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Dietary fiber improves metabolic health, but host-encoded mechanisms for digesting fibrous polysaccharides are unclear. In this work, we describe a mammalian adaptation to dietary chitin that is coordinated by gastric innate immune activation and acidic mammalian chitinase (AMCase). Chitin consumption causes gastric distension and cytokine production by stomach tuft cells and group 2 innate lymphoid cells (ILC2s) in mice, which drives the expansion of AMCase-expressing zymogenic chief cells that facilitate chitin digestion. Although chitin influences gut microbial composition, ILC2-mediated tissue adaptation and gastrointestinal responses are preserved in germ-free mice. In the absence of AMCase, sustained chitin intake leads to heightened basal type 2 immunity, reduced adiposity, and resistance to obesity. These data define an endogenous metabolic circuit that enables nutrient extraction from an insoluble dietary constituent by enhancing digestive function.

Nanaerobes are a newly described class of microorganisms that use a unique cytochrome bd oxidase to achieve nanaerobic respiration at

A multistate experiment involving universities in IL, IN, KY, and MN was conducted as a part of the research efforts by the North-Central Coordinating Committee-42 on swine nutrition. The null hypothesis that there are no differences in the standardized ileal digestibility (SID) of amino acids (AA) among different sources of bakery meal was tested. Eleven sources of bakery meal were procured from swine-producing states in the United States and each source was included in one diet as the sole source of AA. A N-free diet was prepared as well. Diets were prepared in one batch and divided into four sub-batches that were subsequently distributed to the four participating universities. At each university, diets were fed to 12 pigs that had a T- cannula installed in the distal ileum. Pigs were allotted to incomplete Latin square designs with 12 pigs and 4, 5, or 6 periods for a total of 21 replicate pigs per diet. Each period lasted 7 d with ileal digesta being collected from the cannulas on days 6 and 7. Samples were analyzed for AA and the SID of each AA was calculated. Results indicated that there were differences (P < 0.001) in the SID of all AA except Pro among the 11 sources of bakery meal. The differences in SID of AA observed in this experiment were greater than what is usually observed among sources of the same ingredient, indicating that there is more variability among sources of bakery meal than among different sources of other ingredients. This is likely a consequence of different raw materials being used in the production of different sources of bakery meal. Regardless of source of bakery meal, the AA with the least SID was Lys indicating that some of the raw materials in the product streams used to generate the bakery meals may have been overheated. Additionally, the Lys:crude protein ratio in each source of bakery meal was not a good predictor of the SID of Lys, which likely reflects the different raw materials being included in the different meals. In conclusion, the SID of AA varies among different sources of bakery meal and the SID of Lys is less than the SID of all other indispensable AA.

Despite mounting evidence of micro-nanoplastics (MNPs) in food and drinking water, little is known of the potential health risks of ingested MNPs, and nothing is known of their potential impact on nutrient digestion and absorption. We assessed the effects of environmentally relevant secondary MNPs generated by incineration of polyethylene (PE-I), on digestion and absorption of fat in a high fat food model using a 3-phase in vitro simulated digestion coupled with a tri-culture small intestinal epithelium model. The presence of 400 μg/mL PE-I increased fat digestion by 33% and increased fat absorption by 147 and 145% 1 and 2 h after exposure. Analysis of the PE-I lipid corona during digestion revealed predominantly triacylglycerols with enrichment of fatty acids in the small intestinal phase. Protein corona analysis showed enrichment of triacylglycerol lipase and depletion of β-casein in the small intestinal phase. These findings suggest digestion of triacylglycerol by lipase on the surface of lipid-coated MNPs as a potential mechanism. Further studies are needed to investigate the mechanisms underlying the greater observed increase in fat absorption, to verify these results in an animal model, and to determine the MNP properties governing their effects on lipid digestion and absorption.

Food and water are rewarding in part because they satisfy our internal needs1,2. Dopaminergic neurons in the ventral tegmental area (VTA) are activated by gustatory rewards3-5, but how animals learn to associate these oral cues with the delayed physiological effects of ingestion is unknown. Here we show that individual dopaminergic neurons in the VTA respond to detection of nutrients or water at specific stages of ingestion. A major subset of dopaminergic neurons tracks changes in systemic hydration that occur tens of minutes after thirsty mice drink water, whereas different dopaminergic neurons respond to nutrients in the gastrointestinal tract. We show that information about fluid balance is transmitted to the VTA by a hypothalamic pathway and then re-routed to downstream circuits that track the oral, gastrointestinal and post-absorptive stages of ingestion. To investigate the function of these signals, we used a paradigm in which a fluid's oral and post-absorptive effects can be independently manipulated and temporally separated. We show that mice rapidly learn to prefer one fluid over another based solely on its rehydrating ability and that this post-ingestive learning is prevented if dopaminergic neurons in the VTA are selectively silenced after consumption. These findings reveal that the midbrain dopamine system contains subsystems that track different modalities and stages of ingestion, on timescales from seconds to tens of minutes, and that this information is used to drive learning about the consequences of ingestion.

Fermentation of dietary nutrients in ruminants gastrointestinal (GI) tract is an essential mechanism utilized to meet daily energy requirements. Especially in lactating dairy cows, the GI microbiome plays a pivotal role in the breakdown of indigestible plant polysaccharides and supply most AAs, fatty acids, and gluconeogenic precursors for milk synthesis. Although the contribution of the rumen microbiome to production efficiency in dairy cows has been widely researched over the years, variations throughout the lactation and the lower gut microbiome contribution to these traits remain poorly characterized. Therefore, we investigated throughout lactation the relationship between the rumen and lower gut microbiomes with production efficiency traits in Holstein cows. We found that the microbiome from both locations has temporal stability throughout lactation, yet factors such as feed intake levels played a significant role in shaping microbiome diversity. The composition of the rumen microbiome was dependent on feed intake. In contrast, the lower gut microbiome was less dependent on feed intake and associated with a potentially enhanced ability to digest dietary nutrients. Therefore, milk production traits may be more correlated with microorganisms present in the lower gut than previously expected. The current studys findings advance our understanding of the temporal relationship of the rumen and lower gut microbiomes by enabling a broader overview of the gut microbiome and production efficiency towards more sustainable livestock production.

