Search Results (30)

Acetate is naturally produced in the rumen through feed degradation and fermentation. It serves as a primary energy source for ruminants and as a key substrate for de novo fatty acid synthesis in the mammary gland. The interaction of exogenous acetate with different animal and dietary factors is an area of growing interest, as it may have significant implications for milk fat synthesis. This study aimed to assess the effect of two diet fermentability levels on the short-term response of lactation to acetate supplementation in dairy cows. Eight ruminally cannulated multiparous European Holstein cows were randomly assigned to treatments in a crossover design that tested the effect of diet fermentability, acetate supply, and their interaction. Using corn silage as the only forage source and a constant forage-to-concentrate ratio, high-fermentability (HF) and low-fermentability (LF) diets were formulated. Acetate supply was investigated by infusing ruminally 10 moles of sodium acetate/d (ACE) or an equimolar infusion of control (CON). Therefore, the treatments were as follows: LF + CON; LF + ACE; HF + CON; and HF + ACE. No interactions between acetate and diet fermentability were found on performance variables. Acetate infusion decreased dry matter intake (DMI), milk yield, and milk protein yield and content but did not affect milk fat yield; however, it increased milk fat concentration, and this response tended to be more pronounced in the HF diet. Acetate infusions increased plasma β-hydroxybutyrate in the HF diet, but not in the LF diet, and increased plasma non-esterified fatty acid, which was likely a lipolysis response to reduced DMI and decreased energy balance. This study demonstrates that acetate availability can be a constraint on mammary lipogenesis, even with adequate dietary fiber. Full article

The 4Rs of sports nutrition were proposed in recent years as an evidence-based framework to optimize post-exercise recovery within the context of allostasis. Under this paradigm, it is important to consider that each R represents a factor with a tremendous influence on the allostatic response and improves individual components of the allostatic load (AL), which will positively impact the exercise-induced adaptations and the athlete’s recovery. The 4Rs correspond to the following. (i) Rehydration—This is necessary to guarantee the post-exercise consumption of at least 150% of the body mass lost during the exercise accompanied by sodium (if faster replacement is required). (ii) Refuel—Carbohydrate intake (~1.2 g/kg body mass per hour for up to 4 h post-exercise) is essential not only in restoring glycogen reserves but also in supporting the energy needs of the immune system and facilitating tissue repair. Despite changes in substrate utilization, a ketogenic diet generally has neutral or negative effects on athletic performance compared to carbohydrate-rich diets. (iii) Repair—The ingestion of high-quality protein stimulates post-exercise net muscle protein anabolism and might contribute to faster tissue growth and repair. The use of certain supplements, such as creatine monohydrate, might help to enhance recovery, while tart cherry, omega-3 fatty acids, and dietary nitrate (e.g., Beta vulgaris, Amaranthus L.), as well as other herbal extracts containing flavonoid-rich polyphenols, deserve further clinical research. (iv) Recuperate—Pre-sleep nutrition (casein- or protein-rich meal with slow digestion rate) has a restorative effect, facilitating the recovery of the musculoskeletal, endocrine, immune, and nervous systems. In this article, we update the 4Rs framework, delve deeper into the allostasis paradigm, and offer theoretical foundations and practical recommendations (the 4Rs app) for the assessment of AL in athletes. We cautiously propose an AL index (AL_index) for physique competitors and elite athletes to evaluate the cumulative physiological stress induced by exercise and, thereby, to adjust exercise and nutrition interventions. Full article

The increasing demand for sustainable dietary options has intensified the development of plant-based meat analogues. Despite growing market availability, these products often fail to replicate conventional meat’s sensory and nutritional properties. Solid-state fermentation (SSF) has emerged as a promising biotechnological approach to enhance the quality of plant-derived protein ingredients. This review summarizes recent findings on the use of SSF in meat analogue production, focusing on microbial strains, substrate selection, and fermentation conditions. The reviewed studies indicate that SSF improves protein digestibility, enhances essential amino acid profiles, reduces anti-nutritional factors, and generates desirable flavour compounds. Furthermore, SSF offers advantages over submerged fermentation in energy and water efficiency, supporting its application in sustainable food processing. The findings highlight SSF’s potential to address key limitations of current meat alternatives and its relevance for developing nutritionally adequate and sensory-appealing products. Integration of SSF into plant-based protein processing may play a critical role in advancing environmentally friendly protein systems. Full article

