Recent years have seen an explosion in the availability of “free-from” foods for consumers increasingly concerned about the traceability and healthiness of food. After pioneering in the area cage-free eggs the industry now needs to rise to the challenge again as antibiotic free chicken looks set to become a staple of supermarkets and restaurants.
As well as consumer demand, governments are keen for the poultry industry to reduce antibiotic use – particularly when the antibiotics are important for human healthcare too. The US FDA already has a strategy in place to reduce the use of antibiotic growth promoters (AGPs) in poultry production. Likewise, the EU restricted the use AGPs over a decade ago but with limited success at reducing the total quantity of antibiotics used in poultry production. Studies show that there has been increased use of therapeutic antibiotics in some countries since the ban.
To date, there are no universal standards for antibiotic free production but many poultry supply chains have their own protocols in place. These range from not using antibiotics important to human health to no antibiotics at all for the broiler or the parent bird. Although the specific criteria for antibiotic-free chicken are not set, the direction of travel is clear so poultry producers need to prepare for a system which uses fewer antibiotics, especially AGPs, according to Dr Kurt Richardson of Anitox.
“Shifting to antibiotic free production is going to be a challenge but I think we already have most of the tools we need to do it successfully,” he says. “But we need to change the way we think about rearing birds. There is no like-for-like replacement for AGPs, instead we have to look at what they do and achieve the same result in different ways. In essence, AGPs are tools to manage gut health – they prevent colonisation by pathogenic bacteria and modify the intestinal microflora ecosystem in a beneficial way.”
Colonisation of the intestinal tract by pathogens can reduce feed conversion rates and bird health in general, critically any infection can quickly spread within the flock. Pathogens rapidly multiply inside the gut in infected birds and are shed in the faeces in high numbers. This serves as a vector to spread the disease to the entire flock, thus infection of one begets infection of all. Using AGPs prevents colonisation of the gut in this way by eliminating pathogenic bacteria, AGPs also make the gut more hostile to infection by modulating the mucosal immune system. For example, Clostridia thrives in the mucus produced as a result of inflammation so controlling mucus production makes a large contribution to controlling infection.
Considering beneficial bacteria, AGPs tend to target gram-negative bacteria as these are typically pathogenic. This allows gram-positive bacteria including beneficials like lactobacillus to take advantage and fully colonise the gut. Lactobacillus and similar bacteria increase synthesis of a wide range of beneficial metabolites which extends the microvilli in the intestine improving the uptake of nutrition from feed. The benefit shows in the feed conversion and faster development rates in the flock. “Looking at what AGPs have given us, we can see there are two things we need to do to maintain current productivity in an antibiotic free system: Prevent infection and enhance gut microflora.”
“To prevent infection, you need to consider all the different ways that pathogens can be brought into the chicken house,” says Dr Richardson. “Water, feed, rodents, wild birds, insects, personnel, farm equipment and the young chicks themselves are all potential vectors so biosecurity has to be improved all around. Without AGPs there is no final line of defence so pathogens have to be stopped before they get into the bird.”
Birds consume 1.6-2 times more water per day than feed a day so if the water is contaminated, the flock will suffer from gut health problems and poor performance. The recommended maximum level of bacteria in drinking water target is 100cfu/litre. Big strides have been made in the industry in recent decades with the introduction of nipple waterers to replace trays or troughs where bacteria could proliferate. The main danger in modern systems is in the plastic pipework, harmful biofilms can build up, which act as nucleus for infection to be spread by water.
“Poultry farmers should look to effective water sanitisers to keep biofilms in check. To maximise biosecurity, do a full clean of pipework and drinking equipment between flocks and check the hygiene of the original water sources if you are not drawing off the mains supply.
