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Postweaning Salmonella Persists

Salmonellosis remains a primary disease in weaned pigs.

One hundred and twenty years ago, a disease of swine that was described as hog cholera was thought to be due to Salmonella cholerasuis. Later on, it was learned that a virus caused hog cholera; salmonella was often considered a secondary invader of pigs infected with this virus.

But when hog cholera was eradicated, salmonella infections persisted.

Today the bacteria continue to cause the swine industry health concerns, both as a primary infection of pigs and as a cause of food-borne illness in humans.

There are over 2,000 distinct serotypes of salmonella, but only two are common in swine: Salmonella choler — asuis and Salmonella typhimurium.

S. cholerasuis can result in generalized infection, pneumonia, enterocolitis and meningitis. This serotype rarely causes human infections.

S. typhimurium, on the other hand, can result in human illness and in pigs causes an enterocolitis, observed clinically as watery diarrhea.

Outbreaks of salmonellosis are often associated with other stressors such as transport, mixing, temperature extremes and infection with porcine reproductive and respiratory syndrome (PRRS) virus.

Case Study No. 1

A 500-sow, farrow-to-finish producer in central Indiana decided to convert his facilities to nursery-to-finish production. The existing herd was infected with Actinobacillus pleuropneumonia Type 7, Mycoplasmal pneumonia and PRRS.

Farrowing rooms were converted to nurseries. Existing nursery rooms can hold 600 weaned pigs every three weeks. Breeding-gestation was converted to finishing. Nursery and finisher rooms are on the same site, connected by hallways.

The source of new weaner pigs was a single sow herd that was PRRS negative. Against veterinary advice, some old stock finishers remained on site when the first weaned pigs were purchased and introduced to the cleaned and disinfected nurseries.

Within six months after the change in production flow, death loss increased in the 11- to-12-week-old pigs. There were thumping pigs, poor-doing pigs, and some pigs with cyanosis (purple discoloration) of the extremities. Tissue samples sent to the diagnostic lab tested positive for Salmonella cholerasuis.

Avirulent vaccines can be used in the water to immunize pigs against salmonella. Make sure, however, that feed-grade or water-based antibiotics (that would impact the avirulent salmonella organisms) are not given to the pigs for 3-4 days prior to and after vaccine administration.

When nursery groups were vaccinated, salmonella problems disappeared and vaccination was discontinued. PRRS seroconversion was later demonstrated in the herd, which may have exacerbated salmonella problems.

Case Study No. 2

A 1,200-sow, farrow-to-finish herd was experiencing PRRS-circovirus mortality in early finishing. Because the sow herd was PRRS-stable, it was decided to empty nursery and finishing sites to reduce the interaction of these two organisms.

Some 1,500 nursery pigs, 8-9 weeks of age, were moved from two nursery sites to an empty, off-site contract finisher barn over a three-week period. Three weeks after the first pigs were moved, the fieldman reported that mortality increased significantly.

Numerous pigs in the first two of three rooms exhibited lethargy, weight loss, thumping, pallor, diarrhea and generalized to localized cyanosis. There was excess feed in the bottom of the feeders due to poor feed consumption. Mortality was already at 6%. Pigs were on tilmicosin in the feed and had not responded to injections of ceftiofur hydrochloride.

Postmortems showed pneumonia, enlarged lymph nodes and pale to jaundiced subcutaneous tissues. Salmonella was isolated from the liver and lung of three pigs. Microscopic lesions in liver, lung and kidney were due to S. cholerasuis infection.

Immunohistochemistry was positive for porcine circovirus-associated disease (PCVAD) with mild lesions of this virus; primary lesions were due to salmonella.

Feed-grade medication was changed to carbadox and water medication was initiated, but mortality continued. This group was not closed out at the time this summary was written.

Since previous groups through this barn and in the farrow-to-finish site did not have problems with salmonella, it is assumed that low-level carriers are present. Perhaps moving pigs, the presence of PCVAD and PRRS virus aided the development of salmonellosis.

With concerns about PCVAD, and the possibility that salmonellosis could be confused with PCVAD, this case demonstrates the importance of early and accurate diagnosis of finisher problems.

Getting the Scoop on FEED DROPS

Kansas State University (KSU) researchers say check your sow feed distribution system to ensure sows are actually getting the proper amount of feed.

Pork producers planning to construct new sow barns or replace the feed delivery system in existing farrowing and/or gestation facilities should strongly consider the type of feed drop system they install, urge KSU researchers.

