Levels Consumption of Sea Rabbit (Dolabella auricularia) Extract Microcapsule Mixed Feed in Goldfish (Carassius auratus)

Introduction

Goldfish (Carassius auratus) are from China with their English name as goldfish. Goldfish is one of the most popular ornamental fish and has many fans among ornamental fish cultivators in the world [1]. Disease prevention can be done through quarantine, vaccination and disinfection. Medical treatment is often given using antibiotics. The use of this material has some weakness. Vaccines are only effective against one type of disease, not widely available and the price is quite expensive. The use of antibiotics continuously and inappropriate doses can cause resistance of pathogenic organisms [2]. Environmentally friendly immunostimulants can be used as alternative way of vaccines. Immunostimulants are used in terms of protection against disease. This protection is in the form of an increase defense system in non-specific body. An alternative way that is often used is the use of sea rabbit extract. Sea rabbit extract (Dolabella

auricularia) is antibacterial because it can inhibit the growth of bacterial and can increase immunity in fish [3].

The administration of active ingredients can be given to fish in various methods, one of which is through oral. However, the response and preference of fish is different towards the feed. Some factors that attract fish towards the food provided include color, taste, and nutritional content in the feed.

One of the drawbacks of giving supplements through fish feed is that the active ingredients in it are damaged during the feed manufacturing process and can be washed out in the water. Therefore, feeding requires an active ingredient preparation method that can maintain its content against environmental factors. Microcapsule is one method to overcome this challenge. Microcapsules can shield substances from environmental influences, reduce toxicity, and change the nature or performance of substances [4]. Based on the idea that sea rabbit extract is beneficial for fish health and how to make its preparation in feed acceptable to fish, then this study aims to determine the level of consumption of feed mixed with sea rabbit extract microcapsules in goldfish.

Discussion

The results of this study especially about the absolute growth on goldfish showed that the administration of microcapsules of sea rabbit extract in the feed gave a significantly different effect between those two treatments. Based on this, it was indicated that the administration of sea rabbit extract microcapsules in the feed could increase the absolute growth of goldfish. The value of absolute growth was predicted to be influenced by the content of sea rabbits. According to the statement of Manullang [5], that sea rabbit extract contained 12.49% protein, essential amino acid, such as arginine 1.61%, leucine 0.90%, valine 0.54%, threonine 0.50%, I-leucine 0.46%, phenylalanine 0.44%, lysine 0.34%, methionine 0.20%, histidine 0.07%, and contains non-essential amino acid, such as glycine 3.02%, glutamic acid 2.78%, aspartate 1.59%, alanine 1.11%, serine 0.95%, tyrosine 0.41%. The amount of protein in the feed was influenced by the amino acid. As a comparison, the addition of local feed with 5% sweet potato leaves powder of feed could provide a specific growth rate of 0.0370 %d for 60 days of rearing goldfish [6].

Meanwhile, giving 2.1% of Spirulina flour, the weight growth of goldfish was 4.33 g which given for 30 days [7]. According to Cowey CB [8], several types of amino acid such as methionine, phenylalanine, threonine (essential amino acid), and tyrosine (non-essential amino acid) are amino acid which needed for the growth and maintenance of fish. Based on the growth rate of sea rabbit extract microcapsules treatment in feeding, it was the better treatment compared to the treatment with given without sea rabbit microcapsules.

Based on the results of observations which had been conducted, it showed that the amount of feed consumption was significantly different between treatments. It was predicted that the quality of feed from the addition of microcapsules of sea rabbit extract had influence towards the protein in order to achieve efficiency and effectiveness of feed utilization. As Suprayudi, et al. [9] stated that palatability or response towards feed was influenced by feed performance condition which included some aspects, like physical properties in the form of shape, color, texture, and size, as well as chemicals that form taste and aroma. According to Håkan Olsén, et al. [10], during feeding, many fish rely on both their olfactory and gustatory senses. It is needed the stimulus included attractants and stimulants in fish feed. An attractant was the attraction of an object (food) so that fish came to and got the food, while stimulants were related to flavors that could stimulate appetite so that fish received it, swallow it, and consumed it.

The high level of feed consumption in the treatment using sea rabbit extract microcapsules was predicted to be influenced by attractant feed factors which stimulated fish by their senses, namely taste, smell, and texture of the feed. The low level of palatability is indicated by how slowly the fish respond to feed. This is in accordance with the statement of Shankar, et al. [11] that the attractants contained in the feed were as a signal to aquatic animals, so that fish could recognize pellets as a food source. According to Manullang B [5] stated that sea rabbit extract contained nine kinds of essential amino acid and 6 kinds of non-essential amino acid, which generally contained relatively high arginine and glycine. The amino acid, such as glycine, proline, taurine and valine provided a more sensitive feeding response in carnivorous fish [12].

The feed conversion ratio in the feed treatment with microcapsules which had been mixed by sea rabbit extract was lower than the treatment without those which were no sea rabbit extract, this indicated good level of feed quality. According to Gumus E, et al. [13] that feeding goldfish the diet including yeast replaced 35% of the fish meal were better FCR than those of fish fed the other diets which has different portion of yeast. The high feed conversion ratio was due to the fact that the nutrients in the feed were not maximally absorbed by the fish’s body and were only wasted through feces so that the growth rate which obtained was relatively low. Management practices, environmental conditions, feed quality, inherent genetic factors, and fish physiological condition all influenced high feed intake in aquaculture [14]. Feed with poor quality means feed with low nutrition and that is easily destroyed or the smell of feed which do not stimulate them, it caused the fish did not want to eat it.

The efficiency results of the feed utilization showed a significantly different effect between those treatments. One of the factors that influenced the value of high feed efficiency was due to the microcapsules content which was with sea rabbit extract in the feed. In addition, the quality and nutritional content of feed containing microcapsules of sea rabbit extract could affect the growth of goldfish. In the research of Souto, et al. [15] it was concluded that in general, fish fed diets containing 3,200 kcal/kg significantly outperformed fish fed 3,600 kcal/kg (P<0.01), indicating higher feed efficiency. A diet of 3,200 kcal/kg appears to be the optimal efficiency level for meeting goldfish requirements for maximum weight gain.

According to Subramanian S [16], the quality of feed and feeding management is important economic criteria for fish farmers. It is critical to feed fish according to their feed consumption level in order to maximize growth rate. The

level of efficiency in the use of food in fish was determined by the growth and amount of feed given. The efficiency of the use of food showed the value of food which could change the increase of weight of fish body. The best efficiency level of food which used was obtained in the treatment with good feed quality, good feed quality brought good results in giving more energy being for their growth so that through giving less feed, it was expected that the growth rate could increase. Most of the energy which was from food actually used for maintenance, the rest was used for activity, growth and reproduction. Improving feed efficiency is critical to lowering aquaculture production costs and achieving aquaculture sustainability [17].

Conclusion

Feeding with the addition of microcapsules with sea rabbit extract gave higher results in their absolute growth (3.16 g), feed consumption level (62.84 g), feed efficiency (29.49%) in goldfish compared to feeding without the addition of microcapsules with sea rabbit extract. Meanwhile, the feed conversion ratio in feeding with the addition of microcapsules of sea rabbit extract was lower (3.39) compared to their feeding without the addition of microcapsules of sea rabbit extract.

Acknowledgment

Thanks to the staffs of Laboratory of Fisheries and Marine Science, Halu Oleo University and Laboratory of Pharmacy, Halu Oleo University, Indonesia for their technical assistance. We also want to thank the reviewers and journal editors for comments and suggestions to improve the manuscript for publication.