By Hannah Bolinger, Dr. Sophia Kathariou
& Dr. Donna Carver
Special to Poultry Times
RALEIGH, N.C. — The average American eats 15.8 pounds of turkey every year, and production has increased nearly 104 percent since 1970. Turkey meat exported from the U.S. reached nearly 800 million pounds in 2012.
With the increasing popularity of turkey worldwide comes the increasing responsibility to produce healthy birds, as well as a safe product. Due to the difficulty in eliminating pathogens in the processing environment, it is imperative that growers do their best to keep their flocks free of undesirable microorganisms.
Management practices can dramatically impact the health and performance of the birds as well as the risk for human pathogens such as salmonella and campylobacter. Salmonella and its associated disease salmonellosis are extensively recognized, but campylobacter is a much less known pathogen. However, it is responsible for one of the most frequent human foodborne diseases, campylobacteriosis.
The handling or consumption of raw or undercooked poultry is a leading risk factor for contracting campylobacteriosis. In the United States alone, campylobacter is responsible for approximately 850,000 cases of human disease annually and is likely under-reported. It is also considered the most common human foodborne pathogen in Europe.
Campylobacter lives in the intestinal tract of mammals and poultry, with poultry considered to be a leading reservoir for strains causing human foodborne illness. Campylobacter-positive birds shed large numbers of the bacteria in the feces.
Though much attention has been directed to broiler colonization with campylobacter, turkeys are also frequently colonized. Unlike broilers which are typically processed at four to six weeks of age, turkeys are markedly older (typically 14 to 21 weeks) at processing, thus allowing more time and opportunity for campylobacter colonization. Although most brooder turkeys (four to six weeks old) will already be colonized, the standard American practice of brooders being moved by truck to other locations for growout provides additional opportunities for acquisition of campylobacter, e.g. via exposure to contaminated vehicles, equipment or personnel or by enhanced susceptibility to colonization from transportation-related stresses.
Campylobacter is generally considered a harmless commensal organism to poultry. However, recent findings suggest that in fact campylobacter infection of broiler chickens results in diarrhea and poorer bird health, with inflammation and damage to the mucosal lining of the intestine being noted.
Less work has been done in turkeys, and results from chickens cannot necessarily be extrapolated to turkeys. Turkeys and broilers are naturally coprophagic (will eat feces) and utilize communal feeders and waterers; thus, once one bird is colonized the bacterium spreads readily to the rest of the flock.
Many efforts have focused on management practices and feed ingredients (e.g. competitive exclusion cultures) to keep campylobacter out of poultry flocks, but the task has proven to be quite difficult.
Previous studies with turkeys have shown that although campylobacter is frequently found to colonize turkey flocks it is by no means unavoidable, and flocks grown under different management conditions can vary markedly in campylobacter levels.
In this article our objective was to identify which poultry management practices have been shown in the scientific literature to reduce food safety risks pre-harvest, and which are actually implemented in the turkey industry.
We sent surveys regarding farm layout and operations to 27 commercial turkey farms (14 brooder and 13 growout farms) in the United States and fisher’s exact test was used to determine whether a practice was significantly different between farm types.
Perhaps the most critical variables in raising campylobacter-free birds are the actions of the growers themselves and the employees they hire.
Greater numbers of employees working on a turkey farm may constitute a risk factor for campylobacter, as already shown for salmonella. This may be partially due to the difficulty in guaranteeing that employees follow adequate biosecurity procedures.
In our study, we found that 71 percent of brooder and 23 percent of growout farms employed workers from outside the farm. Brooder farms are generally more labor-intensive which may explain this practice.
As with salmonella, increased biosecurity may help with the control of campylobacter. Key to biosecurity is the use of separate boots or fresh overboots for each poultry house. The rationale is that changing boots will reduce the likelihood that the bacteria will be tracked into subsequent poultry houses.
Campylobacter found on boots is often genetically identical to that found in the birds’ feces. Indeed, birds are at higher risk for campylobacter if adjacent houses are already positive.
Although footbaths can help disinfect the bottoms of boots, it is difficult to guarantee sufficient contact time between the boots and sanitizer, or that the sanitizer concentration is appropriate. So, having a set of boots designated for each house and regularly disinfected may be a better strategy.
In our study, almost all farms (100 percent and 92 percent of brooder and growout farms, respectively) reported that rubber boots were required at the start of each work day (Fig. 1).
Relatively few farms required the boots to be changed between houses but all farms required the use of a footbath when moving between turkey houses.
We also asked whether farms require coveralls to be worn on the farm and how often these need to be cleaned. Separate clothing for each house was shown to have a protective effect against campylobacter in broiler production.
Approximately 71 percent of the 14 brooder and 54 percent of the 13 growout farms required coveralls. Of farms that required coveralls, 20 percent of brooders required them to be changed between turkey houses; none of the growout farms reported such a requirement.
Also, of farms requiring coveralls 90 percent of brooders and 57 percent of growouts required that the coveralls be washed daily. Most (86 percent) brooder farms provided coveralls (either reusable or disposable) to their employees, while this practice was less common (31 percent) among growouts. Provision and requirement of coveralls may promote their use.