Puffer and porcupine fishes (families Diodontidae and Tetraodontidae, order Tetradontiformes) are known for their extraordinary ability to triple their body size by swallowing and retaining large amounts of seawater in their accommodating stomachs. This inflation mechanism provides a defence to predation; however, it is associated with the secondary loss of the stomach's digestive function. Ingestion of alkaline seawater during inflation would make acidification inefficient (a potential driver for the loss of gastric digestion), paralleled by the loss of acid-peptic genes. We tested the hypothesis of stomach inflation as a driver for the convergent evolution of stomach loss by investigating the gastric phenotype and genotype of four distantly related stomach inflating gnathostomes: sargassum fish, swellshark, bearded goby and the pygmy leatherjacket. Strikingly, unlike in the puffer/porcupine fishes, we found no evidence for the loss of stomach function in sargassum fish, swellshark and bearded goby. Only the pygmy leatherjacket (Monochanthidae, Tetraodontiformes) lacked the gastric phenotype and genotype. In conclusion, ingestion of seawater for inflation, associated with loss of gastric acid secretion, is restricted to the Tetraodontiformes and is not a selective pressure for gastric loss in other reported gastric inflating fishes.

An N-balance experiment was conducted to test the hypothesis that d-Methionine (d-Met) has the same bioavailability and efficacy as l-Methionine (l-Met) when fed to weanling pigs. A Met-deficient basal diet containing 0.24% standardized ileal digestible (SID) Met was formulated. Six additional diets were formulated by adding 0.036%, 0.072%, or 0.108% d-Met or l-Met to the basal diet, and these diets, therefore, contained 77%, 87%, or 97% of the requirement for SID Met. Fifty-six barrows (10.53 ± 1.17 kg) were housed in metabolism crates and allotted to the seven diets with eight replicate pigs per diet. Feces and urine were collected quantitatively with 7-d adaptation and 5-d collection periods. Blood and tissue samples from pigs fed the basal diet and pigs fed diets containing 0.108% supplemental Met were collected on the last day. Results indicated that N retention (%) linearly increased (P < 0.01) as supplemental d-Met or l-Met increased in diets. Based on N retention (%) as a response, the linear slope-ratio regression estimated the bioavailability of d-Met relative to l-Met to be 101% (95% confidence interval: 57%-146%). The villus height and crypt depth in the jejunum were not affected by the Met level or Met source. Total antioxidant capacity or thiobarbituric acid reactive substance concentrations in plasma or tissue samples from pigs fed the control diet or diets containing 0.108% supplemental d-Met or l-Met were not different. Abundance of mRNA for some AA transporters analyzed in intestinal mucosa of pigs also did not differ. Therefore, it is concluded that d-Met and l-Met are equally bioavailable for weanling pigs.

Anautogenous female mosquitoes obtain the nutrients needed for egg development from vertebrate blood, and consequently they transmit numerous pathogens of devastating human diseases. Digestion of blood proteins into amino acids that are used for energy production, egg maturation and replenishment of maternal reserves is an essential part of the female mosquito reproductive cycle. However, the regulatory mechanisms underlying this process remain largely unknown. Here, we report that the transcription factor E93 is a critical factor promoting blood meal digestion in adult females of the major arboviral vector Aedes aegypti in response to the steroid hormone 20-hydroxyecdysone (20E). E93 was upregulated in the female mosquito midgut after a blood meal, and RNA interference (RNAi)-mediated knockdown of E93 inhibited midgut blood digestion. E93 RNAi depletion repressed late trypsin (LT), serine protease I (SPI), SPVI and SPVII, and activated early trypsin (ET) expression in the female mosquito midgut after a blood meal. Injection of 20E activated E93, LT, SPI, SPVI and SPVII, and repressed ET expression, whereas RNAi knockdown of the ecdysone receptor (EcR) repressed E93, LT, SPI, SPVI and SPVII, and activated ET expression in the midgut. Furthermore, E93 depletion resulted in a complete loss of 20E responsiveness of LT, SPVI and SPVII. Our findings reveal important mechanisms regulating blood meal digestion in disease-transmitting mosquitoes.

A study determined the effects of supplementing corn-based diets for weaned pigs with multi-enzymes on growth performance, apparent total tract digestibility (ATTD) of nutrients, fecal score, and fecal microbial composition. A total of 132 pigs (initial body weight = 7.23 kg) that had been weaned at 21 d of age and fed a drug-free nursery diet for 7 d were housed in 33 pens of 4 barrows or gilts, blocked by body weight and gender, and fed 3 experimental diets at 11 pens per diet. The diets were corn-based diet without or with multi-enzyme A or B. Multi-enzyme A supplied 4,000 U of xylanase, 150 U of β-glucanase, 3,500 U of protease, and 1,500 U of amylase per kilogram of diet. Multi-enzyme B was the same as multi-enzyme A except that it supplied amylase at 150 U/kg, and that its source of amylase was different from that of multi-enzyme A. All diets contained phytase at 1,000 U/kg. The diets were fed for 35 d in 2 phases; phase 1 for the first 14 d and phase 2 for the last 21 d of the trial. Fecal score was determined daily during the first 7 d of the trial. Fecal samples were collected from rectum of 1 pig per pen on days 2, 7, 14, and 35 of the trial for determining bacterial composition. Also, fresh fecal samples were collected from each pen on days 41 and 42 to determine ATTD of nutrients. Multi-enzyme B increased (P < 0.05) average daily gain (ADG) for phases 1 and 2. For the overall study period, multi-enzyme B increased (P < 0.05) ADG from 262 to 313 g, and average daily feed intake (ADFI) from 419 to 504 g. Multi-enzyme A increased (P < 0.05) overall ADG from 262 to 290 g, but did not affect ADFI. Multi-enzyme A or B did not affect ATTD of gross energy, but increased (P < 0.05) the ATTD of ether extract from 30% to 36% or 37%, respectively. Multi-enzyme A did not affect fecal score; however, multi-enzyme B tended to decrease (P = 0.09) fecal score, implying that it tended to decrease diarrhea. Firmicutes were the most abundant phylum of fecal bacteria (its relative abundance ranged from 58% to 72%). Bacteroidetes and Actinobacteria were the 2nd and 3rd most abundant phyla of fecal bacteria. Neither multi-enzyme affected fecal bacterial composition. In conclusion, the addition of multi-enzyme A or B to phytase-supplemented corn-based diet for weaned pigs can improve their growth performance and fat digestibility. However, multi-enzyme B was more effective than multi-enzyme A in terms of improving the growth performance of weaned pigs fed corn-based diet.

