Networking nutrients: How nutrition determines the structure of ecological networks.

Nutrients can shape ecological interactions but remain poorly integrated into ecological networks. Concepts such as nutrient-specific foraging nevertheless have the potential to expose the mechanisms structuring complex ecological systems. Nutrients also present an opportunity to predict dynamic processes, such as interaction rewiring and extinction cascades, and increase the accuracy of network analyses. Here, we propose the concept of nutritional networks. By integrating nutritional data into ecological networks, we envisage significant advances to our understanding of ecological processes from individual to ecosystem scales. We show that networks can be constructed with nutritional data to illuminate how nutrients structure ecological interactions in natural systems through an empirical example. Throughout, we identify fundamental ecological hypotheses that can be explored in a nutritional network context, alongside methods for resolving those networks. Nutrients influence the structure and complexity of ecological networks through mechanistic processes and concepts including nutritional niche differentiation, functional responses, landscape diversity, ecological invasions and ecosystem robustness. Future research on ecological networks should consider nutrients when investigating the drivers of network structure and function.

Effect of exogenus protease on performance, nutrient digestibility, intestinal histomorphometric, meat quality characteristics, carcass yield in broilers fed low protein diets.

The objective of the present study was to evaluate the effects of increasing doses of protease on broilers from 1 to 42 days of age. A total of 1290 Ross AP broilers were used, distributed among five treatments: positive control diet, negative control diet (NC), NC + 50 ppm of protease, NC + 100 ppm of protease, and NC + 200 ppm of protease. Each treatment contained six replicates of 43 animals each. The inclusion of proteases in the diet had effects (P < 0.05) on body weight, feed intake, weight gain, and feed conversion in the 12 to 21 day period; body weight, weight gain, and feed intake in the 29 to 42 day period; nutrient digestibility (energy metabolizability coefficient and crude protein at 28 days); and intestinal parameters (crypt and muscle width of jejunum and ileum at 28 days and villus length, crypt length, and jejunum thickness muscle layer at 42 days). These results indicate that the inclusion of protease in broiler feed can improve production parameters when the amount of crude protein in the diet is reduced.

Effects of full-fat high-oleic soybean meal in layer diets on nutrient digestibility and egg quality parameters of a white laying hen strain.

This study was conducted to understand the impact of including full fat high-oleic soybean meal in layer hen diets on nutrient digestibility and added nutritional value in eggs. Forty-eight layers (∼36 wk old) were randomly assigned to one of 4 isonitrogenous (18.5% crude protein) treatment diets with 12 replicate birds per treatment in a 3-wk study. Treatments were 1) solvent extracted defatted soybean meal + corn diet, 2) dry extruded defatted soybean meal + corn, 3) full-fat soybean meal + corn, 4) high-oleic full-fat soybean meal + corn diet. Apparent ileal digestibility of crude fat (CF) and crude protein (CP) were determined using celite (∼2%) as an indigestible marker. Tibia strength and egg quality parameters (egg weight, shell strength, Haugh unit, shell color, and yolk color) were recorded during the study. Fatty acid profiles, including the monounsaturated fatty acid, oleic acid (C18:1, cis), in eggs and adipogenic tissue (liver, muscle, and fat pad) were measured using gas chromatography (GC-FID). Digestibility values of CF ranged from 71 to 84% and CP varied from 67 to 72% for treatment diets, with treatment mean values being no different (P > 0.05) between treatment diets. No differences between treatment diets in tibia strength or egg quality parameters (egg weight, shell strength, and Haugh unit) were observed (P > 0.05) except for yolk color. Similarly, there were no differences in the total lipids in egg yolk (P > 0.05) between treatment diets. However, oleic acid percentage of total lipid in egg and tissue was significantly higher (P < 0.001) in hens given the high-oleic full-fat soybean meal diet than in other treatment groups. No difference was observed in oleic acid percentage of total lipid in egg between the other 3 treatment diets (P > 0.05). Overall, the results exhibited that the eggs and tissue of layer hens fed the full-fat high-oleic acid soybean meal diet were higher in oleic acid while the CF and CP digestibility remained similar to the digestibility of the other diets.

The effects of three different types of macronutrient feedings on golf performance and levels of fatigue and alertness.