Mike Tokach, Extension swine specialist, and graduate student Jason Schneider, assisted by a team of other KSU researchers, conducted and analyzed results on a series of trials to determine if the angle of feed drops for sows influences the level of feed actually delivered to the feed drop.

“In gestation barns, the feed drops are installed perpendicularly, or at a 90-degree angle,” explains Tokach, thus allowing for the maximum flow of feed from the line into the feed drop. “But over time, from feed lines being stretched or due to changes from the installation of other equipment, many of the feed drops end up at an angle much less than 90 degrees from the feed line.”

Testing Feed Drops

For the study, the KSU team decided to test gestation feed drops at three different angles set at 60, 75 and 90 degrees (Figure 1). The feed drops were measured at delivery rates of 2, 4, 6, 8 and 10 lb. of feed, all using the same corn-soybean meal-based diet, says Schneider.

“The way these feed drops work, the drops are filled from the top of the feed line in a volumetric delivery and the pounds dropped increase linearly as the volumetric setting on the drop increases,” says Tokach.

The most commonly used gestation feed drop is the “box” type. When this type of drop system was tested, KSU research showed that the angle of delivery had a significant impact on the amount of feed delivered to the feeder, says Tokach.

“If all of the boxes are at exactly the same angle, the difference between the volumetric setting and the actual pounds can be measured and dealt with in the feeder settings,” he says. “However, if the boxes are at different angles, it will be very difficult to know the amount of feed dropped for each box because that level will change throughout the barn.”

Especially disturbing is that the level of feed delivered to the feed drop can be above or below the actual predicted value or feed setting, says Tokach.

In the trials conducted, shown in Figure 2, the level of feed delivered when the box drop was at the perpendicular angle was actually more feed than what the setting called for. The bulk density of the diet will also have some influence on the flow of feed through the drop, suggesting that a less dense diet would fall closer to the actual setting, he says.

More of a concern in regards to sow performance is that as feed drops develop more of an angle (less than 90 degrees), less and less feed is dropped.

If the box feed drops were all turned at the same angle, the producer could compensate for this change. But the fact is, they end up at differing angles. This creates a particular problem in sow gestation barns that are 10-15 years old.

“It becomes very difficult in these older barns to maintain the box feed drops at exactly the same angle,” he points out. And once they are out of adjustment, it becomes virtually impossible to return them to their former perpendicular position.

Adjusting Feed Drops

Out-of-alignment gestation feed drops are proving that there is a lot more variation in actual sow feeding levels than was previously thought, Tokach says, based on farms he and fellow KSU researchers have visited.

“And the reality is, most producers don't know exactly how much feed they are dropping. They set it and they think that it's close to the appropriate level. If they do any feed drop measurements at all, they'll do it as they change the bulk density of the diet. They still assume that all of the feed drops in the barn are dropping the same amount (when they are most likely not),” he stresses.

Feed Drops Not Created Equal

Tokach says the lesson producers need to learn is that there are definite differences between types of feed drops. Newer, cylindrical feed drops tested by KSU, depicted in Figure 3, provide a much more precise level of feed to the feeder.

“It seems like a lot of feed equipment companies in the past few years have gone to cylinder feed drops as they are developing newer products for the market,” notes Tokach. “The cylindrical drop amazed me in how well it fit what the feed system called for. It created more consistency, and you can change that feed drop angle between 75 and 90 degrees and still get the same amount of feed dropped into the feeder.”

Tokach says the cylindrical-style feed drop has created a huge innovation in sow feeding. The box-type sow feeder costs $1-2 less, but their research shows that the cylindrical version “should allow you to begin to feed sows more accurately and help achieve the feeding levels suggested for sows based on backfat and weight.” (See “Managing Sows in Gestation,” National Hog Farmer Blueprint series, April 15, 2006, page 18.)

The lactation feed drop tested (depicted in Figure 4) was also shown to be more accurate in feed delivery than the standard box-type design, says Tokach.

He reasons both the cylinder and the lactation feed drops work more consistently in delivering feed because they attach to the feed line differently.

“The results tell us that it may not be that they are round (in the cylinder's case), or smaller (in the lactation case), but rather that those two types of feed drops attach to the feed line such that the volume of feed doesn't change as much when they are at different angles to the feed line,” Tokach observes.

In the end, using the proper type of feed drop will help maximize performance by more appropriately feeding sows housed in individual stalls, he adds.

The final research report on feed drops will be presented at the annual KSU Swine Day, Nov. 16 in Manhattan, KS.

Tokach says future research will assess whether the bulk density of sow diets has any influence on the flowability and accuracy of feed delivery systems.

