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Articles from 2007 In December

Canadian Pig Surge Continues

Pig imports from Canada are setting records about every week. A new record was set last week for feeder pig imports at 152,371 head. A new record for market hog imports of 81,781 head was set the week of Dec. 1. Figure 1 shows these weekly data back to January 2000. These recent surges have pushed feeder pig imports above the six million head mark and market hog imports above 2.6 million head. Those numbers are 11% and 24%, respectively, above the year-to-date (YTD) levels for Dec. 15, 2006.

These shipments are symptoms of the economic situation in Canada that we have discussed here on several occasions. The increases suggest that things aren't getting much better as the Canadian dollar has weakened slightly this month. Of course, any change in the rate will take some time to filter through, and the slight move in the value of the Canadian dollar has been more than offset by the continued strength of grain markets.

I've heard very little talk of any trade action over this surge in imports. Apparently, U.S. producers are pretty loath to pile on the situation that Canadian producers are facing. But the few I have spoken to change their tone quickly when they consider the possibility of the Canadian government offering substantial payments to ease the burden. It is a touchy situation that we all need to be aware of.

Where's the Ceiling?
I have spent the past couple of weeks trying to figure out what might stop corn and soybean prices from rising. Lower wheat prices have not done the trick -- even though it is difficult to argue that "lower" wheat prices are in any semblance "low" wheat prices at present. Corn and soybean markets have not responded at all to drops in wheat futures over the past week.

In fact, corn and soybean futures have reached contract-life highs across the board this (Friday) morning, while soybean meal futures are all higher with contracts from May 2008 and beyond -- all at contract-life highs.

It appears that the only thing that is going to stop these prices from continuing upward is good news -- first from the Southern Hemisphere and then from here in the United States -- as planting begins.

There is a risk premium in the futures market that says, "Just in case, we'll pay this much for you to plant 'X' number of acres this spring." That will not abate until something says the just-in-case factor is not necessary. I haven't seen anything that suggests that yet. Let's hope they have a crop in South America and that planting goes well here -- or we may not have seen anything yet.

The impact of these higher prices can be seen in Figure 2, which shows that my feed costs index is nearing the record level set in July 1996. The index has increased by almost $90/ton since last September, adding roughly $34/head to the cost of raising a pig. That has taken breakeven costs from the upper $30s, live weight, to the low $50s. Carcass-weight breakevens are now very near $70/cwt.

What looked like a breakeven year in 2008 is getting shakier by the day. As of this morning, only the May through August futures would offer a profit at these costs levels -- and those futures prices are still higher than strict supply-demand fundamentals would suggest.

Watch for 'Bears' in the Pig Crop Report
Next week's USDA Hogs & Pigs Report will be very important to this market. Look for some major revisions, especially to the market hog numbers published in the September report. It is possible that USDA will revise the sow herd upward for the past year or so -- given the slaughter numbers we've seen this fall.

A concern is how index funds and other non-ag investors in these futures contracts might interpret major upward revisions. Many of them do not have much experience with the pork industry. We think the potential for a bearish report and a bearish reaction is pretty high.

So what do you do? That's a quandary. December is, historically, a lousy time to sell lean hogs futures contracts. There are better times of the year to sell every futures contract -- again speaking from history. So, if you do not have hogs covered by now, you must balance your ability to stand a bearish report against the possibility of selling hogs at seasonally low prices.

One answer would be to use options -- either put options or sell lean hogs futures and buy out-of-the-money call options. You would be protected against a price break but be able to ride any price rallies beyond your strike price upward. Options, though, tend to be a bit expensive, especially for months far into the future, since the time to expiration is one important component of an option's value.

Merry Christmas
Please accept our wishes for a very Merry Christmas! We hope you take time to be with the people you love and truly celebrate the gift of this season!

Click to view graphs.

Steve R. Meyer, Ph.D.
Paragon Economics, Inc.