Background: Dietary consumption of insulinogenic amino acids (IAA) is known to contribute to the development of insulin resistance. It remains to be studied whether dietary IAA restriction improves glucose metabolism and insulin sensitivity and whether this improvement is related to alterations in glucose metabolism in peripheral tissues. The objective of this study was to examine the effect of IAA restriction on glucose metabolism in a piglet model. Methods: Following the acclimation period, thirty-two seven-day-old male piglets were randomly assigned into one of three groups for three weeks as follows (n = 10–11/group): (1) NR (control): basal diet without IAA restriction; (2) R50: basal diet with IAA restricted by 50%; (3) R75: basal diet with IAA restricted by 75%. IAA were alanine (Ala), arginine (Arg), isoleucine (Ile), leucine (Leu), lysine (Lys), threonine (Thr), phenylalanine (Phe), and valine (Val) as suggested by previous studies. Thermal images, body weight, and growth parameters were recorded weekly, oral glucose tolerance tests were performed on week 2 of the study, and blood and tissue samples were collected on week 3 after a meal test. Results: R75 improved glucose tolerance and, together with R50, reduced blood insulin concentration and homeostatic model assessment for insulin resistance (HOMA-IR) value, which is suggestive of improved insulin sensitivity following IAA restriction. R75 increased thermal radiation and decreased adipocyte number in white adipose tissue (WAT). R75 had a greater transcript of glucose transporter 1 (GLUT1), phosphofructokinase, liver type (PFKL), and pyruvate kinase, liver, and RBC (PKLR) in the liver and glucokinase (GCK) in WAT indicating a higher uptake of glucose in the liver and greater glycolysis in both liver and WAT. R75 increased the mRNA abundance of insulin receptor substrate 1 (IRS1) and protein kinase B (AKT1) in skeletal muscle suggestive of enhanced insulin signaling. Further, R75 had a higher mRNA of fibroblast growth factor 21 (FGF-21) in both the liver and hypothalamus and its upstream molecules such as activating transcription factor 4 (ATF4) and inhibin subunit beta E (INHBE) which may contribute to increased energy expenditure and improved glucose tolerance during IAA restriction. Conclusions: IAA restriction improves glucose tolerance and insulin sensitivity in piglets while not reducing body weight, likely through improved hepatic glycolysis and insulin signaling in skeletal muscle, and induced FGF-21 signaling in both the liver and hypothalamus. Full article

Black soldier fly, H. illucens larvae, efficiently convert low-value organic substrates into high-value products, offering solutions to global challenges in sustainable food production and biotechnology. This study investigated the impact of dietary protein levels (10%, 14%, 16%, and 20% crude protein, CP) on BSFL growth, nutrient utilization, and energy retention using isoenergetic diets (18.5 ± 0.3 MJ/kg dry matter) under commercial-scale conditions. Larvae were harvested after 8 days of feeding, with 5 replicates per treatment. Optimal growth performance and feed conversion ratios were observed in larvae fed 14% CP diet, with a quadratic relationship between dietary CP and biomass gain (p < 0.001, R² = 0.870). Ash and calcium deposition peaked in CP20-fed larvae and were lowest in CP14-fed larvae. Phosphorus and glucosamine deposition remained unaffected, while chitin deposition correlated positively with larval weight. Nitrogen and amino acid retention were highest in CP14-fed larvae but reduced in CP20-fed larvae (p < 0.001, R² = 0.573–0.902). CP10-fed larvae showed impaired growth and nitrogen deposition but increased fat deposition. These findings establish the CP14 diet as the optimal formulation for scalable BSFL production, providing critical insights into dietary protein effects on BSFL physiology and enabling the development of efficient feeding strategies for industrial-scale farming. Full article