Pork Board Elects New Officers

Illinois pork producer assumes the position of president.

The National Pork Board has elected Wayne Peugh, a pork producer from Edelstein, IL, as its new president. He succeeds Danita Rodibaugh, a Rensselaer, IN, producer who remains on the board.

Elected vice president was Lynn Harrison, a pork producer from Elk Mound, WI.

Both Pork Board officers will serve one-year terms.

“We achieved great success under Danita's leadership, and I welcome the challenge of building on that success,” remarks Peugh.

“We'll have a big agenda in the next 12 months,” he says. “We will be launching our new Pork Quality Assurance (PQA) Plus program to deliver on our animal care and well-being solution. We will be building on our tremendous success in export markets. We'll continue our groundbreaking work to assure pork safety. We'll continue our support of environmental stewardship. And, we'll always be looking for ways we can maximize the value of the pork checkoff for all producers.”

Peugh is an Illinois native and a graduate of the University of Illinois with a degree in agricultural economics. Peugh and his wife, Edith, own and manage a 3,000-sow, farrow-to-finish operation. Leading Edge Pork LLC/Peugh Farms markets 60,000 hogs/year. They also raise corn and soybeans on 1,800 acres.

What's Up with Sow Slaughter?

Three weeks back, I posed a question about what could be driving sow slaughter rates so high. We supported that discussion with an older version of the graph in Figure 1. As you can see, the trend is continuing.
Sow slaughter has been higher this year than last in 17 of the 20 weeks, since the first full week of March. Over that time period, sow slaughter has been 5.5% larger in raw numbers and 4.1% larger as a percentage of the breeding herd. Roughly 65,000 more sows have been slaughtered during that time period vs. 2005 -- over 1% of the U.S. breeding herd.
And it's not the Canadians. They have shipped about 6,500 fewer cull breeding animals south during this period.
At the time, I thought the best explanation was depops/repops, but I'm not so sure now. First, this has gone on for a long time and I can find no one who thinks the need or desire to repopulate is widespread.
We also mentioned that some of these may not be health-related depop-repops, but ones aimed at upgrading genetics now while cash is available. That would be a good idea except for the fact that gilt slaughter rates have been above the level needed to leave a sufficient number of gilts available to replace the sows. Figure 2 shows the computed sow loss and gilt replacement number from the University of Missouri, and there has been a shortfall in recent weeks.
I believe it is unlikely that the sow slaughter data is very wrong since sows mainly get slaughtered in sow-specific plants and, thus, can't easily be counted incorrectly. There could perhaps be a little slippage for light sows slaughtered in top hog plants, but that slippage would result in sows being counted as market hogs and push the data the wrong direction.
Yes, the gilt data could be wrong. However, that is one reason the Missouri researchers use a four-week moving average. Their thought is that individual weeks may bounce around but, over time, the series will do pretty well. I agree.
Finally, it is always possible we are reducing the sow herd, but I give that about a zero probability as well. Thirty straight months of profits, higher-than-expected cash and futures prices and, as of Friday's USDA Crop Production report, an 11 billion-bushel corn crop all make that prospect very unlikely.
That leaves us with one unknown variable -- death loss. The level of death loss on U.S. sow farms has been a point of controversy and discussion for some time. Producers had at one time been convinced that modern genetics and the need for generational turnover made 50-55% replacement rates -- that were largely driven by high death losses -- acceptable.
Heightened sensitivity to animal welfare and public image caused producers to eventually reject that proposition, and much has been done in the past five years to improve the survival rates of sows. Better gilt development, breeding at older ages, better attention to body condition, new genetic lines selected with longevity in mind, and a new-found appreciation for the economic importance of sow lifetime production have all driven breeders and producers to do a better job.
It is logical to conclude that at some point we would simply have more sows living long enough to capture salvage value for producers and provide a slaughter animal for sow processors. Given the lack of other explanations for high sow slaughter, perhaps that day is at hand.
If it is so, then congratulations! That's a job well done that benefits everyone, including the pigs.
<b> Prior-Day vs. Slaughter Reports </b>
One item of clarification probably needs to be added to the discussion week before last about the historical pattern of prices reported to USDA under the Mandatory Price Reporting System (see July 28, 2006 <i>North American Preview</i> archived at <a href="" target="_new"></a>).
A further, and perhaps more important, reason that net prices from the prior-day purchase reports display more volatility than base prices from the prior-day slaughter report is that all packers are included in the net price data since they all slaughter hogs each day. That is not necessarily the case for the purchase data.

