What quadrant are you in?
Veterinarians present a visual guide to managing coccidiosis and plotting your success.
You’ve been successfully using
ionophores to control coccidiosis,
but lately performance in
your broilers just doesn’t seem as good
as it used to be. You want to try switching
to a new program, but can’t decide
whether to try a chemical-to-ionophore
shuttle or a few rounds of coccidiosis
How will you know what to expect with different programs? And how can you get the best coccidiosis control as well as optimum growth in birds? A new concept known as the Quadrants of Performance may be just what you need to understand and help predict the impact of various anticoccidial strategies on broiler performance.
“The Quadrants of Performance concept is a visual tool demonstrating the effects of anticoccidial control programs and a pathway for achieving improved outcome and cost effectiveness,” says Dr. Charlie Broussard, director of global technical services for the Schering-Plough Animal Health Corporation’s Poultry Business Unit.
Developed by coccidiosis specialists at Schering-Plough Animal Health, the concept is based on published and non-published work on oocyst cycling in chickens, as well as the company’s extensive worldwide experience managing coccidiosis, the costly protozoan disease that threatens commercial poultry operations worldwide, he says.
The Quadrants of Performance concept starts with a basic graph that plots two major thresholds (Figure 1):
- Level of infection, illustrated by a horizontal line
- Age of infection, illustrated by a vertical line
“The basic graph is then used to illustrate the process of various anticoccidial programs,” Broussard says. “We have plotted real-world experience and feel confident that the Quadrants provide a good approximation of what to expect with each type of anticoccidial program. It takes a lot of guesswork out of anticoccidial control.”
The Quadrants of Performance concept is based on the premise that, at some point during coccidial exposure, there is an age threshold that affects performance markers such as feed conversion, weight gain, caloric conversion, thriftiness and mortality.
During Quadrant 1, for example, when growth is slower, the impact of coccidial exposure is minimal. “Quadrant 1 is a time of early, slower growth with coccidial challenge that is below the horizontal threshold, so the impact on performance is minimal,” Broussard says.
“A coccidial challenge in Quadrants
2 or 4 is quite another matter,” he says,
“because these are times of rapid
growth and a coccidial challenge can
seriously impair the growth rate.”
The worst-case scenario is a coccidial challenge during Quadrant 4, when the growth curve is strong. “You’re to the right of the vertical threshold and above the horizontal threshold,” Broussard says.
Not just a ‘pass/fail’ grade
Poultry veterinarian Dr. Linnea
Newman, a consultant for Schering-
Plough Animal Health, says the
Quadrants concept encourages poultry
integrators to examine how their current
coccidiosis control program interacts
with the broiler growth curve.
“As things are now, the industry thinks of coccidiosis control in terms of a simple pass/fail grade. Each week, feed conversion is assessed and a conclusion is made about whether the program is either working or not. This approach can lead to knee-jerk program changes when performance slips,” she says.
The Quadrants concept goes beyond the simple “pass/fail” system. It considers when coccidiosis control has an effect on the growth curve. “You can have an overall passing grade on total coccidiosis control but could actually be leaving dollars on the table because your passing grade is really only a C+,” she says.
In addition, the Quadrants concept encourages integrators to look at how performance in today’s flock affects subsequent flocks and to aim for a solid grade “A” performance, Newman says.
As an example, Broussard cites experience
with ionophores, which rely on
oocyst “leakage” to stimulate the chicken’s
immune system against coccidial
challenge. In situations where there is a
high coccidial challenge as determined
by the oocyst litter count and intestinal
lesions, the peak challenge shifts with
time to Quadrant 2, the same time
when the growth curve and opportunity
for maximal meat production is
increasing. (See Figure 2.)
Continued use of ionophores can result in the selection of ionophore-tolerant coccidial strains, which make the anticoccidial program less effective. “Increased oocyst leakage can compromise the next flock through heavy carry-over of sporulated oocysts. Ionophore-tolerant coccidia strains may become hard to control, resulting in poor feed conversion and weight gain and increased production costs,” he says.
Ionophores on farms with a low coccidial challenge result in slow development of coccidial immunity, Broussard says. Initially, results may be satisfactory if the coccidial challenge remains low but, with time, the peak challenge shifts to Quadrants 2, 3 and 4, resulting in ionophore-tolerant coccidial strains and a less effective anticoccidial program.
