HP Diet Research Articles

Dietary protein intake and the tubular handling of indoxyl sulfate.

Chronic kidney disease (CKD) patients are advised to limit their protein intake. A high protein diet is known to induce glomerular hyperfiltration, as well as hypertrophy of the remnant kidney, and glomerulosclerosis. Whether the diet causes changes in kidney tubule transport via gut microbiome metabolites is still unknown. We hypothesized that protein intake affects not only the intestinal generation and absorption, but also the kidney disposal of microbial amino acid metabolites. We combined data from animal models and human studies. 5/6th nephrectomy rats were administered a high (HP) or low-protein (LP) diet for 7 weeks. Plasma and urine concentration of the uremic toxins (UTs) indoxyl sulfate (IS), p-cresyl sulfate (PCS), and p-cresyl glucuronide (PCG) were measured. Their fractional excretion (FE) was calculated. The expression of kidney membrane transporters OAT1, OAT3, BCRP, OCT2 and MRP4 was analyzed. Differences in FE of UTs between individuals with higher and lower protein intake in two CKD cohorts were sought. CKD rats on an HP diet showed increased plasma levels of PCS and PCG but not IS compared to rats on a LP diet. Conversely, urinary excretion and FE of IS were higher in the HP CKD group. BCRP, MRP4 and OCT2 were not influenced by the diet. OAT1 and OAT3 were upregulated in the HP CKD group. In two independent cohorts of CKD patients, individuals with a high dietary protein intake showed a significantly higher FE of IS. A HP diet leads to a higher generation and/or absorption of aminoacid-derived UT precursors in CKD rodent models and humans, most likely via gut microbiome modulation. We demonstrate that dietary protein intake modulates transcription and expression of OAT1 and OAT3, corroborating the existence of the remote sensing and signaling hypothesis. Dietary protein intake influences kidney physiology beyond glomerular filtration.

236 Increased dietary protein supports key metabolic and intestinal tissue functions in weaned pigs, without increasing gastrointestinal pathogen abundance

Abstract A common dietary strategy to prevent diarrhea in weaned pigs is feeding low protein diets in the period immediately following weaning. The goal of this intervention is to decrease dietary protein sufficiently to reduce pathogen proliferation and protein fermentation without negatively impacting growth performance. One potential alternative to low protein diets is provision of dietary fiber. However, many studies examining the role of protein and fiber on gastrointestinal microbiota and post-weaning diarrhea are complicated by the presence of other substrates, including polyphenols and antinutritional factors in complex ingredients. To assess the role of increased protein and fiber on gut microbiota and host metabolism, semi-purified diets differing in crude protein (CP) and crude fiber (CF) were fed to weaned pigs (n = 40; 28 d of age). Diets with high protein (HP; CP 24.3%, CF 6.4%), high fiber (HF; CP 18.9%, CF 9.4%), or both (HFHP; CP 24.9%, CF 9.5%) were compared with a control (CON; CP 18.1%, CF 6.3%) diet with industry standard crude protein and fiber levels (n = 10/group). Growth performance and diarrhea prevalence were measured alongside gut microbiota composition and metabolites. Pigs fed the HP and HFHP diets had significantly improved feed efficiency compared with both CON and HF diets. Increased protein fermentation, measured through production of biogenic amines, was observed in HP fed animals (P < 0.001). These effects were mitigated by addition of fiber in the HFHP fed pigs. Despite increased markers of protein fermentation, post-weaning diarrhea incidence was not greater in HP fed animals and no increases in gastrointestinal pathogen abundance were detected. Metabolomic and transcriptomic analyses identified critical alterations in host metabolism and cecal transcriptome in the CON compared with the HP fed animals. While all diets were formulated to meet the dietary requirements of weaned pigs, diets with lower protein levels (CON and HF) induced alteration in transcripts from the serine synthesis pathways (P < 0.001) and integrated stress response (P < 0.001) in cecal tissue alongside increases in metabolic pathways related to lysine degradation (P = 0.005). These results challenge the current practice of low protein feeding following weaning by demonstrating a detrimental effect of low protein diets on intestinal cell function and muscle accretion. This suggests that with careful ingredient selection, increased dietary protein post-weaning could better support pig health and performance compared with current industry standard diets.