Colorado Moves to Phase Out Sow Gestation Stalls

The Colorado Pork Producers Council (CPPC) has announced plans to begin phasing in group housing for pregnant sows on hog farms over a 10-year period, according to a new release dated Dec. 18.

“Although animal welfare experts and professional groups have found no one method of housing gestating sows that is clearly better than the other, when managed properly, some concerns have been voiced about the use of individual stalls for pregnant sows,” explains Ivan Steinke, executive director of the CPPC. “Individual stalls, the standard practice used in the swine industry, are used to provide for the health, safety and well-being for each gestating sow.”

However, Steinke adds: “To address public concerns and changing market conditions, Colorado’s pork producers will embark on a 10-year phase-in that will allow producers to thoroughly evaluate and determine the best animal welfare practices for group housing. Producers may need to reconfigure their farms, acquire new equipment and staff appropriately in order to provide the best animal care with group housing systems.”

Temple Grandin, internationally recognized expert on animal handling and professor at Colorado State University, commended the decision. “A 10-year phase-in period of group housing will be needed to allow producers to change pig genetics and train management to the new system,” she says.

Jill Appell, president of the National Pork Producers Council (NPPC), says animal activist groups sometimes sway public perception into wrongly believing that sow gestation stalls can be cruel.

NPPC’s belief is there may be more than one suitable option for sow housing. However, it should be up to the individual pork producer to decide on the sow housing system that best fits his/her operation or management style, whether it be individual stalls or group housing.

“We stand by our policy that there is more than one way to manage sows,” stresses the Altona, IL pork producer. “We try to make sure our producers know there are many ways they can use to take care of their pigs that are animal friendly and they should decide what works best for them while understanding the alternatives.”

The pork industry’s Pork Quality Assurance Level 3 program contains a section on animal well-being that provides this information, she says.

Colorado has about 150,000 sows, a good percentage of which are already being phased out of stalls as part of Smithfield Foods’ decision in late January to phase out use of gestation stalls at its 187 company-owned sow farms over a 10-year period.

Proper Amino Acid Ratios Cut Costs, Nitrogen Excretion

Proper Amino Acid Ratios Cut Costs, Nitrogen Excretion

Determining proper amino acid ratios in growing pigs' diets limits feed expense and reduces nitrogen excretion, according to a research report from the University of Kentucky.

If the required ratio is set too low, performance will be limited due to inadequate levels of amino acids in the diet. In contrast, if the required ratio is set too high, excess supplementation will occur, increasing cost and nitrogen excretion, says lead researcher Merlin Lindemann.

Lysine is the most limiting amino acid in most swine diets. Once that level is established, it is fairly easy to determine and fill other amino acid needs if the ratio to lysine is known. Researchers disagree about the proper ratio of tryptophan to lysine, however.

Another confounding factor is whether the ratio applies to total dietary amino acids, because not all dietary proteins are digested equally, nor are all amino acids absorbed equally. Therefore, a ratio at the muscle level, where the majority of protein synthesis occurs, may not be the same as the ratio for total dietary amino acids.

To find out the applicable ratio for amino acid absorption, University of Kentucky scientists studied the required standard ileal digestible trytophan:lysine (SID Trp:Lys) ratio for growing pigs fed mainly a corn-soybean meal diet.

A total of 120 crossbred pigs averaging 57 lb. were placed on five separate diets and housed five pigs/pen. The dietary lysine level was set at 0.75% total lysine, which equated to a standard ileal digestible (SID) lysine level of 0.66% based on the ingredients that were used. The dietary treatments were increasing SID Trp:Lys ratios (from 12.43 to 18.42%) fed for 21 days.

Determination of the required ratios was based on growth performance (average daily gain) and plasma urea nitrogen (PUN), which is reduced when the proper ratio is attained.

Analysis of the data confirmed that proper responses were achieved for an optimum Trp:Lys ratio of 15.70 (Figure 1) for average daily gain and a plasma urea nitrogen of 15.64 (Figure 2). This produced a mean ratio of 15.67, based on the true (or standardized) ileal trytophan and lysine values.

