The aim of this experiment was to investigate the effect of Lycium barbarum polysaccharides (LBP) on alleviating soybean meal-induced enteritis (SBMIE) in spotted sea bass Lateolabrax maculatus. The diet with 44% fishmeal (FM) content was used as a blank control, and soybean meal (SM) was used to replace 50% FM as an experimental control to induce enteritis. Then, on the basis of experimental control, 0.10%, 0.15%, and 0.20% LBP were added as experimental diets. A total of 225 spotted sea bass (44.52 ± 0.24 g) were randomly divided into 5 groups and fed the corresponding diets for 52 d. The results showed that 0.15% LBP decreased serum D-lactic acid (D-LA) content and diamine oxidase (DAO) activity (P < 0.05). In addition, in all LBP supplementation groups, the intestinal tissue morphology was significantly improved (P < 0.05); the intestinal microbial structure gradually recovered to a level close to that without adding SM; and the microbial species richness and diversity were significantly increased (P < 0.05). Through transcriptomic and metabolomic analysis, it was found that the expression of proinflammatory factors such as interleukin-1β (IL-1β), interleukin-12 (IL-12), nuclear factor kappa B subunit 2 (NF-κB2), and Toll-like receptor 2 (TLR2) were significantly down-regulated in the mitogen-activated protein kinase (MAPK) and Toll-like receptor signaling pathways (P < 0.05), and the important tight junction protein gene Occludin was up-regulated (P < 0.05). In addition, LBP down-regulated saponin metabolites and up-regulated amino acid metabolites (P < 0.05). In conclusion, LBP demonstrated a significant alleviating effect on SBMIE of spotted sea bass L. maculatus.

The aim of this study was to investigate whether fish size has an effect on the utilisation efficiency of digestible protein, digestible fat and digestible carbohydrates (Carb) for energy gain in rainbow trout. Four different diets ranging in protein, fat and Carb were fed to two size classes of rainbow trout, 30 to 75 g and 92 to 214 g, at three different feeding levels (12, 8 and 4 g/kg^0.8 per day). This led to 24 treatments with 2 replicates (tanks). Tanks contained 36 fish for the 30 to 75 g fish and 24 fish for the 92 to 214 g fish. Faeces was collected for the determination of the digestibility of protein, fat and Carb. Energy retention was determined from the initial and final body composition. The design of this trial allowed for multiple regression analysis to determine the utilisation efficiency of the different digestible macronutrients for energy gain. By doing so, it was also possible to establish specific net energy (NE) formulae for 30 to 75 g and 92 to 214 g rainbow trout. The results showed that there were differences between the two size classes in the estimated NE formulae and the corresponding partial efficiencies of digestible protein, fat and Carb for NE (k_gNE,CP, k_gNE,Fat and k_gNE,Carb). The k_gNE,CP was not different (P = 0.586) between the two size classes (on average 76%), but the k_gNE,Fat decreased (P = 0.005) from 82% to 65% in the bigger fish and the k_gNE,Carb showed a tendency (P = 0.077) to increase from 55% to 73% in the bigger fish. The findings of this study showed that fish size has an effect on the estimation of net energy in feeds for rainbow trout.

Urea is a small molecule that can readily cross the blood-milk barrier into milk, leading to a strong correlation between blood urea nitrogen (BUN) and milk urea nitrogen (MUN) concentrations. Although MUN is a minor component of milk, it is a valuable and cost-effective tool to flag potential nutrition-related problems in dairy herds. Many studies have suggested that intake of dietary protein and energy, as well as their synchronized release in the rumen, are major factors influencing MUN concentration. Therefore, measuring MUN can serve as a valuable indicator for improving nutritional management in dairy herds. Both excessively high and low MUN values are undesirable for dairy cows due to their negative effects on reproductive performance, health, and nitrogen use efficiency. Moreover, research indicates that MUN is a trait with low to moderate heritability and is positively correlated to nitrogen excretion. However, there are still inconsistencies regarding selecting cows with a low MUN phenotype can effectively reduce nitrogen excretion and affect other economic traits in dairy cows. This paper provides an overview of MUN's utility in nutritional assessment, presents its relationship with economically important milk traits, reproductive performance, health, and nitrogen emissions. It also describes the backgrounds of the gastrointestinal microbiota, intestine and kidney physiology in cows with different MUN concentrations, aiming to further enhance our understanding of MUN and provide a reference for optimal diets of cows.

The present study investigated whether replacing dietary rice straw with peanut vine (PEV) and Broussonetia papyrifera silage (BPS) reduces the use of soybean meal and explored its effects on the growth performance, blood biochemical indicators, serum metabolomics, and meat quality of fattening bulls. Forty-five Simmental crossbred bulls (initial body weight = 484.29 ± 8.49 kg) were randomly allotted into three dietary treatment groups (n = 15): (1) CON, 5% rice straw (DM basis); (2) PEV, 5% peanut vine (DM basis); and (3) BPS, 5% B. papyrifera silage (DM basis). The remaining roughage for all three treatment groups was supplemented with 25% corn silage (DM basis). The experiment lasted for 123 d, with the first 14 d serving as an adaptive period. Throughout the experiment, dietary BPS decreased the average daily dry matter intake (P < 0.001) and feed cost (P < 0.001). Serum metabolomics analysis showed that PEV affected the phenylalanine, tyrosine, and tryptophan biosynthesis pathways (P = 0.021) and lysine degradation pathway (P = 0.042), whereas BPS affected the phenylalanine, tyrosine and tryptophan biosynthesis pathways (P = 0.004), lysine degradation pathway (P = 0.012), and serotonergic synapse pathway (P < 0.001). Regarding meat quality, the redness (P = 0.025) and hue angle values (P < 0.001) of the longissimus dorsi muscle were lower in the BPS group than in the CON and PEV groups. The yellowness of the longissimus dorsi muscle was lower in the BPS group than in the PEV group (P = 0.024), and the shear force was lower in the PEV group than in the BPS group (P = 0.014). However, lysine content in beef was higher in the BPS group than in the CON group (P = 0.005). In conclusion, replacing rice straw with PEV and BPS reduced the use of soybean meal but had no adverse effects on growth performance. BPS affected the amino acid metabolism of bulls, thus decreasing feed intake and increasing the lysine content in meat. The PEV group showed better meat quality than the BPS group.

Multiple stressors are believed to deteriorate production performance and cause substantial economic losses in commercial poultry farming. Folic acid (FA) is an antioxidant compound that can improve oocyte function and regulate gut microbiota composition. The current study was conducted to investigate the role of FA in alleviating stress and improving production performance. Sixty Hyline Brown laying hens at 21 weeks of age were randomly divided into three groups, with 10 replicates in each group and each replicate containing two chickens. Each group received basic diet and saline injection (Con group), basic diet with dexamethasone (DXM) injection (DXM group), or basic diet supplemented with FA (13 mg/kg in the premix) with DXM injection (FA group). The feeding trial lasted five weeks. Birds in the DXM and FA groups receiving subcutaneous DXM injections at a dosage of 4.50 mg/kg per day during the first seven days of the trial. Results showed that the levels of corticosterone, triglyceride, total cholesterol, and malondialdehyde in serum were significantly increased in the DXM group (P < 0.05), while the concentrations of FA and 5-methyltetrahydrofolate were decreased in the DXM group (P < 0.05). Laying hens in the DXM group had lower laying rates and egg quality, including egg weight, eggshell thickness, eggshell strength, albumen height, and Haugh units (P < 0.05). Conversely, FA alleviated these negative impacts. Through transcriptome analysis, a total of 247 and 151 differentially expressed genes were identified among the three groups, and 32 overlapped genes were further identified. Moreover, 44 and 59 differential metabolites were influenced by DXM and FA, respectively. Kyoto Encyclopedia of Genes and Genomes enrichment from the transcriptome and metabolomics showed that the reduced production performance may be due to the disturbance of oocyte production, calcium metabolism, and oxidative stress. Analysis of 16S rRNA gene amplicon sequences revealed the differential microbial composition and potential functional changes among the different groups. LEfSe analysis showed that Mucispirillum and Nautella were the predominant bacteria in the DXM group, while Clostridium was the predominant bacteria in the FA group. Functional prediction demonstrated that stressors enhanced fatty acid biosynthesis, while betaine biosynthesis and retinol metabolism were elevated in the FA group. Dietary FA reversed the elevated levels of bile acids (BA), including cholic acid, taurodeoxycholic acid, and taurochenodeoxycholic acid (P < 0.05). The DXM group showed an overall decrease in short-chain fatty acids (SCFA), but FA restored the concentrations of acetic acid, propionic acid, and isobutyric acid (P < 0.05). In conclusion, this study reveals that dietary FA can alleviate the degradation of production performance caused by stress through improving circulating antioxidant capacity, maintaining intestinal microbiota homeostasis, and regulating SCFA and BA biosynthesis. Thus, highlighting the prominent role of gut microbe-host interactions in alleviating multi-stresses.

