Cocci Home Page

Download
PDF version

Other articles
in this issue

Vaccine Cycling Reduce In-Feed Medication Free bird Necrotic enteritis outbreaks Value of vaccination Rising To The Top Chopping Block Cocci News

Don't Mess With Vaccine Cycling

Georgia producer learns a hard but valuable lesson about managing coccidiosis effectively in broiler breeders

For decades, poultry producers have used Coccivac-D live coccidiosis vaccine to manage coccidiosis in broiler breeders.

Sometimes, however, old practices that used to work well - such as medicating vaccinated pullet flocks with amprolium to "take the edge off" the vaccine's reaction - can lead to unexpected problems. And that can be especially true if amprolium is inappropriately paired with modern-day management and vaccination techniques for breeders.

As Chad Mason and his colleagues at Columbia Farms, Lavonia, Georgia, found out recently, such problems can be costly.

Luckily, there's a happy ending to Columbia Farms' story, though - one that's allowing the northeastern Georgia operation to improve costs and save a substantial amount of money per flock.

Breaking old habits

Mason: ‘As fine a flock of chickens as this grower has ever had’

Columbia Farms is a medium-sized diversified poultry operation that processes about 860,000 broilers each week. They place about 375,000 pullets annually and keep about 270,000 hens in the field. Mason, a Clemson graduate and a 15-year poultry industry veteran, is breeder and hatchery manager at Columbia Farms.

Problems at Columbia Farms began about 3.5 years ago and eventually spread to four of the company's seven pullet farms. Columbia Farms was growing Ross 708s, which they received from their primary breeder pre-vaccinated with Coccivac-D, a live vaccine formulated to accommodate the longer life span of broiler breeders and layers. Coccivac-D is administered to day-old chicks in the hatchery with a specially designed spray cabinet.

Following a time-honored practice, Columbia Farms had been administering amprolium, diluted 10 ounces per gallon of water, on days 11 and 12. The amprolium treatment was intended to head off any problems that might appear.

Battling blackhead and tenella

"We began to have difficulties with blackhead (histomoniasis) and Eimeria tenella [a leading cause of coccidiosis]." says Mason. "I'm not sure if it was the blackhead causing the E. tenella or the E. tenella causing the blackhead, but we were definitely having problems."

He was seeing livability percentages - normally in the mid-to-high 90% range - slip downward. Uniformity of his birds was also suffering, plunging to 50% to 60%.

Mason explains that when E. tenella and blackhead are ravishing a flock, they do more than kill birds. They also disrupt the growth and maturation of the birds that survive.

"That means that some of the breeders are late coming into production and some are early," he says. "And you can't fix that."

In other words, continuing to feed helps the smaller birds grow faster but keeps the larger birds growing faster, too. "When the larger birds come into production that fast, you can't maintain them because you're not feeding them enough," he explains. "Then the smaller birds come in late, so your overall peak isn't going to be nearly as high as it should be. The bottom line is you're losing money."

Struggling to gain a footing, Mason doubled the dose of amprolium to 20 ounces/gallon. But that only made things worse. Livability fell to 91.53% in one of the farms - a new low - and uniformity dropped to 40%-50%. Mason knew he needed to take action quickly.

Disruption in vaccine cycling

Alfonso: ‘Amprolium is no longer necessary’

Mason contacted the technical services group of Schering-Plough Animal Health, makers of Coccivac-D, to discuss the problem. He thought that perhaps the problems might somehow be related to the vaccine. It didn't take long for Schering-Plough's veterinarians to identify the problem.

"One of the problems Columbia Farms was having - one that we've seen pretty often at other operations - had to do with inappropriately timed use of anticoccidials, which can disrupt the natural cycling of vaccinal oocysts in vaccinated birds," says Dr. Matilde Alfonso, one of the Schering-Plough veterinarians involved with the discussions.

