The ups and downs of barn temps
Tune up ventilation to handle rapid changes in ventilation due to spring-fall roller coasterThe only thing on the farm that goes up and down as fast and as much as pig prices is the temperatures of the rooms. The time of year for biggest fluctuations is the spring and fall, or "change" seasons. As outside temperatures drop in the evenings and rise in the day, the ventilation system is expected to compensate for these rapid changes.
Go with the flow shows that as temperatures hit the typical spring highs and lows between 35 and 55F, large increases in ventilation rates are necessary to maintain the target indoor set point. Note: These are examples only; base actual numbers on age and density of pigs in a given room.
Below 35F, outside temperature has little influence on the cfm (cubic feet per minute) requirement of the room to maintain a stable temperature.
Given that spring and fall naturally require rapid changes in cfm to maintain the target temperature, what can we do to offset the problems that seem to occur?
* Use a good quality digital max-min thermometer to record temperatures and check it frequently during the cold night-warm day time periods. Adjust ventilation systems as described below if fluctuations exceed plus or minus 2.5F or 1C in 12 hours in farrow and nursery; and plus or minus 4F or 2C in 12 hours in gestation and finisher.
* On warm days, soffit or other attic closure doors restrict air flows, causing increases in room temperature that could affect herd health. At night, when the system cools off, pigs feel chilled and there's a risk of stressing them. Solution: open some of the doors to relieve pressure problems, but not too many so that a late snow storm fills the attic. The best way to check opening is to install a pressure gauge from the attic to the outside and check on low-wind days. Alternatively, take into account that outside winds will cause the red dye to jump quickly. Target static is 0.01-0.02" w.c.
* Check air inlets, particularly self-adjusting types. If they are too loose, as air flow rates rapidly increase, they drop open too far and cause a wind chill. If they are too tight, again, the temperature can rise excessively. Solution: Adjust inlets to proper settings for milder weather.
* Check control settings. If they are too "tight," higher levels of fans come on and even though room temperature is maintained at or close to target, pigs can feel chilled from the rapid air velocities. Solution: Adjust controller so temperatures rise and fall a little more slowly.
* Adjust controller if control settings have been set for cold weather and not adjusted to reflect the outside weather conditions and density of pigs.
* Set up fans so they can operate as required before they are needed. Additional levels of ventilation fans may be required, but cannot operate because they still have winter covers on, are unplugged, or have not been checked for operation and have a problem from the winter.
* Heaters are typically sized for worst case conditions - young pigs in very cold weather. In many cases the heater is oversized further to allow for rapid drying out after washing. During milder weather, some heat is required, so the oversized equipment cycles often, causing temperature fluctuations. Solution: If there is an adjustment on the heater for variable output, set for the lowest possible level once a room has been preheated. If this is not possible, adjust controller so that it turns the heater on and off a little cooler than usual, and more rapidly if this setting is possible. Although the heater will cycle on-off more often, this is only for the spring and fall conditions and should not cause too much excess wear and tear.
Ventilation systems are trickiest to manage during the large fluctuating spring and fall conditions. Be sure to observe temperature and humidity in the barns and prepare your system to compensate and maintain a good indoor environment.
Ron MacDonald, P.Eng, consults with Guelph-based Agviro Inc.
© copyright 1999 Agricultural Publishing Company Limited.
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Scaling the 18-week wall
Respiratory complex fells pigs at 18 weeks, but early Mhyo vaccination gives them a fighting chanceI've previously written on Porcine Respiratory Disease Complex (PRDC) or the "18-week wall" (Pork Producer Vol 4 #1, 1996 pg 28). The PRDC picture has since become much clearer and is thus worthy of a revisit to update on the latest findings and current corrective actions to combat this disease.
The 18-week wall occurs as an increasingly worsening cough, usually starting several weeks after pigs are placed in the finishing barn. In addition to the cough, pigs may also go off feed, develop fevers and exhibit respiratory distress. Mortality then increases, sometimes approaching and even exceeding 10 per cent. Quick review
The higher mortality rates are often associated with pigs bleeding out from gastric ulcers. Because the acute attacks often occur when the pigs are about 18 weeks of age, the condition has been called the 18-week wall.
Acute signs, however, could start as early as 12-13 weeks of age (soon after placement in the finisher) or be delayed until 22-23 weeks of age, commencing just before the pigs are about to be shipped. PRDC is the term that lumps the various agents - PRRS, Swine Influenza Virus (SIV) - that contribute to the 18-week wall and brings them together under one umbrella name.
