Evaluation of oxytetracycline hydrochloride (OTC) on non-specific immunity, enzymatic profiles and tissue level retention in Labeo rohita (Hamilton, 1822) after administration through feed

Abstract

The present study was conducted to assess the effect of oxytetracycline hydrochlo-ride (OTC) in rohu, Labeorohita, with graded doses viz., 80 (1×), 240 (3×), 400 (5×) and 800 (10×) mg kg−1 fish biomass day−1 respectively through feed. Four hundred and fifty healthy rohu juveniles (20 ± 0.12 g) were fed for 30 days followed by 10 days of withdrawal period. Each 10 days intervals, five fish were randomly sampled for blood, serum and tissue for estimation of growth, non-specific immune parameters, enzy-matic activities and retention of OTC in muscle tissue. The results showed that there was no significant difference (p > .05) on growth in the treated fish compared with the control. Respiratory burst activity, myeloperoxidase activity, bacterial haemag-glutination and haemolysis activities were enhanced significantly (p < .05) on 10th and 20th day in the fish fed with 80 and 240 mg kg−1 biomass day−1 respectively during the feeding trial compared with the control. Lactate dehydrogenase and alkaline phos-phatase activity increased significantly (p < .05) in the fish fed with 400 and 800 mg kg−1 biomass day−1 respectively compared with the control. Liquid chromatography– mass spectrometry/mass spectrometry study of muscle tissue reveals that OTC was retained in muscle tissue in a dose dependent manner and significantly (p < .05) low-est level (0.44 ± 0.03 ppb) was observed on 40th day in the treated fish fed with 80 mg kg−1 biomass day−1. Hence, 80 mg kg−1 fish biomass day−1 of OTC may be adhered in L. rohita for treating the fish through feed with 10 days of withdrawal period.