Energy is a crucial component for maintaining egg production in layers. The hypothalamic-pituitary-ovarian (HPO) axis is an energy-sensitive functional axis for follicle development, synthesis, and secretion of reproductive hormones, and plays a key role in modulating sustained ovulation in layers. To investigate the mechanism of integrated network regulation of the HPO axis under energy fluctuation, ninety Hy-line brown layers (265-day-old, 1.92 ± 0.02 kg) were randomly divided into three groups for a 17-day experiment: a control group (Con group) fed ad libitum from days 1 to 17, an energy-deprived group (ED group) that was fed ad libitum from days 1 to 12 and then underwent a fasting period from days 13 to 17 to induce a pause in laying, and a re-fed group (Rf group) that fasted for seven days (specifically, days 1 to 5, day 7, and day 9), had ad libitum access to feed on days 6 and 8, and was continuously fed from days 10 to 17. Each treatment consisted of 10 replicates with 3 birds per replicate. The study found that energy deprivation significantly decreased reproductive performance such as egg laying rate, ovarian index, number of small yellow follicles (SYF), and normal hierarchical follicles (NHIE) (P < 0.05), which recovered after refeeding, indicating the importance of energy availability for sustained ovulation in layers. In addition, estradiol (E2), estradiol to progesterone (E2/P4) ratio, and luteinizing hormone (LH) displayed changes similar to follicle number, whereas follicle-stimulating hormone (FSH) exhibited a contrasting pattern. Transcriptome analysis revealed that energy deprivation downregulated genes related to energy and appetite-regulated neurotransmitter receptors and neuropeptides in the hypothalamus. These signals combined to inhibit gonadotropin-releasing hormone (GnRH) secretion and subsequently downregulated the crucial genes responsible for synthesizing gonadotropins, gonadotropin-releasing hormone receptor (GnRHR), and glycoprotein hormones alpha chain (CGA). Consequently, this suppression of the hypothalamus and pituitary affected ovarian function through ovarian steroidogenesis and the extracellular matrix (ECM)-receptor interaction. These findings suggest that energy deprivation inhibits the function of the HPO axis, leading to impaired follicle development and reduced egg production, and that refeeding can partially restore these indicators.

The objectives of the current study were to compare the difference between standardized ileal digestibility (SID) and standardized total tract digestibility (STTD) of phosphorus (P) in pigs using published data and investigate the factors that affect the hindgut disappearance of P in pigs. A total of 156 observations from 32 experiments that determined the apparent ileal digestibility and total tract digestibility of P in pigs were collected. The SID and STTD of P were calculated by accounting for basal endogenous losses of P. Standardized hindgut disappearance (SHD) of P was determined by subtracting the SID of P from the STTD of P. The Chi-square test was performed to investigate the association between SHD of P and categorical variables, including the use of phytase, the use of inorganic P sources, the use of corn-soybean meal-based diets, and body weight (BW) of pigs. To determine the effects of the SID of P on the SHD of P, a linear equation for the SHD of P was developed using the SID of P as an independent variable. The BW of pigs ranged from 10.0 to 104.8 kg and the SHD of P ranged from −22.8% to 39.8%. The STTD of P was greater than the SID of P (47.1% vs. 49.7%; P = 0.019). Based on the Chi-square analysis, the supplementation of inorganic P sources tended to result in a higher occurrence of a positive value for the SHD of P (P = 0.079). In addition, the occurrence of a positive value in the SHD of P was lower when the BW of pigs was below 30 kg. However, as the BW of pigs increased, the occurrence of a positive value in the SHD of P increased (P = 0.061). A regression analysis of the SHD of P against the SID of P in pigs indicated that the SHD of P decreased as the SID of P increased in pigs (r² = 0.17; P < 0.001). In conclusion, the STTD of P is greater than the SID of P in pigs, and the SHD of P depends on the diet composition, the amount of P entering the large intestine, and the BW of the pigs.

Weaning stress causes substantial economic loss in the swine industry. Moreover, weaning-induced intestinal barrier damage and dysfunction of the gut-liver axis are associated with reduced growth performance in piglets. Metasilicate-based alkaline mineral water (AMW) has shown potential therapeutic effects on gastrointestinal disorders; however, the mechanisms involved and their overall effects on the gut-liver axis have not been explored. Here, sodium metasilicate (SMS) was used to prepare metasilicate-based AMW (basal water + 500 mg/L SMS). A total of 240 newly weaned piglets were allocated to the Control and SMS groups (6 replicate pens per group and 20 piglets per pen) for a 15-day trial period. Histopathological evaluations were conducted using hematoxylin and eosin staining. To analyze the composition of the gut microbiota, 16S rRNA PacBio SMRT Gene Full-Length Sequencing was performed. Western blotting and immunofluorescence were employed to assess protein expression levels. Our results indicated that metasilicate-based AMW effectively alleviated weaning-induced colonic or liver morphological injury and inflammatory response, as well as liver cholesterol metabolism disorders. Further analysis showed that metasilicate-based AMW promoted deoxycholic acid (DCA) biosynthesis by increasing the abundance of Lactobacillus_delbrueckii in the colon (P < 0.001). This consequently improved weaning-induced colon and liver injury and dysfunction through the DCA-secondary bile acid (SBA) receptors (SBAR)-nuclear factor-kappaB (NF-κB)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) pathways. Growth performance parameters, including final body weight (P = 0.034) and average daily gain (P < 0.001), in the SMS group were significantly higher than those in the Control group. Therefore, metasilicate-based AMW maintains gut-liver axis homeostasis by regulating the microbiota-mediated SBA-SBAR pathway in piglets under weaning stress. Our research provides a new strategy for mitigating stress-induced gut-liver axis dysfunction in weaned piglets.

This study aimed to explore the effects of glutamate (Glu) supplementation on the growth performance, carcass traits, meat quality, composition of amino acids and fatty acids in the longissimus dorsi muscle, and the colonic microbial community of Shaziling pigs. A total of 48 healthy male Shaziling pigs (150 d, 31.56 ± 0.95 kg) were randomly assigned to two groups, and fed a basal diet with no supplement (control group) or supplemented with 1% Glu (Glu group) for 51 d, and 6 pigs per group were finally slaughtered. Glu significantly increased the average daily gain (P = 0.039), lean percentage (P = 0.023), and intramuscular fat (IMF) content (P = 0.015), and decreased the fat percentage (P = 0.021) of Shaziling pigs. In the muscle, Glu increased the concentrations of inosine-5′-monophosphate (P = 0.094), Fe (P = 0.002), Cu (P = 0.052), and monounsaturated fatty acids (MUFAs) (P = 0.024), and decreased the content of C18:2n6 (P = 0.011), n-6 polyunsaturated fatty acids (n-6 PUFAs) (P = 0.014), and PUFAs (P = 0.014). Moreover, Glu significantly upregulated the mRNA expression of adipogenesis-related genes (FAS, SREBP-1C) (P = 0.032, P = 0.026) and muscle growth-related genes (MyHCIIb, MyHCIIx) (P = 0.038, P = 0.019) in the muscle, and increased the relative abundance of Spirochaetota (P < 0.001) and the acetic acid content in the colon (P = 0.039). Correlation analysis indicated that the acetic acid content was positively correlated with the relative Spirochaetota abundance and the IMF content, and a negative trend with the fat percentage of Shaziling pigs. In conclusion, these results indicated that Glu could simultaneously increase the lean percentage and IMF content and decrease the fat percentage of Shaziling pigs, and these beneficial effects may be related to increased colonic Spirochaetota abundance and acetic acid concentrations.

The intensifying global warming may increase the impact of heat stress on the dairy industry. Our previous study showed that chromium yeast (CY) alleviated the negative effects of heat stress and improved the lactation performance by increasing milk protein content and yield in mid-lactation dairy cows. This study further investigated whether the increased milk protein after CY supplementation results from the promotion of microbial crude protein (MCP) synthesis by regulating rumen microorganisms and amino acid metabolites. Twelve heat-stressed dairy cows were divided into two treatment groups: one with CY supplementation (0.36 mg Cr/kg DM) and the other without CY supplementation. Samples were collected after eight weeks of formal experiment in a hot summer with the mean temperature-humidity index of 79.0 ± 3.13. Dietary CY supplementation did not affect rumen pH, total volatile fatty acid, acetate, propionate, isobutyrate, butyrate, isovalerate, and valerate, but increased ruminal MCP concentration (P < 0.05). Simultaneously, the alpha or beta diversity of rumen microbial bacteria were not influenced by CY supplementation. At genus level, supplementation with CY increased the relative abundances of Olsenella, Lachnospiraceae_UCG-002, and Shuttleworthia (P < 0.05) and decreased those of Enterobacter, Escherichia-Shigella, Oribacterium, and Bacteroidetes_BD2-2 (P < 0.05). There were 17 up-regulated and 57 down-regulated differential metabolites in the CON and CY groups. The partial least-squares discriminant analysis (PLS-DA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) scores clearly distinguished the two groups. Chromium yeast supplementation reduced the concentrations of D-(+)-proline, DL-glutamic acid, DL-lysine, Gly-l-pro, L-(−)-serine, L-(+)-alanine, and L-(+)-aspartic acid (P < 0.05) in the ruminal fluid, which were involved in arginine biosynthesis (P = 0.029), glutathione metabolism (P = 0.047), lysine degradation (P = 0.069), and D-amino acid metabolism (P = 0.084). Spearman correlation analysis showed that milk protein content was positively correlated with MCP and negatively correlated with amino acid concentrations in the ruminal fluid (P < 0.05). Collectively, CY supplementation promoted the utilization of amino acids by rumen microorganisms to synthesize MCP, thereby increasing milk protein content and yield in heat-stressed dairy cows.

