C. Alonso-alvarez et Jl. Tella, Effects of experimental food restriction and body-mass changes on the avian T-cell-mediated immune response, CAN J ZOOL, 79(1), 2001, pp. 101-105
Citations number
34
Categorie Soggetti
Animal Sciences
Journal title
CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE
The T-cell-mediated immune response (CMI) of birds, measured with the phyto
haemagglutinin skin test, is in most cases positively correlated with their
body mass. This correlation, however, does not imply causality, since high
-quality birds may be more immunocompetent as well as heavier at the time o
f sampling. We assessed this relationship experimentally by measuring the c
hanges in body mass and CMI in individual captive yellow-legged gulls (Laru
s cachinnans) maintained with food provided ad libitum (control group), wit
h no food (fasting group), or with one-third of their daily food requiremen
ts (subfeeding group). We identified a direct, nonlinear relationship betwe
en food intake, body mass, and CMI. Before the experiment started, body mas
s of birds (corrected for size) fed ad libitum did not correlate with their
CMI, while a positive correlation was found after food restriction. This s
uggests that birds may reach a threshold above which increases in food inta
ke and body mass do not enhance CMI. Thereafter, food restriction caused de
creases in CMI that were significantly correlated with the percentage of bo
dy mass lost by each bird. However, for birds that lost similar. proportion
s of body mass, changes in CMI varied according to food-restriction treatme
nt, the subfeeding group exhibiting a stronger CMI than the fasting group.