In most farrowing operations, the number of pigs weaned per litter is impacted more by preweaning mortality than by the number of pigs born alive.
Significant increases in pigs/sow/year (p/s/y) can be gained by maximizing piglet health and minimizing preweaning mortality. The greatest percentage of preweaning mortality occurs within the first three days after farrowing. To optimize health during this period, preparation must begin well before farrowing.
Piglet health status is the balance of immunity and disease challenge. A high level of immunity in a clean environment is most likely to produce healthy pigs. Both of these activities originate with the sow well before farrowing.
Building Pig Immunity
Piglet immunity has two critical mechanisms, generally referred to as “acquired” and “innate.”
Acquired immunity is the focused response to specific disease organisms. Included in acquired immunity are antibodies that are produced by the sow and transferred to the pig via colostrums (first milk).
Innate immunity consists of general barriers to infection, such as moist mucus membranes to filter inhaled pathogens, and normal intestinal bacteria that compete with potential pathogens for food.
Acquired immunity is very specific and efficient, but slow to develop at the first exposure to disease. Innate immunity is less efficient and specific, but generally operates all of the time.
Improving innate immunity depends on proper environmental conditions, such as temperature and humidity, and adequate nutrition for the piglet (See sow and pig nutrition, page 34).
Piglets are born with the ability to use both types of immunity. However, because acquired immunity may take 7-14 days to peak after exposure to a disease, piglets are provided premade antibodies by the sow via colostrums. Figure 1 illustrates the general process of immune system events that have to culminate at farrowing for early protection. The relative timing and quality of each step affects the final concentration of antibodies that the piglet receives.
For example, if vaccination occurs at mid-gestation rather than at late gestation, sow antibody levels will have peaked and be declining when it is time to concentrate them in the colostrum for presentation to the pigs.
Likewise, if gilts do not receive at least two doses of vaccine at least two weeks apart prior to farrowing, the level of antibodies in the colostrum will be greatly reduced.
Similarly, if poor injection technique or vaccine handling means that the sow receives less than the entire dose of a quality vaccine, the level of antibodies available to the piglets in the colostrum will be reduced.
Poor nutritional status of the sow might reduce the energy available for building antibodies, again resulting in lower levels in the colostrum.
From the piglets' standpoint, a poor microenvironment might prevent them from nursing adequately, and soon enough after farrowing, to get maximum antibodies from the colostrum.
Timing is Everything
A recent case study illustrates the importance of timing. A farrow-to-wean farm was experiencing scours with increased preweaning mortality. Diagnostic testing identified the pathogen causing the problem as an Escherichia coli (E. coli) strain that was included in the pre-farrow vaccine. The vaccine specified that sows receive the vaccine three weeks (21 days) before farrowing. However, the farm vaccination protocol was to administer sometime in the “third week” before farrowing, as work flow allowed.
Figure 2 illustrates the real difference in timing of vaccination — although they appear to be similar.
To maintain work schedule flexibility, injections were moved to the fourth week, pre-farrowing, so that there was at least 21 days between vaccination and farrowing.
Additionally, the farm was in the habit of warming the vaccine prior to injection. This is unnecessary and may contribute to the breakdown of the vaccine. When these two problems were corrected, the piglet scours resolved.
An effective pre-farrowing sow and gilt vaccination program that is diligently maintained is a basic requirement. This case demonstrates that there are three crucial considerations: 1) selection of the correct vaccine, 2) correct administration technique, and 3) correct timing.
A number of products are available on the market for vaccinating sows and gilts prior to farrowing in order to boost maternal antibodies by the time of farrowing. Selecting the appropriate product requires veterinary interpretation of diagnostic testing in affected piglets. There are many organisms, such as E. coli, that have non-pathogenic and disease-causing strains. Molecular testing can determine which vaccine is appropriate.
Effective vaccines do not exist for all potential piglet pathogens. Other techniques to immunize sows prior to farrowing include fecal feedback, autogenous vaccines and controlled exposure to wild-type pathogens.
