Simple Summary Essential oils can be used to improve animal performance as well as the health and quality of livestock products. The aim of this study was to evaluate the effects of essential oil supplementation on animal performance, ruminal fermentation, blood metabolites, and meat and milk quality of small ruminants through a meta-analysis. Supplementation with essential oils improved weight gain, milk production and composition, oxidative stability of meat, and blood serum antioxidant enzyme activity. Additionally, essential oils decreased methane emissions. This suggests that the inclusion of essential oils in the diets of small ruminants could be used to improve animal performance and the quality of meat and milk, in addition to reducing the environmental impact and oxidative stress of the animals. Abstract There is an increasing pressure to identify natural feed additives that improve the productivity and health of livestock, without affecting the quality of derived products. The objective of this study was to evaluate the effects of dietary supplementation with essential oils (EOs) on productive performance, rumen parameters, serum metabolites, and quality of products (meat and milk) derived from small ruminants by means of a meta-analysis. Seventy-four peer-reviewed publications were included in the data set. Weighted mean differences (WMD) between the EOs treatments and the control treatment were used to assess the magnitude of effect. Dietary inclusion of EOs increased (p < 0.05) dry matter intake (WMD = 0.021 kg/d), dry matter digestibility (WMD = 14.11 g/kg of DM), daily weight gain (WMD = 0.008 kg/d), and feed conversion ratio (WMD = −0.111). The inclusion of EOs in small ruminants’ diets decreased (p < 0.05) ruminal ammonia nitrogen concentration (WMD = −0.310 mg/dL), total protozoa (WMD = −1.426 × 105/mL), methanogens (WMD = −0.60 × 107/mL), and enteric methane emissions (WMD = −3.93 L/d) and increased ruminal propionate concentration (WMD = 0.726 mol/100 mol, p < 0.001). The serum urea concentration was lower (WMD = −0.688 mg/dL; p = 0.009), but serum catalase (WMD = 0.204 ng/mL), superoxide dismutase (WMD = 0.037 ng/mL), and total antioxidant capacity (WMD = 0.749 U/mL) were higher (p < 0.05) in response to EOs supplementation. In meat, EOs supplementation decreased (p < 0.05) the cooking loss (WMD = −0.617 g/100 g), malondialdehyde content (WMD = −0.029 mg/kg of meat), yellowness (WMD = −0.316), and total viable bacterial count (WMD = −0.780 CFU/g of meat). There was higher (p < 0.05) milk production (WMD = 0.113 kg/d), feed efficiency (WMD = 0.039 kg/kg), protein (WMD = 0.059 g/100 g), and lactose content in the milk (WMD = 0.100 g/100 g), as well as lower somatic cell counts in milk (WMD = −0.910 × 103 cells/mL) in response to EOs supplementation. In conclusion, dietary supplementation with EOs improves productive performance as well as meat and milk quality of small ruminants. In addition, EOs improve antioxidant status in blood serum and rumen fermentation and decrease environmental impact.

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Essential Oils as a Dietary Additive for Small Ruminants: A Meta-Analysis on Performance, Rumen Parameters, Serum Metabolites, and Product Quality

Polysaccharides are the most diverse molecules and can be extracted from abundant edible materials. Increasing research has been conducted to clarify the structure and composition of polysaccharides obtained from different materials and their effects on human health. Humans can only directly assimilate very limited polysaccharides, most of which are conveyed to the distal gut and fermented by intestinal microbiota. Therefore, the main mechanism underlying the bioactive effects of polysaccharides on human health involves the interaction between polysaccharides and microbiota. Recently, interest in the role of polysaccharides in gut health, obesity, and related disorders has increased due to the wide range of valuable biological activities of polysaccharides. The known roles include mechanisms that are microbiota-dependent and involve microbiota-derived metabolites and mechanisms that are microbiota-independent. In this review, we discuss the role of polysaccharides in gut health and metabolic diseases and the underlying mechanisms. The findings in this review provide information on functional polysaccharides in edible materials and facilitate dietary recommendations for people with health issues. To uncover the effects of polysaccharides on human health, more clinical trials should be conducted to confirm the therapeutic effects on gut and metabolic disease. Greater attention should be directed toward polysaccharide extraction from by-products or metabolites derived from food processing that are unsuitable for direct consumption, rather than extracting them from edible materials. In this review, we advanced the understanding of the structure and composition of polysaccharides, the mutualistic role of gut microbes, the metabolites from microbiota-fermenting polysaccharides, and the subsequent outcomes in human health and disease. The findings provide insight into the proper application of polysaccharides in improving human health.