We now know that Mycoplasma hyopneumoniae (Mhyo) is at the core of the 18-week wall. In addition to Mhyo, other agents such as PRRS and SIV may also contribute to PRDC. What we now know
Recent work by Dr. Eileen Thacker, Iowa State University, has shed new light on Mhyo's role in PRDC. Her work shows that when pigs are dually infected with PRRS and Mhyo, the ensuing pneumonia is more severe and lasts longer than if pigs are infected with either PRRS alone or Mhyo alone.
Not entirely surprising. In the field, we know that PRRS attacks first (usually when pigs enter the nursery), then Mhyo comes later, when pigs are moved to the finisher. Dr. Thacker learned, however, that it didn't seem to matter whether PRRS attacked the pigs first, as is usually the case in the field, or if it is Mhyo that gets there first. The outcome is the same.
We have had Mhyo in our herds for most of this century, so why has PRDC emerged as a problem in the mid and late 1990s? Some of the answer lies in the way we are raising pigs in the '90s. Many herds have switched to SEW or adopted some other segregated pig-flow techniques. Why has Mhyo become such a problem now?
Even without SEW many herd operators now use all-in, all-out techniques in the farrowing and nursery rooms. This has resulted in many pigs flowing through the nursery and into the finisher barns without prior exposure to Mhyo. It also means that fewer pigs have been immunized against Mhyo in the early stages of their lives, as they would have been prior to adoption of these technologies.
Our continuous flow systems allowed pigs to come into contact with Mhyo when they were still protected by passive (maternal) immunity. Today, because of the changes in the way we are raising pigs, many of them are confronted with the organism when maternal immunity is gone, leaving them unprotected and thus more vulnerable to Mhyo.
The single most successful intervention, so far, has been vaccination for Mhyo. Pigs are usually vaccinated in the nursery, well before the expected time of the respiratory (PRDC) outbreak. What to do about it?
If PRRS is involved, the sow herd must be stabilized to stop PRRS from infecting the nursery pigs. It may also be necessary to vaccinate piglets for PRRS until the sow herd is stabilized. Vaccinating the sow herd for SIV might be necessary in cases where SIV is also a significant contributor.
Alternatively, strategic medication with antibiotics that have good efficacy against Mhyo is also effective if the medication is given prior to the outbreak. The time of the outbreak can be pinpointed from previous experience. Medication is incorporated into the feed one to three weeks before the time of the expected outbreak. If medication is delayed until clinical signs have developed, the outcome is an uphill battle, with PRDC having the upper hand.
Another strategy that combines keen clinical observation with precise targeted intervention is to use the same antibiotics in the water for two to three days immediately before the predicted time of the outbreak. This is tricky business and has to be timed accurately, with little room for error.
To help with timing, some veterinarians recommend implementing treatment as soon as water consumption, measured at the level of the water lines, declines, or when a reduction in feed intake is observed. Pulse medication programs, using the same products, are also cost-effective. One possibility is to add medication to the feed in the finishing unit two out of every seven days (two days on medication, five days off).
Work is ongoing to break down the 18-week wall. As some questions are answered new ones are raised. We are much further along the road today than we were 18 to 24 months ago, however.
S. Ernest Sanford, DVM, is with Boehringer Ingelheim Vetmedica (Canada)
© copyright 1999 Agricultural Publishing Company Limited.
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Pinpointing quality
When it comes to injection site lesions, time heals old wounds, according to animal drug maker carcass studyThe world is watching as you head out to the barn for morning chores. With scare stories of resistant "superbug" bacteria making headlines, a simple task such as needling pigs has come under unprecedented public scrutiny. And the clout is on the public's side, says Randy Graham, technical services manager with animal pharmaceutical maker Pharmacia & Upjohn Animal Health based in Orangeville.
"Our industry is facing a really big quality image [challenge] in milk and meat," Graham told members of the Eastern Canadian Farm Writers Association in November. "We have a shrinking ag sector and a growing urban sector. How do you even educate 90 per cent with a shrinking two per cent [of the population]?"
And how much information is enough? "Does the consumer at large understand the definitions we're talking about?" Graham asked.
While industry voices such as the Canadian Animal Health Institute take the meat safety message to consumers, Pharmacia & Upjohn, which manufactures swine health products such as Excenel and Lincomix, is taking the meat quality message to producers by encouraging good management practices at the needle end.
Bruce Quinn, manager of product development and marketing, said labels on the company's new products will recommend producers wait 10 days following injection prior to marketing animals, to avoid carcass blemishes - or risk some devaluation or trim-out from the processors.
The aim of the new wording is to reduce the severity of "injection lesions" or marks in the carcass left by the needle. Quinn cited a 1998 carcass study commissioned by Pharmacia & Upjohn involving 28 pigs and six injectable antibiotics, including Pharmacia & Upjohn's recently-registered Excenel RTU (ready to use) injectable.
