Gamma-aminobutyric acid (GABA) is a widely available non-protein amino acid whose physiological importance goes beyond its role as an inhibitory neurotransmitter in mammals. The GABA synthesis ability of ten strains of Lactiplantibacillus plantarum was screened. They produced GABA ranging from 48.19 ± 3.44 to 100.75 ± 1.63 mg/L at 24 h-cultivation. Among them, Lp. plantarum FRT7 showed the highest GABA production. Therefore, FRT7 was chosen for GABA yield optimization. A one-factor-at-a-time strategy analysis of the GABA yield of FRT7 was performed, including the culture temperature, incubation time, inoculum volume, initial pH, the initial amount of monosodium glutamate (MSG), and pyridoxal 5’-phosphate (PLP) concentration, based on which the response surface methodology (RSM) was performed. After being cultured in an MRS culture medium supplemented with 3% MSG and 2 mmol/L of PLP at 40 °C with an initial pH of 7.0 for 48 h, the GABA reached a maximum yield of 1158.6 ± 21.22 mg/L. The results showed the experimental value of the GABA yield was in good agreement with the predicted values. Furthermore, the results from the RSM also indicated that the initial MSG addition, PLP concentration, and incubation time were significant variables. These results suggest that Lp. plantarum FRT7 has the potential to be a health-beneficial probiotic with commercial capabilities.

Obesity has become a major social problem related to health and quality of life. Our previous work demonstrated that Lactobacillus plantarum FRT10 alleviated obesity in high-fat diet (HFD)-fed mice by alleviating gut dysbiosis. However, the underlying functions of FRT10 in regulating liver and cecum contents metabolism remain unknown. Liver and cecum contents metabonomics combined with pathway analysis based on ultraperformance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) were performed to evaluate the alterations of metabolic profiles between obese control mice and obese mice in FRT10-treated groups. The orthogonal partial least squares discriminant analysis (OPLS-DA) score plots showed that there were significant differences in cecum contents and liver markers between experimental groups. In total, 26 potential biomarkers were identified in the liver and 15 in cecum contents that could explain the effect of FRT10 addition in HFD-fed mice. In addition, gut–liver axis analysis indicated that there was a strong correlation between cecum contents metabolites and hepatic metabolites. The mechanism of FRT10 against obesity might be related to the alterations in glycerophospholipid metabolism, primary bile acid biosynthesis, amino metabolism, and purine and pyrimidine metabolism. Studies on these metabolites could help us better understand the role of FRT10 in obesity induced by HFD.

Ruminants would suffer from gastric distension (bloat) when feeding on alfalfa (Medicago sativa L.; Alf), while tannins can relieve this problem. Thus, this study aimed to evaluate the effect of Alf mixed with paper mulberry (Broussonetia papyrifera) leaves (PML) or condensed tannins (CT) extracted from PML on in vitro fermentation performance. Seven experimental treatments based on the mass ratios of Alf and PML were set up: Alf, PML, 3A1P (Alf:PML = 3:1), 1A1P (Alf:PML = 1:1), 1A3P (Alf:PML = 1:3), A1P (Alf with 1% CT extracted from PML), A2P (Alf with 2% CT extracted from PML), and a blank. The results after fermentation were as follows. (1) The degradable dry matter (DDM) and degradable organic matter (DOM) contents increased simultaneously with the increase in the proportion of PML (p < .05). However, the DDM and DOM contents decreased with the increase in PML CT concentration. Moreover, mixing PML with ALF improved (p <.05) the concentrations of acetic (except in 3A1P, p > .05), propionic, and butyric acids compared to Alf alone. Adding CT improved the concentrations of propionic and butyric acids over the Alf treatment (p < .05). (2) The 1A1P, 1A3P, and PML treatments showed the maximum rate of gas production during fermentation when compared with the other treatments (p < .05). The asymptotic gas volumes of the treatments with added CT were less than the Alf treatment (p < .05). It can be concluded that a mixture of Alf and PML after in vitro fermentation for 96 h could improve the DDM and DOM contents, reduce gas production, and produce more short-chain fatty acids.

Compared with the sodium selenite (SeS), nano-selenium (SeN), selenomethionine (SeM), and selenium-enriched yeasts (SeY), as novel selenium sources, are increasingly popular in laying hen production. This study was aimed to investigate the advantages and mechanism of SeN, SeM, and SeY compared with SeS on laying performance and antioxidant capacity of ovary in laying hens. A total of 288 24-week-old Jingfen No.1 laying hens were randomly divided into 4 groups: SeS group, SeN group, SeM group, SeY group. The additive dosage of Se was 0.4 mg/kg. Each group contained 6 replications and each replication contained 12 laying hens. The results showed that SeN, SeM, and SeY increased the laying rate in laying hens compared with SeS, and SeM and SeY had a higher egg selenium conversion rate. SeN, SeM, and SeY significantly increased the levels of T-AOC and SOD, and increased the relative mRNA expression levels of SOD1, SOD2, and GPX2. SeS significantly regulated PPAR signaling pathway and fatty acid elongation of ovary, and the relative abundances of Solobacterium, Monoglobus, Coprobacter, Negativibacillus, Prevotella, and Treponema of gut microbiota. SeM significantly regulated linoleic acid metabolism, glycerophospholipid metabolism, choline metabolism in cancer of ovary, and the relative abundances of Prevotella, Methanocorpusculum, Peptococcus, and Treponema of gut microbiota. SeY significantly regulated biosynthesis of unsaturated fatty acids, fatty acid biosynthesis, glycerophospholipid metabolism, and linoleic acid metabolism of ovary, and the relative abundances of Akkermansia, Olsenella, and Romboutsia of gut microbiota. Meanwhile, the gut microbiota and differential metabolites of ovary were closely related to laying performance and antioxidant capacity of ovary. Therefore, 0.4 mg/kg SeN, SeM, and SeY showed an advantage on improving laying rate, ovary function, and gut microbiota in laying hens, and they could be potential additives using in laying hen production.

Flavoromics and metabolomics were used to evaluate the effects of selenium-enriched yeast (SEY) in hen feed on the volatile flavor and nutritional quality indicators in the resulting chicken meats. Volatile organic compounds (VOCs) were analyzed using GC-MS and odor activity value calculations. Ninety-eight VOCs were identified. The treatment group had more abundant VOCs, with mainly increased fat, mushroom, fruit, and vanilla odor. Modulating the nutritional profile of chicken meat through SEY feed can reduce saturated fatty acid levels, increase unsaturated fatty acid levels, and significantly reduce cholesterol levels in Dongxiang green-shell chicken (DX). Metabolomics analysis has elucidated the potential mechanisms, whereby adding SEY to the diet of DX reduces cholesterol levels through secondary bile acid biosynthesis pathways. Its related metabolic changes may also directly or indirectly promote the formation of key substances that give meat its flavor. Adding SEY to the diet of Jingfen laying hens affects the muscle metabolism environment via the propanoate metabolism pathway, increasing the grassy notes of chicken meat while reducing its gamey taste.