The functioning of the immune system is critical for the prevention
of animal infectious diseases. The strategies currently
employed for the modulation of immune responses are very
limited. One of the approaches commonly used for the prevention
or minimization of animal health diseases is based on the application
of antibiotics. Antibiotics have long been used in poultry diet
to reduce or prevent a number of diseases, such as post-weaning
diarrhea, improve the growth and productivity of poultry flocks,
and enhance the overall production yields of poultry industries [1].
The use of antibiotics has, however, been often criticized for
bringing severe disturbances to beneficial intestinal flora and
conferring bacterial resistance [2].
The growing concerns over the uncontrolled effects of antibiotics
have lead to a search for alternative substitutes to antibiotics [3].
Some of the emerging proposals stipulate that the enhancement of
the immune system can be achieved through the application of
probiotics. Several probiotic strains have attracted special attention
in the last few decades for their promising abilities to enhance