Better Pork - June 2007

Feature

Combatting PRRS II
Coping with ‘the oh-crap feeling of not knowing how severe it’s going to be’

In our April issue, we introduced three producers taking part in a study the OPIC Swine Health Advisory Board (OSHAB) has undertaken to create a better understanding of PRRS in Ontario. Here are the stories of three more who have agreed to open their operations for the benefit of the industry

by KATE PROCTER

Ron Manjin and his son Glen manage a 2,318-head herd of commercial sows near Teeswater in Huron County. Ron had operated a large sow operation, farrow-to-finish, since 1969, before deciding to contract his labour and his facility out to Will Vleet and Guys Geene, owners of Teeswater Pork. Now he works for a paycheque and has different worries than he did as an owner.

The farm was repopulated and new gilts started arriving in August 2006. Some 150 animals were delivered weekly until mid-September, when they started breeding. The Manjins planned to ship 1,000 weaner pigs per week once their herd size reached the target of 2,500 females.

Everything was going well until they answered the phone in mid-November. They learned from their gilt supplier that the load delivered on Nov. 17 had brought an unwelcome passenger – a PRRS virus. “They were on the phone as quickly as they could,” says Ron, but he was still forced to deal with the reality that PRRS had just walked into their new, clean herd. “You’d never know it was there, there were just no signs,” says Ron.

As soon as the Manjins found out about the PRRS-positive blood test result, herd veterinarian Dr. Martin Misener advised putting the herd on Pulmotil, a feed additive made by Elanco which is used as an aid in reducing the severity of respiratory diseases caused by several different organisms. 

They also started an aggressive serum-inoculation program. Since they could not get enough virus from the infected gilts, they used what virus they had to inoculate seven piglets, the most susceptible animals in the herd.

The virus grew inside the piglets for a week. Then they drew blood from them and, on Dec. 19, started serum vaccinating the herd. They needled the pregnant females first, then completed vaccinating the next day. During the vaccinating, the animals never stopped eating nor gave any outward sign of being ill. The abortion rate was just slightly higher than normal.

The gilts started to farrow on Jan. 4, 2007, and the Manjins felt the first real impact of the virus. At farrowing, the piglets were born weak, with a higher than normal level of still-borns and mummified piglets. They did absolutely no fostering between litters for the first six weeks of farrowing, then went to fostering within the first 24 hours after birth, beginning on Feb. 15. They aim to farrow between eight and 42 sows per day.

From this first group to farrow, they only weaned an average of 4.5 pigs per sow. It was really hard not being able to foster, says Ron. The piglets had very low immunity, were susceptible to secondary infections, such as scours, and healed more slowly. “They were just a lower grade piglet.”

In addition to the low weaning numbers, they had an added complication with the sows coming into heat early while still in the farrowing rooms because they were nursing such small litters.

Throughout the PRRS outbreak, the Manjins were able to maintain a farrowing rate of 81.1 per cent, with the lowest week occurring from Jan. 3-9 (74 per cent) and the highest from Jan. 24-30 (89.5 per cent), and they saw no clinical signs throughout the herd. 
Things have been looking up since that dismal first week. By the first week in March, the Manjins were weaning 7.1 pigs per sow and they had 88 per cent of females pregnancy checked positive at 28 days. They are aiming for a 92 per cent pregnancy check positive at 28 days and an 85 per cent farrowing rate. 

Ron and Glen gathered up gilts of different ages to fill their barn, injected them with serum and then shut the doors. No animals entered for a period of six months while they tried to eliminate the virus from their herd. 

Pride was one of the biggest casualties in this outbreak. “When you run a unit and know what you are doing, you want to show results and you just can’t,” Ron laments. Knowing that they were already in a negative cash-flow situation because they were just starting up also put pressure on the Manjins. 

Glen, who is responsible for the breeding side of the operation, thinks the disease has been hard on the gilts. “Just asking them to hop back on the bus and do the next cycle” is expecting a lot, he says. Their immunity has been taxed and they nursed a sick litter of pigs when they were not well themselves. It requires extra vigilance on the part of the staff, who have to be extra careful watching feed intake, double check all areas of upkeep and prevent any extra stress where they can.  

The barn operates with a staff of seven full-time employees and two part-time. They are all working towards a goal of producing PRRS-negative pigs and keeping the herd negative, but Glen asks a question a lot of producers coming through a PRRS outbreak ask, if only to themselves: “What is the chance of maintaining a PRRS-negative herd?”

An operation plagued with health problems
Darryl Terpstra and his sister, Cheryl, operate Birchlawn Farms Ltd. near Dorking in Perth County. They started their herd in 1997 with 600 sows and built it up to 900 with an on-site nursery. 

The operation has been plagued with health problems. While the sow herd did not suffer too much, they were always challenged by an erratic farrowing rate, which fluctuated between 65 and 80 per cent.

They made several changes in order to remedy this situation. They stopped collecting and processing semen in-house in 2002. They also changed the way that gilts were introduced into the herd. In 2000, they set up an off-site gilt barn where the gilts were given nose-to-nose contact with cull feeder pigs from the nursery.