Background: No study has evaluated the effect of macronutrient feedings on golf performance. Aim: Determine the effect of feedings during simulated golf game using a randomized cross-over study design. Methods: Male participants (n = 6, USGA handicap index 8.5 ± 6.72) played three standardized nine-hole rounds, consuming 30 g of carbohydrate, 15 g + 15 g protein and carbohydrate, or a zero-calorie control. Measurements of driving, chipping, and putting distance and accuracy were taken, as well as perceived levels of fatigue and alertness. Results: No relevant differences (P > 0.05) were seen in golf performance or alertness, but self-reported fatigue differed between conditions (P = 0.02), with scores of 2.5 (0.8 to 3.6) for the combination of carbohydrate and protein, 3.0 (1.5 to 4.3) for carbohydrate, and 4.0 (2.9 to 6.5) for the control, with higher levels indicating more fatigue. Conclusion: Macronutrient feedings led to a significantly lower level of self-reported fatigue without affecting golf performance and alertness compared to a control.

Co-option of an extracellular protease for transcriptional control of nutrient degradation in the fungus Aspergillus nidulans.

Nutrient acquisition is essential for all organisms. Fungi regulate their metabolism according to environmental nutrient availability through elaborate transcription regulatory programs. In filamentous fungi, a highly conserved GATA transcription factor AreA and its co-repressor NmrA govern expression of genes involved in extracellular breakdown, uptake, and metabolism of nitrogen nutrients. Here, we show that the Aspergillus nidulans PnmB protease is a moonlighting protein with extracellular and intracellular functions for nitrogen acquisition and metabolism. PnmB serves not only as a secreted protease to degrade extracellular nutrients, but also as an intracellular protease to control the turnover of the co-repressor NmrA, accelerating AreA transcriptional activation upon nitrogen starvation. PnmB expression is controlled by AreA, which activates a positive feedback regulatory loop. Hence, we uncover a regulatory mechanism in the well-established controls determining the response to nitrogen starvation, revealing functional evolution of a protease gene for transcriptional regulation and extracellular nutrient breakdown.

The pathological effects of a Nosema ceranae infection in the giant honey bee, Apis dorsata Fabricius, 1793.

Nosema ceranae is an intracellular microsporidian pathogen that lives in the midgut ventricular cells of all known honey bee Apis species. We suspect that N. ceranae may also cause energetic stress in the giant honey bee because this parasite is known to disrupt nutrient absorption resulting in energetic stress in the honey bee species Apis mellifera. To understand how N. ceranae impacts the energetic stress of the giant honey bee, A. dorsata, we measured the hemolymph trehalose levels of experimentally infected giant honey bees on days three, five, seven, and fourteen post infection (p.i.). We also measured the hypopharyngeal gland protein content, the total midgut proteolytic enzyme activity, honey bee survival, infection ratio, and spore loads comparing infected and uninfected honey bees across the same time frame. Nosema ceranae-infected honey bees had significantly lowered survival, trehalose levels, hypopharyngeal gland protein content, and midgut proteolytic enzyme activity. We found an increasing level of parasitic loads and infection ratio of N. ceranae-infected bees after inoculation. Collectively, our results suggest that the giant honey bee suffers from energetic stress and limited nutrient absorption from a N. ceranae infection, which results in lowered survival in comparison to uninfected honey bees. Our findings highlight that other honey bee species besides A. mellifera are susceptible to microsporidian pathogens that they harbor, which results in negative effects on health and survival. Therefore, these pathogens might be transmitted at a community level, in the natural environment, resulting in negative health effects of multiple honey bee species.

Effects of dietary forage to concentrate ratio on nutrient digestibility, ruminal fermentation and rumen bacterial composition in Angus cows.

This study evaluated effects of dietary forage to concentrate ratio (F:C) on the body weight, digestibility, ruminal fermentation and rumen bacterial composition in Angus cows. Three diets with different F:C (LCD: 65:35, MCD:50:50, and HCD: 35:65) were fed to ninety Angus cows (3.2 ± 0.18 years old, 387.2 ± 22.6 kg). The average daily gain (ADG) and ammonia nitrogen concentration increased (P = 0.039 and P = 0.026, respectively), whereas the acetate to propionate ratio (P = 0.027) and the neutral detergent fiber (NDF) digestibility decreased with increasing concentrate level. The acetate concentration and ruminal pH (P = 0.033 and P = 0.029, respectively) decreased by feeding HCD diet. Serum amyloid A (SAA), C-reactive protein (CRP), haptoglobin (Hp) and lipopolysaccharide binding protein (LBP) increased under the HCD. The relative abundances of Bacteroidetes, Fibrobacterota, Prevotella and Prevotellaceae UCG-003 decreased, whereas the relative abundances of Ruminococcaceae NK4A214 group, Saccharofermentans and Spirochaetota increased with increasing dietary concentrate level. Our study provides a better understanding of rumen fermentation parameters and microbiota under a wide range of dietary F:C ratios, supporting the potential dietary manipulation of microbes, which could enhance feed digestibility associated with cow rearing.