Alfonso explains that when coccidiosis vaccines were first used back in the 1950s and 60s, they were administered in the drinking water and so application of the vaccine wasn't always completely uniform. That sometimes led to reactions in vaccinated flocks, and amprolium was routinely administered prophylactically to deal with such reactions.

"Since then, though, techniques for administering the coccidiosis vaccine have improved a lot," she says. While the vaccine can still be added to feed, most operations now opt for a newer application method - using the specially designed SprayCox spray cabinet to administer the vaccine to dayold birds as they move through the hatchery.

The cabinet showers the birds with live coccidial oocysts, which stimulate the bird's immune system to build lifetime protection against coccidiosis. A red dye in the vaccine helps hatchery workers monitor vaccine coverage but it also encourages preening among chicks - a process that helps to spread the vaccinal oocysts to all birds.

Latest in vaccine administration

Mason: ‘We know what they’re getting from day 1.’

The latest method of vaccine administration involves a further refinement in the SprayCox cabinet. The SprayCox II is now fitted with 2 nozzles, which have been positioned to deliver uniform vaccine coverage without any wasted over-spray. A new AirMix system also provides improved suspension of vaccinal oocysts in the sprayer, and that, too, helps ensure better coverage. "The result of those refinements in vaccine coverage is that routine follow Alfonso: 'Amprolium is no longer necessary'up of vaccination with amprolium is no longer necessary," Alfonso says. "In fact, it can be detrimental to the whole vaccine strategy."

When Coccivac-D is administered to chicks via the spray cabinet, it delivers a uniform and carefully balanced dose of oocysts from the eight species of Eimeria that are known to cause coccidiosis in chickens. Within days of the vaccine's administration, a new generation of oocysts develops in the vaccinated birds and those oocysts are then excreted into the litter, allowing reexposure of the birds to the Eimeria oocysts. This helps trigger natural, long-lasting immunity to coccidiosis. The process usually takes about 2 to 5 cycles of re-ingested oocysts for birds to develop full immunity to all Eimeria species in the vaccine.

When an anticoccidial such as amprolium is routinely added to this finely tuned process - especially added too early or in high dosage - it kills the vaccine-supplied oocysts and thus disrupts their natural cycling. The results can be devastating, such as was the case at Columbia Farms.

Says Mason, "Looking back on it, I think we were knocking down the oocysts that were cycling from the vaccine, and that just threw everything out of whack. We were having blackhead problems at 5 weeks. And on top of the blackhead, we were having outbreaks of E. tenella."

Mason is reluctant to put an exact dollar figure on what the coccidiosis and blackhead episodes were costing him. He says the losses were substantial. But, as mentioned earlier, this story has a happy ending.

First, Mason began a dialogue with Schering-Plough's worldwide technical service director, Charlie Broussard and, working along with Alfonso and other tech service consultants from the company, Mason put a new plan into motion.

Check birds before giving amprolium

To start off, Mason pulled amprolium from the water on days 11 and 12, but continued with his vaccination program. He then monitored his birds closely.

"We suggested he go out to his houses on the 16th or 17th day and take a close look at the birds," Alfonso says. "Look at their overall appearance, look at their droppings, review their mortality figures, and, if he felt the need, do some postings."

Mason followed that advice. Once the vaccine was the only coccidiosis control strategy on board, "that's when we started seeing what we were supposed to be seeing. We saw a little irritation in the gut, that sort of thing, and that showed us that the vaccine was helping the birds develop immunity just as it's supposed to do," Mason says.

There were other more tangible indications that the vaccine was working. Livability figures began edging back up into the mid-to-high 90s - and have stayed there. "We have improved, from down near 91% in some of the barns with the biggest problems, up to better than 97% in some cases," Mason reports.

Other results were equally dramatic. "We saved a lot of money on not having to buy the amprolium," he says. "It was costing us about $400 for each flock." They have also cut down on antibiotics used to control secondary infections.

Gains in uniformity, egg production

Uniformity has also improved significantly, he says, up 15% to 20% over the past 6 months.

