Outdoor study on the use of echinacea (Echinacea purperea), marjoram (Origanum majorana) and yeast (Saccharomyces cerevisiae) as feed additives for Oreochromis niloticus [electronic resource].

Includes references.

A number of 2400 Oreochromis ni/oacus were fed on ration containing Echinacea, Marjoram and yeast at different levels as feed additives to a basal ration (25% protein). There were 10 treatments including; treatment 1 (E1) contained Echinacea in the rate of 0.25% in ration, treatment 2 (E2) had Echinacea 0.5%, treatment, 3 (E3) had Echinacea 1%, treatment 4 (M1) had Marjoram 1%, treatment 5 (M2) had Marjoram 2%, treatment 6 (M3) had Marjoram 3%, treatment 7 (Yl) had Yeast 0.5%0, treatment 8 (Yl) had Yeast 1%0, treatment 9 (Yl) had Yeast 2%0 and treatment 10 (control) had fish fed on basal ration only. The fish were distributed into a number of 40 hapas in the rate of 60 fish per hapa and 4 hapas were designated for each treatment as 4 replicates. The experiment lasted for 3 months, where it was divided into 3 stages, the period of each stage was 1 month. The feeding rate was 10% of the total fish biomass in each hapa in the 1st month then decreased to 5% in the 2"" month and 3% in the 3m month. At the end of each stage, the fish in each hapa were collected, counted, weighed and then transferred to aquaria for liver sampling to conduct total and fractionation protein anaiyses. Challenge test was performed via liP injection of 10 fish from each treatment with a virulent strain of Aeromonas hydrophi/a. Samples of fish were also taken before starting the experiment and at the end of the 3 months for prOXimate analyses. Results revealed that, the best treatments in this study were ranked as Echinacea 1% (E3) followed by Marjoram 1% (M1), Marjoram 3% (M3), Echinacea 0.5% (E2) and then by Echinacea 0.25% (E1) via compiling their results obtained from different tools, which' were used for assessment of immune response of experimented fish. Although yeast gave the least results compared with Echinacea and Marjoram, yeast 1%0 was relatively the best rate among the 3 levels of yeast used in this study.

Summary in Arabic.

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