It has been found that thymol (Thy) and rosmarinic acid (Ros-A) improve the growth performance of piglets and relieve intestinal inflammation in animals. The effects of Thy and Ros-A separately or in combination (Thy × Ros-A) on the intestinal function and health of piglets challenged with Escherichia coli K88 (E. coli K88) were investigated. A total of 30 piglets aged 21 d were assigned to 5 groups (n = 6). The control (Con) and K88 groups piglets received a basal diet, while the Thy, Ros-A, and Thy × Ros-A groups were fed a basal diet supplemented with 500 mg/kg Thy, 500 mg/kg Ros-A, and 250 mg/kg Thy + 250 mg/kg Ros-A, respectively. On the 19th and 20th day, piglets in the K88, Thy, Ros-A, and Thy × Ros-A groups were orally administered 10 mL of phosphate-buffered saline (PBS) containing approximately 1 × 10⁹ CFU/mL of E. coli K88, while the Con group received an equal volume of PBS. The results showed that the Thy × Ros-A treatment reduced the damage to ileal villi induced by the E. coli K88 challenge, leading to longer villi in the ileum (P < 0.05). Thy and Ros-A modulated the composition of the ileal microbiota. Compared to the K88 group, the Thy × Ros-A group had a higher abundance of Lactobacillus and Romboutsia, while Escherichia-Shigella and Desulforvibrio were lower (P < 0.05). Additionally, the Thy × Ros-A group showed elevated levels of gene and protein expressions for zonula occludens-1, occludin, and claudin-1 compared to the K88 group (P < 0.05). In conclusion, combining Thy and Ros-A reduced ileal damage and relieved the inflammation in weaned piglets challenged with E. coli K88 by regulating intestinal microflora and improving barrier function.

Methionine (Met) metabolism is vital for one carbon metabolism, redox status and fetal development. Hence, this study investigated the effects of different levels and sources of Met on maternal metabolism, anti-oxidative capacity and fetal survival in pregnant sows. Forty primiparous sows were assigned to the following four groups: control group (basal diet, CON), 1.5S-OHMet group (supplemented methionine hydroxy analogue [OHMet] at 1.5 g/kg diet), 3.0S-OHMet group (supplemented OHMet at 3.0 g/kg diet), and 3.0S-Met group (supplemented L-Met at 3.0 g/kg diet) (n = 10). The trial lasted from day 60 of gestation to the farrowing day. Maternal 1.5S-OHMet consumption had the lowest stillborn ratio and the highest serum glucose levels during farrowing. Further analysis revealed that dietary 1.5S-OHMet consumption elevated the serum contents of glucose-6-phosphate, citric acid, butyric acid, malic acid, 3-methyladenine, 1-methyladenosine, ferulic acid and salicylic acid, but reduced the serum contents of succinic acid, oxoglutaric acid, 9(S)-hydroperoxylinoleic acid, 13(S)-hydroperoxy-octadecatrienoic acid, uric acid and urea nitrogen when compared to contents observed in the 3.0S-OHMet and 3.0S-Met groups (P < 0.05). Serum metabolomics analysis was conducted to determine the enriched differential metabolites and an enrichment analysis was performed using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The results showed that the enriched metabolites were mainly associated with central carbon metabolism, amino acid metabolism, lipid metabolism, and nucleotide metabolism. Moreover, maternal 3.0S-OHMet or 3.0S-Met consumption upregulated the trans-methylation pathway by elevating the S-adenosyl-methionine (SAM) level and the ratio of SAM to S-adenosyl-homocysteine (P < 0.05) at day 114 of gestation, while increasing homocysteine concentration (P < 0.001). However, compared to the 3.0S-Met group, maternal 3.0S-OHMet consumption elevated fetal survival and glutathione peroxidase (P < 0.05). Thus, this study provided new insights into the mechanisms through which sows fed with a 1.5S-OHMet diet during mid-to late-gestation period had high fetal survival, such as improvements in maternal amino acid, nucleotide and glycolipid metabolism.

This research explored the protective impact of bamboo leaf flavonoids (BLF) in diquat (DQ) stressed broilers; providing insight of antioxidant, immune response and intestinal barrier function. This experiment consisted of two parts. In the first, 240 chicks were allotted to 2 groups with 8 replicates and 15 chicks per replicate. Treatments consisted of a basic feed (control group, CON) and the basic feed plus 1000 mg/kg BLF (BLF group, BLF) for 28 d, respectively. Then, following the conclusion of the first part, 16 healthy broilers were selected from the CON group and the BLF group. They formed the second part of the experiment, and were allotted to 4 treatments with 8 broilers each: CON-no stress (CON-NS) group, CON-DQ group, BLF-NS group and the BLF-DQ group. Broilers were separately injected intraperitoneally with DQ solution at 40 mg/kg body weight or the same dose of phosphate buffer saline. The results revealed adding BLF to diet reduced the ratio of feed to weight gain of broilers compared to the basic feed group (P = 0.021). In comparison to the CON-NS group, BLF improved the levels of serum and jejunal mucosa total antioxidant capacity, immunoglobulin M, serum catalase, immunoglobulin A, interleukin 10, jejunal mucosa interleukin 4, cecal butyric acid, valeric acid, isobutyric acid, isovaleric acid, upregulated zonula occludens-1 (ZO-1), occludin (OCLN) and claudin-1 (CLDN1) expressions, and reduced the levels of jejunal mucosa malondialdehyde (MDA), interleukin 1β, interleukin 6 and serum diamine oxidase (P < 0.05). Diquat stress elevated the contents of serum MDA, D-lactate, jejunal mucosa tumor necrosis factor α, reactive oxygen species and unclassified_f_Lachnospiraceae relative abundance, downregulated ZO-1, OCLN and CLDN1 expressions, and reduced Sobs, Chao and Ace indices (P < 0.05). Compared with CON-NS group, the concentration of isovaleric acid in the BLF-DQ group was higher (P < 0.05). In conclusion, by establishing a DQ stress injury model, it was elucidated that BLF may enhance antioxidant capacity, strengthen immunity, regulate volatile fatty acid contents, improve intestinal morphology, microbiota and other intestinal barrier functions, so as to mitigate the injury induced by oxidative stress in broilers.

Heat stress can lead to decreased feed intake, apoptosis of mammary epithelial cells, and decreased milk yield and quality. Selenium is an important element in the composition of at least 25 selenoproteins. Hydroxy-selenomethionine (HMSeBA) is a novel organic selenium that has been shown to have a better deposition effect. However, whether HMSeBA alleviates damage to the mammary gland blood-milk barrier caused by heat stress and how this affects the performance of dairy cows remain largely unexplored. Therefore, 32 healthy Holstein cows with similar gestation days (150.41 ± 20.07 d), milk yield (36.15 ± 3.02 kg) and parity (3.25 ± 0.51) were selected and randomly divided into two total mixed rations with different selenium (Se) sources: sodium selenite (SSe) and HMSeBA. This study evaluated the outcomes of HMSeBA on antioxidant capacity, immunity, and blood-milk barrier damage in dairy cows during heat stress by collecting the samples of blood, rumen fluid and mammary gland biopsy. The experiment was conducted over 35 d, including a 5-day pre-feeding period and a 30-day experimental period. The temperature and humidity index (THI) were all above 80 throughout the experiment period. The results showed that HMSeBA decreased the respiratory rate (P < 0.001) and the content of inflammatory cytokines in the serum and increased the content of immune factors and antioxidant capacity (P < 0.05). In addition, HMSeBA reduced the expression of inflammatory cytokines and heat shock proteins in mammary gland (P < 0.05). Hematoxylin-eosin-stained pathological sections showed massive thickening of acinar walls and severe destruction of glandular structures in the SSe group, but the structure of the acinar mammary gland in the HMSeBA group was intact. Furthermore, HMSeBA promoted the expression of the phosphatidylinositol 3-kinase (PI3K, P < 0.001)/protein kinase B (AKT, P = 0.011)/mammalian target of rapamycin (mTOR, P = 0.008) pathway and improved the expression of zonula occludens-1 (ZO-1, P = 0.014) and occluding (OCLN, P = 0.012) in the mammary gland, suggesting less damage caused by heat stress to the blood-milk barrier. Our results demonstrated that HMSeBA can improve the antioxidant capacity and immunity of dairy cows and the expression of tight junction proteins in mammary gland to help alleviate the blood-milk barrier damage by heat stress, which could reduce the damage of heat stress on milk yield.

Bacteroides fragilis (B. fragilis), a crucial commensal bacterium within the gut, has shown connections with hepatic lipid metabolism and inflammation regulation. Nonetheless, the role of B. fragilis in the progression of fatty liver hemorrhagic syndrome (FLHS) remains unknown. This study aims to explore the ameliorative effects of B. fragilis on FLHS in laying hens, as well as its underlying mechanisms. This is the first study to employ a chicken FLHS model, combining microbiomics and oxylipin metabolomics to investigate the mechanism of action of intestinal symbiotic bacteria. Exp. 1: 40 laying hens at 25 weeks old were randomly divided into five treatment groups (eight replicates per group and one hen per replicate), including the control group (basal diet), the high-energy and low-protein (HELP) group, and the HELP group with three different levels (10⁸, 10⁹, and 10¹⁰ CFU) of B. fragilis. Exp. 2: 18 chickens at 25 weeks old were randomly divided into three treatment groups (six replicates per group and one hen per replicate) including the control group (basal diet), the model group (HELP diet), and the arachidonic acid (AA) group (HELP diet with 0.3% AA). The experiment period of Exp. 1 and Exp. 2 were 8 weeks. B. fragilis significantly improved body weight of seventh week (P = 0.006), liver lipid degeneration, blood lipid levels (triglycerides, cholesterol, and low-density lipoprotein cholesterol; P < 0.05), and liver function (alanine aminotransferase and aminotransferase; P < 0.05) in laying hens. B. fragilis downregulated the expression of lipid synthesis-related genes fatty acid synthase, acetyl-CoA carboxylase, and liver X receptor α, and inflammation-related genes tumor necrosis factor α, interleukin (IL)-1β, IL-6, and IL-8 in the liver of FLHS-affected hens (P < 0.05), while upregulating the expression of lipid oxidation-related genes carnitine palmitoyl transferase-1, peroxisome proliferator activated receptor (PPAR) α, and PPARγ (P < 0.05). The in-depth analysis indicated alterations in oxylipin pathways triggered by B. fragilis, as evidenced by changes in the expression of pivotal genes arachidonate 15-lipoxygenase, arachidonate 5-lipoxygenase (P < 0.05), subsequently causing modifications in relevant metabolites. This included a decrease in pro-inflammatory substances such as 15-oxoETE (P = 0.004), accompanied by an increase in AA (P = 0.008). B. fragilis regulated the homeostasis of intestinal flora by increasing the abundance of Bacteroides and decreasing the abundance of Succinatimonas and Faecalicoccus (P < 0.05). The integrated analysis revealed a robust positive correlation between Bacteroides abundance and AA levels (P = 0.007). This relationship was corroborated through in vitro experiments. Subsequently, the beneficial effect of AA in mitigating FLHS was confirmed in laying hens with FLHS, further supported by reverse transcription-polymerase chain reaction analysis demonstrating gene expression patterns akin to B. fragilis intervention. This study demonstrated that B. fragilis exerts an anti-FLHS effect through modulation of oxylipin metabolism and gut microbiota stability, with a pivotal role played by AA.

