Studies on fertilization sources with artificial feeds on productivity of earthen ponds stocked with different fish species

The present study was carried out at a private fish farm at Tolombat 7 site Kafr El-Sheikh Governorate, Egypt. The study was performed for 140 days during the period from 5Th July to 27Th November 2010. The study aimed to investigate the effect of different fertilization and feeding systems on growth performance; feed and Nitrogen utilization; whole body chemical composition; water quality; plankton abundance; some blood parameters and economic evaluation of earthen ponds cultured with different fish species in polyculture system. The experimental ponds were stocked with 4000 Nile tilapia (O. niloticus) fingerlings with an average initial weight of 17.18g; 500 Common carp (C. carpio) fingerlings initial weight of 16.50g; 750 Bouri (Mugil cephalus) fingerlings initial weight of 21.43 g; and 750 Tobara (Liza ramada) fingerlings with initial weight of 15.9 g in ten earthen ponds with dimentions of 21 x 100 m. each i.e. 1/2 fadden. Five treatments with two replicates each, were applied as follows: The 1st treatment (T1) was fed only on a commercial fish feed (25% protein), where the daily allowance of the fish was calculated as 3 % of fish biomass/day for 6 days a week. The 2nd treatment (T2) ponds were fed on the same artificial feed and fertilized with poultry manure at a rate of 32.5 kg /pond weekly. The 3rd treatment (T3) was fed on the artificial feed and fertilized with poultry manure (32.5 kg /pond weekly) and 1 kg urea plus 4 kg triple super phosphate /pond weekly. The 4th treatment (T4) received the artificial feed and fertilized with 1 kg urea plus 4 kg triple super phosphate/pond weekly. The 5th treatment (T5) was fertilized by poultry manure 32.5 kg and 1 kg urea plus 4 kg triple super phosphate /pond weekly without artificial feeds.
Results revealed that the highest (P<0.05) final weights and length, weight gain, length gain, daily weight gain, specific growth rate, relative growth rate and gross yield were recorded with T3 in all tested fish species compared to the other treatments, while T5 recorded the highest (P<0.05) condition factor in Nile tilapia, Common carp and Tobara and T2 recorded the highest (P<0.05) condition factor in Bouri. The best (lowest) feed conversion ratio was recorded with T4 followed by T3; T1 and T2, respectively, while T5 recorded no results of FCR, thus it received no artificial feed. Nitrogen utilization (N output/ N input) averages were 35.56; 32.18; 33.81; 35.90 and 116.40 for T1; T2; T3; T4 and T5, respectively. The applied treatments showed significant effects on whole fish body composition (protein, ether extracts, ash, NFE and gross body energy contents in all fish species tested. The treatment T3 recorded the highest total phytoplankton counts (org /ml) followed in a decreasing order by T2; T4; T5 and T1, respectively. The same trend was observed with total zooplankton and total plankton counts. The highest (P<0.05) total fish yield per pond was recorded by T3, followed in a significant decreasing order by T 2; T4 ; T1 and T5, respectively. The economical study showed that treatment T3 resulted in the highest return to cost followed in a decreasing order by treatments (4,2, 1and 5),
respectively. The applied treatments showed significant effects on blood Hematological parameters (Hemoglobin-Hb g/d; RBC x106/ml; WBC x103/ml; Hematocrit Ht %) and Serum components (Total protein g/dl; Albumin g/dl; Globulin g/l; Glucose mg/l; Cholesterol mg %; Triglycerides mg/l; ALT u/ml and AST u/ml) in all fish species tested.
Based on the results obtained in the present study applying the earthen ponds polyculture system (Nile tilapia, Common carp and Mullet species) could be recommended using artificial feeding and fertilizing with poultry manure plus urea
and triple super phosphate for the highest net returns under Egyptian conditions.