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Polysaccharides influence human health via microbiota-dependent and -independent pathways

The traditional media used for the fermentation of Lactobacilli always contain carbohydrate polymers, which interfere with the analysis of the exopolysaccharide (EPS) produced by the bacteria. In this investigation, a novel medium formulation that could avoid such interference was successfully developed. The beef extract, yeast extract, and peptone used in this formulation were subjected to the removal of polysaccharides before use. The factors affecting the EPS production were optimized by a single factor test, Plackett–Burman design, and Box–Behnken design. The optimum formula was ascertained as: 7.5 g L–1 yeast extract, 12.5 g L–1 beef extract, 10 g L–1 peptone, 21.23 g L–1 maltose, 5.51 g L–1 yeast nitrogen base, 2 g L–1 K2HPO4, 5 g L–1 anhydrous sodium acetate, 2 g L–1 ammonium citrate, 0.58 g L–1 MgSO4⋅7H2O, 0.25 g L–1 MnSO4⋅H2O, and 1 mL L–1 Tween 80. The initial pH of the medium was 6.5. The optimized conditions for fermentation of the strain to produce EPS were as follows: seed size 1%, culture temperature 37°C, and culture time 20 h. Optimum results showed that EPS yield was 496.64 ± 3.15 mg L–1, being 76.70% higher than that of unoptimized conditions (281.07 ± 5.90 mg L–1). The EPS was mainly comprised of glucose and guluronic acid, with a weight average molecular weight of 19.9 kDa; it was also characterized by Fourier transform infrared spectroscopy and UV analysis. EPS was found to significantly enhance the phagocytic capacity, promote the NO, TNF-α, IL-1β, and IL-6 secretion, and improve mRNA expression of cytokines in RAW 264.7 macrophages, indicating its considerable immunomodulatory activity. Western bolt and immunofluorescence results demonstrated that the EPS was able to increase p65 nuclear translocation in the macrophages, indicating that EPS enhanced immunity via the NF-κB signaling pathway. EPS investigated in this work has potential as an attractive functional food supplement candidate for the hypoimmunity population.

Statistical Optimization of Novel Medium to Maximize the Yield of Exopolysaccharide From Lacticaseibacillus rhamnosus ZFM216 and Its Immunomodulatory Activity

Laminaria japonica is widely consumed as a key food and medicine. Polysaccharides are one of the most plentiful constituents of this marine plant. In this study, several polysaccharide fractions with different charge numbers were obtained. Their physicochemical properties and anticoagulant activities were determined by chemical and instrumental methods. The chemical analysis showed that Laminaria japonica polysaccharides (LJPs) and the purified fractions LJP0, LJP04, LJP06, and LJP08 mainly consisted of mannose, glucuronic acid, galactose, and fucose in different mole ratios. LJP04 and LJP06 also contained minor amounts of xylose. The polysaccharide fractions eluted by higher concentration of NaCl solutions showed higher contents of uronic acid and sulfate group. Biological activity assays showed that LJPs LJP06 and LJP08 could obviously prolong the activated partial thromboplastin time (APTT), indicating that they had strong anticoagulant activity. Furthermore, we found that LJP06 exerted this activity by inhibiting intrinsic factor Xase with higher selectivity than other fractions, which may have negligible bleeding risk. The sulfate group may play an important role in the anticoagulant activity. In addition, the carboxyl group and surface morphology of these fractions may affect their anticoagulant activities. The results provide information for applications of L. japonica polysaccharides, especially LJP06 as anticoagulants in functional foods and therapeutic agents.