Grape seed proanthocyanidin (GSP) is a type of plant polyphenol with a wide variety of biological activities, such as antioxidant properties. This study investigated the effects of GSP supplementation on growth performance and meat quality in growing-finishing pigs. A total of 180 pigs (with an initial average body weight of 30.37 ± 0.66 kg) were randomly assigned to five treatments: a control diet or a control diet supplemented with GSP at 15, 30, 60, and 120 mg/kg. Each treatment group comprised six replicate pens (6 pigs per pen). Results showed that GSP supplementation linearly increased the average daily gain (P = 0.048) and quadratically decreased the feed intake to gain ratio (P = 0.049) with the lowest values at 30 and 60 mg/kg GSP. Serum concentrations of immunoglobulins (Ig) (IgA, IgG, IgM), total antioxidative capacity, catalase, and total superoxide dismutase were elevated with the peak levels at 30 mg/kg GSP (P < 0.05). Serum glutathione peroxidase increased and malondialdehyde decreased quadratically (P < 0.05), with peak and trough levels at 120 and 60 mg/kg GSP, respectively. The GSP also improved dressing percentage and muscle redness (a^*_{45 min}) with optimal levels at 30 and 60 mg/kg (P < 0.05). Additionally, GSP supplementation quadratically reduced the muscle yellowness (b^*_{24 h}) and shear force (P < 0.05), with the lowest values at 120 mg/kg. The expression level of myosin heavy chain I in muscle was quadratically increased with maximum expression at 30 and 60 mg/kg (P = 0.015). Furthermore, the expression levels of fatty acid synthase, phosphoenolpyruvate carboxykinase (PEPCK), and glucokinase in the muscle were decreased quadratically (P < 0.05) with the lowest values at 120 mg/kg. Additionally, GSP supplementation at 60 mg/kg upregulated the expression of hepatic hormone-sensitive triglyceride lipase and PEPCK (P < 0.05). These results suggest that GSP enhances carcass characteristics and meat quality in growing-finishing pigs, potentially through improved antioxidative capacity, modified muscle fiber type distribution, and altered glucose-lipid metabolism in muscle and liver.

During the growing period, the gastrointestinal tract of layer pullets is not yet well developed and may be susceptible to dietary energy level. The energy level and composition might impact the intestinal energy metabolism of layer pullets. To test this hypothesis, a total of 480 “Jing Tint 6” layer pullets were used in an 8-week study and allocated to 4 groups, each consisting of 8 replicates, with 15 birds per replicate. Pullets were treated with low or high starch:fat ratios (LS, 10:1; HS, 20:1) in a 2 × 2 factorial arrangement with regular energy (RE, 11.85 and 11.68 MJ/kg for birds from 6 to 10 weeks of age and 11-14 weeks of age, respectively) or low energy (LE, 0.55 MJ/kg lower than RE) levels. A significant interaction (P < 0.05) showed that HS increased glandular stomach weight and the jejunal villus length to crypt depth ratio (VCR) in LE diets, but decreased these parameters in RE diets. Dietary energy reduction impaired energy metabolism in the ileum (P < 0.05) mainly via decreasing the gene expression of enzymes involved in the tricarboxylic acid (TCA) cycle (α-ketoglutarate dehydrogenase complex [α-KGDH]; isocitrate dehydrogenase (NAD (+) [IDH] catalytic; citrate synthase [CS]) and adenosine triphosphate (ATP) synthesis, reducing contents of phosphoenolpyruvate (PEP) and adenylate energy charges (AEC) and down-regulating the adenosine monophosphate-activated protein kinase (AMPK) pathway. HS stimulated AMPKα phosphorylation, increased protein abundance of peroxisome proliferator activated-receptor gamma coactivator 1α (PGC1α) and improved contents of amino acids (aspartate, glutamate, glutamine, alanine and threonine) and malate in the ileum regardless of energy levels (P < 0.05). By an interaction (P < 0.05), the transition from LS to HS diets up-regulated ileal gene expression of AMPKα1 and decreased content of adenosine monophosphate (AMP), accompanied by higher AEC but only in birds fed with LE diets. Collectively, these results suggest that low energy feeding may not be enough for maintaining intestinal energy homeostasis in layer pullets and emphasizes the importance of a relatively high starch:fat ratio in restoring energy metabolism in the ileum.

The current study aims to investigate the potential interaction between glycosylation profiles of the Ningxiang breed (NX) and Western Duroc × Landrace × Yorkshire breed (DLY) weaned piglets, and their characteristic microbes, employing integrated analyses of transcriptomics and metagenomics. Twenty-four (12 NX and 12 DLY) at 28 days of age were transported into an experimental house and fed the same weaned piglet diet. The trail period was 7 days. Results revealed that the NX piglets had a higher growth-to-feed ratio, body weight gain scale, and lower pathological score of intestinal injury compared with the DLY piglets (P < 0.01). DLY piglets displayed elevated mRNA expression levels of MUC2 and MUC5AC in colonic mucosal tissue than NX piglets (P < 0.05). Within the O-linked glycosylated differentially expressed genes (DEGs), FNTA, GALNT18, POMGNT1, POMGNT2, and POMT1 were significantly upregulated in DLY piglets relative to NX piglets (P < 0.05). Conversely, C1GALT2, GALNT1, KMT2C, and OGT were significantly downregulated in DLY piglets compared to NX piglets (P < 0.05). The KMT2C gene was hardly expressed in the transcriptome of DLY piglets. At the phylum taxonomic level, NX piglets had a higher abundance of Firmicutes, while DLY piglets had a higher abundance of Proteobacteria. At the genus taxonomic level, NX piglets had a higher abundance of Lactobacillus, whereas DLY piglets had a higher abundance of Collinsella, Enterococcus and Escherichia. The results of the correlation between intestinal differential bacteria and O-chain glycosylated DEG showed that C1GALT2, GALNT1 and KMT2 were associated with Lactobacillus_pontis showed a positive correlation (R = 0.67). Through comparative analysis of differentially glycosylated genes and their associated functions, this study highlights the potential role of reduced expression of GALNT1 and KMT2C genes, involved in O-linked protein and glycan reactions, in impairing the intestinal barrier function of DLY piglets. Furthermore, members of the Lactobacillus and Prevotella genera may actively contribute to the regulation of piglet colon glycosylation profiles.

Growth retardation affects the health and production of livestock, while overexertion can cause sudden cardiac arrest. Both cases are considered to be metabolic disorders and are detrimental to livestock production. Effective measures for relieving or treating these disorders are scarce. However, Pimpinella thellungiana H. Wolff (P. thellungiana), a medicinal herb, has been reported to relieve growth retardation and overexertion in ethnopharmacological clinical trials. This paper summarizes and classifies a total of 106 bioactive compounds that were isolated and identified from P. thellungiana, including flavonoids, simple phenylpropanoids, coumarins, volatile compounds, and simple polyphenols, and discusses its pharmaceutical benefits, including its growth-promoting, antioxidant, anti-inflammatory, anti-atherosclerotic, and hepatoprotective properties. The nutrition, metabolism, biological activities, and pharmacological effects of the principal compounds of P. thellungiana in livestock are reviewed, as well as their potential molecular targets and metabolic signaling pathways in which these compounds are involved. However, the pharmacological and toxicological effects of some compounds have not been well documented, and further investigations of the bioactive compounds are needed. Such studies are crucial for the development of natural drugs or feed additives from P. thellungiana to alleviate growth retardation and mitigate injuries from overexertion in livestock.

This study addressed the escalating demand for aquatic feed by exploring the potential of alfalfa nutrient concentrate (ANC) as feed ingredient for rainbow trout. Test diets contained varying ANC levels (0%, 5%, 10%, 15%, and 20%) to replace fishmeal (32% in the 0% ANC diet) to achieve equal digestible protein and were processed using a cooking extrusion method. Analysis of feed pellets showed that pellet density increased with ANC levels (P < 0.001), resulting in sinking pellets at 20% ANC. Water stability and durability were improved while oil leakage decreased with increasing ANC levels (P < 0.05). Two feeding trials were conducted to test the diets in flow-through water systems with three replicates per diet. The first 10-week trial evaluated their impact on feeding, fecal physical quality, and the apparent digestibility coefficient (ADC) of dietary nutrients in rainbow trout (initial body weight 18.0 ± 0.2 g). ANC inclusion did not impact the palatability and satiety feed intake of the fish (P > 0.05). However, the ADC of dry matter and phosphorus significantly decreased in fish fed the 20% ANC diet (P < 0.05). The second 9-week trial investigated the growth performance, nutrition quality, and metabolism of rainbow trout (initial body weight 19.0 ± 0.2 g). While all fish exhibited substantial growth, fish fed diets with 10% to 20% ANC displayed lower specific growth rate and higher feed conversion ratio compared to those fed with 0% or 5% ANC (P < 0.05). The whole body protein content was higher in fish fed 5% ANC compared to all other treatments (P = 0.030). The biochemical parameters of plasma were similar across treatments, except for a decrease in plasma phosphorus levels in fish fed a 10% ANC diet compared to those fed a 0% ANC diet (P = 0.033). Significant changes were observed in liver metabolism including tricarboxylic acid cycle, amino acid and energy metabolism pathways in fish fed the 20% ANC diet versus the 0% ANC diet (P < 0.05). These results demonstrate that ANC inclusion improved pellet physical quality without impairing feeding behavior and nutritional quality of the fish but inclusion ≥10% in the diet reduced fish growth. This study offers the first comprehensive assessment of the potential of ANC used in fish feed involving feed management, feeding evaluation, and the biological response.