Pigs were injected in four sites in the neck, and slaughtered on the drug's recommended withdrawal, and five and 10 days following. Carcasses were then submitted for a blind "mean lesion score" by a University of Guelph pathologist, based on frequency and severity of swelling, discoloration, bleeding, scar tissue and dead tissue caused at the injection site.
Quinn said the study found that in general the score was similar for all products. Very long withdrawals of 18-28 days, however, allowed more healing of tissue versus short withdrawals. Sometimes, lesions from products with nine-13 days scored worse than products with shorter withdrawals. "All products have the ability to create some injection site lesions, even as long as 10 days post withdrawal," said Quinn.
"They're not huge lesions, but certainly something the industry needs to keep in mind."
What's the message for producers? "Looking at the label and just the withdrawal period is fine for human safety, but it may not address the issue of meat quality," Quinn said. "Producers should consider when they inject the animal, the potential for the lesion to remain there, even though the tissues are safe to eat."
Quinn added that the study indicates that the neck is the best place to inject an animal - not only is it a less valuable cut, but neck lesions heal faster than in the hind leg
"We as an industry need to be sensitive to the importance placed on meat quality," Quinn said.
© copyright 1999 Agricultural Publishing Company Limited.
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Rancour remains on imports
Canada's new swine import regulation allowing live hog imports from pseudorabies Stage Four and Five states is under attack - again."It's very, very strict - so much so that we regard it as being impractical," argues Canadian Meat Council general manager Robert L. Weaver.
"The only reason they're upset about it is just to give another excuse as to why they're not bringing pigs in," warns Canadian Pork Council vice-chairman Carl Moore. He insists packers won't import live hogs while the Canadian dollar is so far below U.S. currency.
Nevertheless, Weaver insists "we don't believe any hogs will be brought in under that protocol unless it's eased up a bit." The regulation, which was supposed to eliminate a major Canada-U.S. trade irritant, became law Dec. 14 after a decade of cross-border bickering among stakeholders.
Even as Agriculture Minister Lyle Vanclief was signing the regulation into law, groups such as the Canadian Swine Breeders Association and the National Farmers Union were still expressing reservations about the potential for American hogs to bring pseudorabies to Canada. Then, early January, a week or so after heralding Canada's new regulation, National Pork Producers Council officials desperate for shackle space flew to Ottawa to request that the Canadian Food Inspection Agency admit pigs from Stage Three states. Under the new law, only pigs from Stages Four and Five states are to be admitted. Stage Five states have been free of pseudorabies for more than a year, while Stage Four states have no known infection.
Weaver won't say exactly what his members object to, preferring instead to try to remedy the situation first with the Canadian Pork Council. Farm & Country has learned at least two packers have objected to provisions for on-site truck clean-out and disinfection, as well as animal identification procedures.
Moore, a key spokesman for producers during negotiations leading to the new law, notes "the Meat Council, the meat packers, were involved from Day One. Now all of a sudden when the protocol was gazetted, they read it."
He says the protocol wasn't as strict as producers had hoped, but says he was satisfied it protects the health of Canadian pigs. "We wanted a regulation that both the packers and the American producers can meet - and they can, [though] not easily," he concedes.
Dr. Brian Jamieson, senior veterinary officer, international trade, CFIA, says most details of the current regulation were known as far back as 1993. Still, he concedes if "there are acceptable alternatives, they need to be looked at." Jamieson says the on-site truck clean-out provision stays unless it is changed by regulatory amendment involving full industry consultation.
If pseudorabies did gain a foothold in Canada, affected herds' pigs would be slaughtered. In December, the annual Canadian Animal Health consultative committee recommended an $800 per head maximum compensation for both purebred and grade swine slaughtered under such an eradication program.
Professional evaluators set individual compensation amounts that are based on fair market value. - Robert Irwin
© copyright 1999 Agricultural Publishing Company Limited.
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New bugs and an old dilemma
Pork industry consultant Andy Bunn reports from the recent Centralia Swine Research Update
In 1993, a severe outbreak of human salmonellosis occurred in Copenhagen. The outbreak was traced to salmonella from pork. Consumer confidence in pork plummeted in Denmark. The industry quickly mobilized and developed a HACCP-based program, including: Danes raise bar
* Mandatory salmonella testing in all feed millsHerds are classified Levels 1, 2 and 3. The program has worked well on Level 1 (mild infection) herds, but is encountering more problems with Levels 2 and 3 herds. According to veterinarian Ernie Sanford, the Danish Salmonella Control Program has "raised the bar" for export markets. Competitors must equal or surpass the Danish program.
