Reducing Antibiotics

Decades ago when the scientific community had concerns about bacterial resistance to antibiotics, the agricultural industry started to produce antibiotic-free (ABF)flocks. Generally speaking, all chicken is antibiotic-free, because there are no antibiotic residues in the meat due to the withdrawal periods in broiler production. So in the U.S., “antibiotic-free” is not allowed to be used on a label but may be found in marketing materials not regulated by the U.S. Department of Agriculture.

In recent years, the term “raised without antibiotics” (RWA) is widely used for the flocks that are raised without the use of products classified as antibiotics for animal health maintenance, disease prevention or treatment of disease. However, it can mean different things depending on the country in which you are producing chickens. Table 1 below shows the different meaning of an RWA flock in Canada, U.S. and Europe.

In Canada, absolutely no antibiotics, ionophores, or chemical coccidiostats are allowed in RWA production, whereas in the U.S., chemical coccidiostats are allowed for RWA flocks. This poses even more challenges for Canadian RWA producers.  

There are many factors that can affect broiler flock performance ranging from nutrition and health status of breeder flocks, hatchery operations, chick quality, nutrition and water quality to flock management. To successfully grow RWA flocks, one should not only provide good management and environmental conditions as for regular broiler flocks, but should create superior conditions such as reducing stocking density, increasing downtime between crops,  acidifying litter, and providing high quality water. Nutritionally, well balanced rations formulated with high quality ingredients are crucial for RWA flocks.

Chick quality
A great flock starts with good quality chicks, and chick quality is even more important for broiler RWA production due to the lack of antibiotic protection. The feeding and management of broiler breeders can play an important part in the offspring’s health and performance. The breeder farms should follow strict biosecurity protocols, and breeders should receive a well-balanced and nutritionally adequate diet. Eggs should be handled in a professional manner and stored in ideal conditions.

Hatcheries should follow a strict biosecurity program, with regimented cleaning and disinfection procedures. Chick boxes and hatcher trays have to be washed with correct temperatures. Good maintenance of hatching temperature and ventilation equipment is critical, as it has been shown that stress from late stage over-heating may result in leg problems and performance issues. Transport can be stressful for chicks. The temperature should be tightly regulated in the compartments with proper ventilation. To ensure uniform chick quality, there should be no over-heating in some areas while dead spots exist in others.

Coccidiosis vaccination
Unlike RWA producers in the U.S., Canadian RWA producers cannot use chemicals to control coccidiosis, so the only option is vaccination. Coccidiosis control is key for successful RWA production, because it impacts intestinal integrity, gut health and is correlated to the risk of necrotic enteritis. Uniform vaccine application and uptake are essential for successful protection from a coccidiosis vaccine. The stocking density for the first seven days should be controlled at a half square foot per chick (or 465 cm2/bird), and litter moisture kept higher than normal at 30 to 35 per cent. The higher density and litter moisture will encourage oocyst sporulation and the opportunity to re-infect each other from their droppings. Thus, the immunity to coccidiosis will be developed earlier, and the flock will be better protected from coccidiosis.

Flock management
Stocking density after 10 days of age is also one of the most important factors that affect RWA flock performance. A minimum density of one square foot per bird is ideal. When the density is reduced, birds have more water line and feeder space, less competition for feed and water, better litter conditions and fewer pathogen challenges.

For RWA broiler production, the litter quality is crucial. The wetter the litter, the more likely it will promote the proliferation of pathogenic bacteria and moulds. Wet litter is also the primary cause of ammonia emissions, one of the most serious performance and environmental factors affecting broiler production today. Controlling litter moisture is the most important step in avoiding ammonia problems. There are many factors that can affect litter conditions, such as leaking water lines, various diseases, improper rations, and ventilation.

Ventilation removes combustion waste by brooders, ammonia, and moisture produced by birds while continually replenishing oxygen. Broiler genetics keep improving, and broilers grow faster every year, so their demand for oxygen is increasing all the time while their output of moisture is also increasing. Thus, producers should not use the ventilation rate of 10 years ago to grow today’s birds. Adequate and effective ventilation is critical for litter management and coccidiosis control, especially for RWA production.