When converted to a total dietary Trp/Lys ratio for the feed ingredients tested, the ratio becomes 17.0.

In sum, this study provides very clear agreement between the response measures for the SID Trp:Lys ratio for growing pigs fed mainly corn-soybean diets.

Researchers: Merlin Lindemann, Anthony Quant and Gary Cromwell, all of the University of Kentucky. Contact Lindemann by phone (859) 257-7524, fax (859) 323-1027 or e-mail

Effects of Dietary Ingredients On Carcass Quality Measures

Three separate Kansas State University (KSU) research trials confirm that adding fat to swine diets increases carcass iodine values. The exact impact on the carcass depends on the fat source.

In the first experiment, researchers found that adding ingredients high in unsaturated fats, such as dried distiller's grain with solubles (DDGS) or extruded expelled soybean meal (EESM), have a greater effect on iodine value of the carcass fat than choice white grease (CWG), even when the calculated dietary iodine values were similar.

When comparing corn-based vs. sorghum-based diets in a second research trial, KSU researchers concluded that feeding sorghum reduces iodine value when compared to feeding corn. They say sorghum could potentially be used to replace corn when iodine values approach the maximum level.

Results of the third research trial suggested for each 10% increase in DDGS added to the diet, iodine value increases by 1.5 to 3 g./100g., depending on where the fat is stored in the body.

The research trials were based on the knowledge that feeding ingredients containing unsaturated fats can have a large impact on carcass iodine values. Iodine value is a measure of the level of unsaturation of fats, and therefore a measure of fat firmness. Calculating a diet's iodine value appears to underestimate the impact of unsaturated fat sources on carcass fat iodine value as compared to saturated fat sources. This indicates dietary iodine values may not be an accurate predictor of carcass iodine value.

For processors targeting the Japanese market or the fresh belly market, fat softness is becoming a major issue. These processors have measured iodine value of carcass fat and, to date, have asked producers to alter diets to be below a maximum iodine value target. Production costs could further increase if lower-cost ingredients, such as bakery products, DDGS or EESM, must be limited or eliminated from the diets.

In the first research trial, researchers took a look at the impact on finishing pig growth performance and fat quality if choice white grease was added to corn and sorghum-based diets. Sorghum is often an economical replacement for corn in some swine diets. The researchers noted that Triumph Foods, St. Joseph, MO, has set a maximum jowl iodine value of 73.

Previous research showed that adding an unsaturated fat source during any portion of the finishing phase can result in iodine values above 73. Researchers speculated that because sorghum has a lower oil content than corn, a lower carcass iodine value may result.

Researchers used 120 crossbred barrows and gilts with an initial weight of 119.9 lb. in an 83-day experiment. Experimental treatments were arranged based on whether the diet included corn or sorghum, if fat was added and the gender of test animals. The fat options included 0, 2.5 or 5% CWG.

Pigs fed sorghum-based diets had increased average daily gain (ADG) compared to pigs fed corn-based diets. The higher ADG was due to an increase in average daily feed intake (ADFI) for pigs fed sorghum-based diets.

Typically, the researchers say they would expect similar ADG and slightly poorer F/G for pigs fed sorghum-based diets compared to corn-based diets. Pigs fed increasing levels of CWG improved ADG, too.

The results shown in Tables 1 and 2 confirm that added dietary fat improves pig growth. Pigs fed corn-based diets had improved dressing percentage, reduced 10th-rib backfat and improved lean percentage compared with pigs fed sorghum-based diets. The results also confirmed barrows had lower lean percentages than gilts.

The researchers found substituting sorghum for corn in diets for finishing pigs can be an effective way to reduce iodine value without affecting growth.

In the second trial, KSU researchers found that DDGS and EESM can be economical to feed to growing and finishing pigs. However, using these ingredients increases the dietary fat level when they are substituted for corn or soybean meal.

