Dietary Protein Digestion Research Articles

Effect of Dietary Digestible Protein Levels on Muscle Growth and Oxidative Stress in Amazonian Pintado (Pseudoplatystoma reticulatum × Leiarius marmoratus).

This study aimed to evaluate the effects of dietary digestible protein levels on the growth dynamics and oxidative stress status of white muscle fibers in Amazonian Pintado (Pseudoplatystoma reticulatum × Leiarius marmoratus). Four hundred and fifty-five juveniles of Amazonian Pintado were fed diets containing varying digestible protein levels (225, 250, 275, 300, 325, 350, or 375 g kg-1) for 75 days. At the end of the experiment, the fish were fasted for 24 h, anesthetized, and euthanized to obtain muscle samples. The linear and quadratic effects of dietary digestible protein levels on white muscle fiber diameter, metabolite concentrations, and oxidative stress were assessed. The results revealed that increasing dietary digestible protein levels linearly raised the concentrations of free amino acids and total proteins in muscle tissue but also led to elevated levels of TBARS, indicating increased oxidative stress. Notably, the average area of muscle fibers with a cell area greater than 1133 µm2 decreased, reflecting restricted muscle hypertrophy, whereas glycogen and glucose levels also declined. These findings suggest that although high dietary digestible protein enhances protein and free amino acid concentrations in muscle tissue, it may compromise muscle hypertrophy and increase oxidative damage in Amazonian Pintado, underscoring the complexity of optimizing diet formulation.

Effects of gastric bypass on the digestibility and postprandial metabolic fate of 15N dietary protein in rats.

Roux-en-Y Gastric Bypass may be associated with an alteration of protein bioavailability in relation to intestinal remodeling. Our study aimed to test this hypothesis by Roux-en-Y Gastric Bypass. Diet-induced obese rats underwent Roux-en-Y Gastric Bypass surgery (RYGB rats) while a Sham-operated control group was used. All rats received a 15N-labeled protein meal 1 or 3 months after surgery and were euthanized 6h later. Protein digestibility, 15N recovered in organs and urea pool, fractional protein synthesis rate, and intestinal morphometry were assessed. Protein digestibility was similar in all groups (94.2±0.3%). The small intestine was hypertrophied in RYGB rats 1 month after surgery, weighing 9.1±0.2g vs. 7.0±0.3g in Sham rats (P = 0.003). Villus height and crypt depth were increased in the alimentary limb and ileum of RYGB rats. However, Roux-en-Y Gastric Bypass had no impact on the fractional synthesis rate. In the gastrointestinal tract, 15N retention only differed in the ileal mucosa and was higher in RYGB rats at 1 month (0.48±0.2% vs. 0.3±0.09%, P = 0.03). 15N recovery from the liver, muscle, and skin was lower in RYGB rats at 1 month. 15N recovery from urinary and plasma urea was higher in RYGB rats at both times, resulting in increased total deamination (13.2±0.9% vs. 10.1±0.5%, P<0.01). This study showed that Roux-en-Y Gastric Bypass did not affect protein digestibility. Dietary nitrogen sequestration was transitorily and moderately diminished in several organs. This was associated with a sustained elevation of postprandial deamination after Roux-en-Y Gastric Bypass, whose mechanisms merit further studies.

Dietary protein splanchnic uptake and digestibility via stable isotope tracers.

Dietary proteins are broken down into peptides across the gastrointestinal tract, with skeletal muscle being a primary deposition site for amino acids in the form of incorporation into, for example, metabolic and structural proteins. It follows that key research questions remain as to the role of amino acid bioavailability, of which protein digestibility and splanchnic sequestration (absorption and utilization) of amino acids are determining factors, impact upon muscle protein synthesis (MPS) in clinical states. Elevated splanchnic amino acid uptake has been implicated in anabolic resistance (i.e. attenuated anabolic responses to protein intake) observed in ageing, though it is unclear whether this limits MPS. The novel 'dual stable isotope tracer technique' offers a promising, minimally invasive approach to quantify the digestion of any protein source(s). Current work is focused on the validation of this technique against established methods, with scope to apply this to clinical and elderly populations to help inform mechanistic and interventional insights. Considerations should be made for all facets of protein quality; digestibility of the protein, absorption/utilization and subsequent peripheral bioavailability of amino acids, and resultant stimulation of MPS. Stable isotope tracer techniques offer a minimally invasive approach to achieve this, with wide-ranging clinical application.

