Combined or Individual Effects of Dietary Probiotic, Pediococcus acidilactici and Nucleotide on Reproductive Performance in Goldfish (Carassius auratus)

Higher intake of β-glucan impairs reproduction in a female teleost, Tor putitora (Hamilton, 1822)

Although the immuno-modulatory and stress-relieving properties of β-glucan is well elucidated in humans and other animal models, including fish, its role as a dietary supplement on reproduction is extremely scarce. Therefore, in this study, adult female fish were fed one of four test diets having 0 (control), 0.5, 1, and 1.5% β-D-glucan for 130 days and its effect on reproductive performance, ovarian and liver histology, sex hormones, and transcript abundance of selected reproduction-related genes was assessed. Low dietary intake of β-glucan improved fertilization and hatching rates (p<0.05). The relative fecundity and percentage of spawning females were higher (non-significant) in 0.5% β-glucan-fed groups. Surprisingly, even after 130 days, spawning did not occur in 1.5% β-glucan-fed individuals. Irrespective of β-glucan intake, all the brooders recorded similar plasma 17β-estradiol and maturation-inducing hormone (p>0.05). Higher intake of β-glucan (1.5%) upregulated aromatase genes without a parallel increase in 17β-estradiol. However, plasma vitellogenin increased with increasing β-glucan up to 1.0% then declined at 1.5% (p<0.05). The fish that received control, 0.5, and 1.5% β-glucan recorded similar vitellogenin levels in their plasma. Significantly higher plasma cortisol was evidenced in 1.5% β-glucan fed brooders (p<0.05). Histologically, higher follicular atresia and leaking of yolk material was evidenced in 1.5% β-glucan-fed group. Liver histology revealed the highest nutrient/lipid accumulation in fish that received 1.0% and 1.5% β-glucan. This study demonstrated the stimulatory effect of β-glucan intake at a lower dose (0.5%) on reproduction. However, higher intake (1.5%) could perturb normal reproductive function in a fish model and caused an increased number of atretic follicles leading to spawning/reproductive failure.

Sustainable Ornamental Fish Aquaculture: The Implication of Microbial Feed Additives

Ornamental fish trade represents an important economic sector with an export turnover that reached approximately 5 billion US dollars in 2018. Despite its high economic importance, this sector does not receive much attention. Ornamental fish husbandry still faces many challenges and losses caused by transport stress and handling and outbreak of diseases are still to be improved. This review will provide insights on ornamental fish diseases along with the measures used to avoid or limit their onset. Moreover, this review will discuss the role of different natural and sustainable microbial feed additives, particularly probiotics, prebiotics, and synbiotics on the health, reduction in transport stress, growth, and reproduction of farmed ornamental fish. Most importantly, this review aims to fill the informational gaps existing in advanced and sustainable practices in the ornamental fish production.

Dietary supplementation of multi-strain probiotic in male rainbow trout (Oncorhynchus mykiss) broodstock: Effects on feed efficiency, hemato-biochemical parameters, immune response, and semen quality

The present study aimed to determine the effects of dietary probiotic supplementation on feed efficiency, physiological parameters, and semen quality of male rainbow trout (Oncorhynchus mykiss) broodstock. For this purpose, a total of 48 breeders with an average initial weight of 1366.1 ± 33.8 g were divided into 4 groups and 3 replicates. Fish were fed with diets containing 0 (control), 1 × 10⁹ (P1), 2 × 10⁹ (P2), and 4 × 10⁹ (P3) CFU multi-strain probiotic kg^-1 diet for 8 weeks. According to the results, P2 treatment significantly enhanced body weight increase, specific growth rate, and protein efficiency ratio and decreased feed conversion ratio. Moreover, the highest values of red blood cells count, hemoglobin, and hematocrit values were observed in P2 treatment (P < 0.05). The lowest levels of glucose, cholesterol, and triglyceride were found in P1, P2, and P3 treatments, respectively. Also, the highest levels of total protein and albumin were obtained in P2 and P1 treatments (P < 0.05). Based on the results, plasma enzymes contents were significantly decreased in P2 and P3 treatments. In terms of immune parameters, the complement component 3, complement component 4, and immunoglobulin M levels were increased in all probiotic-fed treatments (P < 0.05). For spermatological features, the highest spermatocrit value, sperm concentration, and motility time were observed in the P2 treatment (P < 0.05). Consequently, we conclude that multi-strain probiotics can be used as functional feed additives in male rainbow trout broodstock to enhance semen quality, improve physiological responses, and better feed efficiency.