Washing hands between poultry houses is another variable that has been shown to have a protective effect against campylobacter colonization of the birds. We asked whether farms required the use of hand sanitizer or gloves. We found that 50 percent of the 14 brooders and 38 percent of the 13 growouts were required to wear gloves, while 57 percent of brooders and 15 percent of growouts were required to use hand sanitizer at the beginning of every work day (Fig. 1).
Of the eight brooders that required hand sanitizer, six (75 percent) required its use when moving between houses. One farm that did not require its use at the beginning of the day did require it when moving between houses.
Few farms (two of seven brooders and one of five growout farms) that required gloves required them to be changed when moving between houses. Some farms indicated a requirement for hand sanitizer but not gloves, or vice versa.
Campylobacter colonizes the intestinal tracts of many animals, and the presence of other animals on the farm has been identified as a risk factor for the spread of campylobacter.
Pigs, cattle, sheep, and other poultry have all been identified as risk factors for campylobacter colonization of commercial broiler flocks.
Our study showed that no brooder farms kept pigs, cattle, or other poultry. However, among the growouts an estimated 23 percent of the farms also raised pigs while 38 percent had cattle on the same farm.
Besides livestock, insects and other pests (e.g. rodents) can harbor campylobacter as well as salmonella. All surveyed brooder and growout farms stated that they had rodent control programs in place. Measures taken outside of the turkey houses to deter pests included keeping grass trimmed, creating a gravel buffer or concrete pads around the turkey houses and using rodent bait and traps (Fig. 2).
All farms used bait and almost all reported that they kept the grass trimmed. Gravel buffers were used in 36 percent of brooders and 15 percent of growouts, while 57 percent of brooders and 8 percent of growouts had concrete pads around the turkey houses. This means that all but one brooder had a physical barrier around the houses, while less than 25 percent of growouts did. About half of the farms (57 percent and 54 percent of brooder and growouts, respectively) used rodent traps outside the turkey houses (Fig. 2).
Insect controls were addressed in the surveys, and Figure 3 shows the results of the survey questions asking whether growers used sticky tape or traps, bait, surface sprays, litter treatments, or fogs or mists for fly control.
Most farms reported using sticky tape or traps, bait, surface sprays, and litter treatments while fogs or mists were the least popular fly control measure (Fig. 3).
However, if used properly, sprays, fogs, or mists can be highly effective for controlling an existing high population of flies. Additionally, surface sprays may be ineffective as they often get coated in dust and flies have built up resistance. Fly-speck cards can be used to monitor the fly population in poultry houses and assess the need for corrective action.
The role of flies in campylobacter transmission into poultry flocks may partially explain the seasonal spike in campylobacter colonization of flocks during the warmer months since this is when flies are more prevalent.
Studies in Denmark showed that installation of fly screens was accompanied by reductions of campylobacter-positive flocks from 51 percent to 15 percent).
Poultry manure is an excellent breeding ground for insects such as flies and darkling beetles so keeping the litter in the houses dry and well-aerated is recommended to make it less suitable for flies. Additionally, manure piles outside of the houses can be treated or covered with tarps to prevent fly reproduction.
Litter management findings are shown below in Figures 4 and 5. The majority of farms (86 percent of brooders and 85 percent of growouts) reported that used litter was immediately removed at the end of each flock cycle.
Almost half of brooders reported that litter from their farms was used to top-dress growout farms, which may not be ideal as campylobacter can survive in litter. Some growouts report using litter from their houses as fertilizer on their own land or within half a mile of their farm.
Pathogens may be able to survive in litter, which therefore should be properly composted before land applications.
Our survey identified certain practices in the industry that can be improved upon to enhance the likelihood of producing campylobacter-free flocks.
It appears that a number of the important biosecurity behaviors used on brooder farms are no longer practiced at growout. Thus, even if brooders are campylobacter-free, they can become colonized with campylobacter during growout. If birds are going to remain campylobacter-free continued vigilance is needed all the way through the growing chain and into the processing plant.
Designating separate boots or using new plastic over-boots for each poultry house as well as changing clothes between poultry houses may be a useful practice on all farms. Additionally, some sort of hand hygiene should be used when going from one turkey house to another. Fly populations should be monitored with the use of “fly speck” cards (really just 3×5 index cards) in a quantitative way as described here:
“Once placed, cards should be left for a period of 7 days and replaced with new cards at the same place each week. The number of “fly specks” on the exposed side (one side) of each card should be counted and recorded in a record keeping notebook. Generally, 100 or more spots per card indicates the need for fly control measures.” (Williams, Control of Poultry Pests).
Some of the recommended actions, such as changing boots and regular laundering of clothes used on the farm will require more time and effort. Smarter strategies need to be used against flies and other insect vectors such as darkling beetles.
As of May 11, 2016, the USDA Food Safety & Inspection Service (FSIS) began assessing if food producers are meeting the recently approved performance standards to reduce salmonella and campylobacter in ground chicken and turkey, as well as chicken parts.
Improved management practices and continuing vigilance will contribute to helping American turkey producers meet these standards and produce products that fall within the performance standard guidelines.
Hannah Bolinger is a research assistant and Dr. Sophia Kathariou is a food science and microbiology professor, both with the Department of Food, Bioprocessing and Nutrition Sciences; and Dr. Donna Carver is a professor and Extension veterinarian with the Prestage Department of Poultry Science, all with North Carolina State University in Raleigh, N.C.