However all of these approaches have potentially serious side effects for the herd, so plans should be developed with input from a veterinarian who is thoroughly familiar with your herd and its health status.
Maternal Antibodies Are Priceless
After colostrum is absorbed by the piglet, no more maternal antibodies can enter the pig's circulation. The window to absorb antibodies is generally about 24 hours after birth. However, studies suggest that the process of suckling begins to initiate gut closure such that the period to absorb antibodies ends about four hours after the first dose of colostrum. Any activity that interrupts the piglet's first suckling event likely reduces immunity, even if the pig gets another dose of colostrum later.
After the colostrum is consumed, sow milk continues to include antibodies. While these are not absorbed into the piglets' circulation, they can bind and neutralize bacteria in the intestines and reduce the disease challenge for the piglets. Milk replacers can provide useful supplements for energy and hydration, but they do not routinely contain antibodies that replace those found in sow's milk.
While increasing a piglet's immunity to various pathogens is one important aspect of controlling disease, the other important part of balancing health is reducing the piglet's exposure to disease-causing organisms. Even if it is not possible to completely eliminate exposure of piglets to certain disease organisms, there are many opportunities to reduce the numbers of these organisms (pathogenic load) to which piglets are exposed.
Even if a piglet has reasonable immunity to a disease organism as a result of an excellent vaccination program, facing an overwhelming number of these organisms will consume all available maternal antibodies and may still lead to disease. Treating pigs with antibiotics helps lessen the pathogenic load to a level that the pig's immune system can manage. If a scours problem warrants treatment in an individual pig, then consider treating all pigs within that litter since their exposure is likely to be similar.
Beginning with a clean, disinfected farrowing crate and scraping manure out from behind sows in farrowing crates every day is a good way to decrease the pathogenic load that piglets will face in the critical first days of their lives. This protocol can help reduce the number of scours-causing organisms to which young piglets may be exposed. It can also be crucial to the reproductive performance of the sow herd.
Parturition and estrus are two periods when a sow's cervix becomes dilated. An open cervix allows for bacterial organisms from the environment to migrate into the uterus and cause reproductive failure. Therefore, farrowing and breeding are two times when a clean environment becomes more crucial. If you are seeing vulvar discharges and/or poor reproductive performance, sanitation may be one area to address. In either case, there is the opportunity to increase pigs/sow/year by improving sanitation in the farrowing crate.
Most operations will pressure wash farrowing rooms after weaning. Many disinfect the rooms as well. It is important that the disinfectant be given adequate “kill time” on the crates before a new group of sows is placed. Most disinfectants require a minimum of 10 minutes of contact time before they are effective against hardy bacteria and viruses.
Ideally, disinfect the farrowing rooms and allow them to dry overnight. Often it is necessary to move new sows into a farrowing room on the same day that the last group was weaned. This may be necessary to avoid farrowing in the gestation stalls and maintain the flow of the system, but the rooms should still be washed and disinfected. Heaters can be turned up in the empty rooms in order to aid in the drying process.
Reduce Disease Challenges
Biosecurity can go a long way towards maintaining the health of piglets within your farrowing operation. Most of us are very familiar with the notion of external biosecurity measures, such as shower-in/shower-out, isolating incoming stock and limiting visitors.
However, the importance of internal biosecurity should not be overlooked. There are many simple protocols that will help decrease the total number of piglets affected by disease. One very simple way of decreasing disease challenge is to avoid stepping in farrowing crates. This activity is difficult to avoid when one employee has to do all of the processing alone, as often happens on busy or understaffed farms. Piglets can be shedding pathogens before clinical signs become apparent. Therefore, stepping into crates housing apparently healthy litters can contaminate boots and transfer disease to more pigs.
When processing, if any litters show evidence of disease, such as scours, process all of the healthy litters first and then process the diseased litters. Always clean and disinfect the processing cart thoroughly and immediately after each processing job. When done immediately, cleaning should be easier to accomplish, as fecal material will have had less time to dry in place.