Citric acid by-products in animal feed pose a sustainability challenge. Bacillus species are commonly used for fermenting and improving the nutritional quality of feedstuffs or by-products. An experiment was conducted to enhance the nutritional value of citric acid by-products through fermentation with Bacillus subtilis I9 for animal feed. The experiment was carried out in 500 mL Erlenmeyer flasks with 50 g of substrate and 200 mL of sterile water. Groups were either uninoculated or inoculated with B. subtilis I9 at 10⁷ CFU/mL. Incubation occurred at 37 °C with automatic shaking at 150 rpm under aerobic conditions for 0, 24, 48, 72, and 96 h. Inoculation with B. subtilis I9 significantly increased Bacillus density to 9.3 log CFU/mL at 24 h (p < 0.05). CMCase activity gradually increased, reaching a maximum of 9.77 U/mL at 72 h. After 96 h of fermentation with inoculated B. subtilis I9, the citric acid by-product exhibited a significant decrease (p < 0.05) in crude fiber by 10.86%, hemicellulose by 20.23%, and cellulose by 5.98%, but an increase in crude protein by 21.89%. Gross energy decreased by 4% after inoculation with B. subtilis in comparison to the uninoculated control (p < 0.05). Additionally, the non-starch polysaccharide (NSP) degradation due to inoculation with B. subtilis I9 significantly reduced (p < 0.05) NSP by 24.37%, while galactose, glucose, and uronic acid decreased by 22.53%, 32.21%, and 18.11%, respectively. Amino acid profile content increased significantly by more than 12% (p < 0.05), including indispensable amino acids such as histidine, isoleucine, lysine, methionine, phenylalanine, tryptophan, and valine and dispensable amino acids like alanine, aspartic acid, glutamic acid, glutamine, glycine, proline, and tyrosine. Furthermore, citric acid by-products inoculated with B. subtilis I9 exhibited changes in the cell wall structure under scanning electron microscopy, including fragmentation and cracking. These results suggest that fermenting citric acid by-products with B. subtilis I9 effectively reduces dietary fiber content and improves the nutritional characteristics of citric acid by-products for use in animal feed. Full article

Milk and its derivatives are included in a balanced diet of humans as excellent sources of proteins, vitamins, and essential minerals that are functional nutrients. Knowledge about the nutritional benefits or harms due to milk consumption has been expanding in recent years. We previously explored, in rodent models, the metabolic effects of isoenergetic intake of milk derived from cows, donkeys, or humans, while the impact of goat’s milk intake has remained unexplored. The aim of this work was to investigate, in an animal model, the effects of dietary supplementation with goat’s milk on energy homeostasis and inflammatory state, focusing on the modulation of mitochondrial functions in most metabolically active organs, such as skeletal muscle and the liver. In addition, we highlighted a link between nutrient intake, substrate metabolism, and the orexinergic system. Our results indicate that goat milk improves mitochondrial oxidative capacity and reduces inflammation and oxidative stress in both organs. Notably, goat milk lowers the circulating levels of Orexin-A, a neuropeptide that plays a crucial role in regulating peripheral energy balance and central nervous system mechanisms. These data provide the first evidence that the anti-inflammatory and antioxidant effects of goat milk are mediated by the modulation of mitochondrial functions and orexinergic signaling. Full article

Active athletes frequently develop low energy (LEA) and protein availabilities (LPA) with consequent changes in the vital metabolic processes, especially resting metabolic rate (RMR) and substrate utilization. This study investigated the association of energy and protein intakes with RMR and substrate utilization in male and female athletes and those with LEA and LPA. Sixty athletes (35% female, 26.83 ± 7.12 y) were enrolled in this study. Anthropometric measurements and body composition analysis were reported to estimate fat-free mass (eFFM). Dietary intakes were recorded by two-day multiple-pass 24 h recall records and three-day food records and then analyzed by food processor software to calculate protein intake (PI) and energy intake (EI). Indirect calorimetry was used to measure RMR and percentages of substrate utilization. Activity–energy expenditure (AEE) was assessed by using an Actighrphy sensor for three days. Energy availability was calculated using the following formula (EA = EI − AEE/eFFM). The correlation of EI and PI with RMR and substrate utilization was tested with Pearson correlation. In the LEA group, both EI and PI correlated positively with RMR (r = 0.308, 0.355, respectively, p < 0.05). In addition, EI showed a positive correlation with the percentage of fat utilization. In the male and sufficient-PA groups, PI correlated positively with the RMR and negatively with the percentage of protein utilization. In conclusion, the percentage of LEA is markedly prevalent in our sample, with a higher prevalence among males. Athletes with LEA had lower fat utilization and lower RMR, while those with sufficient PA showed lower protein utilization with excessive PI. These findings may explain the metabolic responses in the cases of LEA and LPA. Full article