High protein diets improve the growth of juvenile barramundi (Lates calcarifer) at elevated temperatures

Elevated temperatures and low aquatic oxygen levels are increasingly accompanying climate warming and can adversely affect the production and welfare of farmed fish. Both environmental factors and diet affect fish energetics. Still, little is known about the dietary effects on fish energetics at elevated temperatures and low aquatic oxygen levels and how that influences growth. Thus, a feeding trial was conducted to investigate the effect of two isoenergetic diets, high protein (HP, 57% crude protein and 9% total lipid) and high lipid (HL, 40% crude protein and 19% total lipid), on juvenile barramundi (Lates calcarifer, initial body mass: ∼ 3 g). Fish were acclimated for at least four weeks on the diets (three weeks at 35 °C) before measurements began (i.e.: measurements were taken between weeks four to six of the trial). Additionally, feed intake and maximum metabolic rate were tested under three levels of aquatic oxygen levels (normoxia >80, 60% and 30% air saturation). We found no significant dietary effect on feed intake, routine, maximum and postprandial peak metabolic rate. Gill ventilation rate was also unaffected by diet treatment. However, fish fed the HP diet had increased haematocrit and haemoglobin levels, improved growth rates, feed conversion ratio, and protein deposition relative to those fed the HL diet. Thus, this study demonstrated that a high protein diet enhanced key physiological traits such as oxygen-carrying capacity, potentially supporting improved juvenile barramundi growth at elevated temperatures.

Not feeling the heat? Effects of dietary protein on satiation and satiety in mice are not due to its impact on body temperature

Dietary protein modulates food intake (FI) via unclear mechanism(s). One possibility is that higher protein leads to greater post-ingestive heat production (Specific dynamic action: SDA) leading to earlier meal termination (increased satiation), and inhibition of further intake (increased satiety). The influence of dietary protein on feeding behaviour in C57BL/6J mice was tested using an automated FI monitoring system (BioDAQ), simultaneous to body temperature (Tb). Total FI, inter meal intervals (IMI, satiety) and meal size (MS, satiation) were related to changes in Tb after consuming low (5%, LP), moderate (15%, MP) and high (30%, HP) protein diets. Diets were tested over three conditions: 1) room temperature (RT, 21 ± 1 °C), 2) room temperature and running wheels (RTRW) and 3) low temperature (10 °C) and running wheels (LTRW). The differences between diets and conditions were also compared using mixed models. Mice housed at RT fed HP diet, reduced total FI compared with LP and MP due to earlier meal termination (satiation effect). FI was lowered in RTRW conditions with no differences between diets. FI significantly increased under LTRW conditions for all diets, with protein content leading to earlier meal termination (satiation) but not the intervals between feeding bouts (satiety). Tb fell immediately after feeding in all conditions. Despite a reduction in total FI in mice fed HP, mediated via increased satiation, this effect was not linked to increased Tb during meals. We conclude effects of dietary protein on intake are not mediated via SDA and Tb.

PSV-12 Microbial community structure of dairy cattle is stable through oscillating crude protein inclusion

Abstract Diet has an important role in shaping the structure of rumen microbial communities. However, little is known about the interaction between dietary crude protein (CP) level and CP feeding pattern on the rumen microbiome of dairy cows. Here, the objective was to evaluate the influence of CP level (low protein [LP], 13.8%; high protein [HP], 15.5% of dry matter [DM] basis) and CP feeding pattern (OF = oscillating, SF = static) on the composition and diversity of the rumen microbiome of lactating dairy cows using 16S rRNA gene amplicon sequencing. Rumen-cannulated Holstein cows (n = 8) in mid- to late-lactation were assigned to a 2 x 2 factorial experiment consisting of 4 experimental periods of 28 d. Each experimental period had an adaptation phase to the diet (24 d) and a sampling phase (d 25 to 28). The treatments with oscillating feeding alternated diets every 48 h to vary CP above and below the mean CP level (OF-LP = 13.8 ± 1.8%; OF-HP = 15.5 ± 1.8% CP of DM) whereas diets were constant in the static feeding (SF-LP = 13.8%; SF-HP = 15.5% CP of DM). According to the NASEM (2021) model predictions the LP diet supplied 94% of the microbial protein requirement while the HP diet exceeded (104%) requirement. Rumen samples were collected 4 h after feeding through a rumen cannula and amplicon libraries were generated targeting the V4 region of the 16S rRNA gene. The amplicon sequences were analyzed in qiime2. Sequences where trimmed based on their quality and then grouped in ASVs using DADA2. The ASVs were used to analyze the composition and diversity of the rumen microbiome in each treatment. Alpha diversity of the rumen microbiome did not change across treatments (Kruskal Wallis, P > 0.05), but Pielou’s evenness increased by 0.01 units (Kruskal Wallis, P = 0.04). These results support the hypothesis that the rumen microbiome is stable to oscillating CP feeding patterns and compensates for the changes in crude protein content in the diet. Further research is required to understand the dynamics of this compensation and what other metabolic processes in the ruminant contribute to maintaining production under an oscillating diet.