Orange fibre effects on nutrient digestibility, fermentation products in faeces and digesta mean retention time in dogs.

Fermentable fibres are used in commercial dog food to promote intestinal health by providing substrates for better metabolic activity of the gut microbiota. Brazil is the world's largest producer of oranges, from which it is possible to obtain fibre with a relevant soluble fraction. The present study compared the effects of two inclusions of orange fibre (1% and 3%, on as fed basis) with a negative control (without addition of fibre source) and two positive controls, beet pulp (3%) and purified inulin (1%), totalling five extruded diets for dogs. The experiment followed a randomised block design with 4 blocks of 10 dogs, 2 dogs per food in each block, totalling 8 dogs per diet. The apparent total tract nutrient digestibility was determined by total faecal collection. Faecal pH and fermentation product content were also measured. The digesta mean retention time (DMRT) was evaluated using plastic markers. The inclusion of a 3% fibre source in diets with 3% orange fibre and beet pulp reduced DM, OM, and energy digestibility (p < 0.05). Diets with 3% orange fibre, beet pulp and 1% inulin presented lower crude protein digestibility than the control (p < 0.05). Dietary fibre digestibility was higher for orange fibre-supplemented diets than inulin (p < 0.05). Beet pulp and 3% orange fibre inclusions resulted in increased moisture content in the faeces of dogs (p < 0.05) but did not alter DMRT. Total short-chain fatty acids were higher than the control in the faeces of dogs fed both orange fibre levels and the beet pulp-supplemented diet (p < 0.05), and the inulin diet-fed dogs presented intermediate values. Butyrate was higher in the faeces of dogs fed the diets supplemented with 1% and 3% orange fibre (p < 0.05), and similar values to the control were observed for beet pulp- and inulin-fed animals. Thus, it was concluded that orange fibre presented higher apparent total tract dietary fibre digestibility than beet pulp and had a fermentation profile in the colon that promoted the generation of butyrate, an effect not observed for inulin and beet pulp.

Sanguinarine improved nutrient digestibility, hepatic health indices and productive performance in laying hens fed low crude protein diets.

A major mean to minimize feeding costs and faecal nitrogen excretion on poultry farms is to decrease the supplied dietary protein content. This, however, is associated with the declines in productive performance and systemic health indices. Sanguinarine may improve protein efficiency via decreasing the intestinal amino acid decarboxylation and stimulating the tryptophan-serotonin pathway. The present study was carried out to investigate the effects of dietary supplementation of sanguinarine on the performance, egg yolk biochemical parameters, serum enzyme activities, nutrient digestibility, ovarian follicles, and hepatic health indices in laying hens fed decremental levels of crude protein (CP). For this purpose, 180 laying hens were allocated into nine dietary treatments with four replicates of five birds each. The experimental treatments consisted of three levels of CP (85.0%, 92.5%, and 100% of Hy-Line W-36 manual recommendation) and three levels of sanguinarine (0.00, 3.75, and 7.50 mg/kg) in a 3 × 3 factorial arrangement administered during a 70-day feeding trial. Results showed that the decremental levels of CP led to significant increases in serum aspartate aminotransferase (p < .05), alanine aminotransferase, and alkaline phosphatase (p < .01) activities, egg yolk cholesterol concentration (p = .064), and hepatic fat and malondialdehyde (MDA) contents (p < .05). It also caused the significant declines in ileal dry matter (DM) digestibility (p < .05) and eggshell strength (p < .05), and also tended to decrease CP digestibility (p = .071), Haugh unit (p = .057) and egg production percentage (p = .062). The interaction effects of the experimental factors indicated that dietary supplementation of sanguinarine, especially at 7.50 mg/kg, led to significant improvements in serum aspartate aminotransferase and alanine aminotransferase activities (p < .01), egg yolk cholesterol (p < .001) and triglyceride (p < .05) concentrations, eggshell strength (p < .001), Haugh unit (p < .05), hepatic fat (p < .001) and MDA (p = .059) contents, ileal DM and CP digestibility (p < .01) as well as egg production, egg mass and feed conversion ratio (FCR; p < .05) in birds receiving decremental levels of CP. Taken together, the results indicate that dietary administration of sanguinarine could enhance productive performance via improving nutrient digestibility, hepatic health indices and fortifying systemic antioxidant capacity in laying hens fed low-CP diets.

