Consumer perception is a driving force behind many production decisions made in the poultry industry, and increased general concerns about the potential transfer of antimicrobial resistance from poultry to humans has led to many countries reducing or eliminating the use of antibiotics.
Following best-practice advice with an emphasis on meticulous bird management and attention to detail, such as that found in the Parent Stock Management Handbook, is the foundation of a successful minimal antibiotic (AB) production programme, and allows good-quality broiler chicks that have as little microbial challenge as possible to be delivered to the farm. Although reducing or eliminating antibiotic use is the goal, Aviagen fully supports the rights of a licensed veterinarian to treat a sick animal or flock with an approved antibiotic to control disease and prevent pain and suffering.
Good stockmanship and the role of the stockman in maintaining bird health and welfare become even more important in minimal AB production. Stockmen must pay attention to detail and be able to interpret and apply best-practice recommendations in combination with their own professional competence, practical knowledge and skills to identify and respond quickly to the birds’ needs. Early identification and resolution of potential issues are essential to correctly manage a minimal AB flock.
Taking specific precautions regarding hygiene and microbial testing and monitoring will ensure optimum biosecurity. As a general rule, individual sites should be managed on the principle of “all-in, all-out.” Following this principle will make vaccination and cleaning programmes easier and more effective, with consequent benefits in bird health and performance.
Although thorough cleaning and disinfection of the house is a best practice for all poultry, special care should be taken with houses that will be used to grow minimal AB parent stock. Particular attention should be paid to the floor of the house, using hot water to remove any grease (Figure 1). Houses with earth floors are not recommended for minimal AB production. After cleaning and disinfection, it is good practice to check for Total Viable Count (TVC), Salmonella and E.coli to test the efficacy of the process. Recommended levels of TVC should be less than 10 colony forming units per centimetres squared (cfu/cm2), and E.coli and Salmonella levels should be undetectable.
The areas surrounding the house should be able to be easily cleaned and should be free from vegetation for an area of 15 m (50 ft) around the farm perimeter and 1 m (3 ft) between houses (Figure 1). Removing debris and equipment and eliminating rodent nesting sites and food sources from around the house perimeter will reduce the risk of exposing the flock to harmful bacteria.
Feed and water systems can harbour bacteria and biofilms that can impact bird health. The feeding system, including the feed bins, track, chain and hanging feeders, as well as bulk bins, connecting pipes, seals and openings, should be thoroughly cleaned and disinfected. Water systems should be cleaned with products that remove biofilms and checked for TVC, E.coli, enterobacteriaceae, mold and yeast levels using swab and water samples. The recommended level for TVC in the water system is <10 colony forming units per millilitre (cfu ml) and e.coli, enterobacteriaceae, mold and yeast levels should be undetectable. chlorinating the water and controlling water ph will help control bacterial growth.>
Only litter material that has been tested or is certified to have a TVC of less than 10 colony forming units per gramme (cfu/g) should be used for minimal AB housing.
Optimum chick growth during the first 10 days of life is fundamental to the development of the gastrointestinal tract (GIT) and chick health. Appetite development can be monitored by crop fill. The percentage of chicks with full crops should be 100% by 24 hours. Ensuring chicks develop their appetite and reach 7-day body-weight targets will better prepare chicks for the challenge of coccidiosis in areas that do not allow coccidiostats in the feed. Doing so will also help chicks cope with coccidial vaccination.
As birds age, feeding and drinking space, light intensity and environmental conditions must be kept to the recommended specifications. Unnecessary pressure on the bird, such as inadequate drinker and feeder space, can cause potential intestinal challenges, which can be more difficult to correct in minimal AB production systems. Always take special care when a procedure such as vaccination, or others that involve bird handling, are performed to ensure the challenge to the bird is minimised.
Introducing slats and perches at an early age will help to decrease floor eggs during production and help males find the drinkers after transfer. Floor eggs are potentially contaminated with harmful bacteria that can find their way into the hatchery. Delivering only clean eggs to the hatchery reduces contamination and helps prevent poor-quality chicks that could require antibiotic treatment.
When birds are transferred from the rear to the lay facility, conditions between the two must be kept as similar as possible. Changes in housing environment, such as temperature, feeding systems, drinking systems and lighting schedules, may cause issues that could lead to decreased gut health. If gut health is compromised, minimal AB production becomes more difficult, because treatment of illnesses may be needed. Good biosecurity and assessing crop fill (on the day of transfer, 30 minutes after the first feeding and after 24 hours) will help maintain bird health.
Dirty eggs are a source of contamination to the hatchery. To reduce the numbers of dirty eggs, consider the following:
• To prevent floor eggs, walk the house several times per day between Point Of Lay (POL) and 32 weeks of age.
• Collect eggs from manual nests at least four times per day.
• Run automatic egg belts at least three times per day, and monitor flock production to ensure the last belt run is done after the last eggs have been laid.
• Collect floor eggs separately and more often than nest eggs. Keep floor and nest eggs separate, and wash hands to prevent cross contamination.
• Do not leave eggs in the nests overnight.
On top of that it is essential to keep the nest boxes clean by removing dirty nesting material and faeces daily, clean and change automatic nest box pads periodically and clean and sanitise egg collection belts at least once per week. On top of that cleaning and sanitising packing and grading equipment needs to be done daily and it is helpful to monitor reports from the hatchery on contaminated eggs and rots, reviewing farm hygiene, and egg storage and transfer procedures and adjusting the cleaning schedule as needed.
There is no substitute for clean eggs to produce healthy chicks (Figure 2), and this truth is even more relevant for eggs produced from minimal AB flocks. Dirty eggs or eggs that have been washed present a higher risk of internal contamination of the egg, and should not be used unless absolutely necessary.
Due to the increased possibility of Salmonella contamination and necrotic enteritis when including animal by-products in diets, plant-based diets are recommended in flocks grown with minimal AB use. The addition of grains with higher levels of non-starch polysaccharides (such as wheat and rye) can also affect the balance of gut microflora that causes intestinal disruption. Changes in the gut environment, either due to bacteria or feed ingredients, can cause an increase in viscosity in the mucus layer of the intestines, providing favourable conditions for the growth of Clostridium perfringens, which can lead to an outbreak of necrotic enteritis, requiring antibiotic use.
Best practice management
It is essential that minimal AB parent stock flocks are of good health status, and appropriate vaccination and biosecurity programmes must be in place. Parent stock should be free from vertically transmitted diseases such as Mycoplasma and Salmonella, and should be protected against other vertically transmitted diseases, such as Chicken Anemia Virus (CAV) and Avian Encephalomyelitis (AE). The vaccination programme should also protect against locally relevant diseases that are not vertically transmitted. Parent flock vaccination will also help provide maternal antibodies that help prevent infection from the broiler farm environment in chicks at an early age (e.g. inactivated Gumboro disease). The exact vaccination programme will vary, taking into account the background disease challenge of the parent stock farms and the broiler farms on which the progeny will be placed.