Performance, nutrient utilization and meat quality traits in Bos indicus cattle: a meta-analysis examining the effect of residual feed intake.

This meta-analysis aims to investigate the effects of residual feed intake (RFI) phenotype on performance, nutrient utilization and meat quality traits in Zebu (Bos indicus) cattle. Twenty-three peer-reviewed publications with 37 treatment means were included in the dataset. Weighted mean difference analysis compared animals categorized into low RFI (more efficient) versus medium or high RFI (less efficient) groups. Data heterogeneity via meta-regression and subgroup analysis, considering variables such as animal age, sex class, experimental duration, RFI group, dietary concentrate, and estimated metabolizable energy intake were also explored. The predominant genetic group of cattle in the dataset was Nellore (89.18%), followed by Brahman (10.81%). More efficient animals (low RFI phenotype) exhibited less dry matter intake (DMI; P < 0.010) than medium or high RFI animals (-0.95kg vs. -0.42kg/d). Cattle dietary crude protein and fiber digestibility were consistent across RFI groups (P > 0.05), while dietary ether extract digestibility tended to decrease (P = 0.050) in low RFI animals (-13.20g/kg DM). Low RFI animals tended to increased (P = 0.065) ribeye area (REA) compared to the high/medium RFI groups, while carcass backfat thickness (BFT) decreased (P = 0.042) compared to high/medium RFI groups. Moreover, there was an increase (P < 0.001) of 0.22kg in Warner-Bratzler shear force (WBSF) and a reduction (P < 0.001) in the myofibrillar fragmentation index (MFI) in low RFI animals. Meat color parameters (lightness [L*] and yellowness [b*]) and visual marbling scores were consistent (P > 0.05) across RFI groups. In conclusion, Zebu cattle classified as efficient (low RFI) exhibited reduced DMI, which improves their feed efficiency. However, BFT and meat quality parameters such as tenderness (WBSF and MFI) and redness [a*] were compromised by low RFI phenotype, highlighting the challenge of enhancing feed efficiency and meat quality traits in Zebu cattle.

Dietary CP and digestion kinetics influence BW loss, litter weight gain, and reproduction by affecting postprandial amino acid metabolism in lactating sows

To avoid a high body protein mobilization in modern lean sows during lactation, an adequate dietary amino acid (AA) supply and an efficient AA utilization are crucial. This study evaluated the effects of dietary CP and in vitro protein digestion kinetics on changes in sow body condition, litter weight gain, milk composition, blood metabolites, protein utilization efficiency and subsequent reproductive performance. We hypothesized that a slower digestion of dietary protein would improve AA availability and utilization. In total, 110 multiparous sows were fed one of four lactation diets in a 2 × 2 factorial design, with two CP concentrations: 140 g/kg vs 180 g/kg, and two protein digestion kinetics, expressed as a percentage of slow protein (in vitro degradation between 30 and 240 min): 8 vs 16% of total protein. Feeding sows the high CP diets reduced sow weight loss (Δ = 7.6 kg, P < 0.01), estimated body fat loss (Δ = 2.6 kg, P = 0.02), and estimated body protein loss (Δ = 1.0 kg, P = 0.08), but only at a high percentage of slow protein. A higher percentage of slow protein increased litter weight gain throughout lactation (Δ = 2.6 kg, P = 0.04) regardless of CP concentrations, whereas a higher CP only increased litter weight gain during week 3 of lactation (Δ = 1.2 kg, P = 0.01). On Day 15 postfarrowing, serial blood samples were taken from a subsample of sows fed with the high CP diets. In these sows, a high percentage of slow protein resulted in higher plasma AA concentrations at 150 and 180 min after feeding (Δ = 0.89, P = 0.02, Δ = 0.78, P = 0.03, mmol/L, respectively) and lower increases in urea at 90 and 120 min after feeding (Δ = 0.67, P = 0.04, Δ = 0.70, P = 0.03, mmol/L, respectively). The higher dietary CP concentration increased total nitrogen loss to the environment (Δ = 604 g, P < 0.01) with a reduction of protein efficiency (Δ = 14.8%, P < 0.01). In the next farrowing, a higher percentage of slow protein increased subsequent liveborn litter size (Δ = 0.7, P < 0.05). In conclusion, feeding sows with a high dietary CP concentration alleviated maternal weight loss during lactation when the dietary protein digestion rate was slower, but lowered protein efficiency. A slower protein digestion improved litter weight gain, possibly by reducing AA oxidation and improving plasma AA availability, thus, improving protein efficiency.