When dietary fat level increases, the result is softer carcass fat. The trial to study the effects of DDGS and EESM on growth performance and fat quality included 120 barrows with an initial weight of 105.7 lb.

Diets included: a corn-soybean meal control diet with no added fat; corn-EESM diet with no added fat; corn-EESM diet with 15% DDGS; corn-soybean meal diet with 15% DDGS and 1.55% CWG; corn-soybean meal diet with 3.25% CWG; and corn-soybean meal diet with 4.7% CWG. Diets were formulated to have three dietary iodine value levels of 42, 55 and 62, to compare the impact of the fat source within dietary iodine levels.

Jowl and backfat samples were collected after 83 days. The results indicated pigs fed the control diet, EESM or 4.7% CWG had increased ADG compared with pigs fed either diet containing 15% DDGS (Tables 3 and 4).

Pigs fed the control diet had increased ADFI compared with all other treatments. Pigs fed the EESM with 15% DDGS and the diets with 4.7% CWG had improved feed/gain compared with pigs fed the control diet and pigs fed DDGS with CWG. Pigs fed high CWG diets had greater loin depth compared with pigs fed low-CWG diets.

Pigs fed either of the diets with 15% DDGS had increased backfat iodine values when compared with pigs fed diets without DDGS. Pigs fed EESM had increased backfat iodine values when compared with the control diet or diets with 3.25 or 4.7% CWG.

Adding DDGS, using EESM or adding CWG to the control diet increased iodine value of jowl fat. Feeding ingredients with higher levels of unsaturated fat, such as EESM and DDGS, had a greater impact on fat iodine value than CWG, even when diets were formulated to similar iodine value levels.

The results confirm that adding fat to finishing diets improves growth performance. Feeding DDGS in this trial resulted in decreased ADG and ADFI. Adding DDGS, EESM or CWG increased iodine value and reduced the percentage of saturated fatty acid.

Feeding ingredients with higher levels of unsaturated fat, such as EESM and DDGS, had a greater impact on fat iodine value than CWG, even when dietary iodine values were similar. Feeding pigs a diet with more unsaturated fat may lead to jowl fat and backfat with more similar iodine values.

In the third trial, KSU researchers used 1,112 pigs in a 78-day trial to evaluate the effects of including DDGS at 0, 5, 10, 15 or 20% of the grow-finish diet.

Previous research has shown that DDGS levels could be fed at up to 30% of the diet before growth performance was reduced. The impact of DDGS on growth performance is blamed on product variability between batches. Variations in palatability are suspected to influence performance.

As noted earlier, DDGS has been shown to impact carcass characteristics by reducing percent yield and carcass weight, while making carcass fat softer and bellies less firm.

The research barn was topped at Day 57 to simulate normal pig marketing under commercial production practices. The three heaviest pigs from all pens were removed and marketed. Six barrows from among the tops were randomly chosen from each treatment to collect data for analysis. The remaining pigs were shipped at the end of the experiment for collection of standard carcass data. Samples were collected and frozen for further processing and analysis.

Overall, ADG and ADFI decreased with increasing DDGS (Table 5). However, the greatest difference in ADG occurred when DDGS was increased from 15 to 20% of the diet. Pigs fed 5% DDGS tended to have improved F/G compared with pigs fed other dietary treatments. There were no differences in live slaughter weight or loin depth. Carcass weight and percent yield decreased with increasing DDGS in the diet. Increasing DDGS tended to decrease backfat and fat free lean index (FFLI).

Backfat, jowl fat and belly fat iodine values and percentage of C 18:2 fatty acid (the major unsaturated fatty acid) increased with increasing the DDGS in both topped pigs (Table 6), and pigs marketed at trial completion (Table 7). Percentage saturated fatty acid in backfat and belly fat decreased with increasing DDGS in both sets of pigs.

