Effects of dietary supplementation with a herbal extract on the performance of broilers infected with a mixture of Eimeria species.

摘要

A herbal extract containing a blend of three essential oils, derived from oregano, laurel leaf and lavender, was investigated as a feed additive alternative to the conventional anticoccidial sodium monensin. Broilers were infected with a mixture of Eimeria species or left uninfected. Both infected and uninfected broilers were provided with diets containing either herbal extract (HEX), monensin (MON) or without these supplements (CON). The HEX group had 50 mg herbal extract/kg diet and the MON group 100 mg monensin/kg diet. All of the uninfected broilers exhibited higher body weight gain and better feed conversion when compared with their infected counterparts at d 28 and 42 of age. Both HEX and MON supplements caused significant improvements in performance in the infected broilers, but failed to have any effect on uninfected broilers. Faecal oocyst output measured daily by sampling excreta, and expressed on a per bird basis, was lower in the HEX and MON groups than in the CON group. However, the herbal extract was not as effective as monensin in reducing oocyst excretion. Coccidial infection caused a significant increase in total intestinal length and caecal weight, but the dietary treatments did not influence these measurements. These results indicate that providing a herbal extract in the diet was not as effective as monensin in protecting broilers exposed to a coccidial challenge.