“Continuous oocyst leakage can slowly increase the number of oocysts carried over to future flocks, and it’s not uncommon in these situations to see performance slowly deteriorate. You may not even realize it’s happening but, eventually, production costs start creeping up as the peak oocyst challenge shifts to Quadrants 2, 3 and 4,” he says.
Newman agrees and says, “High oocyst numbers at the end of one flock means that the next flock will have a bigger coccidiosis challenge and more resistant oocysts challenging the next coccidiosis control program.
“If I have 10% resistant oocysts, and I carry over 100 oocysts, it means that I have a grand total of 10 resistant oocysts in my house. If I have the same 10% resistant oocysts and I carry over 100,000 oocysts per gram of litter to the next flock, I have 10,000 resistant oocysts per gram of litter. That’s a big challenge to the next program and contributes to program failures.”
Chemical and ionophore programs
The course of events is similar with
Broussard says. When anticoccidial
chemicals are used in the starter feed,
oocyst shedding is pushed to Quadrant
2, that critical growth period.
Ionophore leakage may allow the number
of chemical-resistant coccidia to
grow. High numbers of residual
oocysts challenge the efficacy of the
ionophore starter in the next rotation.
With chemical-to-chemical programs, the situation changes somewhat. Initially, chemical anticoccidials appear to be very effective. They shut down oocyst shedding in the house and reduce peak coccidial challenge to very low levels during Quadrant 1. But drug resistance can build up fast and shift the peak oocyst challenge to Quadrant 3, due to a quick selection of strains that are resistant to chemical anticoccidials.
“Initially, we see dramatic improvement in performance after switching from straight ionophore programs to a chemical-to-chemical program,” Broussard says. “But then drug resistance appears after one or two growouts, and clinical coccidiosis results. Flock performance is compromised and production costs rise.”
“We have learned that if you’re in Quadrant 2, 3 or 4, performance may be suffering either slightly or severely, and changes need to be made,” he says.
Experience in the field with coccidiosis
vaccines such as Paracox-5, which initiates
life-long immunity against coccidiosis
in chickens, has shown that
vaccination results in an early, mild
predictable pattern of reaction in
Quadrant 1, before the fastest growth
spurt kicks in, Broussard says. (See
Coccidiosis vaccination can be used exclusively for coccidiosis control or integrated into other anticoccidial programs. Research shows that Paracox vaccines seed houses with drug-sensitive oocysts, increasing coccidial sensitivity to ionophores and chemical anticoccidials, he says.
“Either way, vaccination can help producers raise flocks that have the ability to realize their full genetic potential, as shown in the Quadrants of Performance,” Broussard says.
Performance in vaccinated birds can be
improved, Broussard continues, with
management and nutrition. Toward this
end, Schering-Plough Animal Health
has developed the IDEA concept, a
novel nutritional plan for vaccinated
birds. It promotes good nutrition early
in life when the digestive and immune
systems are developed and coccidial
challenge is low. The result, he says, is
healthy gut development in birds that
depend on immunity rather than drugs.
“Resistance to intestinal disease is better and so is performance for the rest of the bird’s life,” Broussard says. When coccidial replication in vaccinated birds reaches it peak, the IDEA concept encourages the use of a highly digestible diet to further maximize intestinal integrity.
“Improved digestibility reduces damage to the enterocytes and reduces the availability of nutrients for bacterial growth,” he says.
With intestinal immunity established, vaccinated birds can express their maximum potential for growth and feed efficiency. IDEA is also economical because it enables feed cost savings, Broussard adds.
Says Newman: “The best overall control
program induces early immunity
that creates low oocyst numbers at the
end of the flock and minimal carryover
to the next flock. Low oocyst numbers
means less total challenge on new
chicks in the next flock and less potential
for developing a significant population
of resistant oocysts for future
Early immunity, Newman notes, also creates in-house “down time” — no coccidiosis activity, just as though the house was empty — from 25 days of age on. “It’s like getting an extra free week or two of layout time in terms of coccidiosis control,” she says.
Broussard says, “As the saying goes, ‘knowledge is power’, and the Quadrants of Performance concept gives us more knowledge. It provides a thorough understanding of each anticoccidial rotational cycle and its impact on subsequent rotational cycles, making it an innovative and valuable tool that can help poultry integrators assemble highly effective annual anticoccidial control programs with the few remaining approved products left on the market today.”
Understanding the Charts
Source: CocciForum Issue No.11, Schering-Plough Animal Health.