Increasing DDGS reduced ADG, carcass weights and percent yield. The reduction in ADG was driven by a reduction in ADFI as DDGS level increased in the diet. The reduced carcass weights equated to a reduction of 4 lb./pig fed the 20% DDGS. Iodine values increased as DDGS levels were increased. For each 10% of DDGS added to the diet iodine value increased by 1.6, 2.4 and 3.0 g./100g. in the jowl fat, backfat and belly fat respectively.

The researchers concluded, based on these results and previously conducted research trials, the linear reduction in yield and increase in iodine value must be considered when determining the economic value of DDGS.

Researchers: Justin M. Benz; Sara K. Lineen; Joel M. DeRouchey; Mike Tokach; Steve Dritz, DVM; Jim Nelssen; and Robert Goodband, Kansas State University. Contact Benz at (785) 532-1270.

Click below to view the accompanying tables

Seeking Answers for Postweaning Diarrhea

Porcine postweaning diarrhea (PWD), caused by enterotoxigenic Escherichia coli (ETEC), is one of the most economically significant swine diseases. It causes an estimated $90 million in annual losses due to death of up to 5% of young pigs.

Symptoms of PWD include severe diarrhea, dehydration, slow growth and weight loss.

Despite its importance, there are no commercially available vaccines or treatment options to protect weaned pigs from PWD.

Key virulence factors for PWD are believed to be bacterial fimbriae and enterotoxins produced by ETEC strains. Bacterial fimbriae attach E. coli strains to the small intestine and cause bacterial colonization. Then the colonized E. coli strains secrete enterotoxins, which cause an overproduction of fluid secretions and result in diarrhea.

However, recent studies at South Dakota State University's Center for Infectious Disease Research & Vaccinology indicate that factors causing PWD could be more complicated, and that other virulence factors could be contributing to the disease, making the development of treatment options even more difficult.

K88 and F18 fimbrial strains of E. coli are the dominant pathogens found in pigs with PWD. These E. coli strains produce one or more enterotoxins.

A study of 304 E. coli strains isolated from pigs with PWD suggests that other E. coli toxins and non-fimbrial adhesions could contribute to PWD.

The study found that fimbrial E. coli strains isolated from pigs with PWD express mainly K88 (64.6%) and F18 (34.3%), but also heat-labile (57.7%) and a variety of heat-stable toxins, all of which remain the dominant fimbriae and enterotoxins associated with PWD.

But it is noticeable that enteroaggregative E. coli toxin is commonly associated with PWD, and that the porcine attaching and effacing-associated factor is showing high prevalence in PWD.

To understand the virulence factors for PWD, a study model was developed using genetically engineered E. coli strains with one fimbria and one enterotoxin. Animal challenge studies were conducted using gnotobiotic (germ free) pigs.

It was found that a K88 E. coli strain and a heat-labile toxin cause severe diarrhea in all pigs, and a strain producing K88 fimbria and heat-stable toxin (STb) causes disease in 60-70% of pigs. Other enterotoxins are being investigated for virulence.

An ongoing research project for vaccine development funded by USDA shows promise. So far the vaccine protects pigs from K88 fimbrial ETEC strains. Work continues to add vaccine protection against heat-stable toxins, and acquisition of funds to complete this research project.

Researcher: Weiping Zhang, South Dakota State University. Contact Zhang by phone (605) 688-4317, fax (605) 688-6003 or e-mail

Serum Sampling is Best PRRS Diagnostic Tool

Serum samples provide the best sample to detect porcine reproductive and respiratory syndrome (PRRS) virus during acute infection, with the blood swab sample performing almost as well in research conducted by the University of Minnesota in collaboration with South Dakota State University, PIC and Boehringer Ingelheim Vetmedica, Inc.

Boar studs are regularly monitored for the presence of the PRRS virus, testing different biological samples by reverse-transcription polymerase chain reaction (RT-PCR).

Usually, samples are run in pools to reduce the cost of submitting individual samples, even though the impact of pooling on the sensitivity of RT-PCR is unknown.

