Iraqi Journal of Veterinary Sciences

Introduction

Arthrospira has cylindrical, multicellular trachomas in an open left-hand helix and can be found in tropical and subtropical lakes with high pH and alkalinity, where other microorganisms struggle to survive (1). A. platensis thrives in alkaline, saline water > 30 g L with a high pH 8.5-11.0. It's also in the soil, marshland, rivers, and thermal springs (2). A. platensis is found in Africa, Asia, and South America, whereas A. maxima is found only in Central America (1). In Central Africa, around Lakes Chad and Niger, and in East Africa, in the Great Rift Valley, the largest spirulina lakes may be found (3). The primary reason for the microalgae's promise is that it includes an excellent mix of protein, fat, and carbohydrates to protect the health of the fish. When compared to certain other additives like bacteria and yeast, microalgae are really a high source of protein and fat (4). Spirulina platensis, a type of microalgae, has a lot of promise and is a great feed ingredient in many aspects. According to studies, this alga includes a wide range of chemicals, including phycobiliproteins, carotenoids, phycocyanin, polysaccharides, unsaturated fatty acids, superoxide dismutase, various vitamins, and others, all of which may help fish improve their color, growth, and immunity (5). Probiotics are administered in a variety of ways, from the oral/water regimen to feed additives, the latter of which is extensively employed in aquaculture. Probiotics can be used in single or multiple strains, as well as in conjunction with prebiotics and immunostimulants like symbiotic. They can also be used in living or dead forms (6). Between 2008 and 2018, 67 antibiotic compounds were utilized in 11 out of 15 nations, according to Lulijwa et al. (7). 73% of these countries used oxytetracycline, sulphadiazine, and florfenicol. Antibiotics have been used by 15 countries, with Vietnam, China, and Bangladesh being the country's most commonly used (8-11).

The purpose of this study is to compare the effects of various food additives at various levels on growth and food utilization of common carp Cyprinus carpio L.

Material and methods

Experimental diets

The common carp Cyprinus carpio L. were fed on sixth experimental diets contained 25.45% crude protein and 13.17 MJ/Kg. Control diet (diet 1) which supplemented with blue green algae (spirulina) by 1 and 2% (diet 2 and 3); symbiotic by 1 and 2% (4 and 5 diets) and antibiotic (Colistin) 3000 IU/Kg (diet 6) (Table 1). Experimental feeds were made after their components were milled and formed as pellets in a meat mincer machine. Twice a day, the fishes were fed 3-5% of their total body weight. The fishes were acclimatized for two weeks in a glass aquarium environment (72 L), containing 10 fish per aquaria. After the acclimatization period ended, the fish were fed on experimental diets for fifty-six days. The fish were randomly distributed at an average weight of 14.31 g/fish to the experimental treatments, with three replications for each treatment.

Table 1: Dietary ingredients and chemical composition of the experimental diets containing different supplementary food

*Calculated according to Smith’s equation: ME (MJ/Kg) = Protein x 18.8 + Fat x 33.5 + NFE X13.8. (11)

Water quality

Air conditioners maintain the water's temperature between 23 and 26 degrees Celsius. The pH is between 7.2 and 7.6 and the dissolved oxygen content ranges from 5.6 to 6.8 mg/L. Every two weeks, the amount of food given to the fish is raised in accordance to the increase in weight. 

Chemical analysis

The major chemical components of the feed, as well as the edible portion components of fish fed on various experimental diets, were determined using the standard methodologies Association of Official Analytical Chemists (12).

Growth criteria

To determine growth rates, food consumption, protein intake, protein efficiency ratio, protein retention standards, and protein productive value, arithmetic formulae based on Hepher (13) are applied.

Statistical analysis

All of the data was analyzed and processed using SPSS (14). The mean standard error of three replicates of pooled samples is provided. The analysis was applied to a one-way analysis of variance. Duncan's (15) novel multiple-range test was utilized to find differences in the criteria's means. P≤0.05 was used to test for significant differences.

