The art of feedback has come a long way from the days when it essentially consisted of scraping baby pig fecal material from solid floors and feeding it back to sows in the next group to farrow in order to offer a natural form of disease protection.

The idea behind “controlled antigen oral exposure” (feedback) was that the harvested scour-causing pathogens fed to sows well ahead of farrowing — whether they were from scouring pigs or the manure of gestating sows — would generate maternal antibodies delivered to new litters via sows’ milk.

“Manure feedback was simpler and more natural when there was more pen gestation, because there was more opportunity for sows to get exposed to manure from other sows than there is in crated gestation,” explains Mark Wagner, DVM, Fairmont (MN) Vet Clinic (FVC). As a rule, low-parity sows shed more scour-causing bacteria in higher numbers, adds Clark Huinker, DVM, FVC.

But as producers moved to more raised farrowing crates, they scraped the solid floors underneath the crates to provide feedback material for the next group of farrowing sows, Huinker explains.

Then, farrowing rooms evolved to slotted floors and deep manure pits, meaning baby pig manure became virtually inaccessible. So farms switched mostly to feeding back farrowing house pit manure.

“There are a couple of problems with that approach,” Huinker points out. “One is that pit manure is a high percentage sow urine and sow feces, which has a lower concentration of piglet scour antigens than piglet feces. The other issue is that chemicals and other products that are used to disinfect facilities end up in the pit — and we don’t want to feed back these products,” Huinker says.

Evolution of Feedback

At the Fairmont clinic, collection of feedback material has changed to baby pig intestines. “Usually we collect intestines from laid-on pigs, low-viability pigs and, once in a while, if a pig is suffering and needs to be euthanized, we will process the intestines from that pig as a source of feedback material,” Huinker says.

The goal is to extract a concentrated material that contains specific bacterial agents that came from sow feces in the first place. The best source for these agents is probably the intestines of young pigs, Wagner says.

Sometimes scouring material will be collected in a paper towel from the farrowing crate floor and then added to the feedback mixture. Periodically, if this feedback material runs short and enough can’t be collected in the farrowing crate, manure from gilts or first- or second-parity sows is substituted as feedback material to be given to sows before farrowing, Wagner notes.

Whatever material is collected, pig intestines or manure, it is placed in a 5-gal. pail with an equal amount of water and stirred up to create a fairly homogenous mixture. Pig intestines are sliced or ground using a garbage disposal, then processed using an industrial-strength blender to create a slurry with a more homogenous consistency. They take extra steps to strain out larger pieces and blend the mixture several times until it attains a near water-like consistency, Wagner explains.

Then they pour the slurry into the sow’s feed trough or spray it on as a top-dressing. “Sows have no trouble eating it; they clean it up,” Huinker says.

Two other procedures are commonly used for gilts. For replacement gilts, feedback is frozen into solid bricks that are placed in the pen for gilts to lick and chew on as they melt. As another option in the gilt developer unit, feedback is mixed with water and sprayed onto feed or run through a water medicator.

Feedback Benefits

Modern methods of pork production don’t afford pigs the opportunity of natural exposure by rooting around in manure to achieve a “properly colonized intestine” and provide protection from scours, Wagner points out.

Feedback is most beneficial for protection against rotavirus and E. coli. Generally, it is not thought to protect against scours caused by Clostridium perfringens or coccidiosis.

It is important to diagnose the scours problem before implementing a feedback program to ensure the contents match the scours problems in your herd, he emphasizes.

“With some of the new diagnostics, we can actually do a better job of typing rotavirus. We assumed that Type A was the most common type of rotavirus scours, but now, we see a little bit more of Types B and C. And rotavirus sometimes leads to problems in the nursery.

“Producers are trying to get these sows better immunized prior to farrowing, and we are also seeing that this protective immunity has some benefits beyond the farrowing room,” Wagner observes.

Rotavirus prevalence is on the rise in the U.S. swine industry. Feedback provides protection against rotavirus Types B and C, for which there are no commercial vaccines available, Huinker explains.

Wagner suggests using multiple protection schemes against scour-causing pathogens. Feedback is similar to “priming the animal” or “stimulating some mucosal immunity.” Some producers rely solely on feedback for protection against these pathogens, while others just use vaccines that may contain rotavirus, clostridium and E. coli antigens.

But Wagner recommends using feedback followed by a killed bacterin/vaccine. “By exposing the animal earlier to the live antigen (via feedback), it helps the vaccine work better by priming the immune system prior to boostering with a killed vaccine,” he says.

Feedback Concerns, Timing

By feeding back material, there is a chance that sows could be exposed to PRRS virus in late gestation, which could create a clinical issue in sows or cause some low-viability pigs to be born, Huinker relates.

“To get around that issue, we recommend that producers do their oral exposure of sows 7-8 weeks prefarrowing, in mid-gestation, to minimize the risk,” he suggests.

Feedback should be done a minimum of a month prior to farrowing to maximize the antibodies produced by the sow in colostrum. To balance the risk and reward, feedback at 8-10 weeks before farrowing provides a better margin of safety, Wagner says.