Two experiments were conducted to determine the effects of protease supplementation on degradation of soybean meal (SBM) allergenic proteins (glycinin and β-conglycinin) and gut health of weaned pigs fed soybean meal-based diets. In experiment 1, 2 SBM samples from 2 different sources were subjected to porcine in vitro gastric degradation to determine the effects of protease (at 15,000 U/kg of feedstuff) on degradation of the soybean allergenic proteins. In experiment 2, 48 weaned pigs (body weight = 6.66 kg) were obtained in 2 batches of 24 pigs each. Pigs were individually housed in metabolic crates and fed 4 diets (12 pigs/diet). The diets were corn-based diet with SBM 1 or SBM 2 without or with protease at 15,000 U/kg of diet in 2 × 2 factorial arrangement. Diets were fed for 10 d and pigs were sacrificed on day 10 for measurement of small intestinal histomorphology, permeability of small intestine mounted in Ussing chambers, and serum concentration of pro-inflammatory cytokines. Two SBM sources (SBM 1 and SBM 2) contained 46.9% or 47.7% CP, 14.0% or 14.6% glycinin, and 9.90% or 10.3% β-conglycinin, respectively. Protease and SBM source did not interact on any of the response criteria measured in the current study. Protease supplementation tended to increase (P = 0.069) the in vitro gastric degradation of glycinin. Protease supplementation tended to reduce (P = 0.099) fluorescein isothiocyanate dextran 4,000 Da (which is a marker probe for intestinal permeability) flow in jejunum, and reduced (P = 0.037) serum TNF-α concentration. Protease did not affect small intestinal histomorphology. In conclusion, protease tended to increase gastric degradation of glycinin and reduce gut permeability, and serum concentration of pro-inflammatory cytokines, indicating that the protease used in the current study can be added to SBM-based diets for weanling pigs to improve gut health.

Adopting a new diet is a significant evolutionary change, and can profoundly affect an animal's physiology, biochemistry, ecology and genome. To study this evolutionary transition, we investigated the physiology and genomics of digestion of a derived herbivorous fish, Cebidichthys violaceus. We sequenced and assembled its genome (N50 = 6.7 Mb) and digestive transcriptome, and revealed the molecular changes related to digestive enzymes (carbohydrases, proteases and lipases), finding abundant evidence of molecular adaptation. Specifically, two gene families experienced expansion in copy number and adaptive amino acid substitutions: amylase and carboxyl ester lipase (cel), which are involved in the digestion of carbohydrates and lipids, respectively. Both show elevated levels of gene expression and increased enzyme activity. Because carbohydrates are abundant in the prickleback's diet and lipids are rare, these findings suggest that such dietary specialization involves both exploiting abundant resources and scavenging rare ones, especially essential nutrients, like essential fatty acids.

Bees acquire carbohydrates from nectar and lipids; and amino acids from pollen, which also contains polysaccharides including cellulose, hemicellulose, and pectin. These potential energy sources could be degraded and fermented through microbial enzymatic activity, resulting in short chain fatty acids available to hosts. However, the contributions of individual microbiota members to polysaccharide digestion have remained unclear. Through analysis of bacterial isolate genomes and a metagenome of the honey bee gut microbiota, we identify that Bifidobacterium and Gilliamella are the principal degraders of hemicellulose and pectin. Both Bifidobacterium and Gilliamella show extensive strain-level diversity in gene repertoires linked to polysaccharide digestion. Strains from honey bees possess more such genes than strains from bumble bees. In Bifidobacterium, genes encoding carbohydrate-active enzymes are colocated within loci devoted to polysaccharide utilization, as in Bacteroides from the human gut. Carbohydrate-active enzyme-encoding gene expressions are up-regulated in response to particular hemicelluloses both in vitro and in vivo. Metabolomic analyses document that bees experimentally colonized by different strains generate distinctive gut metabolomic profiles, with enrichment for specific monosaccharides, corresponding to predictions from genomic data. The other 3 core gut species clusters (Snodgrassella and 2 Lactobacillus clusters) possess few or no genes for polysaccharide digestion. Together, these findings indicate that strain composition within individual hosts determines the metabolic capabilities and potentially affects host nutrition. Furthermore, the niche specialization revealed by our study may promote overall community stability in the gut microbiomes of bees.

Our objectives were to characterize responses in the field to a mix of fibrolytic enzymes using large commercial dairy herds and sufficient study power to evaluate milk production and reproductive responses to an enzyme treatment started during the precalving period. We hypothesized that the use of the enzyme treatment would increase milk production when provided to dairy cows precalving and for approximately 200 d of lactation. The study was conducted on 7,507 cows, in 8 replicates and 16 pens, at 3 dairies in the United States. Eight pens were randomly allocated as control pens and received no enzyme, and another 8 pens received enzyme treatment at a dose of 750 mL/t of dry matter feed. Milk production and energy-corrected milk yield were increased with the enzyme treatment by 0.70 and 0.80 kg/d, respectively, across a 5-month period. Milk fat percentage was not significantly increased by enzyme treatment, but milk fat yield was significantly increased by 0.040 kg/d, compared with controls. Milk protein yield increased 0.010 kg/d with enzyme treatment despite a small reduction of 0.020 percentage units in milk protein percentage. We found no evidence of an increase in the ln somatic cell count for the enzyme-treated cows. Body weight overall was not increased for enzyme-treated cows, but we did observe a numerical increase in dry matter intake (0.20 kg/head per day) for enzyme-treated cows. Most production responses to the enzyme treatment were influenced by dairy. Compared with controls, milk yield in enzyme-treated cows was significantly higher by 3.6 kg/d in dairy 2 and numerically higher by 0.60 and 0.20 kg/d in dairies 1 and 3, respectively. Reproduction, health, and risk of removal or death were not significantly influenced by treatment, apart from a reduced time to first breeding. Production responses to the enzyme treatment varied by dairy from substantial to minor increases, but variation among dairies was not evident in differences in dry matter intake or in partitioning of body weight among enzyme-treated and control pens and cows. It appears likely that the increase in production reflected increased digestibility of feed; however, further work is needed to identify factors influencing the variation in production responses to enzymes.

