Oral Administration of Pulverized Wood Charcoal on Growth, Feed Utilization, Survival and Waste Excretion of Red Tilapia (Oreochromis Sp)

Copyright © 2019 by author(s) and International Journal of Trend in Scientific Research and Development Journal. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0) (http://creativecommons.org/licenses/ by/4.0) ABSTRACT A 35-day feeding experiment was conducted to evaluate the effects of pulverized wood charcoal (PWC) on the growth, feed utilization, survival and waste excretion of red tilapia (Oreochromis sp.). Ninety red tilapias with an initial weight of 7.32 ± 1.31 g were acclimatized and randomly introduced into 9 aquaria in 3 groups with 10 fish per aquarium. Different levels of PWC (0 (T0), 1% (T1), and 2% (T2)) were incorporated in the diets of red tilapia for four weeks. After the experiment, average body weight (ABW), specific growth rate (SGR), relative growth rate (RGR) weight gain (WG), feed conversion ratio (FCR) and survival rate (SR) of the experimental fish were computed. No significant differences were observed on feed utilization, survival, and waste excretion of the fish. Furthermore, ABW and WG of the experimental fish did not show any significant difference, however, significantly higher (P < 0.05) SGR and RGR were observed from T1 compared to the other treatments. Consequently, this study showed that supplementation of 1% PWC in the diet is the most suitable in improving the growth performance of red tilapia.


INTRODUCTION
Tilapia species are known for their ability to tolerate a wide range of environmental factors and stressful conditions. They are considered as one of the most important fish species since the early twentieth century till present (Fitzsimmons 2000). Red tilapia species became popular among culturists due to the similarity in shape with sea bream and excellent growth and feed conversion rates among fresh or brackish water species (Liao & Chen 1983). FAO (2010) reported that in 2009 the global production of red tilapia was 38 064 ton. Fish require variable protein levels in their feeds to maintain optimal growth and survival that is why the quality of feed is one crucial factor in the aquaculture industry. However, the high levels of protein in fish feeds loads more wastes to the aquatic environment. Common wastes coming from aquaculture facilities are the nitrogenous waste, which is toxic to aquatic organisms and affects their growth and survival. One source of these nitrogenous wastes such as ammonia (Kikuchi et al. 1995) is the undigested commercial feeds given to the cultured species (Quiayum et al. 2014). Aside from that, fish and aquatic organisms contribute to the increase of ammonia level in the water through their waste excretions (Floyd et al. 1990; Yu et al. 2007). As part of the growth and survival of animals, they continuously excrete wastes as a result of their metabolic process in acquiring energy and nutrients from their food. Ammonia is the principal metabolic waste excreted by the fish so accumulates easily in aquatic systems. Because of its negative impact on the health of the fish, ammonia should be regulated before it accumulates and harms the fish. (Floyd et al 1990).
Ammonia is considered a very toxic factor to fish that limits their survival and growth (Person-Le Ruyet et al. 1995). High levels of ammonia may result to gill damage, reduced growth, poor feed conversion, and lower resistance to diseases, increased breathing, cardiac output and oxygen uptake and may result to convulsions and death (Floyd et al. 1990, Buttner et al. 1993, Yu et al. 2007, Sichula et al. 2011, Bhatnagar & Devi, 2013. Ammonia in water is composed of two forms; the ionized (NH4 + ) an un-ionized (NH3) ammonia (Floyd et al. 1990, Yu et al. 2007). Between these two forms of ammonia, the un-ionized form is more toxic than the ionized form because of its ability to move across cell membranes (El-Sherif & El-Feky 2008; Yu et al. 2007, Bhatnagar & Devi 2013. The predominant form of ammonia present in water is affected by temperature and pH of the aquatic system (Floyd et al. 1990). Both forms are termed as "total ammonia nitrogen (TAN)" (Floyd et al. 1990, Yu et al. 2007).
Modifying the feeds given to the cultured species is one of the recommended ways to reduce the nitrogenous waste from aquaculture. Currently, a natural substance such as charcoal is used in formulating animal feeds because of their Charcoal is a form of carbon, which is generally produced as a carbonaceous residue of wood and other industrial wastes after heating the organic matter. It contains 70 to 90% pure carbon and several minerals such as calcium, potassium, iron, sodium, copper, zinc, manganese, magnesium, etc. (Brouwer et al. 1996). Charcoal has a large surface area giving it countless bonding sites which can be used in adsorbing toxins, gases, and drugs without any specific action (Osol, 1975). It has been used as a feed additive for many terrestrial animals because of its ability to absorb gases especially nitrogen and ammonia, activate the intestinal function, and eliminate the poisons and impurities from the gastrointestinal tract of land animals This study aimed to evaluate the effect of pulverized wood charcoal on the on growth, feed utilization, survival and waste excretion of Red tilapia (Oreochromis sp.)