A Free Amino Acid Diet Alleviates Colorectal Tumorigenesis through Modulating Gut Microbiota and Metabolites.

Colorectal cancer (CRC), a major global health concern, may be influenced by dietary protein digestibility impacting gut microbiota and metabolites, which is crucial for cancer therapy effectiveness. This study explored the effects of a casein protein diet (CTL) versus a free amino acid (FAA)-based diet on CRC progression, gut microbiota, and metabolites using carcinogen-induced (AOM/DSS) and spontaneous genetically induced (ApcMin/+ mice) CRC mouse models. Comprehensive approaches including 16s rRNA gene sequencing, transcriptomics, metabolomics, and immunohistochemistry were utilized. We found that the FAA significantly attenuated CRC progression, evidenced by reduced colonic shortening and histopathological alterations compared to the CTL diet. Notably, the FAA enriched beneficial gut bacteria like Akkermansia and Bacteroides and reversed CRC-associated dysbiosis. Metabolomic analysis highlighted an increase in ornithine cycle metabolites and specific fatty acids, such as Docosapentaenoic acid (DPA), in FAA-fed mice. Transcriptomic analysis revealed that FAA up-regulated Egl-9 family hypoxia inducible factor 3 (Egln 3) and downregulated several cancer-associated pathways including Hippo, mTOR, and Wnt signaling. Additionally, DPA was found to significantly induce EGLN 3 expression in CRC cell lines. These results suggest that FAA modulate gut microbial composition, enhance protective metabolites, improve gut barrier functions, and inhibit carcinogenic pathways.

Blended-protein changes body weight gain and intestinal tissue morphology in rats by regulating arachidonic acid metabolism and secondary bile acid biosynthesis induced by gut microbiota.

The impact of dietary nutrients on body growth performance and the composition of gut microbes and metabolites is well-established. In this study, we aimed to determine whether dietary protein can regulate the physiological indexes and changes the intestinal tissue morphology in rats, and if dietary protein was a crucial regulatory factor for the composition, function, and metabolic pathways of the gut microbiota. A total of thirty male Sprague Dawley (SD) rats (inbred strain, weighted 110 ± 10g) were randomly assigned to receive diets containing animal-based protein (whey protein, WP), plant-based protein (soybean protein, SP), or a blended protein (soybean-whey proteins, S-WP) for a duration of 8weeks. To investigate the effects of various protein supplement sources on gut microbiota and metabolites, we performed a high throughput 16S rDNA sequencing association study and fecal metabolomics profiling on the SD rats. Additionally, we performed analyses of growth indexes, serum biochemical indexes, and intestinal morphology. The rats in S-WP and WP group exhibited a significantly higher body weight and digestibility of dietary protein compared to the SP group (P < 0.05). The serum total protein content of rats in the WP and S-WP groups was significantly higher (P < 0.05) than that in SP group, and the SP group exhibited significantly lower (P < 0.05) serum blood glucose levels compared to the other two groups. The morphological data showed the rats in the S-WP group exhibited significantly longer villus height and shallower crypt depth (P < 0.05) than the SP group. The gut microbial diversity of the SP and S-WP groups exhibited a higher level than that of the WP group, and the microbiomes of the WP and S-WP groups are more similar compared to those of the SP group. The Arachidonic acid metabolism pathway is the most significant KEGG pathway when comparing the WP group and the SP group, as well as when comparing the SP group and the S-WP group. The type of dietary proteins exerted a significant impact on the physiological indices of SD rats. Intake of S-WP diet can enhance energy provision, improve the body's digestion and absorption of nutrients, as well as promote intestinal tissue morphology. In addition, dietary protein plays a crucial role in modulating fecal metabolites by regulating the composition of the gut microbiota. Metabolomics analysis revealed that the changes in the levels of arachidonic acid metabolites and secondary bile acid metabolite induced by Clostridium_sensu_stricto_1 and [Eubacterium]_coprostanoligenes_group maybe the primarily causes of intestinal morphological differences.