Effects of dietary supplementation of multi-strain probiotics on semen quality, seminal plasma compositions, and fertilization ability of rainbow trout (Oncorhynchus mykiss) broodstock spermatozoa

The present experiment aims to study the effects of dietary multi-strain probiotics on semen quality, seminal plasma compositions, and fertilization ability of male rainbow trout. For this purpose, a total of 48 broodstocks with an average initial weight of 1366.1 ± 33.8 g were divided into 4 groups and 3 replicates. Fish were fed with diets containing 0 (control), 1 × 10⁹ (P1), 2 × 10⁹ (P2), and 4 × 10⁹ (P3) CFU probiotic kg^-1 diet for 12 weeks. Results showed that dietary supplementation of probiotics significantly increased plasma testosterone level, motility time of spermatozoa, sperm density, and spermatocrit value in P2 and P3 treatments and Na⁺ level in P2 treatment compared to the control group (P < 0.05). The activities of aspartate aminotransferase and lactate dehydrogenase had significantly decreased in the P2 treatment compared to the control group (P < 0.05). No considerable variations were observed between control fish and treatment groups (P > 0.05) in semen biochemical parameters, percentage of motile spermatozoa, osmolality, and pH of seminal plasma. Based on the results, the highest fertilization rate (97.2 ± 0.9%) and eyed egg survival (95.7 ± 1.6%) were observed in the P2 treatment, and those values showed remarkable differences with the control group (P < 0.05). The results indicated that multi-strain probiotics have potential efficacy on semen quality and fertilization ability of rainbow trout broodstock spermatozoa.

Individual and combined effects of the dietary Spirulina platensis and Bacillus licheniformis supplementation on growth performance, antioxidant capacity, innate immunity, relative gene expression and resistance of goldfish, Carassius auratus to Aeromonas hydrophila

This study evaluated the individual and combined effects of the dietary Spirulina platensis (SP) and probiotic bacterium Bacillus licheniformis (BL) on the growth performance, immune responses, and disease resistance in goldfish (Carassius auratus). A total of 216 fish (3.39 ± 0.24 g) were randomly distributed in 12 tanks with 18 fish per tank (4 treatments with 3 replications) and fed with diets containing 0% S. platensis and B. licheniformis (T0), 10⁸ CFU/g B. licheniformis (T1), 2.5% S. platensis (T2), and 10⁸ CFU/g B. licheniformis + 2.5% S. platensis (T3(. There were no significant differences in growth parameters. The alternative complement pathway (ACH50) and lysozyme activity were significantly increased in T2 and T3 treatments. No marked differences were observed in total immunoglobulin and protease activity among treatments (P > 0.05). The relative expression of IGF-1 was not affected by experimental diets (P > 0.05). Ghrelin gene showed significantly higher mRNA levels in fish fed with SP and BL (P < 0.05). The relative expression of catalase (CAT), and glutathione reductase (GSR) significantly increased in fish fed with the SP and BL (P < 0.05). No marked difference in glutathione peroxidase (GPX) gene expression was seen between the treatments (P > 0.05). The mRNA levels of lysozyme, IL6, IL-1β, TGF, and TNF2 transcription were higher in fish fed with SP and BL (P < 0.05). No notable difference was observed in TNF1 and IL10 gene expression between treatments (P > 0.05). Moreover, the result of the challenge test with A. hydrophila showed that goldfish fed with SP and BL had a lower mortality rate than the control. In conclusion, the supplementation of SP and BL can be used as feed additives to enhance disease resistance against A. hydrophila infection by stimulating the immune system in goldfish.