253 The influence of corn-based fiber on digesta short chain fatty acid composition and pH in growing pigs

Abstract Pigs can obtain energy from fibrous feedstuffs through a symbiotic relationship with their gastrointestinal microbiome, which results in the production of metabolites, such as short chain fatty acids (SCFA). An experiment was conducted with the objective of investigating how different insoluble corn-based fiber sources influence changes in SCFA composition along the digestive tract of growing pigs. Two replicates of 28 gilts [n = 56; initial body weight (BW) = 26.7 ± 2.5 kg; PIC800 x Camborough], were randomly assigned to one of 7 semi-synthetic diets. Dietary treatments included a control (CTL) diet with a formulated total dietary fiber (TDF) value of < 1% and 6 diets with a CBF replacing 30% of the corn starch in CTL: dehulled degermed corn (DHDG; TDF = 1.09%), ground corn (COR; TDF = 3.24%), high protein dried distiller’s grains (HP; TDF = 8.79%), dried distiller’s grains (DDGS; TDF = 9.35%), corn gluten meal (CGM; TDF = 9.88%), and corn bran (BRN; TDF = 13.15%). Pigs were individually housed, and limit-fed at 2.4 times maintenance. On d 31, pigs were necropsied, and ileal, cecal, and colonic digesta were collected for immediate SCFA analysis and stomach, jejunal, ileal, and cecal digesta pH was measured. Data were analyzed as a linear mixed model with treatment as a fixed effect, replicate as a random slope or fixed effect, where appropriate, using the mixed procedure of SAS. There were no differences in jejunal nor stomach pH (P ≥ 0.51). Ileal pH was greatest (P = 0.01) in HP, DDGS, and CGM diets. Cecal pH was greatest (P < 0.01) in the BRN diet and lowest in COR and HP. Molar proportions of ileal SCFAs did not differ (P ≥ 0.74) among treatments. In the cecum, molar proportions of butyrate production did not differ (P = 0.74). Cecal acetate proportions were less (P = 0.03) in CTL, COR, and HP compared with all other treatments (51.54, 61.09, 51.92, 52.89, 59.16, 63.87, and 63.32%, for CTL, DHDG, COR, HP, DDGS, CGM, and BRN, respectively). Cecal propionate proportions were greatest (P = 0.01) in BRN and least in DHDG, COR, and CGM (30.85, 27.67, 27.67, 30.91, 30.47, 24.03, and 35.86% for CTL, DHDG, COR, HP, DDGS, CGM, and BRN, respectively). Relative to CTL, isobutyrate proportions in the cecum for COR, HP, and DDGS were reduced by 65%, 52%, and 53%, respectively (P < 0.01). In the colon, there were no differences in molar proportions of acetate, butyrate, nor isobutyrate (P ≥ 0.254). However, HP and CGM had a smaller (P = 0.04) proportion of propionate in the colon and COR and BRN had the greatest proportion of colonic propionate (33.92, 29.68, 38.41, 25.3, 30.00, 26.76, and 37.94% for CTL, DHDG, COR, HP, DDGS, CGM, and BRN, respectively). Collectively, the different fibrous components of CBFs can influence SCFA proportions in the growing pig.

