Effect of Oxytetracycline-dosing on the Growth, Safety and Intestinal Histology of Nile Tilapia, Oreochromis niloticus (L.) Juveniles

Abstract

The present study was carried out to evaluate the effect of oxytetracycline (OTC)dosing at five different concentrations, viz., 0 mg (0X), 80 mg (1X), 240 mg (3X), 400 mg (5X) and 800 mg (10X) kg -1 biomass day -1 for 30 consecutive days on the growth, safety and intestinal histology of Nile tilapia, Oreochromis niloticus (L.) juveniles. The OTC-residues in the edible muscle were detected at scheduled intervals by LC-MS/MS. A dose-dependent decline in feed intake, biomass and survival were recorded in OTC-dosed fish. The OTC-residue levels were 0, 204.75±45.75, 318.00±0.00, 778.50±145.50 and 684.00±18.00 ng g -1 in 0X, 1X, 3X, 5X and 10X groups, respectively on day 30 OTC-dosing, which reduced subsequently. Relatively mild histopathological lesions including degeneration of epithelial layer, loss of absorptive vacuoles, necrotized intestinal villi, mucinous degeneration, and necrotized absorptive region were observed in the intestine of OTC-dosed fish. Lamina propria swelling was the characteristic change observed in the 10X group on day 15. The observed data revealed that OTC-dosing is reasonably safe at the therapeutic dose of 80 mg kg -1 biomass day -1 . However, the precise dose for safe usage of OTC is to be determined according to the culture conditions and species cultured.

Accumulation and clearance of tissue residues and health status of Nile tilapia Oreochromis niloticus (L.) juveniles as influenced by the extended oral oxytetracycline-dosing

“…(1.99-2.03 times) followed by 5X (2.03-2.11 times) groups. The signi cant dose-dependent differences in the fold increase in the biomass of Nile tilapia among the dosing groups indicated that OTC at the higher doses may affect the growth so also in an earlier study with similar doses for 30 days dosing (Julinta et al 2019a). The 0.5X-dose had signi cantly high growth increment, while the therapeutic dose (1X) did not affect the growth of Nile tilapia.…”

“…Our results agree with Trushenski et al (2018), who recorded 3% mortality in Nile tilapia fed with 80 mg OTC/kg biomass/day for 10 days. Julinta et al (2019a) also recorded increased mortalities with the increase in OTC-dose, i.e., from 5.00±0.00% in 1X to 13.33±2.89% in 10X groups, respectively when fed for 30 consecutive days. The observations like pale kidney and liver, discolouration and liquefaction of internal organs at the higher doses (3X-10X groups) possibly indicated the consequence of toxicity upon long-term oral OTC-dosing that might have triggered the mortality.…”

“…Though the feed intake increased upon the termination of OTC-dosing, it was lower by 4.25% in 3X to 17.25% in the 10X group than the control. Likewise, a signi cant dose-dependent reduction in feed intake was noted in Nile tilapia when fed OTC (Julinta et al 2019a;Limbu et al 2020) or orfenicol (Gaikowski et al 2013) for extended periods. On the other hand, Gaikowski et al (2003) noted a slight reduction in feed consumption in Walleye (Sander vitreus) at the OTC-dose of 413 mg/kg body weight/day, equivalent to the 5X-dose of our study.…”

Antibiotic-Re¬¬sistant Motile Aeromonads Associated With Cultured Indian Major Carps, Pond Water and Pond Sediment

“…Resistance to third-generation cephalosporins (cefalexin) is known to be associated with the derepression of chromosomal enzymes (Zdanowicz et al, 2020) and anthropogenic Aeromonas infections (Igbinosa et al, 2012). Oxytetracycline resistance was comparatively less as the change in strains' resistance depends on seasonal variation rather than medication (Julinta et al, 2019). The AMR of Aeromonas samples exhibited against fluoroquinolones (ciprofloxacin and enrofloxacin) and sulfonamides (cotrimoxazole, sulfafurazole and trimethoprim) were analogous with the studies of…”

Effects of oral oxytetracycline-dosing on the development of antibiotic-resistance in the intestinal bacterial flora of monosex (all-male) Nile tilapia Oreochromis niloticus fries

“…The incorporation rate of OTC was calculated to deliver an approximate dosage of 0 mg, 80 mg and 800 mg OTC/kg biomass/day for 10 consecutive days. The control and OTCdiets were prepared by top-coating the commercial feed with appropriate amounts of OTC in 5 mL vegetable oil separately as described in Julinta et al (2019) to administer doses of 0, 80 and 800 mg/kg biomass/day when fed at 6% BW/day. The control diet was prepared without medication but coated with vegetable oil to minimize variation between the feeds.…”