Acid-active proteases to optimize dietary protein digestibility: a step towards sustainable nutrition.

Historically, prioritizing abundant food production often resulted in overlooking nutrient quality and bioavailability, however, environmental concerns have now propelled sustainable nutrition and health efficacy to the forefront of global attention. In fact, increasing demand for protein is the major challenge facing the food system in the 21st century with an estimation that 70% more food is needed by 2050. This shift has spurred interest in plant-based proteins for their sustainability and health benefits, but most alternative sources of protein are poorly digestible. There are two approaches to solve digestibility: improve the digestibility of food proteins or improve the digestive capacity of consumers. Enhancing nutrient digestibility and bioavailability across diverse protein sources is crucial, with proteases presenting a promising avenue. Research, inspired by the proteases of human breast milk, has demonstrated that exogenous microbial proteases can activate within the human digestive tract and substantially increase the digestion of targeted proteins that are otherwise difficult to fully digest. Here, we introduce the use of an acid-active family of bacterial proteases (S53) to improve the digestibility and nutritional quality of a variety of protein sources, evaluated using the INFOGEST 2.0 protocol. Results from in vitro digestibility indicate that the most effective protease in the S53 family substantially improves the digestibility of an array of animal and plant-derived proteins-soy, pea, chickpea, rice, casein, and whey. On average, this protease elevated protein digestibility by 115% during the gastric phase and by 15% in the intestinal phase, based on the degree of hydrolysis. The widespread adoption of these proteases has the potential to enhance nutritional value and contribute to food security and sustainability. This approach would complement ongoing efforts to improve proteins in the food supply, increase the quality of more sustainable protein sources and aid in the nourishment of patients with clinically compromised, fragile intestines and individuals like older adults and high-performance athletes who have elevated protein needs.

144 Effect of Protein Source on Piglet Performance and Dietary Protein Digestibility in Regular Nursery and Escherichia Coli Challenged Conditions

Abstract Compared with conventional soybean meal (SBM), processed soy protein has been demonstrated to have greater nutrient digestibility, leading to better animal growth performance and gut health. The aim of the present study was to test hypothesis that Provisoy, a SBM product produced via hydrothermal mechanical treatment could improve weaning piglet growth performance via greater crude protein (CP) digestibility compared with SBM, and this benefit would be greater in pigs under Escherichia coli (ETEC) challenged conditions. A total of 268 weaned pigs [initial body weight (BW) = 6.82 ± 0.85 kg] were allotted to a split plot design and pigs were housed in either a regular nursery condition (5 pigs/pen, 10-11 pens/treatment) or an ETEC challenged condition (3 pigs/pen, 12 pens/treatment, 1 pig per pen was orally gavaged with 10 mL O149K91K88 on d 5 post-weaning). All pigs were fed one of the following diets: SBM, Provisoy or HP300. A standard wheat-barley-SBM based nursery diet was used and test soy products were added to replace SBM in the treatment diets. All diets were formulated to be isocaloric and had similar standardized ileal digestible lysine level in a three-phase (38 days) nursery program. One pig per pen was euthanized for ileal digesta and fecal samples were collected on post-weaning day 13 and 14. Data were analyzed by general linear model in R. In summary, there was no interaction between challenge condition and dietary protein source on intake and gain throughout all three phases. A significant interaction in G:F between d 0-7 post-weaning (P &amp;lt; 0.05) was observed. As expected, pigs performed better in regular conditions compared with challenged conditions (P &amp;lt; 0.05). Dietary protein source significantly affected ADG (P &amp;lt; 0.05) and BW (P &amp;lt; 0.01) on post-weaning d 7 regardless of challenge condition, with pigs fed Provisoy exhibiting increased ADG and d 7 BW versus the control but not different than HP300. Similar improvements in growth performance were observed during d 7-12 post-weaning. However, the effect of protein source on piglet growth was no longer evident during the last phase of nursery. There was no interaction observed between challenge condition and protein source on CP apparent ileal digestibility (AID) or apparent total tract digestibility (ATTD). Dietary protein source affected CP ATTD (P &amp;lt; 0.01), with Provisoy treatment having the greatest value compared with other treatments. Challenge conditions tended to decrease CP AID (P = 0.109). In conclusion, dietary inclusion of Provisoy could improve piglet growth performance during the early nursery phase regardless of challenge condition and this benefit was likely partially due to better CP digestibility.

