Immunomodulation by diet : individual differences in sensitivity in layer hens

Research output: Thesisinternal PhD, WU

Abstract

Enhancing relevant immunity of production animals to achieve more
robust animals is receiving more and more attention. Several epidemics have
hit production animals recently and with devastating consequences, but enhancing
diseases resistance increasingly provides new opportunities. Furthermore,
welfare and health of production animals is becoming a more and
more consumer driven topic. Several routes are being used to approach the
possibility of enhancing immunity such as selective breeding, enriched and
altered housing conditions, vaccination programs, diet supplementation with
immune stimulating components, and other management procedures. Disease
susceptibility has been shown to be related to stress reactivity, which in turn
is related to differences in HPA axis reactivity. Interestingly, independent of
selection criteria used, the extremes of various selection procedures result in
a recurrent dichotomy in HPA axis reactivity, either being hyperresponsive
or hyporesponsive to stress. Animals with a hyperresponsive HPA axis show
greater environmental sensitivity, while the hyporeactive animals are more
intrinsically regulated. Often, research on immunomodulation is performed
with compromised animals and/or exaggerated supplementation of dietary
components in one generation of animals, but epigenetics by definition seems
to be the mechanism for mothers to prepare their offspring for the environment
they will be born into. Enhancing immunity through normal diet in uncompromised
animals is rarely investigated, let alone over generations. In this
thesis the aim was to induce immunomodulation through diet in selection lines
of chicken that have previously been selected on their antibody response to
sheep red blood cells over two generations of chicken. First, potential HPA
axis differences were examined in these selection lines to establish their environmental
sensitivity, whereafter immunomodulation through normal diet
was investigated in humoral and cellular parameters of immunity. As humoral
immunocompentence was not easily modulated, an immune trigger was
used to detect potential differences in humoral reactivity. The selection lines
showed differential sensitivity to immunomodulation by diet in both generations,
suggesting that adaptation to environmental factors may be a line-specific
(genetically based) process, with differential neuroendocrine regulation.
Most interestingly, the second generation showed effects of the diets in all the
selection lines, albeit in different manners. It is concluded that normal diet can
cause immunomodulation, mainly in animals with hyper HPA axis reactivity,
and that introducing such practices may be more beneficial when mothers are
treated, as all offspring showed immunomodulation, irrespective of selection line. While genetic background and/or epigenetic processes on neuroendocrine
and immune regulation of the individual form the framework wherein individual
immunomodulation by diet can take place, environmental conditions
determine if the modulation is beneficial or not.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Savelkoul, Huub, Promotor
  • Kemp, Bas, Promotor
  • Parmentier, Henk, Co-promotor
Award date20 Nov 2009
Place of Publication[S.l.
Print ISBNs9789085855064
Publication statusPublished - 2009

Keywords

  • hens
  • poultry
  • immunomodulators
  • immunotherapy
  • poultry feeding
  • lines

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