Feedback too close to farrowing also runs the risk that sows will shed organisms contained in the feedback into the farrowing crate, thus exposing piglets to that source of infection. “Feedback must be far enough out that sows develop immunity, clear the infection and are not shedding anymore,” Huinker says.

Whether for open gilts in isolation or for bred gilts/sows in gestation, his rule of thumb is to expose them to feedback at least three different days within a two-week period to make sure they get adequate exposure to farm pathogens.

Importance of Diagnostics

Ideally, every sow would get some feedback exposure to known, consistent types of bacterial and viral pathogens on the farm. The problem is sometimes a lack of availability of a consistent source of pathogens. Some piglets provide lots of pathogens, others offer almost nothing, Wagner points out.

Before feedback is frozen or fed, samples are submitted to the University of Minnesota Veterinary Diagnostic Laboratory to determine what’s present in the product. “By knowing what we are feeding back, that allows us to do it more precisely and have a higher confidence of what the outcome might be,” Wagner says. “Our goal is to get uniform exposure to known pathogens without giving them pathogens we may not want to give them.”

The best procedure to follow is to go through farrowing rooms, pull unthrifty and laid-on pigs, process the intestines for feedback and use as prescribed by your veterinarian. But before use, submit a sample set of intestines to the diagnostic lab. Check frequently for these types of piglets to process and create a bank of material that can be frozen in bottles or bags to have available when needed, Wagner says.

The University of Minnesota diagnostic lab provides a feedback analysis profile that includes tests for all major sources of pig scours — transmissible gastroenteritis (TGE), salmonella, E. coli, all three types of rotavirus, clostridium and PRRS virus.

Feedback Goals

One goal of feedback is to help acclimate replacement gilts to the pathogens they are expected to be exposed to when they enter the sow herd. “It is just like when we are acclimating new animals coming into the herd for PRRS or other viral pathogens using vaccines. The same thought process applies to getting that gilt acclimated to intestinal pathogens,” Wagner explains.

“The second rule for feedback is trying to boost or stimulate the colostral milk antibodies in sows to protect the piglet,” he says.

Crucial to those goals is finding a person on staff who is comfortable with sacrificing and collecting intestinal material from a piglet.

“There are multiple ways to do it, but the important thing is to figure out what is going to be the most likely to get implemented efficiently on the farm,” Wagner asserts.

Hen-Way Manufacturing of Fairmont, MN, has made a customized, portable cart to process feedback with a built-in garbage disposal, Wagner adds.

Farm Participation

Some farms follow the philosophy that if they pull enough sick or unthrifty piglets on a regular basis, they will find the pathogens necessary for effective feedback. But diagnostic analyses of potential feedback means producers will get more consistent results, Wagner believes.

Operations like Watonwan Feeder Pig at Lewisville, MN, managed by Jay Borkenhagen, follow Wagner’s advice to look for fresh feedback specimens during the first walk-through of the farrowing rooms in the morning. Staff collect any laid-on piglets.

In the 1,500-sow, farrow-to-wean facility, Borkenhagen checks for two types of pigs to euthanize for feedback. First he looks for newborn stragglers that aren’t responding to treatment. Second, he scans litters near weaning for at-risk pigs that won’t be viable going into the nursery.

“A lot of pigs that you think are starving out have a belly full of milk; they are just not processing it. That’s usually a good indicator that something is wrong. Maybe there are some intestinal bugs at work,” Borkenhagen says.

For this producer, one application of frozen feedback eight weeks prefarrow does the trick. “A lot of farms will talk about using feedback three times per group of sows, but we are able to use fewer doses — usually one dose — because we have confidence there is pathogenic material in what we are giving them,” he assures.

Wagner says the Watonwan farm has always used some type of feedback procedure (manure feedback). But the more specific method of feedback (tissue feedback) and the targeted, individual animal approach that has been followed the last few years has yielded a consistent product and known antigen (protective antibody) for sows.

The refined method has helped produce a dramatic drop in preweaning mortality (PWM) from 17% to 12%, based on PigChamp records, he says.

Feedback Analysis

For a feedback profile of pathogens on clients’ farms, Wagner evaluated 24 random samples from some of the farms he works with:

• Thirteen were positive for rotavirus Type A.

• None were positive for rotavirus Type B.

• Six were positive for rotavirus Type C.

• Twenty-three were positive for Clostridium perfringens Type A beta toxin. “This organism is very, very prevalent in feedback material,” Wagner says.

• None were positive for E. coli, which appears to show the benefits of sow vaccination.

• Three were positive for PRRS virus.

• Eight were positive for hemagglutinating encephalomyelitis virus, a wasting disease classified as a coronavirus commonly seen in pigs.

“The nice thing about feedback analysis is that we can screen for different organisms and get an idea of how prevalent they are. As a result, we can tweak and better match our vaccine programs for sows to the pathogens on the farm,” Wagner says.

Correct processing, storing and feeding back tissues from compromised piglets can lower the incidence of scours, resulting in a reduction in preweaning mortality, less variation and more pigs weaned per sow per year, Huinker reasons.

Huinker and Wagner agree that, done properly, the process works. In fact, more than half of the sow farms in their practice are utilizing this feedback procedure and seeing positive results.