MATERIALS AND METHODS Experimental fish and feeds:
Red tilapia fingerlings were obtained from Freshwater Aquaculture Centre, Central Luzon State University, Science City of Muñoz, Nueva Ecija, Philippines. Experimental fish with an initial weight of 7.32 ± 1.31 g were acclimatized for one week and were starved for 24 hours before the commencement of the experiment. Ten randomly selected red tilapia were placed in each glass aquarium and fed the with their designated feed thrice a day (8:00, 12:00 and 16:00), with an initial feeding rate of 10% of their body weight. Sampling was done once every two weeks to measure their weight and adjust the feeding rate.
This study was designed randomly comprising of 3 treatments with each treatment replicated thrice. Commercially-available diet (35% protein, 4% fat) was used as the control for the experiment. Commercial diet was added with 0% (Control) (T0), 1% (T1) and 2% (T2) PWD and water (200 mL kg -1 ) (Cho and Lee, 2012). Mixtures were mixed thoroughly and dried at room temperature before storing at -20 °C.
Growth performance and Feed Utilization: To assess the growth performance and feed utilization of the experimental fish, the following data were gathered during the experiment which includes specific growth rate (SGR), relative growth rate (RGR), weight gain (WG), survival rate (SR) and feed conversion ratio (FCR). Parameters were calculated as follows: Water Quality Monitoring: Water quality parameters such as temperature, dissolved oxygen (DO) and pH were measured using DO meter and pH meter. For the analysis of TAN, water samples were collected from the aquarium tanks and were placed in polyethylene (PE) bottles prior to the analysis in the laboratory. Analysis of TAN was done every week before water change following the phenate method. Briefly, 25 to 50 mL of water sample was filtered through Whatman No. 42, and 10 mL of the filtered sample was transferred into a 50 mL beaker in a magnetic stirrer. While stirring, 1 drop of manganese sulfate (MnSO4 • H2O) solution, 0.5 mL oxidizing solution and 0.6 mL phenate solution was added. Then, removed from stirrer and allowed 15 minutes for maximum color development before transferring transfer to the 1-cm cuvette. Ammonia-free distilled water (10.00 mL) (reagent blank) and 10.00 mL of the 0.300 mg · L -1 solution of total ammonia-nitrogen (standard) were carried through the procedure with each set. With the spectrophotometer at 630 nm, set 0.0 absorbance (100% transmittance) with the reagent blank, the absorbances of the standard and the samples were read. Lastly, the concentrations of the TAN were calculated using the formula: Statistical Analysis: Results for the growth, survival and feed utilization were subjected to one-way analysis of variance (ANOVA) followed by Duncan's test at a significant level of P<0.05.  Results of growth performance, feed utilization, and survival, at the end of the experiment is shown in Table 1. There were no significant differences observed in the initial and final ABW of the experimental fish. However, PWC inclusion of 1% (T1) significantly (P < 0.05) improved the SGR and RGR of the experimental fish when compared to the control group (T0). WG from T1 was also numerically higher compared to the other treatments (T0 and T2), however, the observed increases were not statistically significant based on comparisons with the other groups. Furthermore, although FCR and SR were better on PWC-supplemented diets, no significant differences were observed upon comparing with the control group.

RESULTS
Water quality parameters such as temperature (28.75 ± 0.85 ºC), pH (8.4 ± 0.22), and DO (2.5 ± 0.83 mg · L -1 ) did not show any significant differences among the treatments. Levels of TAN concentration were found to be varying throughout the culturing period. During the 1 st week until the 3 rd week of feeding experiment, a high concentration of TAN was recorded in PWC-supplemented diets, with readings of 0.996 to 1.016 mg · L -1 , respectively. As the experiment progress, the level of TAN decreases (Fig 1). In the 4 th and 5 th week of the feeding trial, TAN levels from PWC-supplemented diets were numerically lower, however, the observed decrease was not statistically significant based on comparisons with the control group.

DISCUSSION
The quality of the fish diet is one of the most important factors to consider when it comes to the optimal growth potential of an aquaculture organism. Over the years, numerous efforts were made to formulate a diet that can provide optimal growth, and made of readily available and inexpensive ingredients to reduce the cost of feed production. However, despite the capabilities of the feeds to sustain good fish growth rates, they have a negative environmental impact due to their high nitrogenous wastes particularly ammonia that constitutes almost 80% of these wastes (Kikuchi et al. 1995). With that, the use of feed additives especially charcoals to reduce the nitrogenous waste coming from the aquaculture industry and promoting better growth to the cultured species is gaining popularity. The SR obtained in all treatments is noticeably low. Mortalities of the experimental fish started during the 3 rd and 4 th week of the experiment. As an observation, some experimental fish are gliding their bodies along the sides and bottom of the aquarium. It is possible that during the experiment, the fish acquired bacterial disease which is one possible reason why the SR in all treatments is low. Aside from that, the level of oxygen throughout the experiment (2.5 ± 0.83 mg · L -1 ) is lower than the desired dissolved oxygen level of at least 5 mg · L -1 .
In the present study, no significant improvement was observed in the waste excretion of the red tilapia. In contrast, Thu et al. (2009)

CONCLUSION
In conclusion, the result of the present study showed that 1% inclusion of PWC in the diet improved the growth performance of the red tilapia (Oreochromis sp.). Therefore, PWC at 1% can be a useful feed additive in the diet of red tilapia as it is cheap and readily available.

ACKNOWLEDGEMENT
The author would like to acknowledge the assistance of the College of Fisheries and Freshwater Aquaculture Centre where the study was conducted. Also, the author would like to extend his appreciation to the Department of Science and Technology-Accelerated Science and Technology Human Resource Development Program (DOST-ASTHRDP) for financial assistance during the experiment.