A snapshot of translation in Mycobacterium tuberculosis during exponential growth and nutrient starvation revealed by ribosome profiling.

Mycobacterium tuberculosis, which causes tuberculosis, can undergo prolonged periods of non-replicating persistence in the host. The mechanisms underlying this are not fully understood, but translational regulation is thought to play a role. A large proportion of mRNA transcripts expressed in M. tuberculosis lack canonical bacterial translation initiation signals, but little is known about the implications of this for fine-tuning of translation. Here, we perform ribosome profiling to characterize the translational landscape of M. tuberculosis under conditions of exponential growth and nutrient starvation. Our data reveal robust, widespread translation of non-canonical transcripts and point toward different translation initiation mechanisms compared to canonical Shine-Dalgarno transcripts. During nutrient starvation, patterns of ribosome recruitment vary, suggesting that regulation of translation in this pathogen is more complex than originally thought. Our data represent a rich resource for others seeking to understand translational regulation in bacterial pathogens.

Body Size Plasticity of Weevil Larvae (Curculio davidi) (Coleoptera: Curculionidae) and Its Stoichiometric Relationship With Different Hosts.

Parasites obtain energy and nutrients from the host, and their body size is also usually limited by host size. However, the regulatory mechanisms that control the plasticity of parasite body sizes and the stoichiometric relationships with their hosts remain unclear. Here we investigated the concentrations of 14 elements (C, H, O, N, P, S, K, Na, Ca, Mg, Al, Fe, Mn, and Zn) in the acorns of three oak species (Quercus spp.), in their endoparasitic weevil (Curculio davidi Fairmaire) (Coleoptera: Curculionidae) larvae and in the larval feces, and the weight of weevil larvae within different hosts in a warm-temperate zone of China. Our results showed that the three acorn species exhibited significant differences in C, H, O, P, K, Mg, and Mn concentrations. However, in the weevil larvae, only P, Mn, and C:P ratio revealed significant differences. Weevil larvae preferentially absorbed and retained N, Zn, Na, and P, whereas Mn, K, Ca, and O were passively absorbed and transported. The weevil larvae weight was associated with acorn stoichiometry, and positively correlated with acorn size. Weevil larvae P decreased, but Mn and C:P increased with their weight, implying highly variable in somatic stoichiometry are coupled with the plasticity of body size. Interestingly, weevil larvae weight was negatively correlated with acorn infection rate, indicating small-size parasitic insects might have higher fitness level in parasite-host systems than larger-size ones. Our results suggest that variation in P, Mn, and C:P in parasites may play critical roles in shaping their body size and in improving their fitness.

Aspergillus awamori positively impacts the growth performance, nutrient digestibility, antioxidative activity and immune responses of growing rabbits.

In this study, we explored the effects of dietary administration of Aspergillus awamori on the growth, intestinal histomorphology, immune parameters and antioxidant enzyme activity of growing rabbits. The rabbits of 5 weeks of age (body weight, 855 ± 5.53 g) were allotted into four groups (12 rabbits per group) and fed four experimental diets enriched with A. awamori at 0, 50, 100 and 150 mg per kg diet for 8 weeks. After the feeding trial, an equal number of male APRI rabbits (3 months old; 4 groups, 5 rabbits per group) were housed in metabolism cages and fed the test diets for 14 days for the digestibility trial. All A. awamori-enriched diets induced a significant increase in the average body weight and weight gain of rabbits and significantly decreased the feed conversion ratio. In rabbits fed with A. awamori at 100 or 150 mg per kg diet, protein, lipid and fibber digestibility coefficients significantly increased compared with the control group. Intestinal villi measurements (length and thickness) were also enhanced in all rabbits fed with A. awamori. Adding A. awamori as a food supplement generally did not affect rabbit haematology and blood biochemistry values; however, at 150 mg per kg diet, it significantly increased the levels of haemoglobin and total protein, as well as red blood cell count. Furthermore, all enriched diets significantly increased rabbits' phagocytic activity and their phagocytic index. Rabbits fed with A. awamori also showed decreased malondialdehyde but increased catalase activity. In conclusion, A. awamori administered as feed supplement at 100-150 mg per kg of growing rabbits' diet enhances their growth, intestinal health and nutrient digestibility, and it raises the levels of their immune and antioxidative responses.

