Avian Models for Evaluating the Effects of Calorie Restriction
M.A. Ottinger and M.A. Abdelnabi
Department of Animal and Avian Sciences, University of Maryland, College Park, MD 20742
Calorie restriction has been used routinely in domestic species as a
means of enhancing lifetime productivity and health. The use of
calorie restriction has become increasingly critical in domestic breeds
of poultry as the birds have been selected for rapid growth. If
unchecked, the rapidly growing strains of poultry develop a number of
clinical problems, including poor reproduction, joint inflammation, and
other obesity related conditions. In birds destined to become
breeders, calorie restriction is routinely initiated in the first few
weeks of life, often in an alternate day or skip-a-day feeding
regimen. When the birds are photostimulated to induce reproduction,
then they are fed on a daily calorie restricted paradigm. We conducted
studies on heavy poultry breeders as well as on Japanese quail to
ascertain level of calorie restriction that benefits long term
reproduction and minimizes health problem and stress. Results showed
that moderate levels (15-25%) of calorie restriction delayed sexual maturation, whereas more stringent
restriction(35+%)resulted in a lack of sexual maturation, especially
in males. Although delayed in the initiation of reproduction,
moderately calorie restricted birds showed long term benefits in
reproduction, with production of more chicks and longer reproductive
function. These differences between groups was reflected in plasma
steroid hormone levels. Studies in Japanese quail showed similar
responses, with the more severe calorie restriction being associated
with elevated corticosterone levels, suggesting activation of a stress
response. These studies provide evidence for similar benefits of
moderate calorie restriction across phyla.
Key words:
calorie restriction, birds, reproduction
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