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A 60-day feeding trial was conducted to evaluate the combined effect of dietary soy phytoestrogens, specifically genistein and daidzein, on the gonadal recrudescence and maturation of male Cyprinus carpio (Linnaeus, 1758). Adult male C. carpio (60 ± 10 g) were fed with a diet with no added genistein or daidzein (C), 110 mg/100 mg genistein (GL), 210 mg/100 g genistein (GH), 4 mg/100 g daidzein (DL), 8 mg/100 g daidzein (DH), combination of 110 mg/100 mg genistein and 4 mg/100 g daidzein (DGL, equivalent to 17.5% soybean meal) and combination of 210 mg/100 g genistein and 8 mg/100 g daidzein (DGH, equivalent to 35% soybean meal) for 60 days. The fish were spent by injection of the inducing agent before the experiment to maintain the homogeneity in maturity stages. Serum 11-ketotestosterone and 17β-estradiol levels increased substantially (p < 0.05), while serum cortisol and 17α,20β dihydroxy progesterone levels were significantly (p < 0.05) lower in GH, DH, DL, DGL and DGH groups. The gene expression of cyp19a1a and 20β-HSD were significantly downregulated (p < 0.05) in GH, DH, and DGH. The ratio of spermatozoa to spermatocytes was lower in high doses of phytoestrogens and their combination treatments (GH, DH and DGH) than in the lower dose fed groups. The GSI (gonad somatic index) values showed a dose-dependent increase in the isoflavone-fed groups. Hence, the study concluded that the feeding of diets with a combination of 210 mg/100 g genistein and 8 mg/100 g daidzein (DGH), which is equivalent to 35% of soybean meal in the diet, disrupted the sex steroid profile and steroidogenic enzymes expression and caused a delay in maturation in the male common carp. Thus, soybean meal can be included in the diet of male common carp broodstock at levels up to 17.5%. However, inclusion levels above 35% have been shown to impair normal reproductive function., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature B.V.)

Therapeutically popular controlled release-enabling technology has forayed into the nutrition sector. Polymer coated forms of L-methionine used in soy protein diets, and its intermediate metabolite, S-adenosyl-L-methionine, used in myriad of medical conditions have proved more efficacious over (highly catabolized) free forms. In this premier study, L-methionine-loaded chitosan nanoparticles (M-NPs) were synthesized using ionic gelation method and their efficacy was evaluated. Biophysical characterization of the NPs was done using a Nanopartica SZ 100 analyser, transmission electron microscopy, and Fourier transform infrared spectroscopy. The M-NPs were spherical and smooth and 218.9 ± 7.4 nm in size and in vitro testing confirmed the controlled release of methionine. A 60-days feeding trial in L. rohita fish fingerlings was conducted. A basal diet suboptimal (0.85%) in methionine was provided with one of the supplements as under: none (control), 0.8% chitosan NPs (0.8% NPs), 1.2% L-methionine (1.2% M) (crystalline free form), 0.6% M-NPs and 1.2% M-NPs. While the addition of 0.6% M-NPs to the basal diet complemented towards meeting the established dietary requirement and resulted in significantly highest (P < 0.05) growth and protein efficiency and sero-immunological test scores (serum total protein, serum globulin, serum albumin: globulin ratio, phagocytic respiratory burst/NBT reduction and lysozyme activity), 1.2% supplementation in either form (free or nano), for being 0.85% excess, was counterproductive. Liver transaminases and dehydrogenases corroborated enhanced growth. It was inferred that part of the methionine requirement in nano form (M-NPs) can confer intended performance and health benefits in animals relying on plant proteins-based diets limiting in this essential amino acid. The study also paves the way for exploring chitosan NPs-based sustained delivery of amino acids in human medical conditions., (© 2023. The Author(s).)

Background/aims: The growth promoting effect of lysine and betaine as well as the expression of candidate genes reflecting their efficacy, such as ghrelin, leptin, Growth Hormone Secretagogue Receptor (GHS-R), Insulin like Growth Factor (IGF- 1) and Growth Hormone Releasing Hormone (GHRH) was examined in Labeo rohita fingerlings., Methods: One hundred eighty healthy juveniles from a homologous population were randomly distributed to 15 rectangular tanks of 150 litres capacity. The experiment was carried out for 60 days with five treatment groups consisting T1 (0.25% Betaine), T2 (0.5% Betaine), T3 (0.75% Lysine) and T4 (1.5% Lysine) and control group. The experiment was carried out for 60 days with five treatment groups consisting T1 (0.25% Betaine), T2 (0.5% Betaine), T3 (0.75% Lysine) and T4 (1.5% Lysine) and control group. At the end of trial, the growth parameters such as weight gain, SGR, PER were estimated from the weight of the triplicate groups. The digestive, metabolic and antioxidant enzymes were analysed using spectrophotometric methods. The intestine, brain and liver were sampled from the treatments and expression of different genes ghrelin, leptin, GHSR, IGF-1 and GHRH was also performed by realtime PCR., Results: A significant (P<0.05) increase in weight gain, SGR, PER and lowest FCR was found in T4 group which was significantly (p < 0.05) different from other experimental groups. The highest mRNA expression levels of expression were found in T4 group which was similar to that of ghrelin gene mRNA of T2 group. The significantly (p<0.05) highest GHSR, GHRH and IGF-1 gene expression levels were found in T4 treatment group compared to other groups., Conclusion: The present study reveals that the lysine and betaine stimulate growth and expression of ghrelin GHRH, GHS-R and IGF-1 genes. The increase of IGF-I mRNA expression with lysine and betaine supplementation revealed that these compounds act as growth modulators. However, lysine was found to be a more potent modulator of growth compared to betaine., Competing Interests: The authors report no conflict of interest., (© Copyright by the Author(s). Published by Cell Physiol Biochem Press.)