This paper reviews recent advances on the use and mode of action of pr
obiotics (direct-fed microbials) in poultry. The addition of probiotic
s to the diet has been found to improve growth performance and feed co
nversion in broilers, and egg mass, egg weight and egg size in layers.
The mode of action of probiotics in poultry includes (i) maintaining
normal intestinal microflora by competitive exclusion and antagonism;
(ii) altering metabolism by increasing digestive enzyme activity and d
ecreasing bacterial enzyme activity and ammonia production; (iii) impr
oving feed intake and digestion; and (iv) neutralizing enterotoxins an
d stimulating the immune system.