To assess the impact of pooling and collection method on PRRS virus by detection, 29 boars were inoculated with a low virulent PRRS strain. Serum, blood swab and semen samples were obtained from each boar every two to three days for two weeks and tested by RT-PCR.

Eleven of the 29 boars did not appear to become infected from the inoculation. Data from the other 18 boars showed that serum provided the best sample, followed by blood swab.

Other results showed that semen samples failed to detect PRRS infection in most of the cases.

For most of the samples, pooling did not affect the performance of the test. But PRRS detection was missed in a small proportion of pooled samples. The impact of pooling on the sensitivity of PCR was higher in samples taken when infection started. Sensitivity was decreased by 6-8% when serum or blood swab samples were run in pools of five.

This decrease in sensitivity should be taken into account when designing surveillance protocols for boar studs by proportionally sampling more boars.

Researcher: Albert Rovira, DVM, University of Minnesota. Contact Rovira by phone (612) 625-7702, fax (612) 625-1210 or e-mail

Immune Parameters May Signal Why Some Pigs Clear PRRS Virus

Porcine reproductive and respiratory syndrome (PRRS) virus is difficult to rid from herds because infection elicits a weak immune response that is not fully protective.

This results in persistent infection in a subset of pigs, thus providing a continued source of virus circulation within the herd.

Substantial research efforts have not yielded the exact components of a protective anti-PRRS virus immune response, particularly as it relates to persistence.

These shortcomings led researchers at the U.S. Department of Agriculture Agricultural Research Service's (ARS) Beltsville Animal Research Center (BARC) and Kansas State University to use “Big Pig” samples to determine whether immune markers that control PRRS virus persistence can be identified.

The Big Pig project was a PRRS CAP1 (Coordinated Agricultural Project)-supported, multi-institutional (university and commercial), multi-disciplinary experiment initiated in 2005. It was designed to analyze pig responses to PRRS disease, virus replication and immunity in 109 pigs (and 56 control pigs), sampled for up to 203 days post-infection.

Blood samples collected throughout the Big Pig project were evaluated for blood protein levels that might be predictive for pigs that clear PRRS virus rather than pigs that remain persistently infected with PRRS.

The hypothesis was that protective serum cytokine levels 7-42 days post-infection would help predict which pigs were more likely to have persistent viral infection (147-203 days post-infection).

Samples from pigs that apparently cleared PRRS virus from serum and tissues by 28 days post-infection were labeled the Non-Persistent (NP) pigs. Persistent (P) pigs were those that showed evidence of long-term, persistent PRRS infection at 150 days post-infection.

Sera from P and NP pigs collected over the course of the PRRS infection were tested for serum cytokine levels (substances that are secreted by cells of the immune system) following PRRS infection.

NP pigs appeared to have faster and higher levels of serum cytokine Interleukin-8 and anti-viral Interferon-gamma than the pigs with persistent infections. This immune cytokine trend correlated with the clearance of virus from serum and tissues.

Researchers noted this effect might indicate that the NP pig's immune response was faster and more effective than that for pigs with persistent infections, and possibly enabled the NP pigs to prevent PRRS virus infections from becoming persistent.

This conclusion sets the stage for identifying prognostic indicators of persistent infection and for targeting these proteins for anti-PRRS virus biotherapeutics or vaccines.

At present, it is estimated that 60% of U.S. hog operations are infected with PRRS. The National Pork Board calculates PRRS is the most economically significant disease facing the swine industry, costing $560 million annually.

Researchers: Joan K. Lunney, USDA, ARS, BARC; Bob Rowland, Kansas State University. Contact Lunney by phone (301) 504-9368, fax (301) 504-5306 or e-mail Contact Rowland by phone at (785) 532-4631 or e-mail

Electric Prod Use Can Be Costly

Research at Canada's Prairie Swine Centre (PSC) confirms that use of an electric prod to move market hogs elevates stress levels in the animals vs. other means of handling.