Background: The microbial metabolites short-chain fatty acids (SCFAs) are proposed to largely contribute to improvements in metabolic health associated with dietary fiber (saccharolytic) fermentation. Nevertheless, towards the distal colon, fermentable carbohydrates become depleted, and gut bacteria switches towards protein (proteolytic) fermentation. This yields a diversity of metabolites like branched-chain fatty acids (BCFAs), often considered detrimental to metabolic health. We previously demonstrated that acute SCFA administration to the distal, but not the proximal colon, led to beneficial alterations in human substrate and energy metabolism. Hence, we hypothesize that a switch from proteolytic to saccharolytic fermentation in the distal colon has the most pronounced metabolic health effects and aimed to identify a complex carbohydrate mixture capable of inducing such a microbial substrate switch. Methods: The TIM-2 model, an in vitro computer-controlled dynamic model, was used to mimic colonic fermentation, simulating amongst others body temperature, luminal pH, microbial metabolite absorption, and peristalsis. TIM-2 was inoculated with standardized pooled microbiota from individuals with overweight/obesity and disturbed glucose homeostasis. After an overnight adaptation period, pre-digested proteins were added to the model to create a high protein background. Subsequently, either separately or in combination, potato fiber, native inulin from chicory, pectin from sugar beet, or no fibers (protein control) were administered. Samples of the lumen and dialysate were taken at various time points and assessed for proximal (0–8 h) and distal (8–24 h) SCFA and BCFA levels. Results: Of all the tested combinations, combining potato fiber and pectin resulted in the highest distal SCFA production (26.3 vs 6.4 mmol) and SCFA:BCFA ratio (13.3 vs 2.2) compared to the protein control. Discussion: The combination of potato fiber and pectin was best able to increase distal SCFA production in pooled microbiota of individuals who were overweight/obese. To assess whether these results translate to improvements in metabolic health, we are currently conducting a 12-week double-blind placebo-controlled randomized study. 44 individuals who are overweight/obese and have a disturbed glucose homeostasis are randomized to supplementation with a potato fiber/pectin mixture or placebo (maltodextrin) while consuming an eucaloric high protein diet (25 E% protein). The primary outcome will be the change in peripheral insulin sensitivity. Full article

Infections represent the main cause of acute metabolic derangements and/or the worsening of the clinical course of many inherited metabolic disorders (IMDs). The basic molecular mechanisms behind the role of infections in these conditions have not been completely clarified. This review points out the different mechanisms behind the relationship between IMDs and infections, providing an overview of this still-under-investigated area. Classically, infections have been considered as the consequence of a compromised immune system due to a biochemical defect of energy production. An adjunctive pathogenetic mechanism is related to a genetically altered protein-attached glycans composition, due to congenital glycosilation defects. In addition, a dietary regimen with a reduced intake of both micro- and macronutrients can potentially compromise the ability of the immune system to deal with an infection. There is recent pre-clinical evidence showing that during infections there may be a disruption of substrates of various metabolic pathways, leading to further cellular metabolic alteration. Therefore, infective agents may affect cellular metabolic pathways, by mediation or not of an altered immune system. The data reviewed here strongly suggest that the role of infections in many types of IMDs deserves greater attention for a better management of these disorders and a more focused therapeutic approach. Full article