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Physicochemical Properties and Anticoagulant Activity of Purified Heteropolysaccharides from Laminaria japonica

Introduction The crude protein level in the diet will affect the fermentation parameters, microflora, and metabolites in the rumen of ruminants. It is of great significance to study the effect of crude protein levels in supplementary diet on microbial community and metabolites for improving animal growth performance. At present, the effects of crude protein level in supplementary diet on rumen fermentation parameters, microbial community, and metabolites of Jersey-Yak (JY) are still unclear. Methods The purpose of this experiment was to study the appropriate crude protein level in the diet of JY. The rumen fermentation indexes (volatile fatty acids and pH) were determined by supplementary diets with crude protein levels of 15.16 and 17.90%, respectively, and the microbial community and metabolites of JYs were analyzed by non-target metabonomics and metagenome sequencing technology, and the changes of rumen fermentation parameters, microbial flora, and metabolites in the three groups and their interactions were studied. Results and Discussion The crude protein level in the supplementary diet had significant effects on pH, valeric acid, and the ratio of acetic acid to propionic acid (p < 0.05). The protein level had no significant effect on the dominant microflora at the phylum level (p > 0.05), and all three groups were Bacteroides and Firmicutes. The results of metabolite analysis showed that the crude protein level of supplementary diet significantly affected the metabolic pathways such as Bile secretion and styrene degradation (p < 0.05), and there were different metabolites between the LP group and HP group, and these different metabolites were related to the dominant microbial to some extent. To sum up, in this experiment, the effects of crude protein level in supplementary diet on rumen microorganisms and metabolites of JY and their relationship were studied, which provided the theoretical basis for formulating a more scientific and reasonable supplementary diet in the future.

https://www.frontiersin.org/articles/10.3389/fmicb.2023.1124917/pdf

Effects of dietary crude protein levels in the concentrate supplement after grazing on rumen microbiota and metabolites by using metagenomics and metabolomics in Jersey-yak

Polysaccharides derived from Laminaria japonica (LJPS) have shown a variety of beneficial effects on improving human health; however, the structural features and bioactivities of long-chain LJPS remain unclear. This study aimed to investigate the structural characteristics and bioactivities of a novel long-chain LJPS. Results showed that the LJPS was composed of Fuc, Rha, Ara, Gal, Glc, Xyl, Man, Fru, Rib, GalA, GluA, GlcA, and ManA, with a molar ratio of 35.71:1.48:0.28:13.16:0.55:2.97:6.92:0.58:0.41:0.14:3.16:15.84:18.79. Of these, Fuc, Gal, Man, GlcA, and ManA were the predominant components with an accumulated proportion of 93.6%. The LJPS was found to consist of seven types of the monomer residues, and the main interchain glycosidic linkages were β -D-(1 → 2), α -D-(1 → 3), (1 → 4), and (1 → 6), and the molecular mass was 5.79 × 104 g/mol. Regarding the molecular conformation, LJPS was a multi-branched, long-chain macromolecule, and appeared in a denser crosslinking network with highly branched and helix domains in the terms of morphology. Additionally, the LJPS had no toxicity to mouse macrophage cells and exhibited biphasic immuno-modulating capacity. The present findings suggested that the long-chain LJPS might be an attractive candidate as an immunopotentiating and anti-inflammatory functional food, and this study also provides a feasible approach to decipher the structural characteristics and spatial conformations of plant-derived polysaccharides.

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Structural Characteristics and Immunomodulatory Effects of a Long-Chain Polysaccharide From Laminaria japonica