Nutrition consistently affects microbe-host interactions in the gastrointestinal tract. This study aimed to unravel how undernutrition reshapes the microbial composition and the homeostasis of epithelium in the jejunum and ileum. Sixteen late-gestation Hu-sheep were randomly assigned to the control group (n = 8, 100% ad libitum feeding levels) or the undernutrition group (n = 8, which received 30% ad libitum feeding levels). After 15-d treatment, all ewes were slaughtered, and jejunal and ileal digesta and epithelium samples were collected for 16S rRNA gene sequencing and transcriptome sequencing, respectively. Results indicated that undernutrition decreased the jejunal and ileal tissue weights (P = 0.005 and P = 0.022) and the levels of volatile fatty acids (P = 0.019 and P = 0.007) and microbial protein levels (P = 0.019 and P = 0.031) in jejunal and ileal digesta. The relative abundance of acetate producing microbiota, including Clostridia UCG-014 norank, Ruminococcus, [Ruminococcus] gauvreauii, and Lachnospiraceae_Blautia, were significantly reduced (P < 0.05) in the jejunum and ileum. Undernutrition up-regulated (P < 0.05) the expression of genes involved in amino acid synthesis and fatty acid oxidation, but down-regulated (P < 0.05) the expression of genes associated with amino acid degradation, fatty acid synthesis, and extracellular structures in jejunal and ileal epithelium. In the jejunal epithelium, genes associated with extracellular matrix–receptor interactions, cell growth, and immune response were down-regulated (P < 0.05) upon undernutrition. Taken together, undernutrition changed the microbial community in the jejunum and ileum, which altered the fermentation mode and the production of volatile fatty acids and microbial protein. These affected the energy and protein system in the epithelium and reprogrammed substance metabolism and extracellular structures, which probably further influenced cell growth and immune response. These insights provide a foundation for completely clarifying the crosstalk between small intestinal microbiota and the host.

The synchronized absorption of amino acids and glucose in the gut is essential for amino acid utilization and protein synthesis in the body. The study aimed to investigate how the starch digestion rate and amino acid levels impact the growth and intestinal starch and amino acid digestion, transport, and metabolism in juvenile broilers. The experiment was conducted with 702 Arbor Acres Plus broilers at 1 d old, which were randomly divided into 9 treatments with 6 replicates of 13 chickens each. The treatments included 3 different starch sources (corn, waxy corn, and tapioca) with 3 different apparent ileal digestible lysine (AID Lys) levels (1.08%, 1.20%, and 1.32%). A notable interaction was noted for dietary starch sources and AID Lys levels in the feed-to-gain ratio (F/G) and distal ileal starch digestibility (P < 0.01). The tapioca starch and waxy corn starch diets with 1.32% of AID Lys significantly decreased F/G compared with corn starch (P < 0.01). There was no significant difference in F/G of broilers among waxy corn starch diet with 1.08% AID Lys level, tapioca starch diet with 1.20% AID Lys level, and corn starch diet with 1.32% AID Lys level (P > 0.05). The 1.32% AID Lys level and the waxy corn starch both improved the body weight (BW) of broilers from 0 to 3 weeks of age, intestinal starch digestibility, and intestinal villi height or the ratio of villi height to crypt depth (P < 0.05). Compared with the corn starch diet, waxy corn starch and tapioca starch diets significantly elevated the AID of Met, Glu, Lys, Arg, Asp, His, Ile, Tyr, Gly, and Val levels (P < 0.05). The carbon metabolomics results revealed that the waxy corn starch diet significantly reduced malic acid and cis-aconitic acid levels (P < 0.05) in the tricarboxylic acid cycle compared to the corn starch diet. It was concluded that a waxy corn starch diet improves the growth performance of broilers by improving intestinal morphology, increasing the absorption and transport of amino acids, reducing the amino acid oxidation for energy supply in the intestinal mucosa, and promoting protein synthesis in muscles, which not only reduces the need for dietary AID Lys but also saves on production costs.

Feeding frequency represents a potential strategy to improve the utilization of protein sources by fish. This study investigated its impact on the utilization of protein blend in gibel carp. The dietary fishmeal was totally substituted with three protein blends consisting of Tenebrio molitor meal, Chlorella meal, Clostridium autoethanogenum protein, cottonseed protein concentrate, at ratios of 1:1:8:2, 1:1:6:4, and 1:1:4:6, respectively. During an 8-week feeding trial, a total of 960 healthy fish (18.10 g) were randomly assigned to eight groups, each with three replicates. Then they were fed either twice daily (two meals per day) or four times daily (four meals per day) with four different diets. Higher feeding frequency increased feed intake and intestinal trypsin activity (P < 0.05), and up-regulated the expression levels of genes related to amino acid or peptide transporter (pept1, y⁺lat2) and sensory receptors (casr, gprc6a, mglur4) in intestine (P < 0.05). Moreover, it accelerated muscle protein turnover by increasing free amino acid content, aspartate aminotransferase activity and akt1 transcript levels (P < 0.05), ultimately promoting growth. However, higher feeding frequency reduced protein apparent digestibility and feed efficiency (P < 0.05). Dietary blended proteins elevated trypsin and chymotrypsin activities (P < 0.01). Notably, the adverse effects observed with blended proteins (ratio at 1:1:8:2) on total essential amino acid digestibility and muscle protein metabolism-related gene expression were mitigated with increased feeding frequency, thus alleviating growth inhibition. Furthermore, the blended proteins at a ratio of 1:1:6:4 increased protein apparent digestibility (P < 0.05), down-regulated mstn expression level (P < 0.05), and up-regulated expression levels of genes related to protein synthesis (akt1, mtor, s6k1, eif4b, eif4e; P < 0.05); thereby promoting protein utilization and muscle growth at four meals per day. Overall, feeding frequency interacted synergistically with blended proteins to influence growth and protein utilization in gibel carp, and a protein blend with a ratio of 1:1:6:4 was a superior alternative to fishmeal at both feeding frequencies. Future strategies aimed at replacing dietary fishmeal should consider the role of feeding frequency as a critical factor.

Gut microbiota disruption during the weaning process is a significant factor of intestinal injury. Our previous studies have suggested that Prevotella may play a critical role in causing intestinal inflammation. This study aimed to clarify the impact of Prevotella copri on intestinal injury and the protecting effect by dihydroquercetin (DHQ) in weaned piglets. A total of 108 healthy Duroc × Landrace × Yorkshire weaned piglets, aged 21 d, were randomly allocated into 3 groups with 6 replicates and 6 piglets per replicate. The piglets were the following diets for 28 d: 1) a basal diet, 2) basal diet containing 1.0 × 10⁸ CFU/kg P. copri, 3) basal diet supplemented with 1.0 × 10⁸ CFU/kg P. copri and 100 mg/kg DHQ. Results showed that P. copri decreased significantly the average daily gain (ADG) (P < 0.001), which was recovered by supplementation of DHQ with decreased serum levels of malondialdehyde (MDA), interleukin (IL)-2 and IL-8 but increased total superoxide dismutase (T-SOD) activity and IL-10 in weaned piglets (P < 0.001). Moreover, DHQ increased the expression of tight junction proteins (claudin-2, occludin and tight junction protein zonula occludens protein-1 (ZO-1) and the mRNA expression of glutathione peroxidase 4 (GPX-4) in ileum (P < 0.001). Intestinal flora analysis showed that P. copri increased the relative abundance of Prevotella (P = 0.026) and Eubacterium coprostanoligenes group (P < 0.001), but decreased the relative abundance of Lachnospiraceae NK4A136 group (P < 0.001), while supplementation of DHQ reduced the relative abundance of Prevotella (P = 0.026). Metabolomics results indicated that P. copri enhanced the content of 12-OH bile acid, but decreased the contents of glycodeoxycholic acid (GDCA) and glycochenodeoxycholic acid (GCDCA) (P < 0.001), while DHQ reduced the 12-OH bile acid content (P < 0.001) and increased the GDCA content (P = 0.020). In summary, P. copri caused intestinal injury and reduced growth performance in weaned piglets, and DHQ showed a protective effect by modulating gut microbiota and bile acids metabolism.