Effect of a Baobab Powder Diet on Growth and Digestive Balance in Growing Rats

Introduction: The fight against malnutrition (over- and undernutrition) requires knowledge of the fruits we eat. Baobab is a fruit from the north of Côte d'Ivoire whose consumption can help improve nutrition. Aim: The aim of this study was to investigate the chemical composition of baobab pulp and evaluate its nutritional impact after consumption in growing rats. Methodology: To achieve this objective, the physicochemical parameters and macronutrient contents of baobab flour were determined. Then, 3 batches of 5 rats were fed separately with three diets: RFB (baobab pulp), RM (baobab pulp + cornstarch) and RFM (cornstarch). Regular weighing was carried out to determine growth and digestibility parameters. Results: At the end of the work, it was found that baobab pulp is an acidic food (pH = 3.2), composed mainly of carbohydrates (92.47), mainly energy. It has a high starch content (56.34), a high sugar content (21.37), hence its sweet taste; with a considerable fiber content (7.82), in terms of dry matter (DM). Baobab flour contains very low levels of protein (2.08) and lipids (0.37). From a nutritional point of view, the baobab pulp diet (RFB) does not promote rat growth, and therefore the utilization of dietary protein. In addition, the RFB diet results in negative digestibility of dietary proteins and very low digestibility of the dry matter in the food consumed. On the other hand, rat growth and the digestibility of dietary protein and dry matter increased with the reduction (RM) or elimination (RFM) of baobab flour from the diet. Conclusion: Ultimately, these results enable us to assess the nutritional quality of baobab flour. Its consumption, which does not promote weight gain despite its high carbohydrate content, can therefore be used in the fight against obesity.

Effects of Co-Fermented Feed Using Lactobacillus acidophilus, Limosilactobacillus reuteri and Lactiplantibacillus plantarum on Growth, Antioxidant Capacity, Fatty Acids and Gut Microbiota of Largemouth Bass (Micropterus salmoides)

The effects of diets fermented with compound probiotics, namely Lactobacillus acidophilus, Limosilactobacillus reuteri and Lactiplantibacillus plantarum, on the growth performance, physiological and biochemical indexes, fatty acid composition and intestinal health of juvenile largemouth bass (Micropterus salmoides) were investigated. Three hundred healthy juvenile M. salmoides (5.29 ± 0.02 g) were selected and randomly divided into two groups with triplicates for each. The basic diet was set as the control group (CON), and fermentation of the basic diet with a mixed bacterial solution (1.8 × 109 cfu/mL, L. acidophilus:L. reuteri:L. plantarum = 1:1:1) was set as the fermentation group (FER). Fish were hand fed to satiation for 56 days and two-thirds of the culture water was renewed every 3 days. The results showed that feed intake of fish in the FER group was significantly lowered, thereby increasing feed efficiency (FE) and protein efficiency (PER) (p &lt; 0.05). Serum alanine aminotransferase (ALT) activity was significantly decreased, and catalase (CAT) activity was significantly increased in the FER group (p &lt; 0.05). The liver superoxide dismutase activity (SOD) was significantly enhanced, and intestinal trypsin was significantly increased in the FER group (p &lt; 0.05). Being fed with the fermentation diet significantly increased the content of n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and the n-3/n-6 PUFAs ratios in the liver (p &lt; 0.05). Intestinal histology showed that villus height and width of the intestine and the number of goblet cells were significantly increased in the FER group (p &lt; 0.05). Those fed with fermentation diets had limited diversity of gut microbiota. Compared to the CON group, the relative abundance of Aeromonas decreased significantly (p &lt; 0.05), while the relative abundance of Fusobacteria, Cetobacteria and Lactobacillusis in FER increased greatly in the gut microbiota of the FER group. In conclusion, fermented feed with the three probiotics effectively improved the feed utilization and antioxidant capacity, promoted digestion and absorption of dietary protein, improved the ability of synthesize DHA and n-3 PUFAs in the liver and reduced the abundance of pathogenic bacteria in the gut. Therefore, the present research provided a new way of co-fermented feed with three probiotics for the aquaculture of M. salmoides.

