ESPN2011: Nutrition affects immunity in poultry

Gary Butcher of the University of Florida, College of Veterinary Medicine in Gainesville, USA kicked off the day with the topic “Interrelationship between nutrition and immunity in commercial poultry”.

He told the audience that poultry encounter stressors each day they are alive. These stressors cause hormone changes, declines in feed intake, altered nutrient metabolism and suppressed immune function.

“It is known that through selection on meat production problems occur with the immune system. However, enhancing the immune function has a negative effect on performance. It is a fact that the immune system has a direct negative effect on bird performance,” Butcher said.

Stressors are a part of every poultry operation. Management of these stressors to minimize the stress response in the bird should be the goal of every good poultry manager.

The successful poultry enterprise is the one in which the nutritionist, production manager, veterinarian and other personnel have an understanding of stress and make an attempt to do everything possible to minimize the stressors in the operation.

“A three-way interrelationship exists among nutrition, immunity and stress and in order to totally understand the metabolic consequences that each one has on bird performance they must always be considered together because of this interrelationship,” Butler concluded.

Developing the digestive tract
More fundamental was the presentation of Aharon Friedman of the Section of Immunology, Faculty of Agriculture, Food and Environmental, of the Hebrew University of Jerusalem, Israel.

Due to physical problems Friedman presented his paper through Skype. He talked about “Development of immunity in poultry with special emphasis on developmental adaptations of immunity in the avian digestive tract.”

The gut of a hatchling is unprotected against colonizing microorganisms by adaptive immunity during the first few days of life.

Protection during this critical period might be the result of maternal antibody activity or that of the innate immune system. This system appears to be functional at this time, though much work is needed to establish this possibility.

Given that the adaptive immune response is under-developed at hatch, the efficacy of vaccines administered in-ovo or in the hatchling should be considered.

The rational for vaccinating in-ovo is twofold: to immunize the chick as early as possible, and to develop a technology allowing mass vaccination in the poultry industry.

But, if the adaptive immune response is immature in-ovo, how could such a strategy provide immune protection against natural infection in the chick, questioned Friedman.

Ecological managers
A bit closer to practice was the presentation of Peter Ferket, Department of Poultry Science of North Carolina State University, Raleigh, USA who talked about “Nutrition-disease interactions regarding gut health in chickens.”

Gut health may be of greatest concern among poultry producers because of its impact on economic sustainability, and their customers concern about food safety and traceability.

“There are ten times more bacteria and other microflora in the gut than there are cells in a chicken,” Ferket said. “We are ecological managers, not nutritionists.”

Gut health and nutrition are intricately dependent upon one another and it is often difficult to distinguish which one is the predisposing factor.

To resolve gut health problems, one must first be able to identify the nature of a gut health problem and understand the fundamentals and modifiers of enteric development.

Strategic use of different feed additives can be used to stabilize the enteric ecosystem. These enteric conditioning feed additives include antibiotics, probiotics, prebiotic non-starch polysaccharides, essential oils, organic acids and short-chain fatty acids, and mananoligosaccharide derivatives of yeast cell wall, and microbial enzymes.

“Understanding the mode of action of these feed additives is necessary to design compatible feed additive programs to control gut health,” Ferket ended.