The ketogenic diet (KD) restricts carbohydrate consumption, leading to an increase in ketone bodies, such as acetoacetate, β-hydroxybutyrate, and acetone, which are utilized as energy substrates. This dietary approach impacts several biochemical processes, resulting in improved clinical management of various disorders, particularly in childhood. However, the exact mechanisms underlying the efficacy of KD remain unclear. Interestingly, KD may also impact the gut microbiota, which plays a pivotal role in metabolism, nutrition, and the development of the immune and nervous systems. KD has gained popularity for its potential benefits in weight loss, blood sugar control, and certain neurological conditions. This narrative review sums up KD-related studies published over 30 years. While short-term studies have provided valuable insights into the effects of KD on the gut microbiota, persistent uncertainties surround its long-term efficacy and potential for inducing dysbiosis. The significant influence of KD on epigenetic mechanisms, intracellular pathways, and gut microbial composition underscores its potential as a therapeutic choice. However, a judicious consideration of the potential risks associated with the strict adherence to a low-carbohydrate, high-fat, and high-protein regimen over prolonged periods is imperative. As KDs gain popularity among the adolescent and young adult demographic for weight management, it becomes imperative to undertake additional research to comprehensively assess their impact on nutritional status and gut microbiota, ensuring a holistic and sustainable approach to medical nutrition. Full article

Undigested dietary and endogenous proteins, as well as unabsorbed amino acids, can move from the terminal part of the ileum into the large intestine, where they meet a dense microbial population. Exfoliated cells and mucus released from the large intestine epithelium also supply nitrogenous material to this microbial population. The bacteria in the large intestine luminal fluid release amino acids from the available proteins, and amino acids are then used for bacterial protein synthesis, energy production, and in other various catabolic pathways. The resulting metabolic intermediaries and end products can then accumulate in the colorectal fluid, and their concentrations appear to depend on different parameters, including microbiota composition and metabolic activity, substrate availability, and the capacity of absorptive colonocytes to absorb these metabolites. The aim of the present review is to present how amino acid-derived bacterial metabolites can affect microbial communication between both commensal and pathogenic microorganisms, as well as their metabolism, physiology, and growth. Full article

The effects of yeast cell wall compounds (YCWs) being added to cat food on hindgut fermentation metabolites and fecal microbiota were assessed in in vivo Experiment 1 (Exp. 1) and in vitro Experiments 2 and 3 (Exp. 2 and 3). In Exp. 1, the cats’ diets were supplemented with two dietary concentrations (46.2 and 92.4 ppm) of YCWs (YCW-15 and YCW-30, respectively), and a negative control diet with no compound in three groups (six cats per group) was used to assess the fecal score, pH, digestibility, fermentation products, and microbiota. In Exp. 2, feces from the cats that were not supplemented with YCWs (control) were used as an inoculum. A blend of pectin, amino acids, and cellulose was used as a substrate, and the YCW compound was added at two levels (5 and 10 mg). In Exp. 3, feces from cats fed YCWs were used as an inoculum to test three different substrates (pectin, amino acids, and cellulose). In Exp. 2 and 3, the gas production, pH, and fermentation products (ammonia, SCFAs, and BCFAs) were assessed. YCW-30 resulted in a higher digestibility coefficient of the crude protein, organic matter (OM) (p < 0.05), and energy of the diet (p < 0.10). Regarding the fermentation products, YCW-15 showed a trend toward higher concentrations of propionate, acetate, lactate, ammonia, isobutyrate, and valerate, while YCW-30 showed a trend (p < 0.10) toward higher levels of butyrate and pH values. The bacteroidia class and the genus Prevotella were increased by using YCW-30 and the control. At the gender level, decreased (p < 0.01) Megasphaera was observed with YCW inclusion. The microbiota differed (p < 0.01) among the groups in their Shannon indexes. For beta diversity, YCW-30 showed higher indexes (p = 0.008) than the control. The microbiota metabolic profile differed in the pathway CENTFERM-PWY; it was more expressed in YCW-30 compared to the control. In Exp. 2, the YCWs showed a higher ratio (p = 0.006) of the fermentation products in the treatments with additives with a trend towards a high dose of the additive (10 mg). In Exp. 3, the effects of the substrates (p < 0.001), but not of the YCWs, on the fermentation products were observed, perhaps due to the low dietary concentrations we used. However, the marked responses of the fermentation products to the substrates validated the methodology. We could conclude that the YCWs, even at low dietary concentrations, affected fecal SCFA production, reduced the fecal pH, and modulated the fecal microbiota in the cats. These responses were more pronounced under in vitro conditions. Full article