Regulation and repurposing of nutrient sensing and autophagy in innate immunity.

Nutrients not only act as building blocks but also as signaling molecules. Nutrient-availability promotes cell growth and proliferation and suppresses catabolic processes, such as macroautophagy/autophagy. These effects are mediated by checkpoint kinases such as MTOR (mechanistic target of rapamycin kinase), which is activated by amino acids and growth factors, and AMP-activated protein kinase (AMPK), which is activated by low levels of glucose or ATP. These kinases have wide-ranging activities that can be co-opted by immune cells upon exposure to danger signals, cytokines or pathogens. Here, we discuss recent insight into the regulation and repurposing of nutrient-sensing responses by the innate immune system during infection. Moreover, we examine how natural mutations and pathogen-mediated interventions can alter the balance between anabolic and autophagic pathways leading to a breakdown in tissue homeostasis and/or host defense.Abbreviations: AKT1/PKB: AKT serine/threonine kinase 1; ATG: autophagy related; BECN1: beclin 1; CGAS: cyclic GMP-AMP synthase; EIF2AK4/GCN2: eukaryotic translation initiation factor 2 alpha kinase 4; ER: endoplasmic reticulum; FFAR: free fatty acid receptor; GABARAP: GABA type A receptor-associated protein; IFN: interferon; IL: interleukin; LAP: LC3-associated phagocytosis; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAP3K7/TAK1: mitogen-activated protein kinase kinase kinase 7; MAPK: mitogen-activated protein kinase; MTOR: mechanistic target of rapamycin kinase; NLR: NOD (nucleotide-binding oligomerization domain) and leucine-rich repeat containing proteins; PI3K, phosphoinositide 3-kinase; PRR: pattern-recognition receptor; PtdIns3K: phosphatidylinositol 3-kinase; RALB: RAS like proto-oncogene B; RHEB: Ras homolog, MTORC1 binding; RIPK1: receptor interacting serine/threonine kinase 1; RRAG: Ras related GTP binding; SQSTM1/p62: sequestosome 1; STING1/TMEM173: stimulator of interferon response cGAMP interactor 1; STK11/LKB1: serine/threonine kinase 11; TBK1: TANK binding kinase 1; TLR: toll like receptor; TNF: tumor necrosis factor; TRAF6: TNF receptor associated factor 6; TRIM: tripartite motif protein; ULK1: unc-51 like autophagy activating kinase 1; V-ATPase: vacuolar-type H+-proton-translocating ATPase.

Competition for nutritional resources masks the true frequency of bacterial mutants.

BACKGROUND: It is widely assumed that all mutant microorganisms present in a culture are able to grow and form colonies, provided that they express the features required for selection. Unlike wild-type Escherichia coli, PHO-constitutive mutants overexpress alkaline phosphatase and hence can hydrolyze glycerol-2-phosphate (G2P) to glycerol and form colonies on plates having G2P as the sole carbon source. These mutations mostly occur in the pst operon. However, the frequency of PHO-constitutive colonies on the G2P selective plate is exceptionally low. RESULTS: We show that the rate in which spontaneous PHO-constitutive mutations emerge is about 8.0 × 10-6/generation, a relatively high rate, but the growth of most existing mutants is inhibited by their neighboring wild-type cells. This inhibition is elicited only by non-mutant viable bacteria that can take up and metabolize glycerol formed by the mutants. Evidence indicates that the few mutants that do form colonies derive from microclusters of mutants on the selective plate. A mathematical model that describes the fate of the wild-type and mutant populations under these circumstances supports these results. CONCLUSION: This scenario in which neither the wild-type nor the majority of the mutants are able to grow resembles an unavoidable "tragedy of the commons" case which results in the collapse of the majority of the population. Cooperation between rare adjacent mutants enables them to overcome the competition and eventually form mutant colonies. The inhibition of PHO-constitutive mutants provides an example of mutant frequency masked by orders of magnitude due to a competition between mutants and their ancestral wild-type cells. Similar "tragedy of the commons-like" cases may occur in other settings and should be taken into consideration while estimating true mutant frequencies and mutation rates.

