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

This work evaluated the effect of dietary supplementation of probiotic, Pediococcus acidilactici and nucleotide (combined or individual) on reproductive performance including semen quality (motility and density) and egg indices (egg diameter, ovum diameter, absolute fecundity, relative fecundity, gonadosomatic index, hepatosomatic index, fertilization rate, and hatching rate) in goldfish (Carassius auratus). Fish (46.9 ± 2.15 g) were acclimatized and divided into eight experimental diets supplemented with P. acidilactici different concentrations (0.1, 0.2, and 0.3% diet) and nucleotides (0 and 0.5% diet) for 180 days. Female fish fed experimental diets showed significant differences in reproductive parameters as compared to control diet (P < 0.05). Combined diet (probiotic 0.2% and nucleotide) had the highest percentage and duration of sperm motility, absolute fecundity, and fertilization success as compared to other diets (P < 0.05). The significance of the results obtained herein underlines the importance of diet in the reproductive processes, supporting the hypothesis that feed additives could improve gamete quality.

Enrichment of common carp (Cyprinus carpio) fingerlings diet with Psidium guajava: The effects on cutaneous mucosal and serum immune parameters and immune related genes expression.

The present study aimed at evaluation of possible effects of Psidium guajava as immunostimulant on mucosal and serum immunity, as well as related genes expression in common carp (Cyprinus carpio) fingerlings. In an eight weeks feeding trial, fish were fed with experimental diets containing guava leaf powder [GLP] (0, 0.25, 0.5 and 1%). Then, skin mucus and serum immune parameters (total Ig, alkaline phosphatase activity, lysozyme activity), as well as immune related genes expression (TNF-alpha, IL1b, IL8) were measured. All levels of GLP inclusion in the diet brought about the increase in total Ig in the serum, while in the mucus only the highest level of GLP was effective. No significant differences were observed in mucus alkanine phosphatase activity, while fish fed 0.25% of GLP had noticeably higher serum lysozyme activity. The mucus total protein electrophoretic pattern revealed some differences between the control and the treated fish. Two high MW bands were present in the control group but not in the treated groups. Three bands with a low MW comprised between 35 and 17 mw were noticed in GLP fed carps and not in the control. Gene expression studies revealed no noticeable alterations in TNF-alpha gene between treated fish and control. However, the level of expression of IL-8 was strongly upregulated in fish fed 0.5 and 1% of GLP. Also, feeding on 0.5% of GLP significantly upregulated IL1b gene expression. Evaluation of growth performance revealed improved performance parameters in GLP treated groups. These results confirmed possible immunomodulatory and beneficial effects of GLP on common carp fingerlings.

Enrichment of rainbow trout (Oncorhynchus mykiss) fingerlings diet with microbial lysozyme: Effects on growth performance, serum and skin mucus immune parameters.

A two-month study was conducted to determine the influence of different levels of microbial lysozyme (LZ) contents (0, 0.5, 1.0, and 1.5 g kg-1 of diet) on growth performance, serum and skin mucus immune parameters as well as intestinal immune-related genes expression in rainbow trout Oncorhynchus mykiss fingerlings (5.5 ±â€¯0.1 g). Growth performance and feed utilization were not affected significantly by dietary LZ. Fish fed LZ-supplemented diets had higher serum total immunoglobulins concentration than the control group. In addition, fish fed 1.5 g LZ kg-1 diet had the highest skin mucosal total protein and immunoglobulin contents compared to other experimental groups. Furthermore, skin mucosal lysozyme and alkaline phosphatase activities as well as intestinal tumor necrosis factor-α and interlukine-1ß relative genes expression were higher in fish fed 1.0 and 1.5 g LZ kg-1 diets than the other groups. Overall, the present results clearly showed that LZ powder can be considered as a potential immunostimulant in O. mykiss fingerlings, but in the long term period it may result in negative effects on intestinal health as a consequence of inducing pro-inflammatory cytokines gene expression in the intestine.

Combined or Individual Effects of Dietary Probiotic Pedicoccus acidilactici and Nucleotide on Growth Performance, Intestinal Microbiota, Hemato-biochemical Parameters, and Innate Immune Response in Goldfish (Carassius auratus).

This study investigated the effect of dietary supplementation of probiotic Pedicoccus acidilactici and nucleotide (separately or combined) on growth performance, intestinal microbiota, hemato-immunological parameters, and immunity response in goldfish (Carassius auratus). Fish (average weight 5-6 g) were acclimatized and divided into eight experimental diets supplemented with P. acidilactici of different concentrations (0.1, 0.2, and 0.3% diet) and nucleotides (0 and 0.5% diet) for 6 months. Fish fed with experimental diets showed significant differences in terms of final weight, weight gain, feed conversion ratio, daily growth rate, and condition factor when compared to control diet (P < 0.05). Fish fed with probiotic (0.3%) separately and combined with nucleotide (0.5%) had highest RBC and WBC when compared to other diets (P < 0.05), while the highest values for Hb and Hct as well as total protein, glucose, albumin, and globulin were observed in probiotic (0.2%) and nucleotide (0.5%) combined diet. Serum lysozyme and anti-protease activities were significantly higher in probiotic (0.1 and 0.2%) and nucleotide (0.5%) combined diets. Similarly, these two diets combined showed the highest colonization of P. acidilactici when compared to other diets. In conclusion, combined dietary probiotic and nucleotide improve the growth performance, hemato-biochemical parameters, and intestine growth in C. auratus.