Living cells depend on a constant supply of energy-rich organic molecules from the environment. Small molecules pass into the interior of the cell via simple diffusion or active transport carried out by membrane bound transporters; macromolecules, or entire cells, are taken up by endocytosis/phagocytosis, and are degraded intracellularly in specialized membrane bound compartments (lysosomes). Whereas all cells are capable of transporting molecules through the membrane, the efficient procurement, digestion and uptake of nutrients have become the function of specialized cell types and organs, forming the digestive system in multicellular animals. In mammals, for example, the digestive system is comprised of glandular organs with classes of cells specialized in the secretion of enzymes for the extracellular digestion of food particles (e.g., exocrine cells of the salivary gland, pancreas), as well as other organs with absorptive function (e.g., small intestine). Numerous other cell types, such as smooth muscle cells, neurons and enteroendocrine cells, are associated with glandular cells and intestinal cells to promote the digestive process.

Work was conducted to test the hypothesis that the nutritional composition of bakery meal varies depending on where in the United States the meal is produced due to different raw materials being used in the production of the meals. Forty-six samples of bakery meal were collected from feed mills located in the swine producing states in the United States. Based on the state where samples were collected, they were grouped into 5 regions: 1) AL, DE, GA, NC, PA, and VA (10 samples); 2) CO, MO, OK, and TX (10 samples); 3) IN, KY, OH, and TN (8 samples); 4) IA (11 samples); and 5) MN (7 samples). All samples were analyzed for proximate components, GE, AA, carbohydrates, and minerals, and IVDMD and in vitro energy digestibility (IVGED) were also determined. Results indicated that the average concentration of DM was (91.84 ± 1.29%) and there was no difference among regions. The concentration of ash in bakery meal from MN was greater (P < 0.05) than in meals from other regions, but for all other proximate components, no differences among sources were observed. The average concentration (DM basis) of CP (12.20 ± 2.16%), acid hydrolyzed ether extract (AEE, 9.38 ± 1.95%), starch (44.61 ± 5.47%), and NDF (13.77 ± 4.23%) indicated that bakery meal consists of a mixture of food ingredients originating from flour or whole cereal grains and with some high-fiber ingredients such as brans or canola coproducts also included. It also appears that oil or fats were added during production. With the exception of His, no differences among regions were observed for indispensable AA and the average concentrations (DM basis) of Lys, Met, Thr, and Trp were 0.35 ± 0.08%, 0.19 ± 0.03%, 0.38 ± 0.06%, and 0.13 ± 0.03%, respectively. The bakery meals from MN contained more (P < 0.05) Ca than bakery meals from other regions, indicating that limestone may have been added to bakery meal from MN to improve flowability. However, bakery meals from MN and IA contained less (P < 0.05) total P, phytate, and phytate-bound P than bakery meals produced in the states east of the Mississippi River. There were, however, no differences in IVDMD (79.06 ± 6.62%) or of IVGED (74.84 ± 8.20%) of bakery meals among regions. The present results indicate that variations in the chemical composition of bakery meal obtained from different regions in the United States are relatively small and likely without great impact on the nutritional value of the meals, but in vivo digestibility experiments are needed to confirm this hypothesis.

A 30-d feeding trial was conducted to investigate effects of dietary eucommia ulmoides leaf extract (ELE) on growth performance, activities of digestive enzymes, antioxidant capacity, immunity, expression of inflammatory factors and feeding-related genes of large yellow croaker larvae. Five micro-diets were formulated with supplementation of 0 g kg−1 (the control), 5 g kg−1 (0·5 %), 10 g kg−1 (1·0 %) and 20 g kg−1 (2·0 %) of ELE, respectively. Results showed that the best growth performance was found in larvae fed the diet with 1·0 % ELE. Furthermore, ELE supplementation significantly increased the npy expression at 1·0 % dosage, while increased ghrelin in larvae at 0·5 % dosages. The activity of leucine aminopeptidase in larvae fed the diet with 1·0 % ELE was significantly higher than the control, while alkaline phosphatase was significantly upregulated in larvae fed the diet with 2·0 % ELE. A clear increase in total antioxidant capacity in larvae fed the diet with 1·0 % ELE was observed, whereas catalase activity was significantly higher in 1·0 % and 2·0 % ELE supplementation compared with the control. Larvae fed the diet with 1·0 % ELE had a significantly higher activities of lysozyme, total nitric oxide synthase and nitric oxide content than the control. Moreover, transcriptional levels of cox-2, il-1β and il-6 were remarkably downregulated by the supplementation of 0·5–1·0 % ELE. This study demonstrated that the supplementation of 1·0 % ELE in diet could increase the growth performance of large yellow croaker larvae probably by promoting expression of feeding-related genes, enhancing antioxidant capacity and immunity and inhibiting expression of inflammatory factors. [ABSTRACT FROM AUTHOR]

Protein digestion is critical for infants. Dissimilarities between infants and adults in food intake and digestive physiology lead to distinct patterns of proteolysis between individuals. However, such differences are not well represented in many studies on protein digestion of baby foods. The complex biological structures of baby foods and the physiology of the infant digestive system are key factors affecting proteolysis during the first two years of life. Well-controlled in vitro studies have demonstrated that varying digestion conditions alter the specificity, rate, and extent of proteolysis of baby foods. Nonetheless, these models do not completely replicate in vivo proteolysis or the complex biogeography of the gastrointestinal tract. Animal and clinical studies have revealed the fate of dietary proteins along the digestive tract and the overall health impact on subjects. Building comprehensive and annotated datasets from human infants will require innovative and standardized measurement. Now, more systematic evaluations of digestion are emerging to advance the knowledge and its translation as food design for effective diet and health management in infants.

