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The effect of Weissella cibaria and Lactococcus lactis bacteria in the diet of Rutilus kutum fingerlings propagated naturally and artificially on growth, hematological indices, serum biochemical and immunological parameters
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Siavash Pirasteh1   , Hosein Oraji1 * , Khosrow Janikhalili1 |
| 1-Department of Fisheries, Faculty of Fisheries and Animal Science, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran , hoseinoraji@yahoo.com |
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Abstract: (34 Views) |
Introduction: Among the fish exist in the southern Caspian Sea, the Caspian Kutum (Rutilus kutum) has a special place due to its nutritional preference. This fish species has been endangered because of unsuitable ecological conditions, reduced water flow, and the destruction of their natural habitats. Therefore, by increasing the production of Caspian white fish through aquaculture, it will be possible to increase its supply in the country and increase the per capita consumption of this aquatic animal. Fish obtained from different breeding methods, whether natural or artificial, may exhibit potential differences in growth performance and hematological and immune indices, which can be practical and useful in fisheries planning, and there are lack of researches that have addressed these differences in Caspian Kutum. Lactobacilli are the most commonly used microorganisms as probiotics (Roman et al., 2012). Studies have shown that the use of these probiotics leads to improved immune responses and increased resistance to pathogens (Mohammadian et al., 2018; Qin et al., 2018). Weissella cibaria and Lactococcus lactis are among the lactic acid bacteria identified as part of the natural flora in various species, including aquatic animals (Bakhshzad Mahmoudi et al., 2023). Few studies have compared the differences in fish bred through natural and artificial methods. Given the importance of probiotics in aquaculture and the lack of sufficient studies on the use of these probiotics in the Caspian Kutum, the current study evaluated the effects of diets containing probiotic bacteria W. cibaria and L. lactis on blood indices, serum biochemical parameters, and immunity in juvenile Kutum bred naturally and/or artificially.
Material and methods: For this research, 2400 fingerlings with an average initial weight of 10.01±13.01 g were selected, of which 1200 were obtained from natural breeding and 1200 from artificial breeding. The experimental diets included 4 levels (0, 150, 300, and 450 mg/kg with an equal ratios of W.cibaria and L.lactis bacteria) added to the diets of fish from 2 breeding type (natural and artificial) (4×2 factorial). One hundred fingerlings were assigned to each of the 24 experimental units. The distribution of the fish was completely random. In this experiment, water quality parameters and variable conditions were considered constant. The desired amounts of bacteria strains were weighed in sterile plastic containers, gelatin was added for coating and was evenly sprayed to the experimental diets. After 8 weeks of trial, all fish weighed to measure growth and nutritional factors. In addition, biochemical factors including total protein, albumin, cholesterol, triglycerides, and liver enzymes (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase) were assessed using an autoanalyzer. Immune indices such as lysozyme activity, ACH50, and IgM were also evaluated. For data comparison, one-way analysis of variance (ANOVA) and Duncan's multiple range test were used at a 95% confidence level. Furthermore, factorial analysis (2×4) was employed to examine the interactions between probiotic levels (4 levels) and breeding types (2 types).
Results and Discussion: Results indicated that the inclusion of probiotic levels led to improve growth performance and feed conversion ratio, with 300 mg/kg being the optimum dosage. Probiotic bacteria had positive effects on digestive tract by modulating intestinal microbial balance. Meanwhile, complex carbohydrates are broken down and short-chain fatty acids (SCFAs) provide energy sources for fish and promote growth development (Ringø et al., 2022). In addition, the production of bioactive compounds by probiotic bacteria, such as vitamins, organic acids, and enzymes, can have beneficial effects on growth and health, improving nutrient absorption (Liu et al., 2010). On the other hand, red and white blood cells, hemoglobin, and hematocrit improved by the addition of probiotics. Changes in white blood cells are one of the important indicators showing how the fish responded to pathogens, and an increase in these factors can indicate stimulation of the immune system (Bakhshzad Mahmoudi et al., 2023). Moreover, since in anemia red blood cells are hemolyzed or their production is reduced (Hedayati et al., 2013), so, the increase in these indices in fish fed mixture of W. cibaria and L. lactis could indicate a positive effect on hematopoiesis. This may be due to modulation of the gut microbiota and increased bioavailability and absorption of elements and/or synthesis of vitamins by beneficial bacteria. Some lactic acid bacteria may, by producing lactic acid and other organic acids, increase intestinal iron permeability and enhance erythropoiesis (red blood cell production) (Padalino et al., 2012). Biochemical serum parameters such as cholesterol, triglycerides, AST, ALT, and ALP were not affected by the type of breeding or the probiotic levels. Since, liver enzymes increase in hepatic injury (Kumar et al., 2011), the current results may indicate that the probiotic mixture (W. cibaria and L. lactis) has no adverse effects on the liver. Based on the current result, complement activity (ACH50), lysozyme, and immunoglobulin enhanced up to the 300 mg probiotic level, but relatively decreased at the 450 mg level. This could be attributed to microbial imbalance, increased populations of undesirable bacteria, and antagonistic effects on immunity, however, these parameters were higher than the control. Probiotic bacteria may stimulate the expression of antimicrobial peptides in fish, leading to increased lysozyme production (Kim et al., 2013). Short-chain fatty acids can lead to activation in both innate and adaptive immune pathways through the expression of genes related to cytokines and other signaling molecules (El-Kady et al., 2022).
Conclusion: The present study clearly showed that the bacteria W. cibaria and L. lactis acted effectively as hematological and immunological stimulants in fingerlings produced by both artificial and natural spawning and can be used to increase productivity. Since, growth performance, hematological and immune parameters of the fingerlings were not affected by the breeding type (natural or artificial), providing an appropriate probiotic dosage of these probiotic mixtures can have positive effects in both groups of fish. However, additional studies are needed at older ages and higher weights and also using genetic techniques to clarify the more precise mechanisms. Based on the optimal level found in the current study, 300 mg of this probiotic blend is recommended in the diet of the Caspian kutum.
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| Keywords: Probiotic, immune stimulator, lactic acid, Caspian whitefish fingerlings, breeding method |
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Type of Study: Research |
Subject:
Special
Received: 2025/05/25 | Accepted: 2025/06/2
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