The animals stayed in this barn for at least three weeks before being transferred to the main herd. They were vaccinated with PRRS PLE twice and sows were vaccinated at weaning. The pigs leaving the nursery at this time tested positive for the PRRS virus.     
In 2004, they changed the protocol for the gilt barn. While the vaccination program and feeder pig exposure remained the same, the gilts entered and left the barn in batches and stayed for two months, creating an all-in, all-out gilt flow.

Gilt isolation provided a safety net for the Terpstra operation when they learned that their supplier had a positive PRRS test. Because the gilts were kept separate from the main herd, the Terpstras were able to protect their sows from the virus and the gilt barn was depopulated.

These changes resulted in a dramatic improvement in reproductive performance, but their nursery was “horrible”, says Darryl. Any extra stress would affect the piglets very seriously. They had a high mortality rate, the worst reaching 20 per cent. Strep suis was out of control and they were also troubled by greasy pig.
 
In the fall of 2005, herd veterinarian Dr. Martin Misener recommended that they implement a McRebel program. This program restricts fostering of baby piglets and segregates litters within the rooms they are born. By following a strict McRebel procedure, the Terpstras hoped that they could eliminate the PRRS virus circulation from their farrowing rooms.

The first four weeks saw pre-wean mortality go up, but then the numbers stabilized and the number of pigs weaned per litter returned to the original level. They do not plan to go back to fostering piglets after Day 1, explains Darryl. “We definitely don’t wean cookie-cutter pigs,” he says, but they seem to get along better with less fostering and they sort the sizes at the nursery.

Because of the health situation, the Terpstras built an off-site, 2,400-head nursery that they filled in January, 2006, for the first time. “This enabled us to produce a PRRS-negative pig,” says Darryl.

They still maintain the on-site nursery, but it is operated strictly on an all-in, all-out basis.  Mortality and morbidity rates have dramatically decreased. “We had very few pigs held back because of health,” says Darryl. Within three months, they were shipping PRRS-negative pigs from their nursery. There was a six to seven month transition period and then they walked the virus out of their sow herd as well. 

PRRS seemed like it might become nothing more than a bad memory, but the Terpstras were in for a nasty Christmas present. In December 2006, they had six abortions over one weekend. They also had two sows die and lost a total of 10 litters due to early farrowing. They did the blood test and found that their sow herd had broken with a different PRRS virus strain than they had before. 

It was not an extreme outbreak, but their number weaned decreased by about two pigs per sow. The highest pre-wean mortality rate they saw was 15 per cent and it was a very short-term spike, lasting only two weeks. “Litters born early were the most frustrating thing,” says Darryl.

While their pre-wean mortality was not affected a lot, their total number weaned dropped by about 50 per cent, simply because so many sows did not make it to the farrowing crate.

As soon as they had a positive confirmation, they started feeding Pulmotil. The sows were on this medication for two weeks and it cost about $20 per sow. They also gathered blood from sows that aborted or had low viable pigs and selected the blood with the highest titre. Darryl notes that one of the sows from which they drew blood died the next day. The thought ran through his head at the time, “She died and we’re going to give this to all of them?” This serum was injected into young piglets where it grew for seven days and was then collected to make vaccinations for the herd.

Because they routinely sent their cull sows to the gilt barn, the gilts were unintentionally exposed, explains Darryl. They were also battling a swine influenza outbreak at the same time. When the gilts were injected with serum, they showed no reaction to the injection and things returned to “fairly close to normal,” he adds.

Darryl does not blame PRRS entirely for the challenges that his herd has battled. He blames his semen supplier in part for an erratic conception and farrowing rate. He switched suppliers in the late fall of 2006 and has seen an improvement in born alive numbers, piglet viability and farrowing rate. “I don’t think it has anything to do with PRRS,” he notes.

Birchlawn Farm is located within close proximity to a number of different swineherds, the closest a 300-head sow herd about a mile away. Everything they move is transported in their own trailer, explains Darryl. It is washed with hot water in a controlled environment and is sometimes disinfected. Staff shower when they go into the barn and are supplied with a complete change of clothes.  

They have also made some other biosecurity changes. All supplies delivered for the unit are left at the house, which is situated closer to the road than the barn. Drug and semen shipments used to be delivered right to the barn door, explains Darryl. They allow a very limited number of people into the barn and have a strict shower-in policy for their veterinarians, who visit about twice a year.

PRRS is tough on the people who work in the barn. The Terpstras have a barn manager, Paul Evens, and they manage to run the operation with Cheryl working as farrowing room manager and Darryl working in the barn and in the field. There was a big emotional letdown, says Darryl, because they realized they weren’t going to meet their production targets. “It is the oh-crap feeling of not knowing how severe it was going to be,” he says. 

All the diseases going
Piet Vanden Boogaard and his family began raising pigs in April 1988 with a 60-sow herd near Gorrie, in Huron County. When they started, they had all the diseases going, explains Piet. Over the years, they acquired more land, built more barns and expanded their sow herd, continually improving disease status as they went. 