Replacing sorghum with palm kernel cake in the diet decreased intake without altering crossbred cattle performance.

Palm kernel cake is a viable alternative for use in cattle feed to reduce production costs. The aim of this study was to evaluate the effects of concentrations in diet dry matter (DM) of palm kernel cake on intake and digestibility of nutrients and performance of cattle finished in a feedlot system. Forty non-castrated crossbred cattle, with an average age of 24 ± 2 months and an average weight of 331.12 ± 36.20 kg, were distributed among four treatments (control 0%, without heart of palm kernel cake in the diet; 8%, 16%, and 24% of palm kernel cake in diet DM). Variance and regression analysis were performed in function of the palm kernel cake concentrations in diet DM (P < 0.05). The dry matter intake decreased linearly (P < 0.05) as the concentrations in diet DM of palm kernel cake in the diet increased. The inclusion of palm kernel cake in the animals' diet decreased (P < 0.05) on dry matter digestibility. No effects (P > 0.05) of palm kernel cake on average daily gain or feed conversion were observed. The palm kernel cake can be included in the diet of crossbred bulls finished in confinement at concentrations in diet DM of up to 24%, as it has not influenced performance.

Interactive effect of exogenous protease enzyme and dietary crude protein levels on growth and digestibility indices in broiler chickens during the starter phase.

This study was conducted to study the effect of protease as well as three dietary crude protein levels on growth and nutrient digestibility in broilers. The broiler chickens (n = 540) were assigned to six dietary treatments with six replicates. Three dietary crude protein (CP) levels (17, 19, and 21%) along with two levels of protease (0 and 30,000 IU/kg) were investigated in 3 × 2 factorial arrangement during the starter phase. Body weight was higher (P < 0.05) in group fed with CP-21; however, feed intake was significantly (P < 0.05) lower in CP-19 and CP-21. Resultantly, FCR was significantly (P < 0.05) improved in birds fed with CP-21. Similarly, body weight, feed intake, and FCR were significantly (P < 0.05) improved in enzyme-treated birds compared to the untreated birds. For practical purpose, birds fed CP-19 with protease enzyme resulted in improved FCR compared to birds fed with CP-21. The results revealed that CP and apparent metabolizable energy (AME) were significantly (P < 0.05) higher in birds fed with CP-21 along with supplementation of enzyme while abdominal fat was significantly (P < 0.05) lower in the same group compared to birds fed with CP-17. These results indicated that a diet having 21% CP supplemented with 30,000 IU/kg protease enzyme was superior in improving the performance and digestibility of nutrients in broiler during the starter phase.

Gut Bacteria Mediate Nutrient Availability in Drosophila Diets.

Drosophila melanogaster gut microbes play important roles in host nutritional physiology. However, these associations are often indirect, and studies typically are in the context of specialized nutritional conditions, making it difficult to discern how microbiome-mediated impacts translate to physiologically relevant conditions, in the laboratory or nature. In this study, we quantified changes in dietary nutrients due to D. melanogaster gut bacteria on three artificial diets and a natural diet of grapes. We show that under all four diet conditions, bacteria altered the protein, carbohydrates, and moisture of the food substrate. An in-depth analysis of one diet revealed that bacteria also increased the levels of tryptophan, an essential amino acid encountered scarcely in nature. These nutrient changes result in an increased protein-to-carbohydrate (P:C) ratio in all diets, which we hypothesized to be a significant determinant of microbiome-mediated host nutritional physiology. To test this, we compared life history traits of axenic flies reared on the three artificial diets with increased P:C ratios or continuous bacterial inoculation. We found that while on some diets, an environment of nutritional plenitude had impacts on life history, it did not fully explain all microbiome-associated phenotypes. This suggests that other factors, such as micronutrients and feeding behavior, likely also contribute to life history traits in a diet-dependent manner. Thus, while some bacterial impacts on nutrition occur across diets, others are dictated by unique dietary environments, highlighting the importance of diet-microbiome interactions in D. melanogaster nutritional physiology.IMPORTANCE Both in the laboratory and in nature, D. melanogaster-associated microbes serve as nutritional effectors, either through the production of metabolites or as direct sources of protein biomass. The relationship between the microbiome and the resulting host nutritional physiology is significantly impacted by diet composition, yet studies involving D. melanogaster are performed using a wide range of artificial diets, making it difficult to discern which aspects of host-microbe interactions may be universal or diet dependent. In this study, we utilized three standard D. melanogaster diets and a natural grape diet to form a comprehensive understanding of the quantifiable nutritional changes mediated by the host microbial community. We then altered these artificial diets based on the observed microbe-mediated changes to demonstrate their potential to influence host physiology, allowing us to identify nutritional factors whose effects were either universal for the three artificial diets or dependent on host diet composition.

