Abstract:

The present trial was conducted to evaluate whether Biotronic® Top Liquid (BTL) supplementation would benefit during the nursing of Nile tilapia (Oreochromis niloticus) fry in terms of survival, growth, and disease resistance. Isonitrogenous (22.9±0.2% CP) diets were prepared by supplementing 0.0, 0.5, 1.0, 1.5, 2.0 to 2.5 L/ton of BTL diet i.e. T1 to T6, respectively. Each of the 18 aquaria (100 L) was stocked with 45 fish (16.17±0.40g, Mean±SE) having three replicates per treatment. During the trial, fish biomass increased linearly with the increase in BTL dose i.e. 230g (10.3%) of fish biomass/L of BTL. Results showed that higher dose of BTL/ton of feed resulted in to increase growth rate, with an indication of improved growth beyond the tested level i.e. >2.5 L/ton. Bacterial challenge test using Aeromonas hydrophila showed that the highest BTL dose could maintain average fish survival rate above 65%, which was 25% higher than that of control. Average survival improved linearly i.e. (y)=8.857x+40.317 (R²=0.64) with a nearly 9% increase in survival per liter of BTL supplementation. BTL improved SGR, DWG, and PER by 3.4, 1.6 and 2.1 times, respectively as compared to the control when the fish were challenged by bacteria. Therefore, the dose of 2.5 L/ton of feed is recommended based on the present study.

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