“Compared to water, biosecurity with feed is a bit more complicated, for starters there is no agreed benchmark for a safe level of bacteria in feed although Anitox has years of data showing fewer bacteria results in better performance across the board. But like in-coming chicks, feed must be considered as a critical control point in any well designed, comprehensive biosecurity programme, i.e. feed is delivered to every farm multiple times throughout the grow-out cycle, and is consumed by every bird. If a pathogen is in the feed, even at very low levels, there is a very good chance that the birds are going to find it.”
With feed, you need to consider what happens in the feed mill but also how it is stored and transported. On farm, there are basic steps like keeping stores and silos secure from vermin and water penetration but the challenge is at the microbiological level. The first question is how clean is the feed coming from the feed mill?
Heat treatment is the most common method for controlling bacteria in the mill. When done with the correct duration (several minutes), it is very effective at reducing bacteria but not all mills have the capacity to heat treat for long enough as it may cause a backlog. The other thing is that heat treatment offers no residual protection hence, feed can be re-contaminated by bacteria the second it leaves the pellet die. Sometimes this is not necessarily a high challenge problem if the feed is going to be consumed without a long delay but on farm feed is often left in silos and hoppers for days so bacteria can multiply to high numbers.
Other common options for feed treatment, including irradiation and organic acids, also lack residual protection which raise questions over their value for antibiotic free production. “Short chain organic acids are great for water treatment but the evidence for feed is hit and miss. Efficacy varies and we don’t have a good handle on why,” explains Dr Richardson. “Anyone looking at organic acids as a direct replacement for AGPs will be disappointed – at high levels they are good bactericide but they don’t keep the feed clean and I’m not convinced that they have any benefits to the function of gut microflora because the shorter chain acids are broken down by the time they reach the intestine.
“With feed, I would look to the provide the best protection against bacteria and then look to manage the gut microflora with other products. A treatment like Termin-8 has proven superior kill activity with significant residual control of bacteria for greater than 14 days, this gives producers the best chance to keep the microbiological burden low and help with antibiotic free production.”
The breeding and turkey sector have already implemented better biosecurity at the farm, “no antibiotic ever chicken” means the broiler producer is going to have to close this gap.
“Once you’ve taken the right biosecurity steps for in-coming chicks, water, feed and the environment, the other part of the challenge is to promote beneficial bacteria,” says Kurt Richardson.
“Chicks receive some microflora by maternal transmission but it takes around three weeks to reach homeostasis – during this time in particular farmers should to support the development of the gut microflora.”
There are several supplements claiming to improve gut health. The most common are prebiotics and probiotics. Prebiotics are nutrition for gut microflora whereas probiotics are the beneficial bacteria themselves. Dr Richardson believes that both pre- and probiotics will play a useful supporting role in broiler production but that biosecurity, particularly of feed and the environment, is likely to be most important for production without antibiotics.
Another thing to keep in mind is that the birds themselves can also be a carrier for bacteria if they come from breeder houses with existing disease problems. In fact, breeders are a big part of the antibiotic free production picture. Breeders obviously have a longer production cycle than broilers, are usually on very restrictive diets in the pullet cycle, and under stress during the lay cycle so are more at risk of colonisation by pathogens for much longer meaning antibiotics are very important for disease prevention. According to Dr Richardson whether antibiotics will still be widely used in breeders is not clear.
Breeders aren’t the only question; the definition of antibiotic is not fixed. For Dr Richardson, whether ionophore anti-coccidials also face restrictions in antibiotic free production is a big concern: “Coccidial protozoa are like the artillery which weakens the gut defences and then clostridia follow up – if ionophore anti-coccidials are also restricted then I believe dealing with clostridium is going to be a lot tougher.”
“In Europe the indication is that ionophore anti-coccidials will be restricted so we need to see how that plays out.” On the question of Europe, Dr Richardson has sobering thoughts for anyone who believes that antibiotic free is going to be easy. “When Europe ruled out AGPs, therapeutic use rocketed – the legislation made no real difference to usage of antibiotics just to how they were classified. However, I don’t think that is going to be the case in other markets and Europe is likely to become more stringent on therapeutic use too.”