Hydroponic barley supplementation fed with high-protein diets improves the production performance of lactating dairy cows

The study investigated the effects of dietary protein level and the inclusion of hydroponic barley sprouts (HB) on lactation performance, blood biochemistry and N use efficiency in mid-lactation dairy cows. Treatments were arranged in a 2 × 2 factorial design with 2 crude protein (CP) levels [16.8% and 15.5% of dry matter (DM)], with HB (4.8% of DM, replacing 4.3% of alfalfa hay and 0.5% of distillers dried grains with solubles (DDGS)) or without HB. Forty-eight multiparous Holstein dairy cows (146 ± 15 d in milk, 40 ± 5 kg/d of milk) were randomly allocated to 1 of 4 diets: high protein diet (16.8% CP, HP), HP with HB (HP+HB), low protein diet (15.5% CP, LP), or LP with HB (LP+HB). An interaction between CP × HB on dry matter intake (DMI) was detected, with DMI being unaffected by HB inclusion in cows fed the high CP diets, but was lower in cows fed HB when the low CP diet was fed. A CP × HB interaction was also observed on milk and milk protein yield, which was higher in cows fed HB with HP, but not LP. Inclusion of HB also tended to reduce milk fat content, and feeding HP resulted in a higher milk protein and milk urea N content, but lower milk lactose content. Feed efficiency was increased by feeding HP or HB diets, whereas N efficiency was higher for cows fed LP or HB diets. There was an interaction on the apparent total-tract digestibility of DM and CP, which was higher when HB was fed along with HP, but reduced when fed with LP, whereas the digestibility of ADF was increased by feeding low protein diets. In conclusion, feeding a low protein diet had no adverse effect on cow performance, while feeding HB improved milk and milk component yield, and N efficiency when fed with a high CP diet, but compromised cow performance with a low CP diet.

High starch intake favours body weight control in neutered and spayed cats living in homes fed ad libitum.

Different starch-to-protein ratios were compared among neutered and spayed domiciled cats. Male and female obese and non-obese cats were fed kibble diets ad libitum for 4 months high in starch (HS (38 % crude protein (CP)): starch 32 %, protein 38 %; DM basis) or high in protein (HP (55 % CP): starch 19 %, protein 55 %) but similar in energy and fat in a crossover design. Physical activity was evaluated using an accelerometer, and body composition (BC), energy expenditure (EE) and water turnover (WT) using the doubly labelled water method. Results were compared in a 2 diet × 2 sex × 2 body condition factorial arrangement. Cats fed the HS (38 % CP) diet maintained a constant body weight, but lean mass (LM) tended to be reduced in female obese but to be increased in male non-obese (P < 0·08) and increased in female non-obese cats (P = 0·01). The HP (55 % CP) diet induced an increase in cat body weight and LM (P < 0·05) without altering BC proportion. EE tended to be higher in males (351 (se 8) kJ/kg0·67/d) than females (330 (se 8) kJ/kg0·67/d; P = 0·06), was unaffected by diet or BC, decreased as age increased (R 2 0·44; P < 0·01) and increased as physical activity increased (R 2 0·58; P < 0·01). WT was higher for the HP (55 % CP) diet (P < 0·01) and increased with EE (R 2 0·65; P < 0·01). The HS (38 % CP) diet favoured body weight control during 4 months of ad libitum feeding. Caution is necessary to balance protein in diets of female obese cats over 5 years, as they may have low energy and food intake, with LM loss.

Effect of substituting fish meal with various by-product meals of swine-origin in diet on olive flounder (Paralichthys olivaceus)

The increased global market value of fish meal (FM) and the overfishing of wild fishery resources have boosted efforts to identify protein sources that can be cheaply and reliably supplied as an alternative to FM, which is commonly used as a main protein source in fish diets. Numerous studies over the years have demonstrated that animal by-product meals are the effective alternatives for FM in fish diets. This study aimed to elucidate the effect of substituting FM with various by-product meals of swine-origin in diet on growth, feed utilization, chemical composition, plasma biochemical parameters, and superoxide dismutase (SOD) and lysozyme activity of juvenile olive flounder (P. olivaceus). All experimental diets were formulated with five isonitrogenous (56.5%) and isolipidic (10.0%) diets. The control (Con) diet included 65% FM and 12% dehulled soybean meal as the protein sources and 4.2% fish oil as a lipid source. Thirty percent of FM was replaced with plasma powder, heme powder, globin powder, and pork greaves meal, named as the PP, HP, GP, and PM diets, respectively. Three hundred and seventy-five juvenile (9.2 ± 0.01 g; mean ± SD) fish were placed into 15 flow-through tanks with three replicates. Fish were carefully hand-fed to apparent satiation twice a day for 56 days. At the end of the feeding period, weight gain and specific growth rate of fish fed the GP and PM diets were comparable to fish fed the Con diet. Feed consumption of fish fed the PP, GP, and PM diets was comparable to fish fed the Con diet. Feed utilization and condition factor of fish fed the HP diet were the lowest. Plasma biochemical parameters, chemical composition, amino acid profiles, and SOD and lysozyme activity of fish were unaffected by dietary treatments. Thus, GP and PM are the appropriate replacers for FM in the olive flounder diets, wherein 30% FM is substituted by diverse by-product meals of swine-origin.