Maternal inulin intake has been shown to alleviate oxidative stress in piglets, but the role of bile acids (BAs) in this process remains unknown. This study aimed to investigate the roles of gut microbiota and BAs metabolism in the amelioration of intestinal oxidative stress in piglets through a maternal inulin diet. A total of 40 sows were allocated into two dietary treatments from day 85 of gestation until the end of lactation: CON (control diet) and INU (diet with 2% wheat bran replaced by inulin). An oxidative model was further established on the intestinal porcine epithelial cell-jejunum 2 cell line (IPEC-J2) to examine the effect of bacterial BAs on intestinal oxidative stress. Results showed that the maternal inulin diet promoted the average daily gain of piglets during suckling and reduced diarrhea rate during weaning (P = 0.026 and P = 0.005, respectively). Piglets from the INU group had lower serum levels of reactive oxygen species (P = 0.021), malondialdehyde (P = 0.045), along with higher serum levels of glutathione peroxidase (P = 0.027), catalase (P = 0.043), and total superoxide dismutase (P = 0.097). Compared to the CON group, maternal inulin intake increased fecal ursodeoxycholic acid (UDCA) by 10.84%, hyodeoxycholic acid (HDCA) by 250.64% (P = 0.026), and lithocholic acid (LCA) by 16.41% (P = 0.048) in piglets. Moreover, the fecal abundance of Ruminococcus and Christensenellaceae_R-7_group increased by 167.08% and 75.47% in INU piglets (P = 0.046 and P = 0.037, respectively). Furthermore, the in vitro study using IPEC-J2 cells demonstrated that UDCA, LCA, and HDCA attenuated intestinal oxidative stress by mediating kelch-1ike ECH-associated protein 1/nuclear factor E2-related factor 2 signaling. In conclusion, our results suggested that maternal dietary inulin intake during late gestation and lactation alleviates intestinal oxidative stress of piglets by regulating gut microbiota and BA metabolism.

Improving the nutrient utilization efficiency of ruminants is of utmost significance for both economic and environmental benefits. Optimizing dietary protein levels represents a key nutritional strategy to enhance ruminant growth performance and reduce nitrogen emissions. In a 63-day experiment, 24 healthy Hulunbuir lambs (initial weight 17.1 ± 2.0 kg, 2.5 months old) were subjected to three treatments: a low-protein diet (LP; crude protein of 78.4 g/kg dry matter [DM]), a medium-protein diet (MP; crude protein of 112.0 g/kg DM), and a high-protein diet (HP; crude protein of 145.6 g/kg DM), with 8 lambs in each treatment (4 males and 4 females). Lambs in the MP treatment presented greater daily weight gain and feed conversion ratio than those in the HP treatment (P < 0.05, quadratically). Compared with the LP treatment, the MP treatment resulted in greater crude protein digestibility (P < 0.001, quadratically) and acid detergent fiber digestibility (P = 0.022, quadratically). In the serum, the urea nitrogen level increased quadratically with increasing dietary protein levels (P < 0.001), while the LP treatment exerted the highest concentrations of glutamate, glycine, alanine, and histidine (P < 0.05, quadratically). The ammonia nitrogen concentrations in the rumen and colon increased quadratically with increase in dietary protein levels (P < 0.05). The HP treatment increased the molar concentrations of isobutyrate and isovalerate in the rumen and colon (P < 0.05, quadratically). In contrast, the LP treatment decreased the molar proportion of acetate (P = 0.007, quadratically) and increased the molar proportion of butyrate (P < 0.001, quadratically) in the colon. The microbial diversity and structure were significantly altered by dietary protein level intervention across all gastrointestinal regions. The rumen of the MP treatment was enriched with fiber-degrading bacteria Fibrobacter_succeinogenes and starch-degrading bacteria Selenomonas_ruminantium. The colon in the LP treatment harbored microbial biomarkers including Escherichia spp. and Lactobacillus amylovorus, and the colon in the MP treatment was characterized by the enrichment of Solibacillus_cecembensis. These findings suggest that the MP diet with a crude protein content of 112.0 g/kg DM improved the growth performance and nutrient efficiency of lambs, which was achieved via the involvement of the gastrointestinal microbiota.

Feedstuffs derived from canola, predominantly canola meals plus whole, "full-fat" canola seed, and even canola protein isolates and/or concentrates, have the potential to decrease soybean meal inclusions in diets for broiler chickens. The protein content of soybean meal exceeds that of canola meal; however, canola meal contains more methionine and cysteine in absolute and relative terms. The purpose of this review is to explore this potential as Australian chicken-meat production is uniquely positioned to take advantage of this opportunity to the extent that it can be realised. Australia harvests ample quantities of canola, the bulk of which is exported as seed; alternatively, soybean production is very limited; therefore, large quantities of soybean meal are imported as the principal source of dietary protein for broiler chickens. This importation of soybean meal is not sustainable; however, canola meal inclusions in broiler diets do not usually exceed 100 g/kg. Regression equations derived from 15 recent studies indicate that dietary inclusions of 150 g/kg solvent-extracted canola meal would compromise weight gain by 4.04% and feed conversion ratio (FCR) by 4.72%. The foremost factors driving these depressions in canola meal are probably (1) high fibre contents coupled with low energy densities and (2) the presence of glucosinolates, which may be converted into toxic metabolites including thiocyanates. Moreover, regression equations from nine studies suggest that calculated dietary glucosinolate concentrations of 2.00 μmol/g would compromise weight gain by 5.72% and FCR by 6.56%. The nutritive value of canola meal could be enhanced by improvements in canola breeding programs, processing methods in canola meal production, and dietary formulations including judicious application of exogenous enzymes. Consideration is given to these aspects in this review as any improvements would increase the extent to which canola meal can feasibly replace soybean meal in broiler diets. An additional pathway to decrease the reliance on soybean meal could be the adoption of reduced-crude protein (CP) diets containing canola meal. The combined strategy of canola meal replacing soybean meal in reduced-CP diets, if successful, would tangibly decrease soybean meal requirements in global chicken-meat production.

Maternal proline (Pro) supplementation enhances fetal survival and placental development in mice. However, the effect of Pro on fetal and placental development in gilts remains to be investigated, particularly in the context of obesity-induced impaired pregnancy. Here, we investigated the effect of dietary Pro on fetal and placental development in obese gilts. Exp.1: On day 60 of gestation, 48 gilts with similar delivery times were selected and followed up until delivery to determine the relationship between maternal obesity, litter performance, and Pro abundance in term placentae. The results showed that impaired reproductive performance was associated with body condition parameters and inadequate placental Pro availability of gilts. Exp. 2: A total of 114 gilts were then used in a 2 × 3 factorial design to investigate the interaction between body condition (factor I: normal or obese gilts) and dietary Pro levels (factor II: low [0.89%, L-Pro], medium [1.39%, M-Pro], and high [1.89%, H-Pro]) on farrowing performance and placental angiogenesis. This resulted in six treatment combinations: normal-L-Pro, obese-L-Pro, normal-M-Pro, obese-M-Pro, normal-H-Pro, and obese-H-Pro. The effective number of replicates per group was 17, 21, 19, 21, 18, and 18, respectively (1 gilt per replicate). The results showed that increasing Pro intake increased piglet birth weight (P = 0.001), litter weight (P < 0.001), placental efficiency (P = 0.036) and placental vascular density (P < 0.001), and decreased the number of mummified fetuses (P = 0.001), the rate of low-birth-weight piglets (P = 0.005), and the rate of invalid piglets (P = 0.029). Interaction effects were observed between body condition and dietary Pro levels on piglet birth weight (P = 0.046), within-litter birth weight variation (P = 0.012), and placental vascular density (P = 0.007). Moreover, the beneficial effect of Pro on farrowing performance may be related to the improvement of sirtuin 1-superoxide dismutase 2-mitochondrial reactive oxygen species axis homeostasis and angiogenesis in the placenta. Our results suggest that gestation diets need to provide adequate Pro to meet the needs of fetal and placental development, particularly in obese gilts.

Diarrhea is the leading cause of mortality in postnatal goat kids, seriously impacting breeding efficiency. This study aimed to explore the effects of Bacillus pumilus 315 (B. pumilus) on goat kids’ diarrhea and its regulatory mechanism. Thirty-six 1-day-old goat kids were assigned into four treatments, the control (CON) group and low-, medium- and high-dose groups supplemented with B. pumilus at 1 × 10⁸ (BP1), 5 × 10⁸ (BP5), and 1 × 10⁹ CFU/d (BP10). Each group consisted of 9 replicates with 1 goat kid per replicate. The results showed that the incidence of diarrhea and fecal scores decreased significantly (P < 0.05). A dose of 5 × 10⁸ CFU/d B. pumilus reduced pro-inflammatory factors (including tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β], interleukin-6 [IL-6], P < 0.05), increased the expression levels of anti-inflammatory factors (including transforming growth factor-β [TGF-β], peroxisome proliferate-activated receptor-gamma [PPAR-γ], interleukin-10 [IL-10], P < 0.05), immune indicators (including immunoglobulin G [IgG], immunoglobulin A [IgA], immunoglobulin M [IgM], secretory immunoglobulin A [sIgA], P < 0.05) and antioxidant indicators (including total antoxidative capacity [T-AOC], superoxide dismutase [SOD], glutathione peroxidase [GSH-Px], catalase [CAT], P < 0.05) in both jejunum and colon, and ultimately improved the barrier function of the jejunum and colon mucosa. The enhanced gut immunity and barrier function were associated with increased abundance of Enterococcus and Lactobacillus (P < 0.05) and decreased abundance of Campylobacter and Escherichia-Shigella (P < 0.05). In conclusion, dietary addition of B. pumilus may improve gut health by modulating the composition and function of the flora, ultimately alleviating diarrhea in goat kids.