Complementary feeding starts at around six months of age because neither breast milk nor formula assure the proper nutrition of infants. Therefore, along with breast milk, solid foods are gradually introduced, particularly cereal-based foods, which will provide starch as a new source of energy and nutrients. As a result, the need of an adequate in vitro digestion method to study the influence of different aspects of weaning period is unquestionable. This critical review summarizes the in vitro digestion methods available for the analysis of starch hydrolysis under infant conditions considering different features, namely, starch digestion, infant digestive conditions and in vitro models suitable for the study of starch digestion (static, semi-dynamic and dynamic). Key factors such as enzyme concentrations, transit time, oral, gastric and intestinal conditions and differences with current adult models, have been addressed. The need for standardized infant digestion models adapted to the complementary feeding period was discussed. Existing literature data demonstrate that more effort has to be done to improve the research on this issue, in order to obtain comparable results that would address a better understanding of the digestibility of different food nutrients under infant conditions facilitating the development of appropriate formulations that may assure proper infant nutrition. [ABSTRACT FROM AUTHOR]

Background: Insect species are suitable for farming as "mini livestock" for human and animal consumption. It is important to assess the protein quality of relevant species to understand the potential of these novel protein sources in future sustainable food systems.Objectives: We aimed to determine the protein quality of 5 insect species-lesser mealworm (LMW), yellow mealworm, house cricket (HC), banded cricket (BC), and black soldier fly-using the digestible indispensable amino acid score (DIAAS) in a pig model.Methods: Five diets were formulated to contain 10% insect crude protein (CP). A nitrogen (N)-free diet was included to estimate endogenous losses. In a 6 × 6 Latin square design, 6 ileal cannulated crossbred [Duroc × (Danish Landrace × Yorkshire)] male pigs with an initial body weight of 35 ± 2 kg were fed the 6 diets. Each diet was fed for 1 wk over 6 wk. Ileal digesta were collected for 8 h on days 5 and 7 each week. Analyzed CP, amino acid (AA) contents, and calculated values of standardized ileal digestibility for CP and AAs were used to assess the DIAAS of each insect.Results: The DIAAS for young children aged 6 mo-3 y and for older children, adolescents, and adults identified sulfur AAs (cysteine + methionine) as the first limiting AA in all 4 species of cricket and mealworm. For young children, both cricket species had DIAASs > 75 and for older children, adolescents, and adults both cricket species and LMW had DIAASs > 75.Conclusions: Both cricket species (HC and BC) are classified as good-quality protein sources for young children aged 6 mo-3 y and for older children, adolescents, and adults. One mealworm species, LMW, is a good-quality protein source for older children, adolescents, and adults. [ABSTRACT FROM AUTHOR]

Ulcerative colitis (UC) is a chronic inflammatory bowel condition that is frequently related with Spleen-Kidney Yang Deficiency Syndrome (SKYD) in Chinese medicine. Fuzi Lizhong Pill (FLZP), a traditional medicine for SKYD, has been utilized in China for generations, although the exact mechanism by which it treats UC is unknown. The goal of this study is to further understand FLZP's therapeutic mechanism in SKYD-associated UC. To investigate the impact of FLZP on SKYD-associated UC, we used a comprehensive method that included serum metabolomics and gut microbiota profiling. The chemical composition of FLZP was determined using mass spectrometry. UC rats with SKYD were induced and treated with FLZP. Serum metabolomics and 16S rRNA microbial community analysis were used to evaluate FLZP's effects on endogenous metabolites and gut microbiota, respectively. Correlation analysis investigated the association between metabolites and intestinal flora. A metabolic pathway analysis was undertaken to discover putative FLZP action mechanisms. FLZP contains 109 components, including liquiritin (584.8176 μg/g), benzoylaconine (16.3087 μg/g), benzoylhypaconine (31.9583), and hypaconitine (8.1160 μg/g). FLZP predominantly regulated seven metabolites and eight metabolic pathways involved in amino acid and nucleotide metabolism, with an emphasis on energy metabolism and gastrointestinal digestion. FLZP also influenced intestinal flora variety, increasing probiotic abundance while decreasing pathogenic bacteria prevalence. An integrated investigation identified associations between changes in certain gut flora and energy metabolism, specifically the tricarboxylic acid (TCA) cycle. FLZP successfully cures UC in SKYD rats by regulating amino acid and energy metabolism. Its positive effects may include altering microbiota composition and metabolite profiles in UC rats with SKYD. These findings shed light on FLZP's mode of action and its implications for UC management. [Display omitted] • FLZP primarily regulates metabolic pathways related to amino acid and nucleotide metabolism. • FLZP may treat UC rats in SKYD by modulating the species richness and diversity of intestinal flora. • Some gut bacteria changes in UC rats with SKYD link to TCA cycle energy metabolism. • FLZP's relief of UC in SKYD rats may involve microbiota and metabolite changes. [ABSTRACT FROM AUTHOR]

African house snakes (Lamprophis fuliginosus) were used to compare the metabolic increments associated with reproduction, digestion, and activity both individually and when combined simultaneously. Rates of oxygen consumption ([Formula: see text]) and carbon dioxide production ([Formula: see text]) were measured in adult female (nonreproductive and reproductive) and adult male snakes during rest, digestion, activity while fasting, and postprandial activity. We also compared the endurance time (i.e., time to exhaustion) during activity while fasting and postprandial activity in males and females. For nonreproductive females and males, our results indicate that the metabolic increments of digestion (∼3-6-fold) and activity while fasting (∼6-10-fold) did not interact in an additive fashion; instead, the aerobic scope associated with postprandial activity was 40%-50% lower, and animals reached exhaustion up to 11 min sooner. During reproduction, there was no change in digestive [Formula: see text], but aerobic scope for activity while fasting was 30% lower than nonreproductive values. The prioritization pattern of oxygen delivery exhibited by L. fuliginosus during postprandial activity (in both males and females) and for activity while fasting (in reproductive females) was more constrained than predicted (i.e., instead of unchanged [Formula: see text], peak values were 30%-40% lower). Overall, our results indicate that L. fuliginosus's cardiopulmonary system's capacity for oxygen delivery was not sufficient to maintain the metabolic increments associated with reproduction, digestion, and activity simultaneously without limiting aerobic scope and/or activity performance.