Dietary protein levels modulate the gut microbiome composition through fecal samples derived from lactating ewes.

In ruminants, the digestion and utilization of dietary proteins are closely linked to the bacterial populations that are present in the gastrointestinal tract. In the present study, 16S rDNA sequencing, together with a metagenomic strategy was used to characterize the fecal bacteria of ewes in the early lactation stage after feeding with three levels of dietary proteins 8.58%, 10.34%, and 13.93%, in three different groups (H_1), (H_m) and (H_h), respectively. A total of 376,278,516 clean data-points were obtained by metagenomic sequencing. Firmicutes and Bacteroidetes were the dominant phyla, regardless of the dietary protein levels. In the H_h group, the phyla Proteobacteria, Caldiserica, and Candidatus_Cryosericota were less abundant than those in the H_I group. In contrast, Lentisphaerae, Chlamydiae, and Planctomycetes were significantly more abundant in the H_h group. Some genera, such as Prevotella, Roseburia, and Firmicutes_unclassified, were less abundant in the H_h group than those in the H_I group. In contrast, Ruminococcus, Ruminococcaceae_noname, Anaerotruncus, Thermotalae, Lentisphaerae_noname, and Paraprevotella were enriched in the H_h group. The acquired microbial genes were mainly clustered into biological processes; molecular functions; cytosol; cellular components; cytoplasm; structural constituents of ribosomes; plasma membranes; translation; and catalytic activities. 205987 genes were significantly enriched in the H_h group. In contrast, 108129 genes were more abundant in the H_I group. Our findings reveal that dynamic changes in fecal bacteria and their genes are strongly influenced by the levels of dietary proteins. We discovered that differentially expressed genes mainly regulate metabolic activity and KEGG demonstrated the primary involvement of these genes in the metabolism of carbohydrates, amino acids, nucleotides, and vitamins. Additionally, genes responsible for metabolism were more abundant in the H_h group. Investigating fecal bacterial characteristics may help researchers develop a dietary formula for lactating ewes to optimize the growth and health of ewes and lambs.

SLC15 family of peptide transporters in GtoPdb v.2023.1

The Solute Carrier 15 (SLC15) family of peptide transporters, alias H+-coupled oligopeptide cotransporter family, is a group of membrane transporters known for their key role in the cellular uptake of di- and tripeptides (di/tripeptides). Of its members, SLC15A1 (PEPT1) chiefly mediates intestinal absorption of luminal di/tripeptides from overall dietary protein digestion, SLC15A2 (PEPT2) mainly allows renal tubular reuptake of di/tripeptides from ultrafiltration and brain-to-blood efflux of di/tripeptides in the choroid plexus, SLC15A3 (PHT2) and SLC15A4 (PHT1) interact with both di/tripeptides and histidine, e.g. in certain immune cells, and SLC15A5 has unknown physiological function. In addition, the SLC15 family of peptide transporters variably interacts with a very large number of peptidomimetics and peptide-like drugs. It is conceivable, based on the currently acknowledged structural and functional differences, to divide the SLC15 family of peptide transporters into two subfamilies [3].

Effect of dietary digestible undegradable protein and amino acid concentration on the growth and development of post-pubertal dairy heifers

Effect of dietary digestible undegradable protein and amino acid concentration on the growth and development of post-pubertal dairy heifers

Dynamic, Mechanistic Modeling Approach as a Tool to Mitigate N Excretion in Broilers

The nitrogen (N) load of broiler meat production is known for its high contribution to the environmental footprint of animal agriculture. The modeling work presented here is to be used as a tool to understand and quantify N excretion via a dynamic mechanistic nutrient partitioning simulation. The model has been developed for broilers, representing energy and protein utilization. Three case studies are presented and discussed, such as (1) feeding schedules with adjusted protein content feeds; (2) feeding diets with different digestibility of crude protein; and (3) feeding diets with the same digestible protein and different SID lysine, methionine plus cystine or threonine contents. In addition to N retention and total N excretion, diagnostic variables for N excretion via urine and obligatory urinary N excretion were studied to evaluate N partitioning in response to different feeding schedules. The excess N was calculated in each scenario for the whole fattening period. This in silico study has confirmed that unprecise diet formulation has considerable consequences: overestimation of digestibility or oversupply of dietary protein increases the total ammonia N in the manure and thus the N emission potential of poultry meat production. The presented approach may be recommended to design alternative feeding strategies with a low environmental footprint.

