Supporting the broiler bird’s immune system

Feed additives have an important role to play in optimising bird health and performance, as Poultry World reports
The ban of antibiotic growth promoters some years ago, coupled with the industry’s move to reduce the use of prescription antibiotics in feed, has led to a shift in emphasis on optimising bird performance.
The focus is now on supporting the broiler bird’s immune system, while achieving good growth, through targeted nutrition and management strategies.
“Managing the birds’ environment can positively affect the level of disease pressure that the bird comes into contact with,” explains John Round, ABN poultry nutritionist. “But it’s nutrition that can help support the broiler in dealing with a disease threat.
“The genetic potential of most breeds has increased significantly compared with what it was 20 years ago and this has increased performance,” he says. “However, a disease challenge will prevent this potential from being realised, which has serious implications for production and profits.”
Mr Round explains that there is an important balance to strike between enabling the bird to mount an adequate immune response in the face of a challenge, but without promoting a response which is too strong. “In the event of a low-level challenge, or no challenge at all, a bird’s performance can be negatively affected,” he warns.
Prebiotics
Harriet Lea, ABN’s development poultry nutritionist, also points to the need to balance the levels of in-feed immune support with the expected risk of disease challenge, which needs to be assessed and ideally anticipated.
Her recent PhD included the study of the effects of prebiotics on broiler performance, gut health and immunity. “Prebiotics are feed materials that are designed to alter bacterial populations in the gut, which may lead to an alteration in the immune system,” she explains.
“Across the trials I performed, I saw the largest benefits where the birds were stocked at their highest density. This may have resulted from the birds being in an increased disease challenge environment,” she says.
“It demonstrated that there may be little gain from feeding supplements designed to stimulate the immune system to healthy birds under no disease challenge. But in a commercial situation it is likely that there will be a higher level of disease challenge, meaning the addition of a prebiotic may be an insurance policy.”
Ms Lea established from her research that, if there is some sort of challenge holding the birds back from optimum growth potential, then supporting the immune system through supplements and immune modulators is beneficial.
To be able to promote productive, healthy birds requires a joined up, holistic approach, adds Mr Round. “We routinely meet with customers, their vets and farm managers alongside our on-farm technical colleagues, to ensure that, in addition to designing a bespoke feed tailored to their birds’ requirements, the issues of clean out, vaccination and disease challenges are also addressed.
“With the knowledge and history of a unit, we are able to make an informed decision on the level of disease risk and assess if it is necessary to include supplements designed to stimulate the immune system as part of the diets we recommend.”
Options
There are many options available, he explains. “These include prebiotics and probiotics, organic acids, antioxidants such as selenium and vitamin E, and various plant extracts. The best way to determine what is right for your crop is to work alongside your advisers and nutritionist to ensure a comprehensive approach to bird health that considers the issue from all angles.
“New additives continue to be developed, and at ABN we carry out many research trials, both in the field and independently at research institutes,” he adds.
“Feeding supplements, or other immune modulators to support the immune system when there is no challenge will not result in any positive effects and may not be cost effective,” Mr Round concludes. “However, if there is likely to be some sort of challenge ahead, it’s important to prepare the birds to be ready to fight it off quickly, as this will reduce any potential production drops.”
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