Effect of yeast-fermented de-hulled rice on in vitro gas production, nutrient degradability, and rumen fermentation.

The aim of this experiment was to test the effect of yeast-fermented de-hulled rice (YDR) levels of protein-rich feed with different kinds of roughages on in vitro gas production, nutrient degradability, and rumen fermentation. The treatments were randomly assigned according to a 2 × 4 factorial arrangement in a completely randomized design (CRD). The two experimental factors were comprised of two roughages (R) (untreated rice straw (RS) and sweet grass hay (SGH)) and four ratios of roughage to yeast-fermented de-hulled rice (R:YDR) (100:0, 75:25, 50:50, and 25:75). Thus, there were 8 treatment combinations. The results revealed that the interaction between R and R:YDR ratios influenced on the gas production rate constant for the insoluble fraction ratio (c) (P < 0.01). The in vitro dry mater degradability (IVDMD) was improved by SGH and R:YDR ratios (P < 0.05). Supplementation of YDR with both of roughage sources (RS and SGH) increased propionate (C3) (P < 0.05) and total VFA production (P < 0.01); both factors showed interactive effects on rumen methane production (P < 0.01). Moreover, bacterial population was significantly increased by the SGH:YDR ratios (P < 0.05). Therefore, it could be summarized that supplementing YDR, an enriched protein source with SGH:YDR ratio at 50-75:50-25 ratio significantly enhanced nutrient degradability and in vitro rumen fermentation efficiency.

Processed false yam seed meals in broiler chicken diets: effects on feed preference and apparent nutrient digestibility.

This study evaluated feed preference and apparent nutrient digestibility of a maize-based diet and modified diets containing treated false yam seed meals (TFYSM). False yam seeds were sun-dried (Un_T), or first soaked in water and treated with one of the following: urea (Urea_T), sodium chloride (NaCl_T), sodium hydroxide (NaOH_T), or potassium hydroxide (KOH_T) and blanched. The TFYSM replaced maize (wt/wt) in experimental diets at 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50%, respectively in a feed preference test (experiment 1). In that study, feed preference test was conducted with 6 × 4 broiler chicks aged 21 days in a randomized complete design; each level of each TFYSM was fed for 24 h and feed intake recorded. In experiment 2 of the study, apparent nutrient digestibility of TFYSM-based diets was evaluated for 15 days with 4-week-old chicks allocated to 5 groups of 20 birds which were further subdivided into 5 treatment groups of 4 birds (replicates) using the inclusion levels of 10, 20, 30, 40, and 50% respectively. The preference test data indicated that feed intake was not compromised when maize was substituted by NaCl_T, NaOH_T, Urea_T, and KOH_T FYSM at all levels, and Un_T FYSM up to 5% inclusion. Dry matter digestibility was generally high (> 75%) in all diets except for Un_T. Control diet and NaOH_T diets had similar CP digestibility, but higher than KOH_T diets, while Un_T diets had reduced CP digestibility. Digestibility of NFE ranged from (77.4%) (Un_T) to (93.8%) (KOH_T). Improving apparent nutrient digestibility of FYSM by sequential use of water-based and chemical treatment methods especially NaOH_T or KOH_T offers the potential to use this alternative feedstuff in broiler diets.

Nutrient regulation of somatic growth in teleost fish. The interaction between somatic growth, feeding and metabolism.

This review covers the current knowledge on the regulation of the somatic growth axis and its interaction with metabolism and feeding regulation. The main endocrine and neuroendocrine factors regulating both the growth axis and feeding behavior will be briefly summarized. Recently discovered neuropeptides and peptide hormones will be mentioned in relation to feeding control as well as growth hormone regulation. In addition, the influence of nutrient and nutrient sensing mechanisms on growth axis will be highlighted. We expect that in this process gaps of knowledge will be exposed, stimulating future research in those areas.