This study evaluated the effect of maternal glycerol monolaurate (GML) supplementation during late gestation and lactation on sow reproductive performance, transfer of immunity and redox status, milk fat and fatty acid profile, and fecal microbiota. Eighty multiparous sows (Landrace × Large white) were randomly allocated to two treatment groups (with or without 1000 mg/kg GML) with 40 replicates per treatment. The feeding experiment lasted from d 85 of gestation (G85) to d 23 of lactation (L23). The samples were collected on d 1 (L1) and 21 (L21) of lactation. Our results showed that maternal GML supplementation significantly increased litter weight (P = 0.002), average daily gain of piglets (P = 0.048), and sow average daily feed intake (P = 0.032). Compared with CON group, the concentrations of lauric acid (C12:0; P = 0.022), C16:0 (P = 0.001), and total saturated fatty acids (P = 0.006) in colostrum as well as C12:0 in L21 milk (P = 0.001) were higher in GML group. Besides, the concentrations of immunoglobulin A (IgA) and IgG in colostrum as well as sow and piglet plasma, the total antioxidant capacity and superoxide dismutase activity in sow colostrum were also significantly higher in the GML group (P < 0.05). Microbiome results showed that GML addition increased fecal microbial alpha diversity as well as the relative abundances of short chain fatty acids producing bacteria Ruminococcaceae and Parabacteroides; and decreased the harmful Proteobacteria of sows (P < 0.05). The Spearman analysis showed that the microbial biomarkers Prevotellaceae, Ruminococcaceae, and Parabacteroides were positively correlated with IgA and IgG of sow plasma and milk (P < 0.05). Besides, maternal GML addition up-regulated the relative protein expressions of proliferating cell nuclear antigen, cyclin D1, G protein-coupled receptor 84 (GPR84) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway in the duodenum and jejunum of piglets. Collectively, current findings suggested that maternal GML supplementation enhanced piglet growth during lactation, which might be associated with improving milk fat and lauric acid contents, microbiota derived immunoglobulins transfer, and gut health through potential involvement of GPR84 and PI3K/Akt signaling pathway.

An inadequate amino acid (AA) supply in animals under protein-restricted conditions can slow skeletal muscle growth. Protein translation can be activated by short-term leucine (Leu) stimulation; however, whether muscle mass increases under long-term Leu supplementation and how the gut and muscle respond to Leu supplementation are largely unknown. In this study, we investigated if muscle mass increases with long-term Leu supplementation under protein-restricted conditions. We identified changes in the link between the gut and muscles under different amino acid supply conditions, using goats as the study object. A total of 27 Xiangdong black male goats with average initial body weight (BW) of 10.88 ± 1.22 kg were randomly divided into three dietary treatments: a normal protein diet (NP, 14.24% crude protein [CP]); a low protein diet (LP, 8.27% CP with supplemental 1.66% rumen-protected lysine [RPLys] and 0.09% rumen-protected methionine [RPMet]); and LP diet with rumen-protected Leu (RPLeu) (LP + RPLeu, 8.75% CP with supplemental 1.66% RPLys, 0.09% RPMet and 1.46% RPLeu). The animal trial lasted for 110 d, consisting of 20 d of adaptation and a 90 d of experimental period. The results showed that long-term protein restriction increased gut tryptophan hydroxylase 1 (TPH1) activity (P < 0.001), tryptophan (Trp) catabolism (P < 0.001), and 5-hydroxytryptamine (5-HT) synthesis (P < 0.001), which all subsequently reduced goat appetite. Long-term Leu supplementation inhibited 5-HT synthesis (P < 0.001), decreased Trp catabolism in the gut, and increased appetite in goats. Long-term protein restriction enhanced jejunal and ileal branched-chain amino acid transferase (BCAT) (P < 0.001) and branched-chain α-Keto acid dehydrogenase (BCKD) (P = 0.048) activities, which increased branched-chain amino acid (BCAA) catabolism. Immunofluorescence results showed that protein restriction decreased the intestinal mucosal expression of solute carrier family 1 member 5 (SLC1A5) (P = 0.032) and solute carrier family 7 member 5 (SLC7A5) (P < 0.001), reduced BCAA transport from the mucosa to the blood, lowered BCAA levels in the blood (P < 0.001). Western blot results showed that protein restriction inhibited mammalian target of rapamycin (mTOR) pathway activation in goat muscles. Leu supple-mentation increased BCAA translocation from the intestine to the blood and promoted activation of the muscle mTOR pathway and protein synthesis. In conclusion, our results suggest that Leu supplementation in low-protein diets improves appetite and alleviates the inhibition of muscle protein synthesis in goats.

Increasing forage proportion (FP) in the diets of dairy cows would reduce competition for human edible foods and reduce feed costs, particularly in low-input systems. However, increasing FP reduces productivity and may increases methane (CH₄) emission parameters. This work aimed to investigate the impact of FP and breed on feed efficiency and CH₄ emission parameters. Data from 32 individual experiments conducted at the Agri-Food and Biosciences Institute between 1992 and 2010 were utilised in this study resulting in data from 796 Holstein-Friesian (HF), 50 Norwegian Red (NR), 46 Jersey × HF (J × HF) and 16 NR × HF cows. Diets consisted of varying proportions of forage and concentrate dependent on the experimental protocols of each experiment. A linear mixed model was used to investigate the effect of low (LFP; 10% to 30%), medium (MFP; 30% to 59%), high (HFP; 60% to 87%) and pure (FOR; 100%) FP (dry matter [DM] basis) and breed on feed efficiency, and CH₄ emission parameters and multivariate redundancy analysis identified associations between animal and dietary drivers on the same variables. Total dry matter intake (DMI) was higher for cows offered LFP (17.3 kg/d) and MFP (17.9 kg/d) compared to HFP (15.3 kg/d) and FOR (13.8 kg/d) (P < 0.001). Milk yield (P < 0.001), milk yield/DMI (P < 0.001), energy corrected milk (ECM)/DMI (P < 0.001) and milk energy/DMI (P < 0.001) were higher for LFP and MFP compared to HFP and FOR. Methane/DMI was higher for HFP (24.3 g/kg) compared to MFP (22.4 g/kg) (P < 0.001). Methane/milk yield (P < 0.001) or CH₄/ECM (P < 0.001) was higher for HFP (22.5 or 21.6 g/kg) and FOR (27.0 or 25.8 g/kg) compared to MFP (19.1 or 17.9 g/kg). There were no differences between LFP and MFP or between HFP and FOR for milk yield, milk yield/DMI, ECM/DMI, milk energy/DMI, CH₄/milk yield and CH₄/ECM (P > 0.05). Differences existed between breeds for residual feed intake (P = 0.040), milk yield/DMI (P = 0.041) and CH₄/DMI (P = 0.048) with multivariate redundancy analysis demonstrating negative correlations with efficiency and positive correlations with CH₄/DMI and CH₄/milk yield. Feeding concentrates at 70% to 90% of DMI (LFP group) would not result in any further benefits for productivity, feed efficiency or CH₄ yield and intensity when compared to feeding 41% to 70% concentrates of DMI (MFP group). There may be opportunity to improve profitability for lower intensity farms with less concentrate input.

This study investigated the effect of peroxidized lipids on piglets' growth performance, intestinal morphology, inflammatory reactions, oxidative stress in the liver, duodenum, jejunum, ileum, and colon, and ileal microbiota. Twenty piglets (Duroc × [Landrace × Yorkshire]; age = 21 d old, BW = 6.5 ± 1 kg) were randomly assigned to two groups with 10 replicates per group and one piglet per replicate. The control group was fed 6% fresh soybean oil and the peroxidized soybean oil (PSO) group fed 6% PSO. The experimental feeding period lasted 24 d. The study found no impact on ADFI, ADG and gain to feed ratio (P > 0.05). However, the PSO group increased the diarrhea index and the serum levels of lactate dehydrogenase triglycerides, cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol (P < 0.05), along with decreased concentrations of alanine aminotransferase and blood urea nitrogen (P < 0.05). For oxidative enzymes, PSO increased the concentration of F2-isoprostane in urine (P = 0.032), malondialdehyde (MDA) in the duodenum (P = 0.001) and jejunum (P = 0.004), decreased thiobarbituric acid reactive substances (TBARS) in the liver (P = 0.001) but increased TBARS in duodenum (P = 0.001), and carbonylated proteins in the duodenum (P = 0.003). For antioxidant enzymes, PSO decreased superoxide dismutase (SOD) in the liver (P = 0.001), colon (P = 0.002), and jejunum (P = 0.015), along with glutathione peroxidase (GSH-Px) in the liver (P = 0.008) and NAD(P)H:quinone oxidoreductase 1 (NQO1) in ileum (P = 0.001). For inflammatory reactions, PSO increased interleukin (IL)-1β concentrations in the duodenum and colon, and IL-10 in the jejunum, while decreasing IL-4 concentration in the duodenum (P < 0.05). For intestinal morphology and ileal microbiota, PSO increased ileal crypt depth, while decreasing the crypt-to-villus ratio (P < 0.05). Peroxidized soybean oil increased the relative abundance of Prevotella, Clostridium_sensu_stricto_1, Clostridium_sensu_stricto_6, Pasteurella and Klebsiella (P < 0.05). In conclusion, this study revealed that PSO worsened diarrhea, increasing the ileal crypt depth and the relative abundance of harmful microbiota, and induced oxidative stress and inflammation in the intestines and liver, primarily in the jejunum and ileum.

