Effect of Marjoram Origanum majorana L. Extract on Growth Performance and Some Haematological Parameters of Common Carp Cyprinus carpio L.

The current study examines the effects of different levels of marjoram Origanum majorana extract (0, 0.5, 1.0, and 1.5 %) on growth performance and haematological parameters in diets of common carp Cyprinus carpio. Four units of the Recirculating Aquaculture System (RAS) were used. Each unit had three plastic tanks (30×30×60 cm), representing four treatments with three replicates, each tank containing ten fish with an average weight of 16.31 + 0.02g - 16.48 + 0.10.  Fingerlings were fed at a rate of 3% of the total fish weight. All diets contained an average of 33.89 ± 0.067 % crude protein and about 20.32±0.16 (kJ/g) of gross energy. Fish are fed twice daily, six days a week. The study lasted eight weeks (56 days) during November and December 2021. According to our findings, a group of fish fed 1.5% marjoram extract had the highest rate of final body weight, daily weight increase, relative growth rate, specific growth rate, food conversion ratio, and feed conversion efficiency. The 1.5 % marjoram extract treatment had the highest rate of total protein +5.68 0.84 g/dl, albumin +4.48 0.48 g/dl, globulin +1.17 0.54 g/dl and 3.82 + 0.51% albumin/ globulin. Based on the results, it can be concluded that the use of 1.5 % O. majorana extract was best for growth, and blood profile. The results suggest that the inclusion of O. majorana can improve the nutrient efficiency, growth performance, and haematological parameter of C. carpio fingerlings without negative effects on the fish.