Taste preferences and taste thresholds to classical taste substances in the carnivorous fish, kutum Rutilus frisii kutum (Teleostei: Cyprinidae).

The objective of this study was to compare the taste preferences in the closely related sympatric fish species with different feeding patterns. For this purpose, palatability for four classical taste substances was evaluated for carnivorous kutum Rutilus frisii kutum and the results were compared with the taste preferences of the omnivorous roach Rutilus rutilus which had been studied earlier. In addition, the threshold concentration and the dose-response relationship of the most palatable tastants were evaluated and the ability of kutum to differentiate food with tastants in different concentrations was estimated. It was found that citric acid significantly increases the agar gel pellet consumption within the range of concentrations from 0.01M to 0.52M; the pellets with a concentration of 0.026M were the most palatable. The pellet consumption is significantly different if the concentration of citric acid in the pellets differs more than two times. The absolute threshold concentration is 0.01M, or 2.74µg of citric acid per pellet. Sucrose and NaCl have deterrent taste at the highest concentrations tested (0.29 and 1.73M, respectively). Both substances are palatable at 10 times lower concentrations and become indifferent after further gradual decrease in their concentration. CaCl2 decreases the pellets consumption at 0.9M but is an indifferent tastant at lower concentrations (0.45, 0.09 and 0.045M). The number of rejections and repeated grasps of a food pellet is fewness and is not related to the pellet's palatability, while the retention time of pellet in the oral cavity positively and highly correlates with the pellet's palatability. Kutum have opposite taste preferences for most substances tested in comparison with the roach. It indicates that the taste preferences mediated by the oral taste receptors are different in closely related sympatric fish displayed diet divergences.

Effects of diets containing genistein and diadzein in a long-term study on sex steroid dynamics of goldfish (Carassius auratus).

The effect of long-term exposure of goldfish to dietary genistein and diadzein on the concentrations of plasma sex steroids (testosterone (T), 17ß-estradiol (E2)) and the gonadosomatic index (GSI) was assessed. The study was conducted on four groups for a period of 2 years, from the age of 20 weeks to first spawning. Four doses of genistein and diadzein were applied in the feed: genistein: 0 µg/g, diadzein: 0 µg/g (control group); genistein: 24.26 µg/g, diadzein: 21.7 µg/g (diet 1); genistein: 51.55 µg/g, diadzein: 46.13 µg/g (diet 2); and genistein: 75.83 µg/g, diadzein: 67.82 µg/g (diet 3). Throughout the experiment, there were no significant dose- or time-related effects of genistein and diadzein contents on the T level in both sexes. Furthermore, at the highest genistein and diadzein contents, there was an elevating plasma concentration of E2 at all sampling points (p < 0.05) and a time-related effect occurred (p < 0.05). Although the E2 concentrations in the plasma of female, throughout the experiment, were higher than in males, at the last sampling, the plasma concentrations of E2 reduced among females and became lower than that in males. The effects of isoflavone content were found on GSI of females at the fourth and fifth sampling among the treatments. Isoflavone contents also affect GSI of males at the second, fourth and the last sampling. Our findings suggest that overall genistein and diadzein exposure in early life stages can cause alterations in the reproductive organs and influence sex steroidogenesis.

Reproductive impairment and endocrine disruption in goldfish by feeding diets containing soybean meal.

A long-term feeding experiment was conducted to investigate the inclusion of soybean meal in diets for goldfish (Carassius auratus) on fish reproduction. In the present study, 20 weeks after hatching, goldfish with an initial average weight of 2±0.03g (mean±SD) were divided into 12 groups (three tanks per dietary treatment) and fed 400gkg(-1) crude protein diets. The four experimental diets were as follows: diet 1, fish meal (FM); diet 2, 35% soybean meal (SBM35%); diet 3, 65% soybean meal (SBM65%); diet 4, 100% soybean meal (SBM100%). After feeding with experimental diets, the impact on reproduction was investigated. In both males and females, the plasma testosterone (T) was significantly decreased, while 17ß-estradiol (E2) levels were significantly increased. Levels of 17α, hydroxyprogesterone. (17-OH-P) did not differ as a result of soybean meal feeding in either males or females. The average number of eggs spawned and sperm quality were reduced on feeding with soybean inclusion. Histological examination showed impact on oocyte maturation progress and spermatogenesis process in female and male fish, respectively. In addition, feeding goldfish with soybean meal until maturation caused reduction in fertilization and hatching rates in parallel to increasing soybean meal inclusion. The results demonstrated that inclusion of soybean meal might cause sex hormone biosynthesis disruption and reproductive impairments in fish, ultimately decreased fertilization as well as hatching rates in the offspring.