Dietary β-glucan influences the expression of testicular aquaporins, antioxidative defence genes and sperm quality traits in endangered golden mahseer, Tor putitora (Hamilton, 1822)

The effect of dietary β-glucan on seminal plasma composition, sperm characteristics, expression of aquaporins, and antioxidative defence genes of golden mahseer was evaluated. For that, four experimental diets containing 0 (control), 0.5, 1, and 1.5% β-glucan were fed to male golden mahseer brooders for 130 days. Feeding of 0.5% β-glucan was found to improve sperm characteristics, viz. sperm count, motility, viability, and morphology with no effect on gonadosomatic index and seminal plasma energy resources. The marked down-regulation in the transcript abundance of testicular aqp3a noticed in 1.5% β-glucan fed brooders corresponds to their poor sperm quality. Further, the mRNA expression of genes encoding antioxidant enzymes, namely gst and sod1, was lowest in 0.5% β-glucan fed brooders. In contrast, control and higher β-glucan (1 and 1.5%) groups displayed relatively higher expression levels of testicular gst and sod1. On the other hand, the higher seminal plasma total antioxidant capacity observed in 0.5 and 1% β-glucan fed brooders indicated increased scavenging ability of reactive oxygen species. Overall, supplementation of 0.5% β-glucan improved sperm quality and antioxidative potential, but the higher inclusion (1.5%) negatively affected sperm characteristics. Collectively, dietary β-glucan (0.5%) can be a practical approach to developing quality broodstock of golden mahseer.

Synbiotic (FamiLact) administration in idiopathic male infertility enhances sperm quality, DNA integrity, and chromatin status: A triple-blinded randomized clinical trial

BACKGROUND

Idiopathic male infertility is often treated empirically. A recent body of evidence has indicated the association between pro ± prebiotics administration and improvement in semen parameters.

OBJECTIVE

To assess the effect of FamiLact (probiotic + prebiotic) administration on male subjects with idiopathic infertility.

MATERIALS AND METHODS

Fifty-six men with idiopathic male infertility were randomly/equally divided into two groups. Men in the case and control groups received 500 mg of FamiLact and an identical placebo for 80 days, respectively. A semen sample was obtained from each of the participants before initiation and after the termination of the treatment course. Samples underwent regular semen analysis and were further analyzed to assess the level of DNA damage (sperm chromatin structure assay), oxidative stress (BODIPY C11 staining), and protamine deficiency (chromomycin-A3 staining) in spermatozoa.

RESULTS

No significant difference was observed between the baseline values of both groups. After intervention, mean sperm concentration, motility, and normal morphology were significantly higher in the FamiLact group compared to the placebo group (p < 0.05). In the FamiLact receivers, we detected improvement regarding the following parameters: concentration, motility, abnormal morphology, sperm lipid peroxidation, and DNA fragmentation (p ≤ 0.02). Likewise, in the placebo group, we noticed a decrease in the post-medication mean value of DNA fragmentation (p = 0.03) while observing no significant difference regarding other parameters.

CONCLUSION

FamiLact administration improves sperm concentration, motility, and abnormal morphology and decrease sperm DNA damage, possibly through alleviating oxidative stress in the seminal fluid.

Gut Microbiota and Energy Homeostasis in Fish

The microorganisms within the intestinal tract (termed gut microbiota) have been shown to interact with the gut-brain axis, a bidirectional communication system between the gut and the brain mediated by hormonal, immune, and neural signals. Through these interactions, the microbiota might affect behaviors, including feeding behavior, digestive/absorptive processes (e.g., by modulating intestinal motility and the intestinal barrier), metabolism, as well as the immune response, with repercussions on the energy homeostasis and health of the host. To date, research in this field has mostly focused on mammals. Studies on non-mammalian models such as fish may provide novel insights into the specific mechanisms involved in the microbiota-brain-gut axis. This review describes our current knowledge on the possible effects of microbiota on feeding, digestive processes, growth, and energy homeostasis in fish, with emphasis on the influence of brain and gut hormones, environmental factors, and inter-specific differences.