Estimation of dietary protein and energy requirements of doctor fish, Garra rufa, using a bioenergetic factorial approach

The use of doctor fish, Garra rufa, is widening in the treatment of psoriasis and in recreational spas all over the world. The increasing demand for the fish has created pressure on its wild stocks, making its rearing in captivity necessary. However, there is no specifically formulated diet meeting the dietary nutrient requirements of doctor fish at different developmental stages. The present study was planned to estimate the dietary protein and energy requirements of doctor fish based on a factorial approach. Two growth experiments were conducted using fish with initial mean weights of 0.46 g (small) and 0.84 g (large) at various feeding levels to estimate the maintenance requirements of energy and protein and their utilization efficiencies. Metabolic body weight (BW) exponents for energy and protein were estimated from a starvation study as 0.81 and 0.67, not significantly different from the largely accepted values of 0.80 and 0.70, respectively (P > 0.05). The maintenance requirements of digestible energy (DE) and digestible protein (DP) were 55.5 (kJ/kg BW0.80/day) and 0.49 DP g/kg BW0.70/day, and the utilization efficiencies of DE and DP were 0.61 and 0.35, respectively. Dietary DP:DE demands decreased as fish size increased. The key sizes of fish for changing DP:DE requirements were estimated with one and two-break point analysis. Based on those estimated critical sizes, two hypothetical diet specifications were provided for doctor fish weighing between 0.1 g and 5.0 g. A video shooting study carried out to measure the fish’s nibbling behavior showed a strong influence of feeding level (P < 0.05) where the lowest feeding level (21 kJ/kg BW0.80/day) induced fish to longer skin feeding behavior. The findings of the study allow the creation of specific doctor fish diet formulations for their cultivation and maintenance in spas and health centers.

Bile Acid Profile Influences Digestion Resistance and Antigenicity of Soybean 7S Protein.

Soybean 7S storage protein (β-conglycinin) is the most important allergen, exhibits resistance in gastrointestinal (GI) digestion, and causes allergies in humans and animals. A previous study has demonstrated that 7S proteins contained innate amyloid aggregates, but the fate of these specific protein aggregates in intestinal digestion and correlation to allergenicity are unclear. In this study, via a modified INFOGEST static in vitro digestion and IgE binding test, we illustrate that the survived amyloid aggregates of soybean 7S protein in GI digestion might be dominant IgE epitopes of soybean protein in humans. The impact of conjugated primary bile acid salt (BS) profile on digestion resistance and immunogenicity of soybean protein is assessed, regarding the binding affinity of BS to protein aggregates with consideration of the BS composition and the physiologically relevant colloidal structure. The results show that chenodeoxycholate-containing colloidal structures exhibit high affinity and unfolding capacity to protein amyloid aggregates, promoting proteolysis by pancreatic enzymes and thus mitigating the antigenicity of soybean protein. This study presents a novel understanding of bile acid profile and colloidal structure influence on the digestibility and antigenicity of dietary proteins. It should be helpful to design in vitro digestion protocol and accurately replicate physiologically relevant digestion conditions.

Optimal Levels of Fish Meal and Methionine in Diets for Juvenile Litopenaeus vannamei to Support Maximum Growth Performance with Economic Efficiency.