A total of 192 hogs near market weight were walked from their finishing pens in groups of six, through a 984-ft.-long handling course that included numerous turns, curves, reversals and partially obstructed alleys.

The course took an average of 10 minutes to complete. Three handling regimens were imposed on the animals.

Hogs in the gentle treatment group were moved with a herding board, quiet voice and gentle slaps at a comfortable walking pace. These hogs were essentially unstressed by the procedure (Table 1).

Hogs in the second group were handled aggressively, at a fast pace, with shouting and slapping, but without use of an electric prod. These animals showed a higher incidence of stress, but none showed extremes that might lead to animal losses.

For the third group, pigs were moved at a fast pace, a louder voice and use of slapping or an electric prod. The use of the electric prod resulted in more than 40% of the pigs showing behavioral and physiological signs of stress, with 4% to the extreme point of stumbling and falling.

“Losses resulting from aggressively handled pigs can approach 4% in a commercial swine operation,” says PSC researcher Harold Gonyou. “For a 600-sow, farrow-to-finish operation marketing 14,000 hogs/year, assuming a 2% loss due to aggressive handling, this would represent lost revenue on 280 market hogs, or approximately $37,000 for that operation.”

In the trials, pigs that were highly stressed had higher temperatures, lower blood pH and higher blood ammonia levels than did pigs with no outward signs of stress.

“Clearly, we should be minimizing the use of the electric prod when handling animals,” points out Gonyou. “Before prodding a pig while it is being loaded, the handler should consider if another means of encouraging movement could be effective, even if it took slightly longer. If one pig is repeatedly being difficult to move, it should be left behind and perhaps herded separately rather than prodding it again.

“If producers find that they must use the electric prod frequently during the load out process, they should consider changes to their load out design and/or handling techniques.”

Researcher: Harold Gonyou, Prairie Swine Centre, Saskatoon, Saskatchewan. Contact Gonyou by phone (306) 373-9922, fax (306) 955-2510 or e-mail Kenneth Engele, assistant manager, Information Services, PSC, at

Table 1. The Incidence of Highly Stressed Pigs
in Three Different Handling Treatments
Gentle No-Prod Prodded
No signs of stress 47 41 54
Highly stressed but not falling 1 7 23
Highly stressed and falling 0 0 9
Total number of pigs 48 48 96
Handling time in course (sec.) 701 467 467

More Animal Welfare Research Articles:
‘Pig-Friendly’ Loading Chute Minimizes Loading Stressors
Management Effects on Group Sow Housing
Curing Water Wastage In Postweaning Pigs
View all 2007 Swine Research Review Articles

Circovirus Spread Via Semen Studied

Because porcine circovirus-associated disease (PCVAD) has spread rapidly across North America, boar semen has been implicated as a possible source for dissemination of the virus.

To address this issue, and determine if there are differences in semen shedding of porcine circovirus type 2 (PCV2) isolates, 15, 7-month-old PCV2-negative boars were randomly allotted to three different groups. The first group served as control, the second was inoculated with PCV2a (North American-like virus) and the third group was inoculated with PCV2b (European-like virus).

Semen and serum were collected during the 90-day trial at Iowa State University (ISU).

Research concluded that PCV2a and PCV2b were both shed in low levels in semen in the two groups, of experimentally infected boars. Semen was shed for up to 12 weeks.

Overall, the amount of shedding was low and variable among individual boars within groups, and peak shedding occurred approximately three weeks post-challenge.

Detection of PCV2 in semen corresponded well with detection of PCV2 DNA in serum samples and blood swabs.

This trial verified that mature boars shed low quantities of PCV2a and PCV2b in semen, and that semen is a potential route for PCV2 transmission amongst swine herds.

In a second trial, a swine bioassay model was used to determine if PCV2-positive semen was infectious. Twelve, 4-week-old, PCV2-negative pigs were divided into four groups. All of the 4-week-old naїve pigs that were inoculated intraperitoneally (abdominal area) with PCV2-positive semen became infected with either PCV2a or PCV2b.

