Effect of a yeast fermented feed additive on coccidia challenge in broiler chickens

The objective of the study was to evaluate the productive performance, tibia measurements, histopathology of the small intestine and immune response in broiler chickens fed diets added with a yeast fermented product (YFP) and challenged with a coccidia vaccine (COC). One hundred and eighty chicks were allocated in battery cages. From 1 to 20 d of age (phase 1), chicks were assigned to two treatments: 1) Control with not addition of YFP, and 2) Group with addition of 800 ppm of YFP in the feed. The diet was supplemented with nicarbazine. On day 20, 30 birds from each treatment were killed, and the rest of the broilers were divided in two subgroups: one subgroup was challenged with COC, while the other one was not challenged. The vaccine was mixed in the feed. From 21 to 28 d of age (phase 2) the anticoccidial drug was withdrawn from the feed. Results were subjected to ANOVA. In phase 1, YFP-fed broilers had higher diameter of the lower epiphysis of the tibia (P < 0.10), and higher lymphoid clusters (P < 0.10), hyperplasia of the Peyer patches (P < 0.05) and IgA concentration (P < 0.10) but had lower hyperemia/hemorrhage (P < 0.10) in the duodenum. In phase 2, the FCR (P < 0.01), length of the tibia (P < 0.01) and weight of ashes (P < 0.05) were lower in COC challenged broilers. The FI, the diameter of the inferior epiphysis and diaphysis were improved while the oocyst counts were reduced in COC challenged YFP-fed broilers (COC and YFP interaction, P < 0.05). In summary, the addition of YFP improved the FI and tibia mineralization and reduced the oocyst counts in broilers challenged with COC, but it did not show any effect on the duodenal IgA and serum MBL concentrations.