soybean meal, we can improve digestibility of soy and reduce the anti-nutritional factor content.”
From a bioactive standpoint, isoflavones and saponins are consistent performers, she adds. They have been evaluated by several groups of researchers and shown benefit. With the help of her Cargill colleagues, Smith recently took her thesis research results one step further. Using the market weights at harvest, they modeled them to three regionally relevant packer grids.
“When you have more pigs that reach market, even if they’re not full value and there’s some weight penalization, there’s still that proportional increase in revenue,” Smith says. “It was approximately 30% more projected revenue, because those pigs made it to market even if they weren’t as valuable as a pig that had never been challenged. So, that’s the real big takeaway.”
Today’s nutrition decisions are made with a lot of data in mind, she points out. While these decisions often come down to economics, more emphasis is being placed in trying to balance that with diets that promote health.
Think Again About Soy
The future of soybean genetics is exciting, Smith says. Researchers are trying to create a bean that has higher amounts of bioactives like saponins and isoflavones so the industry can use their benefits more.
“Saponins and isoflavones are a very small percentage of what the total bean is made up of,” she says. “They are also used as a human nutraceutical. For that reason, it will likely always be priced out and not feasible as a standalone supplement.”
Another avenue for the pork industry could be selecting soy based on its composition.
“We know that you can see variations between different soybean lineages and growing conditions year to year. In theory, that’s something that could be selected for,” Smith says. “But for now, work with your nutritionist to make your diets as digestible as possible in those populations of pigs that need the help.”
She encourages producers not to be “scared” of using more soybean meal in growing pigs.
“Soy offers compounds that can be beneficial, particularly in health,” Smith says. “With such a huge PRRS prevalence today, the likelihood that a pig will be exposed at some point in its life is really high.”
Increasing soybean meal in the diet is very easy, especially with the prices right now, Dilger points out.
“Biologically, the benefits are clear. It provides nutritional support, almost insurance ahead of time if pigs might experience a respiratory challenge. The more of these soy-derived isoflavones and saponins you get, the better the pig is going to be to a certain level,” he says. “We still need to provide a balanced diet for the pig, but with soybean meal as a primary protein source in providing amino acids. This line of research confirms there’s more to soy than we originally thought.”
