Abstract:
Executive Summary
Coccidiosis is one of the major parasitic diseases in the commercial broiler industry.
Probiotics can protect poultry against Eimeria infection. However, the mechanisms are not
fully known.The study aimed to determine the probiotic efficacy of native isolates of
Lactobacillus salivarius as probiotic in different doses to investigate their anticoccidial
properties. Five hundred broilers were allocated to five treatments: control diet (NC),
control diet Eimeria infection (IC), control diet containing 10
8
cfu/g Probiotic-I (low dose of
L. salivarius) + Eimeria infection (P-I), control diet containing 10
10
cfu/g Probiotic-II (high
dose of L. salivarius) + Eimeria infection, and control diet+ Eimeria infection+ Aprolium
(DC). At day 14, all treatments except NC were inoculated with sporulated oocysts. Results
indicated that Eimeria infection increased the mortality and oocysts shedding, and declined
the growth performance as well as the intestinal barrier in Eimeria - treated broilers. On the
contrary, dietary supplementation of low level, high level Lactobacillus salivarius and DC
decreased the mortality and oocysts shedding, but improved the growth performance and
intestinal barrier. The impaired intestinal morphology in the IC group was also improved by
probiotics and anticoccidial treatments. Besides, the elevated oxidative stress and proinflammation
in Eimeria -infected broilers were reduced by P-I, P-II and anticoccidial
treatments. Bacteriological analysis indicated Lactobacillus salivarius altered the structure
of the gut microbiota, and the alteration was more obvious at day 21 than day 35. Notably,
IC also increased the abundances of Eimeria species at day 21, while P-I and DC decreased
the abundances. Correlation analysis revealed that bacteria in Eimeria -treated broilers
positively correlated with the intestinal permeability, oxidative stress and inflammation,
while bacteria in broilers receiving P-I and DC negatively correlated with the
aforementioned pathological indices. In conclusion, dietary Lactobacillus salivarius
supplementation inhibited oocyst shedding and improved the growth performance as well as
the intestinal health of broilers infected with Eimeria , which was closely related to the
regulation of gut microbiota. Moreover, the effects of Lactobacillus salivarius may be more
effective in the early infection of coccidia.