In 2003, they built a 2,700-head finishing facility and, including some rented space, were now able to finish all the pigs they produced from their 900-head sow herd. 

In November 2004, the Vanden Boogaard herd broke with PRRS. The number of piglets born alive had been averaging between 11.5 and 12 and this was not affected much by the break.

However, the farrowing rate dropped immediately from 85 per cent to 75 per cent and stayed there until about September 2005. Pre-wean mortality jumped from 15 per cent to 25 per cent. This dropped back to 20 per cent, where it remained for about a year, explains Piet. As of December 2006, the average pre-wean mortality for the herd was 14.9 per cent.

In January 2005, they resumed doing biofeedback – feeding lungs, hearts, livers, stillborns and low-viability piglets back to all the sows in the herd. They did some blood testing and saw a big improvement by April, but the disease was not gone from their herd. There were still a small number of weaners testing positive and their mortality rates in the weaner barn were very erratic, ranging from a low of five per cent to a high of 30 per cent. “We were on a learning curve and I think the vets were too,” says Piet.

In April, Vanden Boogaard vaccinated with a commercial PRRS vaccine and brought gilts of varying ages in.  They closed the sow barn for four or five months after completing vaccination and feedback. 

They cleaned out the weaner barns, as well as the 600-head finishing barn, and started blood testing the animals. When the weaned piglet test results came back negative, they started filling their main finishing barn again. 

With mortality rates in the weaner barn still not stable, they went through the herd again and vaccinated against PRRS. They saw an increase in mortality in the finishing barn over the summer, which stayed at 25 per cent for about two months.  

Vanden Boogaard had repeated PRRS-negative blood tests and thought they had cleared the virus out of their herd. Then, in November 2005, some tests came back positive.  They did not see a huge effect, but Piet could tell that things were not quite right and mortality rates increased from two per cent to four per cent.

In January 2006, they had a plan to collect blood and serum inoculate all of the animals in the herd. They took blood from all the pigs that showed clinical signs of illness, but all came back with negative PRRS virus tests. They did more testing, which also came back negative.

They realized that a low level of virus was acting in the herd and had to decide if it was worth doing anything radical to get rid of it. At that time, the mortality rate in the weaner barn was about four per cent and the average finishing mortality was between three and five per cent, with some flare-ups.

They did a lot of culling of older sows that had been kept around throughout their PRRS trials, resulting in a 67 per cent replacement rate. Beginning in April 2006, Vanden Boogaard saw a definite improvement in most areas of the herd. The pre-weaning mortality fell from around 20 per cent to 15 per cent, which he attributes in part to continuing on with the McRebel protocols of reduced fostering.

However, Piet says they thought they should be able to do better. “It was not disastrous compared to some horror stories,” he says, but the low level of virus acting in the herd continued to affect production numbers.

In November 2006, they decided to eradicate the PRRS virus from the herd. They collected blood from weaner pigs and had some come back with positive results. They harvested serum from these animals and stored it in liquid nitrogen. 

Then they focused on changing the way they moved females from wean to finish and back into the breeding herd. They rented a small barn that would enable them to hold animals away from their main herd and started a different cycle of not bringing females back and forth. “We plan to make it a one-way street instead of them going around,” explains Piet. 

On March 13, they vaccinated all the animals with serum they had collected from their herd, including sows, gilts and weaners over 50 pounds. They closed the barn and plan to start farrowing on May 20. They have enough females in the herd now to take them through to the end of July and they are planning to vaccinate some gilts, then keep them in isolation for 10 weeks to use as replacement animals.

Throughout the battle with PRRS, Piet says one of toughest things to deal with was the dead pigs. It was depressing to go into the barn, treat pigs and see no positive response day after day. Now that they are getting the virus out, the pigs have better response to treatments given for other illnesses. “Thinking you were over it and finding positive results again,” he explains, makes it a difficult disease to fight. “The thing that scares me is that we still don’t know how we brought it in.”

Piet also points an accusing finger at the Canadian Agricultural Income Stabilization program (CAIS) program. “It made it tough,” he says. While his sow inventory numbers did not change through 2005, the ravages of PRRS meant that they shipped 4,500 fewer pigs to market, a decrease of 25 per cent. As a result, their gross income was also dramatically less. “The whole operation had to be carried with 25 per cent fewer pigs,” he says. 

When the people responsible for administering the CAIS program reviewed the numbers, they assumed that the Vanden Boogaards were downsizing, recalculated the gross margin and informed them that they were not eligible for a payment. They were forced to embark on the appeals process, which resulted in a lot of extra work and stress at a time when they were still battling disease in their barns.

“We were trying to deal with PRRS, then this issue came on top and we didn’t need that.  In the end, we got a payout, but it didn’t arrive until the end of 2006,” says Piet. He wonders why a program designed to provide assistance to producers who go through difficult times is structured to add even more stress and hardship.

In spite of the battle he has waged over the course of several years, Piet remains optimistic. The industry as a whole seems to have learned a lot over the past few years.  “I’m positive about the outcome in the long term for PRRS in Ontario,” he concludes. BP