Discipline: Veterinary Medicine
A total of 400 straight-run broiler chicks (Ross 308) were used to compare the efficacy of oregano extract and amprolium in the control of coccidiosis in broilers infected with mixed Eimeria oocysts. The treatments were as follows: T1- uninfected control; T2- infected control; T3- infected, amprolium-treated group; T4- infected, oregano-treated group. At 21 days of age, each chick, except in T1, was orally given 1.0ml of diluted inoculum containing about 30,000 mixed Eimeria oocyst. Twenty-four h after infection, chicks in T3 and T4 were given amprolium and oregano extract the recommended dose of 0.60 g/L and 0.30 ml/L of drinking water, respectively, until five days before marketing. Four days post-infection (PI), birds in T2, T3 and T4 showed clinical signs suggestive of coccidiosis, whereas, birds in T1 remained apparently normal. Lesion scores of birds sacrificed at 6, 14, and 21 days PI showed that birds in T2 developed moderate to severe intestinal coccidiosis while those in T3 and T4 had mild to moderate lesion scores that were consistently lower (P<0.05) that those in T2. Sacrificed birds from T1 showed no gross lesions of coccidiosis at 6 and 14 days PI, however, At 21 days PI, 50% of the sacrificed birds apparently developed a natural infection as evidenced by the presence of mild lesions of coccidiosis in the small intestine. Oocyst output taken over a 24-h period on the 9th-10th day PI and five days after withdrawal of medication showed that birds in T3 and T4 had oocyst counts that were consistently lower (P<0.05) than those in T2. Fecal samples from T1 were negative for coccidian oocysts on the 9th-10th day PI, but were found positive on the 20th -21st day PI. Overall performance at 42 days of age showed that weight gain of birds in T2 and T3 was lower (P<0.05) than that of T1, while that of T4 was not significantly different from the other groups.