Figure 2 illustrates the point by comparing just the "base" prices from the prior day purchase and slaughter reports. On some days, packers that pay low base prices and high premiums are in the "purchase" report, while other packers are not. On other days, high-base/low-premium packers may be in the market. The fact that not every packer is in purchasing mode every day causes the prior-day purchase data to be quite volatile.
On the other hand, virtually every packer slaughters every day and, thus, the slaughter data represent a smoothing of purchasing philosophies. In addition, the slaughter-day data represent prices of animals purchased over several days. This blending smoothes data as well. It also causes the slaughter data base prices to lag the purchase data base price just slightly. See how the red line is just slightly to the right of the blue line?
If your contract is tied to the current- or prior-day purchase data, it matters who is in the market on the day you ship your hogs. If your contract is tied to prior-day slaughter data, that source of variation is largely removed.
<a href="" target="_new"><img align="left" valign="top" src="" vspace="0" border="0" hspace="3"></a><br><br> Click to view graph.<br><br>
<font color="red">Steve R. Meyer, Ph.D.<br>
Paragon Economics, Inc.<br>
e-mail: <a href="mailto:[email protected]">[email protected]</a></font>

Mack Whiteker Passes Away

McElwyn D. “Mack” Whiteker, passed away July 11 at his residence in Lexington, KY.

Whiteker was a retired director of Extension at the University of Kentucky.

He was the first recipient of a Service Award from the Kentucky Pork Producers Association. He was presented with the National Hog Farmer Distinguished Service Award in 1980, and also received the National Pork Producers Council Distinguished Service Award in 1993.

During his career, he lectured in many countries around the world.

Dr. Alex Hogg Passes Away

Alex Hogg, 86, DVM, a past president of the American Association of Swine Veterinarians (AASV), passed away July 18 after a long illness.

He served as secretary/treasurer of the group in the mid-1970s and was president in 1979. In July 2005, he was recognized as the first recipient of the AASV Foundation Heritage Award to honor a lifetime of achievements in swine veterinary medicine.

A recognized international expert in swine diseases, Dr. Hogg was credited with our 300 publications and presentations.

During his retirement, he worked as a technical consultant for MVP Laboratories.

He worked for many years as a swine extension veterinarian and professor at the University of Nebraska, following a few years in mixed animal practice at Coin, IA.

Activists Pursue Ballot Initiative

Animal activists have raised 218,000 signatures in support of a proposed ballot initiative to ban sow gestation stalls and veal calf tethers in the state of Arizona.

Groups needed about 123,000 valid signatures from registered state voters to place Proposition 204 on the ballot. The Arizona secretary of state still must verify the validity of the signatures.

If approved by Arizona voters in the November election, the ban would take effect in 2012.

Joining in opposition to the ballot initiative is the Campaign for Arizona Farmers, comprised of the Arizona Farm Bureau Federation, Arizona Cattlemen’s Association, United Dairymen of Arizona and the Arizona Pork Council.

Their Web site, highlights the message “Proposition 204 is Hogwash” and debunks a number of myths propagated by activists.

New Manure Fact Sheet

Staff at the Iowa Manure Management Action Group (IMMAG) is developing a new resource for crop and livestock farmers around the state.

The group will write and distribute a monthly series of fact sheets on manure management.

“This valuable tool comes in response to the continued need to provide information on regulations, best management practices, neighbor relations and sources of additional information for people who produce and apply manure as crop nutrients,” explains Angela Rieck-Hinz of the Iowa State University Agronomy Department.

The July fact sheets served as an introduction and covered the various types of livestock operations. Future topics will include land application, winter manure application and manure stockpiling.

The fact sheets will be available through IMMAG’s Web site at

Rapid Diagnostic Test Announced

A rapid diagnostic test for seven major livestock diseases has been announced by Colorado State University.

Also involved were the U.S. Department of Homeland Security, the Agriculture Department’s National Veterinary Services Laboratory and the National Animal Health Laboratory Network and Lawrence Livermore National Laboratory.

The new diagnostic tool reduces the time of detection from days to hours and can simultaneously test for detection of foot-and-mouth disease and a number of similar diseases: bovine viral diarrhea, bovine herpes-1, bovine parapox virus complex, bluetongue, swine vesicular disease and vesicular exanthema of swine.

“This new diagnostic assay will significantly enhance the future security of U.S. agriculture by providing improved technology for animal disease diagnostics,” says Tammy Beckham, deputy director of science for the Department of Homeland Security at the Plum Island Animal Disease Center.