Results

Final weight, weight gain and daily weight gain

Final weight, weight gain and daily weight gain for the initial weight criterion, statistical analysis of the growth criteria assessed in Table 2 indicated no significant differences (P≤ 0.05) between all treatments. The fish fed on the third diet (2% Spirulina) significantly outperformed the total weight gain criterion, which amounted to 21.55 g/fish, then the fish fed on diets, control, fourth (1% Symbiotic), fifth (2% Symbiotic) and the sixth (Colistin), which amounted to 16.72 and 14.98 and 15.33g/fish, respectively, as well as the daily weight gain. The daily weight gain (gm/fish/day) characteristic followed the same trend as the total body weight characteristic, as fish fed the third diet, with a value of 0.385, were significantly superior to fish fed the first, fourth, fifth, and seventh diets, with values of 0.297, 0.298, 0.268, and 0.264 respectively.

Table 2: Effect of different supplementary food on final weight, weight gain, and daily growth rate

* Means not sharing a common superscript letter are significantly different (P ≤ 0.05).

Relative growth rate and specific growth rate

All treatment groups showed 100% survival rates throughout the trial, demonstrating that all fish had adapted to the study's conditions and test diets. Fish given spirulina at 1.0 and 2.0% (diet 2 and 3) exhibited the greatest significant (P≤ 0.05) relative growth rates when compared to the control diet and other treatments. The second and third diets exhibited the highest relative growth rates 138.21 and 151.01%, as well as the highest specific growth rates, according to table 3. (1.56 and 1.52). Between the control (diet 1) and the fish-fed probiotics (diets 4 and 5) groups, as well as between the antibiotic group and the antibiotic group, there were no significant differences (diet 6).

Feed conversion ratio and feed efficiency ratio

Table 4 demonstrates that there was no significant difference in total food consumption (P≤ 0.05) between fish fed the control diet and fish fed other diets containing different supplemental foods at varying rates, with the exception of fish fed the second and fifth diets. The FCR of common carp fed 2.0% spirulina (second diet) decreased to 2.02, which was less significantly ((P≤ 0.05) than the control group 2.61 and fish fed probiotic (diets 4 and 5) and antibiotic (diets 4 and 5) diets (diet 6, Table 4).

Table 3: Effect of different supplementary food on relative growth rate, specific growth rate and survival rate

* Means not sharing a common superscript letter are significantly different (P ≤ 0.05).

Table 4: Effect of different supplementary food on food intake, food conversion ratio and feed efficiency ratio

* Means not sharing a common superscript letter are significantly different (P≤ 0.05).

Protein intake and protein efficiency ratio

Table 5 demonstrates that there were no significant differences in protein intake between the fish fed various additional materials and the other treatments, with the exception of the fifth diet (P≤ 0.05). Supplementing with spirulina at a rate of 2.0% (diet 2) raised the PER value to 1.97 (diet 4), 2.05 (diet 2), and 1.50 for the fourth, fifth, and sixth diets, which were respectively 1.53, 1.44, and 1.46. The amount of protein deposited by fish fed second diets was 3.95 gm/fish, which was significantly (P≤ 0.05) more than the control and other treatments.

Protein productive value

The protein productive value criterion was significantly higher (P≤ 0.05) for fish fed a diet containing green blue algae (Spirulina) at 1.0% 34.63% than in fish fed diets 1, 3, 4, and 5, which were 25.26, 25.29, 28.30, 27.25%, and 23.07%, respectively.

Table 5: Effect of different supplementary food on protein intake, protein efficiency ratio, protein retention and protein productive value

* Means not sharing a common superscript letter are significantly different (P≤ 0.05).

Protein, fat and ash retention

At the ending of the feeding trial, Table 5 shows the biochemical composition of the common carp's edible portion. Moisture and dry weight of all fish groups fed diets containing various feed additives at various doses could not differ significantly from the control diet, according to biochemical analyses of the edible portion of the fish. All experimental treatments of the edible portion content had significantly lower percent ages of ether extract than the control treatment (P≤ 0.05). Spirulina (diets 2 and 3) and probiotic (diets 4 and 5) offered to fish showed a significant increase in crude protein (P≤ 0.05) when compared to the control and antibiotic diets. (Diets 1, 6, and 8). When compared to fish given the third and fourth diets (symbiotic 1 and 2%), the ash percentage of fish fed the second diet (1% spirulina) increased significantly (P≤ 0.05), reaching 3.61, 2.85, and 2.81, respectively. treatments.

Table 6: Effect of different supplementary food on chemical composition (%) of the edible portion of common carp

 *Means not sharing a common superscript letter are significantly different (P≤0.05).