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First report on using chamomile (Matricaria chamomilla) flower meal [CFM] and marjoram (Origanum majorana) leaves meal [MLM] as dietary supplements in low-protein fish diets on Nile tilapia (Oreochromis niloticus) reared in a bio-floc system. The experiment consisted of 6 groups in triplicates, where the first (T1) and second (T2) groups were fed diets containing 25 and 20% protein, respectively, without any additives. In contrast, the rest of the groups were fed a 20% protein diet, adding CFM at rates of 1% (T3) and 2% (T4) or MLM at rates of 1% (T5) and 2% (T6). The fish were initially weighed 18.44 g ± 0.38 (S.E.) and randomly stocked in 18 experimental tanks at six fingerlings in a water volume of 40 litres (150 fish/m3). Molasses was used as a carbon source with a carbon-to-nitrogen ratio of 16:1 in the treatments fed 20% protein; 12:1 in the treatments provided 25% protein. Feeding was done twice daily, six days a week, at a rate of 3% of body weight for 42 days. Water quality was within the desirable tilapia growth and health limit regarding temperature (23.20 - 24.70 °C), pH (8.43 - 8.65), dissolved oxygen (5.5 - 6.1 mg/L), and NH3 (0.03–0.051 mg/L). Fish fed on a 20% CP diet containing 1% CFM had the highest values in all growth indicators, followed by 2% CFM and 1% MLM then T1 and T2 groups. Blood analysis showed variation (P ≤ 0.05) among groups, and T3 had the highest levels of hemoglobin (Hb), hematocrit (Hct), and red blood cells (RBCs) followed by T5 then T4, T2, while T6 and T1 were the least. In conclusion, using chamomile or marjoram as a feed supplement maximizes the benefits of using the bio-floc system, especially in a lack of water resources and poor protein feeds. Nile tilapia growth and hematological parameters were the best with a 1% chamomile (M. chamomilla) supplement under a biofloc system. |