Aquaculture requires new, economical, and eco-friendly protein sources to replace traditional fisheries and plant ingredients. Using agriculture by-products as protein sources would reduce land-based feed production pressure and waste production, promoting a circular economy and sustainable aquaculture. Distiller’s dried grains with solubles (DDGS) is the main by-product of bioethanol production. Corn DDGS has a high protein level, but its high fiber content limits its use as a feed ingredient, particularly for carnivorous fish. Solid-state fermentation (SSF) uses lignocellulosic-rich substrates, such as DDGS, for microbial growth in the near absence of water, promoting enzyme production that degrades the lignocellulosic matrix, increasing free reducing sugars, protein, and antioxidant levels of the substrate. In the present work, the SSF of corn DDGS with Aspergillus carbonarius, A. ibericus, and A. uvarum was tested. Then, the digestibility of the most promising fermented DDGS (in terms of upgraded nutritional composition) was tested by including it in a reference diet (70% of a reference diet; 48% crude protein; 15% crude lipids) for European seabass (Dicentrarchus labrax) juveniles (171 g averaged weight; trial duration of 52 days). Among the fungi tested, Aspergillus ibericus led a generally higher upgrading of the DDGS nutritional composition, leading to a high amount of protein (from 42.7 to 49.7 g N/kg DM), phenolic compounds (1.49 to 4.86 mg/g caffeic acid equivalents), free sugars (9.5 to 31.9 mg/g), and enzyme production (45 U/g and 68 U/g of cellulase and xylanase, respectively), and a high reduction in acid detergent fiber and neutral detergent fiber content (up to 29 and 43%, respectively). Compared to the unfermented DDGS, fermented DDGS presented increased protein, lipids, starch, and energy digestibility, while phosphorous digestibility was similar. Compared to the reference diet, dietary inclusion of unfermented or fermented DDGS increased trypsin and chymotrypsin activities. The activity of digestive enzymes was not affected by the inclusion of fermented DDGS, except for amylase activity, which was lower with the fermented DDGS than with the unfermented DDGS diet. In conclusion, SSF of DDGS enhanced its nutritional value, increasing DDGS digestibility when included in diets for European seabass juveniles. Full article

Copper (Cu) is essential for the health of livestock, however, the optimal source and level of dietary Cu for yaks are uncertain. To fill this important gap, we designed an in vitro study to examine the effects of three Cu sources, namely Cu methionine (Met-Cu), Cu chloride (CuCl₂) and tribasic Cu chloride (TBCC), at five levels, namely 5, 10, 15, 20 and 25 mg/kg DM (includes Cu in substrate), on rumen fermentation in yaks. In vitro dry matter degradability (IVDMD) and amylase activity were greater (p < 0.05) with added Met-Cu than the other two Cu sources, and ammonia nitrogen (NH₃-N), microbial protein (MCP) and propionate contents were greater with Met-Cu and CuCl₂ than with TBCC. Total gas production and lipase activity were greater with Met-Cu and TBCC than CuCl₂ (p < 0.05), which meant that the metabolizable energy yield was greater in the two former Cu sources than the latter, but CH₄ production did not differ (p = 0.92) among Cu sources. IVDMD and lipase activity were greatest (p < 0.05) at 15 mg Cu/kg DM in the substrate and MCP, isobutyrate, butyrate and isovalerate contents, and amylase and trypsin activities were greatest or second greatest at 10 and 15 mg Cu/kg DM. It was concluded that Met-Cu was the best source of Cu and 10 to 15 mg Cu/kg DM was the optimal level for yaks, at least under in vitro conditions. Full article