In many operations, it is common to use feed as a drying agent in the bottom of the processing cart. This is less than ideal, as feed can serve as a reservoir for potential pathogens that are shed into it by piglets in the cart. In many cases, the feed will stick to piglets from other litters and allow them to carry pathogens on their bodies. When male piglets are placed back in the cart after being castrated, they will often sit down immediately, and the wet feed particles stuck to wet wound edges can impede healing.
A much better option is to use a small piece of flooring raised slightly above the bottom of the cart. This should be fitted to cover the entire bottom so that piglets are not getting caught at the edges. The floor can easily be removed after processing for cleaning and disinfecting along with the rest of the cart.
Processing activities, including iron supplement injections, tail docking and castration, should occur between 24 hours and 4 days of age. Piglets require iron as a component of hemoglobin, which is found in red blood cells and carries oxygen from the lungs to various parts of the body. Piglets with inadequate amounts of iron can become anemic and will often appear noticeably pale. Anemic piglets will not perform as well as their counterparts, and, the anemia may limit the effectiveness of their immune system.
A processing schedule, which is both ideal and realistic, involves processing twice weekly in order to catch all pigs when they are older than 24 hours of age and no older than 4 days of age. Delays in iron injection are more important when disease is present. One tool piglets use to fight bacteria is to store iron where it can't be used by bacteria. Unfortunately, this might further compromise the pig as well.
Many operations include injectable antibiotics as a routine part of processing, often mixed with the iron injection. Blanket treating all pigs is rarely necessary, and is not the judicious use of medications that is expected by our consumers. Additionally, the practice of mixing antibiotics and iron dextran may create unknown effects or chemical reactions and is considered the practice of compounding. Compounding to reduce labor or expense is prohibited by the U.S. Food and Drug Administration.
Accurate Diagnosis is Key
When facing serious problems with sows or piglets in the farrowing room, aggressive diagnosis is necessary and a veterinarian should be consulted. He or she will likely want to sacrifice some affected live piglets that are representative of the problem. This will not only allow for better gross necropsy observations by the veterinarian, but also provide for the collection of fresh, representative samples that will provide a more accurate diagnosis.
Bacterial culture and subsequent antibiotic sensitivity testing at a diagnostic lab will help define treatment. Clinical disease is often multifactorial resulting from both management and health deficiencies.
Two ways to lower veterinary expense and improve performance are to: 1) develop tools to help employees eliminate management contributions to disease, and 2) give the veterinarian high quality information about the problem.
To do this, develop troubleshooting flow charts that help employees solve common problems and collect important information about more complex problems.
The sidebar (below) explains how and provides an example (Figure 3) of how a flow chart is used to troubleshoot lactation problems on sow farms.
Crossfoster with Care
Crossfostering among litters is a common practice. There is only one reason to crossfoster pigs — to get every pig a productive teat to nurse. Beyond this, crossfostering has significant negative impacts, including spreading disease to more pigs and decreasing milk intake in both the pigs that are moved and the resident pigs that must reestablish teat order.
When necessary, crossfostering should be carried out within the first 24 hours of the piglets' lives. Once piglets are moved onto a new litter, they should remain there for good. Ensure that piglets being fostered, as well as those in the litters receiving fosters, all receive adequate colostrum before movement. The addition of new piglets to a litter can also be a setback to the pigs in the receiving litter. The amount of time and energy devoted to crossfostering would serve a more useful purpose if focused on other aspects of farrowing care.
Knowledge Ensures Health
The most valuable health strategy uses expertise and technology to conclusively diagnose health challenges. It increases colostral antibodies with appropriate vaccines given at the optimum time to sows and gilts.
Piglet-acquired immunity is maximized by ensuring colostral intake and minimizing crossfostering. Piglet innate immunity is maximized by providing the appropriate environmental conditions and sow nutrition. Disease challenge load is limited by sanitation and internal biosecurity. Veterinary costs are limited by empowering employees to troubleshoot common problems and gather valuable observations to relay to the veterinarian.