But when the same semen samples were extended, and used to artificially inseminate PCV2-negative gilts in a third trial, those gilts did not develop PCV2 infection, nor did they show evidence of PCV2-associated reproductive failure. All gilts inseminated with PCV2-positive semen became pregnant and carried pregnancy to term. There was no evidence that fetuses became infected with PCV2.

Researchers concluded that experimental inoculation of boars with PCV2 produces infection; however, it has yet to be determined if PCV2-positive semen is a risk for transmission and dissemination of PCVAD.

Research was funded by the Pork Checkoff.

Researcher: Tanja Opriessnig, Iowa State University. Contact Opriessnig by phone (515) 294-1950, fax (515) 294-6961 or e-mail

Dam Parity May Impact Pigs' Immunity Levels

Dam Parity May Impact Pigs' Immunity Levels

Preliminary results of research at the University of Nebraska suggest that health status, as indicated by circulating immunoglobulin concentrations in baby pigs, may be affected by dam parity.

Researchers investigated the health status of different parities by evaluating the ability of Parity 1 (P1) and Parity 3 (P3) dams to produce and passively transfer immunoglobulins (IgA and IgG) to their offspring.

General observation is that P1 progeny have reduced health status compared to progeny from older sows (Table 1). But these differences in health status of pigs from different dam parities have not been fully clarified.

The objective of the University of Nebraska study was to provide baseline information to gain a greater understanding of parity health differences by evaluating production and transfer of immunoglobulins from dams of increasing parity to their progeny.

Large White x Landrace females were part of an ongoing sow longevity experiment at the University of Nebraska.

After farrowing, 4-5 piglets from five, Parity 3 sows and four, Parity 1 gilts were randomly selected for analysis.

Three parameters were evaluated to assess the health status of progeny derived from different parities:

  • Circulating concentrations of IgA and IgG in P1 and P3 dams;

  • Concentrations of IgA and IgG during lactation in colostrum and mid- and late-lactation milk; and

  • Circulating concentrations of IgA and IgG in P1 and P3 progeny.

Whole blood was obtained from each dam 24 hours pre-farrowing and from dam progeny at 0, 8, 15, 20 (weaning), 29 and 37 days post-farrowing.

The concentrations of IgA and IgG in serum obtained from P1 and P3 females 24 hours prior to parturition are depicted in Figure 1. The values for both immunoglobulins are within normal ranges.

However, P3 females had greater concentrations of both IgA and IgG compared to P1 females. The higher stress load on P1 females may dampen their immune response, researchers noted.

This trend for differences in circulating concentrations of immunoglobulins at the time of parturition did not continue when IgA and IgG concentrations were evaluated in colostrum and milk samples from the same females (Figure 2). The IgA and IgG concentrations observed in colostrum samples obtained within 12 hours of farrowing were greater than immunoglobulin levels detected in milk samples obtained at mid- or late lactation.

“Although differences exist in immunoglobulin concentrations in the serum of these same females, it was somewhat surprising that no differences in colostrum or milk immunoglobulin concentrations were observed during lactation,” says lead researcher Thomas E. Burkey.

Figure 3 depicts circulating IgA and IgG concentrations in P1 and P3 progeny at several time points following parturition. The progeny of P3 females had greater levels of IgG compared to the progeny of P1 females at every time point evaluated, with a similar trend observed for IgA.

Progeny immunoglobulin concentrations from birth to about 2 weeks of age are almost completely due to passive transfer from the dam. Baby pigs rely on passive transfer of immunity via colstrum, and milk from the dam until they can mount their own immune response at 2 to 5 weeks of age.

Researchers: Thomas E. Burkey, Phillip S. Miller, Rodger K. Johnson, Duane E. Reese and Roman Moreno, all of the University of Nebraska. Contact Burkey at (402) 472-6423.