* Heat-treating feedstuffs to 81C
* Mandatory testing of all swine breeding and market hogs
Most hog carcasses with dark hair roots must spend additional down-time scraping hair roots that are not removed in the singeing and scalding process. Dark hair dilemma
According to a study by the University of Guelph's Cathy Aker, the dark hair roots cost the Ontario processing industry an estimated $5.76 per hog or about $1 million overall.
Of a total 76,010 carcasses assessed, overall incidence of dark hair roots in a cross-section of Ontario hogs was 4.2 per cent. In herds where the farmer raised his own gilt replacements, the incidence of dark hair roots was 40.6 per cent higher than from farms with purchased replacements.
York-Landrace gilt replacements had the most desirable dark hair roots. When they were mated to Hamp-Duroc boars, the average incidence of dark hair roots was 11.08 per cent; when purchased Duroc boars were used, the incidence was 13.6 per cent.
Post-Weaning Multi-Systemic Wasting Syndrome (PMWS) is a new disease to hit Ontario farms. It may be associated with Porcine Circovirus Type II (PCV). New bug on the block
University of Guelph graduate research student Tiffany Cottrell visited 25 farms, sampling blood from 30 nursery pigs and 30 sows. Each farm sacrificed three poor-doing nursery pigs for post-mortems.
Five of the 25 farms appear to have had epidemic outbreaks of PMWS and seven further farms appear to have endemic PMWS at a high level. The disease affects pigs between five and nine weeks of age.
Cottrell cited the following disease indicators: jaundice, pale, wasting, laboured breathing, diarrhea and coughing. There is currently no treatment for the condition.
E. coli bacteria normally reside and multiply in the intestinal tract of all animals. Up to 25 strains have been identified at any one time, with one strain usually predominating. Super bugs
There are literally thousands of strains of E. coli. Based on submissions to veterinary laboratories, however, the number of K88+ submissions have increased over the past seven years. K88 strains (F4) adhere to the intestinal walls and produce enterotoxins, which cause an outpouring of water into the small intestine.
In 1998, 221 cases were identified in 187 Ontario herds. The average age of affected animals in 1998 was 25.6 days compared to 13.6 in 1995.
Losses in SEW operations often follow feed changes. These pigs are markedly dehydrated, with sunken eyes, and intestines are ballooned with watery, occasionally blood-tinged contents.
Vaccination of the sow herd is of no benefit in preventing this condition in the post-weaned pig. Gaylan Josephson, swine health adviser with the OVC's animal health lab, said recent research at the Ontario Veterinary College, Guelph, using oral administration of genetically altered strains of E. coli bacteria, shows some promise in preventing or reducing the impact of this disease.
Removing antibiotics from the finishing ration would have minimal effect on profitability, said OMAFRA veterinarian Tim Blackwell. Antibiotic assault
The use of antibiotics leads to bacterial resistance, said Blackwell, noting that half the antibiotics produced in North America are fed to livestock.
Antibiotics are, however, necessary to treat sick animals, he said: The younger and sicker a pig is, the greater the response to antibiotics. Feed additives are inexpensive and cost-effective on many farms. Regardless of the antibiotic levels in the feed, the amount of active ingredient is low compared to other feed additives, Blackwell said.
Restrictions on antibiotic use are stronger in Quebec, the U.S. and most of Europe than in Ontario, he said. While a ban on low-level antibiotic feeding in Canada would have some negative effect at the onset, finishers could stop feeding antibiotics without hurting the bottom line, he concluded.
Accurately evaluating feed conversion performance and other traits in specific sire lines is the goal of a study underway at Ridgetown College. 10-plus meals a day!
Feed Intake Recording Equipment (FIRE) is used to measure average feed consumption, number of trips to the station and duration of visits.
With a maximum 14 pigs per feeding station, pigs were put on trial at 30 kg to a market weight of 105 kg. Average feed consumption was 2.3 kg per pig. Pigs entered the feeders an average 10.3 times per 24 hours, for a total of 1.27 hours each at the feeder. Night-time activity was higher than expected, possibly due to the number of pigs per pen, with a single feeder.
Ridgetown College's Jim Morris suggested FIRE feeders can be used to determine the true cost of variability in pig performance.
There is an optimal average shipping weight for any group of hogs, reported Ridgetown College economist Ken McEwan. Sorting pays
In a recent Ridgetown study, after 91 days on feed, hogs' liveweight ranged from 87.3 kg to 132.6 kg, despite all hogs having the same genetics, diet, husbandry practices, buildings and environment.
Bottom line: There is value in sorting pigs a couple of times.
Andy Bunn is a pork industry consultant based in London, Ont.
© copyright 1999 Agricultural Publishing Company Limited.
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