Egg production has also increased. "The latest flock we have, from one of our problem farms, is doing real well," Mason says. "The way things are right now, it's as fine a flock of chickens as this grower has ever had."

Accounting for all production costs, Mason says Columbia Farms has improved cost greatly since the changes were made.

But he is quick to point out that besides pulling the amprolium, some other adjustments were made in the program.

"One of the farms we'd had trouble in was cold-house brooding their birds (not using air heaters)," he says. "In other words, we had brooders only. We were running about 700 birds per brooder, which is too many. When you've packed them in one spot like that, what happens? They're going to peck more in that one spot and that's where the oocysts are. So we fixed that." Mason says they have now cut back density to 400 to 500 birds per brooder and it has made a noticeable difference in production. "Proper brooding is critical," he adds.

Mason also says he now releases the birds to full house before 14 days of age, and that he feels that helps achieve uniform oocysts shedding on the litter.

He says he also makes sure heat and moisture conditions in the barns and in the litter remain within healthy limits. "Before, we were cleaning out after every flock," Mason explains. "Now we're cleaning out once a year, which was the recommendation from the vaccine people."

Another step Mason's taking to keep his program on track: Make sure birds have adequate feed available and are not pecking in the litter and ingesting extra oocysts. "A lot of people in the industry feed a full feed the first 2 weeks and then the third week they go to poundage," referring to a specified volume of feed, measured in pounds of feed per 100 birds.

Mason says he found that when he used that approach he couldn't maintain consistent feed volume from farmto- farm. The first couple of weeks some of the farms would be feeding more than others. And when, on the third week, they went to the specified amount of feed per 100 birds, some of the birds would, in effect, be having food taken away from them.

Maintaining adequate feed

"So now we know what they're getting from day 1. The first week we feed them 3.5 pounds (1.59 kg) of feed per 100 chickens. The second week we're feeding them 5.5 pounds (2.49 kg). The third week it's 6.4 pounds (2.90 kg)," he says.

On that third week he goes to a skip-a-day feeding program - double the daily amount, then skipping feed the next day. So the birds are getting 13 pounds (5.90 kg) per 100 birds on even days, nothing on the odd days.

"It gives the birds more feeder space, reduces competition, and keeps them eating at the feeders instead of pecking in the litter," he says. Again, the aim is to limit the birds' excessive ingestion of oocysts.

Still another ration-related matter Mason has changed is that he is paying more attention to feed texture.

"We try to make sure we do nothing at all to irritate that bird's gut," Mason says. "Can I say we're successful all the time? No. It's not a perfect world. We do sometimes have milling issues that come up. But the majority of the time, the mill does an excellent job of getting our feed the way we want it."

Not just one fix

Mason: ‘Many issues that affect the livability of birds’

Summing up, Mason says it is clear that what happened at Columbia Farms was a complex situation that required action on a number of fronts. He kept Coccivac-D as a key part of his management program, while fixing the problems that were causing poor performance.

"I can't say that pulling the amprolium fixed the whole problem," he says. "You know, there are so many issues that affect the livability of birds and affect their uniformity - from feed texture, to litter conditions, to heat, to bird densities. But we've seen very good improvements over the past 6 months or so and I think it's a combination of everything."

For Mason, the experiences of the past couple of years underscore the importance of individualizing his approach to each flock of birds. "You've got to look at each one on its own. They're all unique, a little bit different." Mason does emphasize that he hasn't completely pulled amprolium from his barns. He just doesn't use it routinely, during early vaccine cycling. "There's definitely a place for it, but now when we need it we use it on individual flocks, at low doses, and we use it late. That way, we don't interfere with the vaccine," he adds.

Dr. Alfonso agrees with him and emphasizes that every breeder/grower should expect consistent results from Coccivac-D coccidiosis vaccine. If that's not happening, she says, Schering- Plough's technical service team is standing by to help identify problems that might be affecting the flock - and to provide solutions.

In the meantime, Mason's quest for perfection continues. "We're a work in progress," he says. "We might stub our toe next week, but it won't be because we stopped trying."