325 Understanding Variation in Residual Feed Intake of Brahman Steers Fed Two Different Diets

Abstract Improving feed efficiency in cattle is a long-standing aim of the beef industry. However, discrepancies in the ranking of bulls based on the diets used and calculation methods employed for defining feed efficiency have been observed. Hence, the objective of this research was to assess the extent to which different factors influence feed efficiency in Brahman steers. Individual DMI and ADG were measured, and residual feed intake (RFI) calculated using linear regression of DMI on ADG and midtest metabolic body weight. Eight-nine steers were initially fed a low-protein diet (LP, 8.8% CP) for 70 days, followed by a high-protein (HP, 13.5% CP) diet for another 70 days. The genetic variation among steers and the proportion of Bos indicus genes were determined using the GGP Indicus 50K assay (Neogen Corporation, Ipswich, Australia). Rumen bacteriome variation was determined with 16S rRNA gene sequencing of rumen fluid collected before and after feeding. Daily diet refusals were visually scored for the proportion of pellets versus hay and expressed as a diet selection index (1 to 3). Organic matter digestibility (OMD) was determined using total feces collection in metabolism crates. Plasma urea nitrogen (PUN) was measured in blood samples collected at four time points. The diet-animal fractionation of nitrogen isotopes (Δ15Ntail hair) was quantified in tail hair using isotope-ratio mass spectroscopy to indicate differences in nitrogen metabolism. Finally, carcass characteristics were determined at slaughter. Including carcass fat depth improved (P = 0.01) DMI prediction (R2 increased from 78.4 to 80.4%) in the LP diet but had a smaller effect (P = 0.39) in the HP diet (R2 increased from 75.0 to 75.2%). In the LP diet, the variation in carcass fat-correct RFI (RFIc) could be explained by DMI (14.5% of the variation), rumen bacteriome (5.89%), diet selection index (3.08%), PUN (1.88%), genetic distance (0.76%) and OMD (0.50%), accounting for a total of 26.6% of the RFIc variation. In the HP diet, the regression model explained 35.3% of the RFIc variation, with DMI explaining 25.9%, diet selection index 7.19%, rumen bacteriome 1.02%, genetic distance 0.73% and Δ15Ntail hair 0.50%. In conclusion, this study highlights the importance of measuring diet selection to accurately determine RFI in cattle. The results also suggest that variations in the rumen bacteriome and nitrogen metabolism parameters play a role in individual variations of feed efficiency. However, most of the variation in feed efficiency remained unexplained.

PSIII-13 Supplementary Effects of Carbohydrate Enzymes and Protease to Two Protein Levels in the Diet of Finishing Pig on the Growth Performance, Toxic Gas Emissions, Meat Quality, and Colonic Microbiota Community

Abstract The study investigated the effects of carbohydrate-active enzymes and protease complex on growth performance, meat quality, toxic gas emissions, and the structure and functions of colonic microbiota under two protein levels. Duroc × (Landrace × Yorkshire; n = 200) finishing pigs (68.03, SD = 3.57 kg) were allocated to 1 of 4 treatments and received different diets including high protein (16.73%, HP) with/without 0.1% multi-enzymes (ENZs) and medium-high protein (14.73%, MP) with/without 0.1% ENZs, using a 2 × 2 factorial arrangement. The trial was carried out for 7 weeks. The results indicated that ENZs supplementation increased average daily gain (ADG, P &amp;lt; 0.05) probably resulted from an improved apparent total tract digestibility of dry matter and gross energy. The HP diet promoted augmented ADG during the overall period. The MP-treated pigs had greater marbling and intramuscular fat in the longissimus dorsi muscle (P &amp;lt; 0.01). As expected, The HP groups released more ammonia and hydrogen sulfide in the excretion (P &amp;lt; 0.05). The HP improved α-diversity, as revealed by greater observed_ ASVs and Chao1 (P &amp;lt; 0.05) and boosted greater abundance of Firmicutes, Desulfobacterota, Verrucomicrobiota, and Fibrobacterota than the MP diet. The interactive effect of HP and ENZs showed greater Shannon and Pielou's evenness (P &amp;lt; 0.05) with greater Bacteroidota and decreased Firmicutes abundance. Dietary ENZs increased the abundance of Actinobacteriota, Desulfobacterota, and Lactobacillus and reduced pathogenic Clostridium_sensu_stricto_1. Spearman’s correlation indicated that greater acetate concentration in colonic digesta was positively associated with Lactobacillus, Muribaculaceae, Rikenellaceae_RC9_gut_group, Oscillospiraceae-NK4A214_group, Ruminococcus, [Eubacterium]_coprostanoligenes_group at the genus level. Taken together, HP or ENZs supplements improved the ADG and nutrient digestibility of finishing pigs. The interactive effects of CP levels and ENZs supplements did not show the growth performance but the effect of HP with ENZs promoted microbial diversity and stability in the colon.