The pelleted total mixed ration (PTMR) has a positive effect on the productivity of fattening lambs. However, whether the beneficial effects are underpinned by altering the rumen microbiota and metabolome that remain unclear. This study aimed to investigate correlations among growth performance, ruminal microbiota, and ruminal metabolome of lambs fed PTMR diet. A total of 100 crossbred (Dorper sheep × Fine-wool sheep) ram lambs at 55 days of age with similar body weight (BW) (13.2 ± 0.5 kg) were randomly allocated to 10 pens that were fed either PTMR (PTMR group) or unpelleted total mixed ration (UPTMR group) with the same dietary ingredients and nutritional contents. The average daily gain (ADG) and average daily feed intake (ADFI) were determined during the 62-day experimental period and ruminal pH, volatile fatty acid (VFA) concentrations, microbiota, and metabolome in the rumen of the lambs were examined at the end of the experiment. Compared to those of the UPTMR group, the PTMR group had greater ADFI (P = 0.002), ADG (P = 0.003), and feed efficiency (G/F) (P < 0.05). Similarly, feeding PTMR increased the concentration of total VFA (TVFA) and the molar proportion of propionate, but decreased the proportion of butyrate and acetate to propionate ratio in the rumen of lambs compared to that in lambs from the UPTMR group (P < 0.05). In addition, the PTMR group demonstrated lowered alpha-diversity of the ruminal microbiota and enhanced the relative abundance of Fibrobacter (P < 0.05), Veillonellaceae (P < 0.05), and the abundance of Rikenellaceae (P = 0.064) in the rumen compared with those in the UPTMR group. Feeding lambs with PTMR significantly upregulated the metabolic pathways involving tryptophan, histidine, cysteine and methionine, β-alanine, tyrosine metabolisms, and steroid biosynthesis. Moreover, the abundance of the microbiota strongly correlated with the altered performance, ruminal VFA, metabolites, and metabolic pathways of lambs. Taken together, feeding PTMR shaped the ruminal microbiota of lambs with decreased diversity, while improving relative abundance of some specific microbes and upregulating certain growth-related metabolic pathways, which contributed to the augmented growth performance and G/F of fattening lambs. Thus, feeding PTMR to fattening lambs for superior production performance and G/F is recommended.

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Diet Type Impacts Production Performance of Fattening Lambs by Manipulating the Ruminal Microbiota and Metabolome

Polysaccharides from alfalfa (Medicago sativa L.) (APS) exhibit a variety of bioactivities; however, little information is available on the effects of the ecological environment on the structural characteristics and bioactivities of APS. This study aimed to investigate the structural characteristics and bioactivities of two APS types isolated from alfalfa; these APSs were obtained from alfalfa cultured in normal soil (APS1) or saline-alkali soil (APS2). Results indicated that the two kinds of APS had the same monomer compositions in different molar proportions, where APS2 had greater content of arabinose and galacturonic acid than APS1. Furthermore, APS1 exhibited a greater molar mass of 1.77 × 105 g mol-1 as compared to 1.01 × 105 g mol-1 for APS2. Likewise, APS1 and APS2 had highly branched molecules with crosslinking nets composed of similar monomer residues but with different glycosidic linkages. Additionally, both APS significantly inhibited both adipogenesis and lipid accumulation in 3T3-L1 cells by downregulating mRNA expression of Ppar-γ, C/ebp-α, and Fas; APS2 had superior antiadipogenic effects as compared to APS1. Altogether, the ecological environment impacts the structural characteristics and biofunctions of APS, making them potential candidates for antiadipogenic use through functional food. These findings provide a novel perspective for the selection of phytogenic polysaccharides with specific bioactivities by considering growth environmental conditions.

Influence of the ecological environment on the structural characteristics and bioactivities of polysaccharides from alfalfa (Medicago sativa L.).

Correction for 'Influence of the ecological environment on the structural characteristics and bioactivities of polysaccharides from alfalfa (Medicago sativa L.)' by Chongyu Zhang et al., Food Funct., 2022, https://doi.org/10.1039/d2fo00371f.

Correction: Influence of the ecological environment on the structural characteristics and bioactivities of polysaccharides from alfalfa (Medicago sativa L.).

Yunpeng Wang

Papers

Structural Characteristics and Immunomodulatory Effects of a Long-Chain Polysaccharide From Laminaria japonica

Diet Type Impacts Production Performance of Fattening Lambs by Manipulating the Ruminal Microbiota and Metabolome

Influence of the ecological environment on the structural characteristics and bioactivities of polysaccharides from alfalfa (Medicago sativa L.).

Correction: Influence of the ecological environment on the structural characteristics and bioactivities of polysaccharides from alfalfa (Medicago sativa L.).