The inclusion of various forages in a normal forage-to-concentrate ratio has widely been reported to reveal the changes that occur in the foregut tissues. However, the mechanism by which the wheat straw, alfalfa hay, or both alter the orchestrated crosstalk of microbiome and host-transcriptome in the rumen of lambs fed a high-concentrate diet is elusive. Sixty-three Hulunbuir lambs were randomly allotted to 3 dietary groups, and each dietary group had 3 pens with 7 lambs. The lambs were fed high-concentrate diets (70%) supplemented with either 30% wheat straw (30S), a mixture of 15% alfalfa hay and 15% wheat straw (30M), or 30% alfalfa hay (30A) over a 2-week adaptation period and a 12-week formal trial. Compared with the 30S and 30A groups, the 30M group had greater (P < 0.05) levels of plasma glucagon-like peptide (GLP-2), interleukin-2 (IL-2). Humoral immunity showed a tendency to increase in the 30M group, as evidenced by the greater levels of plasma immunoglobulins (Ig) A and IgG (P > 0.05). The 16S rRNA result showed that the abundance of Lachnospiraceae (NK3A20 group and unclassified), Olsenella, Shuttleworthia, and Succiniclasticum were enriched in the 30M group. Meanwhile, the abundances of Ruminococcaceae NK4A214 and prevetolla_7 were enriched in 30S and 30A, respectively. The RNA-seq identified 35 shared differentially expressed genes (DEGs) between the "30S vs. 30M" and "30S vs. 30A," enriched in lipid metabolism pathways, including glycerophospholipid and arachidonic acid metabolism. The weighted gene co-expression network analysis results revealed that the expression of genes in the darkred (194 genes) and darkgreen (134 genes) modules showed a strong positive correlation with phenotypic traits and bacterial genera, respectively. The genes in the darkgreen module were involved in carbohydrate, lipid, and amino acid metabolism and showed a wide range of associations with Prevotella_7, Shuttleworthia, and Succiniclasticum, indicating that ruminal microbes might act as a vital driver in the microbiome-host interaction, likely through fermentation of end-products or metabolites. In conclusion, the results indicate that microbiome enrichment in response to feeding wheat straw and alfalfa hay might drive microbiome-host crosstalk to regulate rumen function in lambs fed a high-concentrate diet.

This study aimed to evaluate the effects of dietary geniposide supplementation on growth performance, lipid metabolism, health status, and ammonia stress resistance in turbot (Scophthalmus maximus). Four hundred fifty fish were randomly allocated into 5 treatments with triplicate tanks (30 fish per tank). They were hand-fed to apparent satiety for 56 d with a basal diet (GP0) or diets containing 100, 200, 400, and 800 mg/kg geniposide (termed as GP100, GP200, GP400, GP800, respectively). After the conclusion of the feeding trial, the fish were exposed to ammonia stress for 96 h. The results showed that the growth performance were not affected by geniposide (P > 0.05). Dietary supplementation with geniposide decreased crude lipid in viscera without liver, subcutaneous adipose tissue (SAT), and the liver, as well as triglyceride concentrations in plasma, the liver and SAT (P < 0.05). Dietary supplementation with 400 and 800 mg/kg geniposide significantly down-regulated lipogenesis-related gene expression, as well as fatty acid uptake-related gene expression, while significantly up-regulated triglyceride secretion-related gene expression in the liver compared with the control group (P < 0.05). The GP800 group exhibited a significant reduction in plasma malondialdehyde contents compared with the control group, while both the GP200 and GP800 groups showed a significant increase in plasma complement C3 activities (P < 0.05). Furthermore, there was a notable enhancement in plasma lysozyme and total superoxide dismutase levels in the geniposide supplemented groups compared to the control group (P < 0.05). Additionally, a significant decrease in the mRNA level of pro-inflammatory cytokine and a remarkable increase in the mRNA expression of anti-inflammatory cytokines were discovered in geniposide supplemented groups relative to the control group (P < 0.05). Cumulative survival rates after ammonia stress in the GP400 and GP800 groups were statistically higher than that in the control group (P < 0.05). In conclusion, dietary geniposide supplementation could reduce lipid deposition in turbot by regulating lipid metabolism and transportation, and remarkably enhance immunity, antioxidant ability, and resistance to ammonia stress in turbot. Based on the quadratic regression analyses, the optimal concentrations of geniposide were estimated to be 545.21 to 668.41 mg/kg feed.

An 8-week feeding trial was conducted to investigate the effects of replacing dietary fish oil (FO) with black soldier fly larval oil (BSFO) on growth performance, antioxidant and immune response, lipid metabolism and mitochondrial function of the juvenile mud crab. A total of 160 mud crabs (18.58 ± 0.02 g) were randomly distributed into five treatments spread across 160 aquaria. There were 4 replicates per treatment and 8 crabs per replicate. The basal diet (Control) contained 3% fish oil and fish oil was replaced with BSFO at 25%, 50%, 75%, and 100% in the remaining four treatments. The results showed that when the proportion of BSFO replacing FO was less than 50%, there were no significant differences in percent weight gain (PWG), specific growth rate (SGR) and feed efficiency (FE) between the experimental and the control groups (P > 0.05); however, PWG and SGR decreased as the percentage of substitution increased from 50% to 100% (P < 0.01). When the percentage of substitution was less than 50%, the expression levels of genes related to lipid synthesis and catabolism were significantly up-regulated and down-regulated, respectively (P < 0.05). When 25% and 50% FO were replaced with BSFO, the antioxidant and immune responses enhanced (P < 0.05), and antioxidant and immune-related enzyme activities and metabolite concentrations in the hemolymph and hepatopancreas significantly increased (P < 0.05), and the concentrations of malondialdehyde (MDA) and protein carbonyl (PC), and the apoptosis index in the hepatopancreas significantly decreased (P < 0.05). Moreover, mitochondrial function indexes in the hepatopancreas, such as mitochondrial DNA copy number and expression levels of energy metabolism-related genes were significantly up-regulated (P < 0.05). Hepatopancreas mitochondria were more abundant in crabs fed diets with 25% and 50% replacement of FO with BSFO, while adenosine triphosphate content was the highest in 25% FO replacement group (P = 0.003). In summary, the results of the present study demonstrated that the replacement of FO with BSFO at less than 50% (i.e. in-feed BSFO level of 1.5%) did not negatively affect the growth performance of mud crabs, and could improve the antioxidant capacity, immune response, and enhance mitochondrial function.

Antarctic krill meal (KM) (Euphausia superba) as a substitute for fishmeal in aquatic animal diets is gaining popularity worldwide. A quantitative approach investigating the efficacy of using this protein on the production performance of aquatic animals remains widely limited. Here, we employed a meta-analysis to quantify the overall effects (Hedges’g [g] value effect size) of KM on the specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), and survival rate (SR) of several aquaculture species. A total of 22 records published during 2006 to 2022 from different countries, targeting 14 aquatic species, were employed in the present study. Overall, KM has a high nutritional value relative to fishmeal, particularly from the high protein and amino acid composition. Dietary KM significantly increased the overall effect size of SGR (g = 1.92) (P = 0.001); the positive effect was illustrated in marine species (g = 1.32 to 9.10) (P < 0.05) and sturgeon (Acipenser gueldenstaedtii) (g = 6.59) (P < 0.001). The overall g value for FCR (–2.42) was significantly improved compared to the control group (P < 0.001). The inclusion of KM in aquatic animal diets did not affect g value of PER (1.52, 95% confidence interval: –1.04 to 4.07) and survival rate (0.08, 95% confidence interval: –0.63 to 0.79) (P = 0.252 and 0.208, respectively). The meta-regression models indicated that SGR of rainbow trout (Oncorhynchus mykiss) was significantly correlated with dietary KM by a positive linear model (P = 0.022). The cod and sturgeon (A. gueldenstaedtii) appeared to efficiently utilize krill-containing diets as illustrated by a negative linear model (P = 0.011 and P = 0.024, respectively) between dietary KM and FCR. Dietary KM positively correlated with PER for Atlantic cod (P = 0.021). Our meta-analysis highlighted the significant outcome of KM in diets for aquaculture species by reducing pressure on forage fish from marine resources and sparing edible foods. Specifically, including KM significantly reduced economic fish-in fish-out (eFIFO) in four taxa—the top forage fish consumers (P < 0.05): marine fish, salmon, shrimp, and trout. The meta-analysis revealed the decreased food-competition feedstuff in diets for important aquaculture species (P < 0.05) fed dietary KM. The outlook for efficient use of KM from marine resources in aquafeeds was elucidated in the present work.

Scutellariae radix flavonoid extract (SFE) has been acknowledged for its antioxidant, anti-inflammatory and antimicrobial properties in enhancing gastrointestinal microbial communities and improving the host’s immunity. Nevertheless, the impacts of dietary supplementation with SFE on the gastrointestinal microbes and host metabolism in dairy cows remain uncertain. Therefore, the aim of this study was to assess the effects of dietary supplementation with SFE on the lactation performance, gastrointestinal microbes, and plasma biochemical parameters of dairy cows. Six ruminally and duodenally cannulated multiparous dairy cows were used in a crossover design over 28-d periods that included a 21-d adaptation and a 7-d sample collection period. Cows were fed a basal diet (CON group) or a basal diet supplemented with SFE at 25 g/d (SFE group). SFE supplementation tended to increase milk yield (P = 0.067) and milk urea N concentration (P = 0.079), and decreased the milk somatic cell counts (SCC, P = 0.036). Cows in the SFE group had lower plasma aspartate aminotransferase (AST), malondialdehyde (MDA), tumor necrosis factor (TNF-α), and interleukin-1β concentrations compared with the CON (P < 0.05). Meanwhile, SFE supplementation increased butyrate concentration in the rumen (P = 0.044). The microbial structure of rumen and duodenum were affected by SFE supplementation (P = 0.009 and P = 0.031; respectively), resulting in enrichment of Butyrivibrio in both parts of the SFE cows (P = 0.034 and P = 0.029; respectively). However, microbial structure and composition of feces were not affected by SFE supplementation. Overall, our study indicated that dietary supplementation with SFE could enhance lactation performance and milk quality in dairy cows by improving the gastrointestinal inner environment and health status.