Exogenous fibrolytic enzymes have been shown to be a promising way to improve feed conversion efficiency (FCE). β-Mannanase is an important enzyme digesting the polysaccharide β-mannan in hemicellulose. Supplementation of diets with β-mannanase to improve FCE has been more extensively studied in nonruminants than in ruminants. The objective of this study was to investigate the effects of β-mannanase supplementation on nutrient digestibility, FCE, and nitrogen utilization in lactating Holstein dairy cows. Twelve post-peak-lactation multiparous Holstein cows producing 45.5±6.6kg/d of milk at 116±19.0d in milk were randomly allotted to 1 of 3 treatments in a 3×3 Latin square design with 3 periods of 18d (15d for adaptation plus 3d for sample collection). All cows were fed the same basal diet and the 3 treatments differed only by the β-mannanase dose: 0% dry matter (DM; control), 0.1% of DM (low supplement, LS), and 0.2% of DM (high supplement, HS) supplemented to the basal diet. Supplementation of β-mannanase enzyme at the LS dose reduced dry matter intake (DMI) but did not affect milk yield or milk composition. Cows receiving LS produced 90g more milk per kg of DMI compared with control cows. Somatic cell count (SCC) in milk was lower for cows fed the LS diet compared with cows fed control diets. Cows fed LS diet had lower DM, organic matter and crude protein digestibility compared with cows fed control diets. Starch, neutral detergent fiber, and acid detergent fiber digestibility were not affected by LS. Milk yield, DMI, SCC, and nutrient digestibility did not change for HS. Despite the reduced crude protein digestibility, reduced N intake led to similar fecal N excretions in LS cows and control cows (234 vs. 235g/cow per day). Urinary N excretions remained similar between enzyme-fed and control cows (~190g/cow per day), although the percentage of N intake partitioned to urinary N tended to be greater in LS than in control cows (31 vs. 27%). Cows fed LS significantly improved the percentage of apparently absorbed N partitioned to milk protein N (42 vs. 38%). When supplemented at 0.1% of dietary DM, β-mannanase can improve FCE and lower the SCC of dairy cows without affecting milk yield, milk composition, or total manure N excretions of dairy cows.

Gastric protein hydrolysis may influence gastric emptying rate and subsequent protein digestibility in the small intestine. This study examined the gastric hydrolysis of dietary protein from raw and roasted almonds in the growing pig as a model for the adult human. The gastric hydrolysis of almond proteins was quantified by performing tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subsequent image analysis. There was an interaction between digestion time, stomach region, and almond type for gastric protein hydrolysis (p

The herbivore gut is a fascinating ecosystem exquisitely adapted to plant biomass degradation. Within this ecosystem, anaerobic fungi invade biomass and secrete hydrolytic enzymes. In a recent study, Solomon et al. characterized three anaerobic fungi by transcriptomics, proteomics, and functional analyses to identify novel components essential for plant biomass deconstruction.

Crustaceans are a diverse group, distributed in widely variable environmental conditions for which they show an equally extensive range of biochemical adaptations. Some digestive enzymes have been studied by purification/characterization approaches. However, global analysis is crucial to understand how digestive enzymes interplay. Here, we present the first proteomic analysis of the digestive fluid from a crustacean (Homarus americanus) and identify glycosidases and peptidases as the most abundant classes of hydrolytic enzymes. The digestion pathway of complex carbohydrates was predicted by comparing the lobster enzymes to similar enzymes from other crustaceans. A novel and unbiased substrate profiling approach was used to uncover the global proteolytic specificity of gastric juice and determine the contribution of cysteine and aspartic acid peptidases. These enzymes were separated by gel electrophoresis and their individual substrate specificities uncovered from the resulting gel bands. This new technique is called zymoMSP. Each cysteine peptidase cleaves a set of unique peptide bonds and the S2 pocket determines their substrate specificity. Finally, affinity chromatography was used to enrich for a digestive cathepsin D1 to compare its substrate specificity and cold-adapted enzymatic properties to mammalian enzymes. We conclude that the H. americanus digestive peptidases may have useful therapeutic applications, due to their cold-adaptation properties and ability to hydrolyze collagen.

Peptidomics is an emerging field branching from proteomics that targets endogenously produced protein fragments. Endogenous peptides are often functional within the body-and can be both beneficial and detrimental. This review covers the use of peptidomics in understanding digestion, and identifying functional peptides and biomarkers. Various techniques for peptide and glycopeptide extraction, both at analytical and preparative scales, and available options for peptide detection with MS are discussed. Current algorithms for peptide sequence determination, and both analytical and computational techniques for quantification are compared. Techniques for statistical analysis, sequence mapping, enzyme prediction, and peptide function, and structure prediction are explored.

Nutrient loading and air emissions from swine operations raise environmental concerns. The objective of the study was to describe and evaluate a mathematical model (Davis Swine Model) of nutrient partitioning and predict manure excretion and composition on a daily basis. State variables of the model were AA, fatty acids, and a central pool of metabolites that supplied substrate for lipid synthesis and oxidation. The model traced the fate of ingested nutrients and water through digestion and intermediary metabolism into body protein, fat, water, and ash, where body protein and fat represented the body constituent pools. It was assumed that fluxes of metabolites follow saturation kinetics, depending on metabolite concentrations. The main inputs to the model were diet nutrient composition, feed intake, water-to-feed ratio, and initial BW. First, the model was challenged with nutrient partitioning data and then with excretion data. The data had 48 different feeding regimes with contrasting energy and lysine intakes at 2 different stages of growth. The overall observed and predicted mean were 109 and 112 g/d for protein deposition and 132 and 136 g/d for lipid deposition respectively, suggesting minor mean bias. Root mean square prediction error (RMSPE) was used in evaluation of the model for its predictive power. The overall RMSPE was 2.2 and 4.1 g/d for protein and lipid deposition, respectively. The excretion database used for evaluation of the model was constructed from 150 digestibility trials using growing-finishing pig diets that had a wide range of nutrient chemical composition. Nutrient and water excretion were quantified using the principle of mass conservation. The average daily observed and predicted manure production was 3.79 and 3.99 kg/d, respectively, with a RMSPE of 0.49 kg/d. There was a good agreement between observed and predicted mean fecal N output (9.9 and 9.8 g/d, respectively). Similarly, the overall observed and predicted mean urine N output was 21.7 and 21.3 g/d, respectively, suggesting minor mean bias. The RMSPE was 1.9 and 4.1 g/d for fecal and urinary N, respectively. Evaluation of the model showed that the model predicts manure excretion and N content well and can be used to assess environmental mitigation options from swine operations.