This work investigated the optimal levels of fish meal (FML) and dietary methionine (Met) required for maximum growth performance of juvenile Litopenaeus vannamei with economic efficiency. Four sets of diets were prepared to contain 0.00, 6.00, 12.00 and 18.00% FML. Each set was supplemented with DL-methionyl-DL-methionine (DL-Met-Met) to result in a total dietary Met (Met + Cys) content of 0.58 (1.05), 0.69 (1.16), and 0.82% (1.29%), on a fed basis. Shrimp of 1.00 ± 0.08 g were stocked in 60 outdoor tanks of 1 m3 with 100 shrimp/m2, allowing five replications per dietary group. Shrimp in all the groups were fed 10 times daily for 70 days. In a subsequent trial, dietary protein and amino acid digestibility of four FML groups, but only at high dietary Met levels (~0.82%), were evaluated in 40 60 L indoor tanks (11 replicates per diet) for 93 days with 70 shrimp/m2. Final shrimp survival (92.85 ± 4.82%, mean ± standard deviation), weekly weight gain (1.17 ± 0.08 g), apparent feed intake (13.3 ± 0.5 g of feed per stocked shrimp), and feed conversion ratio (1.18 ± 0.06) were unaffected by dietary FML level and Met content. Gained yield was adversely affected when FML was reduced from 18 and 12% (1156 and 1167 g/m2, respectively) to 0 (1090 g/m2), but no change was observed at 6% (1121 g/m2). A significant interaction was detected between FML level and dietary Met. Under 0 and 6% FML conditions, higher levels of total dietary Met, 0.69 and 0.82%, respectively, were required to maximize shrimp BW. In comparison, at 12 and 18% FML, a dietary Met content of only 0.58% was sufficient. Overall, results indicated the use of FML can be minimized or completely eliminated without major detrimental effects on feed digestibility or shrimp growth performance, as long as proper supplementation of Met is carried out. Diets with 0 FML or with only 6% delivered the highest profit and return on investment compared to diets with higher levels.

Protein digestion and absorption: the influence of food processing.

The rates of dietary protein digestion and absorption can be significantly increased or decreased by food processing treatments such as heating, gelling and enzymatic hydrolysis, with subsequent metabolic impacts, e.g. on muscle synthesis and glucose homeostasis.This review examines in vivo evidence that industrial and domestic food processing modify the kinetics of amino acid release and absorption following a protein-rich meal. It focuses on studies that used compositionally-matched test meals processed in different ways.Food processing at extremely high temperature at alkaline pH and/or in the presence of reducing sugars can modify amino acid sidechains, leading to loss of bioavailability. Some protein-rich food ingredients are deliberately aggregated, gelled or hydrolysed during manufacture. Hydrolysis accelerates protein digestion/absorption and increases splanchnic utilisation. Aggregation and gelation may slow or accelerate proteolysis in the gut, depending on the aggregate/gel microstructure.Milk, beef and eggs are heat processed prior to consumption to eliminate pathogens and improve palatability. The temperature and time of heating affect protein digestion and absorption rates, and effects are sometimes non-linear. In light of a dietary transition away from animal proteins, more research is needed on how food processing affects digestion and absorption of non-animal proteins.Food processing modifies the microstructure of protein-rich foods, and thereby alters protein digestion and absorption kinetics in the stomach and small intestine. Exploiting this principle to optimise metabolic outcomes requires more human clinical trials in which amino acid absorption rates are measured and food microstructure is explicitly considered, measured and manipulated.

High levels of dietary digestible protein transiently promote beneficial bacteria in adult dog feces

Nowadays, many commercial dog diets select the ingredients not only to meet the needs of the individual and maintain a balance between nutrition/microbiome/health; fiber and protein quality is known to be one of the most important factors in this balance. Diets high in low digestible protein tend to favor microorganisms that when fermenting amino acids generate substances that induce inflammation, while high digestible protein and fermentable fibers have been related to beneficial bacteria. The study's objective was to identify changes in the relative abundance of specific microorganisms (Clostridium perfringens, Enterococcus faecium, Lactobacillus salivarius, Bacteroides fragilis and Fusobacterium varium) by PCR (polymerase chain reaction), associated with two diets of different quality and digestibility. Twenty adult dogs were used, divided into two groups, the first one fed with a high digestibility diet (HD) (n = 10), the second one with a low digestibility diet (LD) (n = 10). After 3 days of adaptation to the diet, fecal samples were taken at days 15 and 30. The results showed that the high-quality diet promotes a transient increase (15 days) in the relative abundance of F. varium and E. faecium, as well as a persistent increase in that of L. salivarius and B. fragilis until day 30. Apparently, however, healthy adult dogs eventually balance their fecal microbiota, regardless of the dietary protein level and digestibility. Therefore, it is difficult to identify clear patterns of the ideal dietary profile in this species.