Producers should check and manage watering systems to prevent leaks that would increase litter moisture. Furthermore, producers should adjust drinker height and water pressure as birds grow to avoid excessive water wastage into the litter.

Chick growth rate should be moderately controlled to avoid fast weight gain. This is particularly important in a flock that is 10 to 30 days of age, when there is more challenge from coccidiosis, thus a higher risk of necrotic enteritis. Producers should modify the lighting program, by slightly increasing dark hours to nine or even 10 hours, in order to improve the health condition and immunity of the birds. This modification is even more necessary for RWA flocks than for regular flocks.

Nutrition for RWA flocks
Sound nutrition starts with a good selection of high-quality ingredients. Composition of feed ingredients should be consistent, and all grains should be free from toxin contamination. This is critical for the first four weeks of age. Nutritionally, all ingredients should be highly digestible, since the nondigested portions might enhance unwanted microbial growth and increase the chance for necrotic enteritis. The maximum inclusion rate for some ingredients such as wheat and corn distiller grains must be closely monitored, if not eliminated. There is evidence that suggests a strong relationship between higher inclusions of these ingredients with necrotic enteritis. Some reports suggest that animal protein may increase the risk for necrotic enteritis. It is generally accepted that lower crude protein levels should be fed to RWA flocks, because higher protein may increase the chance for necrotic enteritis.  Mineral balance is vital for RWA rations. Mineral levels that are either too high or too low will not only affect broiler body weight gain and feed conversion ratio (FCR), but also impact litter quality, gut health, and hence flock performance.

With reduced growth and high-quality ingredients, the RWA feeds can cost more than the regular feeds. Together with a higher FCR  for RWA flocks, it will result in a higher feed cost per kilogram of body weight gain.

Alternative feed additives
Over the last few decades, there has been a lot of research to explore alternatives for antibiotics in broiler production. Generally, these alternatives are categorized into feed enzymes, phytogenic additives, probiotics, prebiotics and symbiotics (a probiotic and prebiotic combination). Feed enzymes which help improve the digestion and nutrient utilization, and in some cases improve gut health, are widely used by nutritionists in both regular feeds and RWA feeds.

Phytogenic additives (herbs, spices, essential oils or extracts) that originate from plants have been used in human food and medicine for thousands of years. Among these phytogenic products, essential oils have received considerable attention. Their active ingredients such as carvacrol, thymol, eugenol, alicin and cinnamaldehyde have been evaluated extensively as alternatives for antibiotics to improve animal health and performance. Some phytogenic products have direct antimicrobial effects, and other products show their effects on immune-regulation.

Probiotics are also called direct fed microbial (DFM) in the U.S. The mode of action is to compete for available receptor sites and nutrients with pathogens, and produce or secrete metabolites (such as short chain fatty acids and bacterocin), thus changing the gut microflora and bird performance.

Prebiotics are feed components that are not digested by host animals but selectively promote beneficial bacterial growth, hence improving animal performance. In this category, some commonly used products are mannan-oliglosaccharides (MOS) and fructo- oliglosaccharides (FOS).

There has been considerable research done to investigate the effects of these alternative products on animal performance and health. Yet, the responses are quite variable due to the purity and concentration of these products, how they interact with flock management and health conditions, as well as the nutritional status of the birds.

Summary
To date, there is no silver bullet as an alternative to antibiotics. In conclusion, a decent RWA flock relies on the following factors:

1. Good quality chicks that come from a healthy breeder flock and well managed hatchery;
2. A successful coccidiosis vaccination program with higher stocking density and higher litter moisture for the first 10 days;
3. Sound management practices with an emphasis on improving ventilation and reducing litter moisture;
4. An RWA ration formulated with highly digestible ingredients and optimized mineral levels;
5. Moderately reduced growth by providing more dark hours.