Effet de la source du sélénium sur le statut du sélénium, de la GSH-Px et sur le système immunitaire des bovins de boucherie
Abstract The aims of this study were to determine the effects of selenium (Se) supplementation sources (organic and inorganic) on Se and GSH-Px concentrations of beef cows (n=33) and their calves and on immune parameters of the calves. Two groups of cows were given daily 3 mg of either organic or inorganic Se in mineral supplement starting from 12 weeks before calving until weaning. The third group had no Se added into the diet and their calves were divided into two subgroups either injected or not with 0.087 mg/kg of sodium selenite after birth. Serum Se and whole blood GSH-Px were respectively measured by HPLC-UV and by kinetic-enzymatic technique. Calves immune parameters were evaluated using commercial kits for phagocytosis, respiratory burst and CD4:CD8 ratio and radial immunodiffusion for total IgG concentrations. In cows and calves, Se supplementation increased significantly serum and colostrum Se concentrations (P<.02) with significant higher effect for organic source. However, milk Se concentrations increased significantly only with the organic source (P≤.0007). Se supplementation increased GSH-Px concentrations in cows (P≤.04) and their calves (P≤.0004); organic source induced a higher effect than inorganic one in calves (P≤.0004). Se injection in calves allowed a temporary increase (P<.0001) of serum Se concentrations. No significant differences were noticed throughout the experiment for all of the immune parameters measured (P>.01, not significant after Bonferroni adjustment). Our results showed that Se supplementation improved colostrum, milk and serum Se and GSH-Px concentrations in cows and their calves without effect on the measured immune parameters in calves.  Key words: selenium, beef calves, phagocytosis, respiratory burst, antibodies, CD4:CD8 ratio, GSH-Px.
GSH-Px selenium Beef calves Phagocytosis Respiratory burst Antibodies CD4:CD8 ratio GSH-Px