Zinc (Zn) requirements are increased during lactation. Increased demand is partially met through increased Zn absorption from the diet. It is estimated that 60-80% of women of reproductive age are at risk for Zn deficiency due to low intake of bioavailable Zn and increased demands during pregnancy and lactation. How Zn is redistributed within the body to meet the demands of lactation, and how Zn deficiency affects this process, is not understood. Female C57bl/6J mice were fed a control (ZA; 30mg Zn/kg) or a marginally Zn deficient (ZD; 15mg Zn/kg) diet for 30 days prior to mating through mid-lactation and compared with nulliparous mice fed the same diets. While stomach and plasma Zn concentration increased during lactation in mice fed ZA, mice fed ZD had lower stomach Zn concentration and abrogated plasma Zn levels during lactation. Additionally, femur Zn decreased during lactation in mice fed ZA, while mice fed ZD did not experience this decrease. Furthermore, red blood cell, pancreas, muscle and mammary gland Zn concentration increased, and liver and adrenal gland Zn decreased during lactation, independent of diet, while kidney Zn concentration increased only in mice fed ZD. Finally, maternal Zn deficiency significantly increased the liver Zn concentration in offspring but decreased weight gain and survival. This study provides novel insight into how Zn is redistributed to meet the increased metabolic demands of lactation and how marginal Zn deficiency interferes with these homeostatic adjustments.

Bacteria play many important roles in animal digestive systems, including the provision of enzymes critical to digestion. Typically, complex communities of bacteria reside in the gut lumen in direct contact with the ingested materials they help to digest. Here, we demonstrate a previously undescribed digestive strategy in the wood-eating marine bivalve Bankia setacea, wherein digestive bacteria are housed in a location remote from the gut. These bivalves, commonly known as shipworms, lack a resident microbiota in the gut compartment where wood is digested but harbor endosymbiotic bacteria within specialized cells in their gills. We show that this comparatively simple bacterial community produces wood-degrading enzymes that are selectively translocated from gill to gut. These enzymes, which include just a small subset of the predicted wood-degrading enzymes encoded in the endosymbiont genomes, accumulate in the gut to the near exclusion of other endosymbiont-made proteins. This strategy of remote enzyme production provides the shipworm with a mechanism to capture liberated sugars from wood without competition from an endogenous gut microbiota. Because only those proteins required for wood digestion are translocated to the gut, this newly described system reveals which of many possible enzymes and enzyme combinations are minimally required for wood degradation. Thus, although it has historically had negative impacts on human welfare, the shipworm digestive process now has the potential to have a positive impact on industries that convert wood and other plant biomass to renewable fuels, fine chemicals, food, feeds, textiles, and paper products.

Pathogen transmission by mosquitoes is tightly linked to blood feeding which, in turn, is required for egg development. Studies of these processes would greatly benefit from genetic methods, such as the binary Gal4/UAS system. The latter has been well established for model organisms, but its availability is limited for mosquitoes. The objective of this study was to develop the blood-meal-activated, gut-specific Gal4/UAS system for the yellow-fever mosquito Aedes aegypti and utilize it to investigate the regulation of gut-specific gene expression. A 1.1-kb, 5(') upstream region of the carboxypeptidase A (CP) gene was used to genetically engineer the CP-Gal4 driver mosquito line. The CP-Gal4 specifically activated the Enhanced Green Fluorescent Protein (EGFP) reporter only after blood feeding in the gut of the CP-Gal4 > UAS-EGFP female Ae. aegypti. We used this system to study the regulation of CP gene expression. In vitro treatments with either amino acids (AAs) or insulin stimulated expression of the CP-Gal4 > UAS-EGFP transgene; no effect was observed with 20-hydroxyecdysone (20E) treatments. The transgene activation by AAs and insulin was blocked by rapamycin, the inhibitor of the Target-of-Rapamycin (TOR) kinase. RNA interference (RNAi) silence of the insulin receptor (IR) reduced the expression of the CP-Gal4 > UAS-EGFP transgene. Thus, in vitro and in vivo experiments have revealed that insulin and TOR pathways control expression of the digestive enzyme CP. In contrast, 20E, the major regulator of post-blood-meal vitellogenic events in female mosquitoes, has no role in regulating the expression of this gene. This novel CP-Gal4/UAS system permits functional testing of midgut-specific genes that are involved in blood digestion and interaction with pathogens in Ae. aegypti mosquitoes.

Aquaporins (AQPs) are proteins that span plasma membranes allowing the movement of water and small solutes into or out of cells. The type, expression levels and activity of AQPs play a major role in the relative permeability of each cell to water or other solutes. Research on arthropod AQPs has expanded in the last 10 years due to the completion of several arthropod genome projects and the increased availability of genetic information accessible through other resources such as de novo transcriptome assemblies. In particular, there has been significant advancement in elucidating the roles that AQPs serve in relation to the physiology of blood-feeding arthropods of medical importance. The focus of this review is upon the significance of AQPs in relation to hematophagy in arthropods. This will be accomplished via a narrative describing AQP functions during the life history of hematophagic arthropods that includes the following critical phases: (1) Saliva production necessary to blood feeding, (2) Intake and excretion of water during blood digestion, (3) Reproduction and egg development and (4) Off-host environmental stress tolerance. The concentration on these phases will highlight known vulnerabilities in the biology of hematophagic arthropods that could be used to develop novel control strategies as well as research topics that have yet to be examined.

ObjectivesFat is digested in the intestine into free fatty acids (FFAs), which are detergents and therefore toxic to cells at micromolar concentration. The mucosal barrier protects cells in the adult intestine, but this barrier may not be fully developed in premature infants. Lipase-digested infant formula, but not fresh human milk, has elevated FFAs and is cytotoxic to intestinal cells, and therefore could contribute to intestinal injury in necrotizing enterocolitis (NEC), but even infants exclusively fed breast milk may develop NEC. Our objective was to determine whether stored milk and milk from donor milk (DM) banks could also become cytotoxic, especially after digestion.MethodsWe exposed cultured rat intestinal epithelial cells or human neutrophils to DM and milk collected fresh and stored at 4°C or -20°C for up to 12 weeks and then treated for 2 hours (37°C) with 0.1 or 1 mg/mL pancreatic lipase and/or trypsin and chymotrypsin.ResultsDM and milk stored 3 days (at 4°C or -20°C) and then digested were cytotoxic. Storage at -20°C for 8 and 12 weeks resulted in an additional increase in cytotoxicity. Protease digestion decreased, but did not eliminate cell death.ConclusionsPresent storage practices may allow milk to become cytotoxic and contribute to intestinal damage in NEC.

