The present study was carried out to study the effect of different doses (40, 80, 120mg/kg basal diet of oxytetracycline, (OTC) and florfenicol, FF (7.5, 15, 22.5mg/kg basal diet) on growth performance, feed utilization, physiological activities and residues in Oreochromis niloticus (7±0.66g).
Fish fed the diet supplemented by 40mg OTC/kg basal diet showed the highest final body weight (BW), weight gain (WG), condition factor (K), specific growth rate (SGR), protein efficiency ratio (PER) and the best FCR, while the lowest final BW, WG, K values were achieved by fish fed the diet 120mg oxytetracycline/kg diet. Fish fed the diet supplemented by 22.5mg FF/kg diet showed the highest final BW, BL, K, feed intake (FI) and the lowest final BW, BL, WG and K values were fed the diet 7.5mg FF/kg diet compared with control group and other doses of FF, for fishes.
Liver transaminase enzymes, Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) increased with increasing the doses OTC and FF. the fish fed the diet supplemented by 40mg OTC/kg recorded the highest value of ALT, AST and insignificant decrease in total protein (TP) and the fish fed the diet supplemented by 15mg FF/kg basal diet recorded the highest value in the ALT, AST and TP compared with control group and the other doses of FF.
The fish fed the diet 120mg OTC/kg diet recorded the highest value in the Haemoglobin (Hb), white blood cells (WBCs) and significant increase in red blood cells (RBCs) while the fish fed the diet supplemented by 40mg OTC/kg basal diet recorded the lowest value of Hb, WBCs and RBCs compared with other OTC doses with insignificant increase in Hb, RBCs compared with control group.
Fish fed the diet supplemented by 7.5mg FF/kg diet recorded the highest value of Hb, RBCs and insignificant decrease in WBCs but the fish fed the diet 22.5mg FF/kg diet recorded the lowest value in Hb, WBCs and RBCs compared with control group and the other FF doses.
Residues of OTC and FF in fish tissues showed that all the doses of oxytetracycline and florfenicol after 21 days no risidue in tissues while at the experimental end all samples were positive and the dose 40mg OTC/kg diet and the dose 7.5mg FF/kg diet caused the lowest values in fish tissues compared with other doses.
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