The stick insects or phasmids (Phamsatodea) have a series of pyriform ampulles with long, thin filaments on the posterior end of their midgut referred to as the "appendices of the midgut." Found only in phasmids, their function had never been determined until now. Their similarity to the Malpighian tubules, which are ubiquitous insect organs of excretion, suggested a similar function. To differentiate between the appendices and the Malpighian tubules and compare functional differences between the two tissue types, vital staining (the injection of histological stains into living organisms) was done in conjunction with light and scanning electron microscopy in multiple phasmid species. The results showed that the appendices originated in the basal phasmids (Timematidae) and grew more numerous in derived species. The appendices stain selectively, notably failing to pick up the indicators of the two known systems of invertebrate excretory function, indigo carmine and ammonium carmine. Appendices sequester stains in the ampule portion before eliminating the compounds into the midgut. We conclude by confirming that the appendices do have an excretory function, but one unlike any other known in invertebrates. Their function is likely cation excretion, playing a role in calcium regulation and/or organic alkaloid sequestration. The appendices must thus be considered distinct organs from the Malpighian tubules.

The absorptive epithelium of the proximal small intestine converts oleic acid released during fat digestion into oleoylethanolamide (OEA), an endogenous high-affinity agonist of peroxisome proliferator-activated receptor-α (PPAR-α). OEA interacts with this receptor to cause a state of satiety characterized by prolonged inter-meal intervals and reduced feeding frequency. The two main branches of the autonomic nervous system, sympathetic and parasympathetic, contribute to this effect: the former by enabling OEA mobilization in the gut and the latter by relaying the OEA signal to brain structures, such as the hypothalamus, that are involved in feeding regulation. OEA signaling may be a key component of the physiological system devoted to the monitoring of dietary fat intake, and its dysfunction might contribute to overweight and obesity.

A meta-analysis investigation based on literature data was conducted to estimate the effect size of nutritional and animal factors on phosphorus (P) excretion in feces and concentrations of P in milk. Two data sets were created for statistical analysis: One to derive prediction equations for P in feces (25 studies; 130 treatments) and another for P in milk (19 studies; 94 treatments). Prediction equations were derived using mixed model regression analysis with a random effect for study, and equations were evaluated based on values for Bayesian information criterion (BIC), root mean square prediction error (RMSPE), and concordance correlation coefficient (CCC) statistics. In terms of RMSPE and CCC values, fecal P excretion was best predicted by P intake, where P in feces (g/d)=-3.8(±3.45) + 0.64(±0.038) × P intake (g/d) (RMSPE: 18.3%, CCC: 0.869). However, significant effects of crude protein [g/kg of dry matter (DM)], neutral detergent fiber (g/kg of DM), and milk yield (kg/d) on fecal P excretion were also found. Despite a lack of improvement in terms of RMSPE and CCC values, these parameters may still explain part of the variation in fecal P excretion. For milk P, expressed as a fraction of P intake, the following equation had the highest CCC and the lowest RMSPE value: P in milk as a fraction of P intake (g/g)=0.42(±0.065) + 0.23(±0.018) × feed efficiency (i.e., fat- and protein-corrected milk yield/dry matter intake) - 0.11(±0.0199) × P in feed (g/kg of DM) (RMSPE: 19.7%; CCC: 0.761). Equations derived to predict fecal P as a fraction of P intake (g/g) or milk P content (g/kg) could not adequately explain the observed variation and did not perform well in terms of RMSPE and CCC values. Examination of the residuals showed that P balance was a seemingly confounding factor in some of the models. The results presented here can be used to estimate P in feces and milk based on commonly measured dietary and milk variables, but could also be used to guide development of mechanistic models on P metabolism in lactating dairy cattle. Factors to consider in future research and modeling efforts regarding efficiency of P use include the effects of dietary neutral detergent fiber, crude protein, starch, variation in P content of milk, and effects of P resorption from bone and body tissues during early lactation.

Background & aimsAbnormal delivery of bile acids (BAs) to the colon as a result of disease or therapy causes constipation or diarrhea by unknown mechanisms. The G protein-coupled BA receptor TGR5 (or GPBAR1) is expressed by enteric neurons and endocrine cells, which regulate motility and secretion.MethodsWe analyzed gastrointestinal and colon transit, as well as defecation frequency and water content, in wild-type, knockout, and transgenic mice (trg5-wt, tgr5-ko, and tgr5-tg, respectively). We analyzed colon tissues for contractility, peristalsis, and transmitter release.ResultsDeoxycholic acid inhibited contractility of colonic longitudinal muscle from tgr5-wt but not tgr5-ko mice. Application of deoxycholic acid, lithocholic acid, or oleanolic acid (a selective agonist of TGR5) to the mucosa of tgr5-wt mice caused oral contraction and caudal relaxation, indicating peristalsis. BAs stimulated release of the peristaltic transmitters 5-hydroxytryptamine and calcitonin gene-related peptide; antagonists of these transmitters suppressed BA-induced peristalsis, consistent with localization of TGR5 to enterochromaffin cells and intrinsic primary afferent neurons. tgr5-ko mice did not undergo peristalsis or transmitter release in response to BAs. Mechanically induced peristalsis and transmitter release were not affected by deletion of tgr5. Whole-gut transit was 1.4-fold slower in tgr5-ko than tgr5-wt or tgr5-tg mice, whereas colonic transit was 2.2-fold faster in tgr5-tg mice. Defecation frequency was reduced 2.6-fold in tgr5-ko and increased 1.4-fold in tgr5-tg mice compared with tgr5-wt mice. Water content in stool was lower (37%) in tgr5-ko than tgr5-tg (58%) or tgr5-wt mice (62%).ConclusionsThe receptor TGR5 mediates the effects of BAs on colonic motility, and deficiency of TGR5 causes constipation in mice. These findings might mediate the long-known laxative properties of BAs, and TGR5 might be a therapeutic target for digestive diseases.