Abstract P3196: Voluntary Exercise Training Does Not Prevent High Phosphate Diet-induced Mitochondrial Dysfunction

Inorganic phosphate (Pi) is used extensively as a preservative and a flavor enhancer in processed foods consumed as part of a Western diet. Mice fed high-Pi diet (HP) for 12 weeks display decreased maximal exercise capacity but no change in cardiac function. Expression of fatty acid metabolism genes are decreased and expression of glucose metabolism genes are increased in skeletal muscle after HP diet. Consequently, mitochondrial function is significantly impaired in skeletal muscle from mice fed HP diet. In the current study we test the hypothesis that voluntary exercise training prevents the negative metabolic consequences of HP diet. We housed mice in voluntary wheel running cages and fed them a normal-Pi (NP) or HP diet. HP diet did not alter body weight or composition, and NP- and HP-fed mice voluntarily ran the same distance in wheel cages throughout the study. Using incline treadmill exercise tolerance tests we observed no differences in medium-intensity exercise capacity between NP- and HP-fed mice subjected to voluntary wheel running, contrary to findings in sedentary mice. Despite preserved exercise capacity, muscle mitochondrial function in mice fed HP diet was significantly decreased after 5 weeks, which continued to decline after 12 weeks of HP diet and voluntary exercise. To investigate mechanisms of HP-induced mitochondrial dysfunction we measured expression of key metabolic genes and found that fatty acid metabolism genes were significantly decreased in muscle from mice fed HP diet and subjected to voluntary exercise. These data suggest that voluntary exercise training does not prevent the negative metabolic consequences of consuming a high-phosphate diet. Thus, dietary Pi may represent a novel and modifiable target to reduce physical inactivity associated with the Western diet.

Protein supplementation changes gut microbial diversity and derived metabolites in subjects with type 2 diabetes

High-protein diets are promoted for individuals with type 2 diabetes (T2D). However, effects of dietary protein interventions on (gut-derived) metabolites in T2D remains understudied. We therefore performed a multi-center, randomized-controlled, isocaloric protein intervention with 151 participants following either 12-week high-protein (HP; 30Energy %, N= 78) vs. low-protein (LP; 10 Energy%, N= 73) diet. Primary objectives were dietary effects on glycemic control which were determined via glycemic excursions, continuous glucose monitors and HbA1c. Secondary objectives were impact of diet on gut microbiota composition and -derived metabolites which were determined by shotgun-metagenomics and mass spectrometry. Analyses were performed using delta changes adjusting for center, baseline, and kidney function when appropriate. This study found that a short-term 12-week isocaloric protein modulation does not affect glycemic parameters or weight in metformin-treated T2D. However, the HP diet slightly worsened kidney function, increased alpha-diversity, and production of potentially harmful microbiota-dependent metabolites, which may affect host metabolism upon prolonged exposure.

Accelerated cystogenesis by dietary protein load is dependent on, but not initiated by kidney macrophages.

Disease severity of autosomal dominant polycystic kidney disease (ADPKD) is influenced by diet. Dietary protein, a recognized cyst-accelerating factor, is catabolized into amino acids (AA) and delivered to the kidney leading to renal hypertrophy. Injury-induced hypertrophic signaling in ADPKD results in increased macrophage (MФ) activation and inflammation followed by cyst growth. We hypothesize that the cystogenesis-prompting effects of HP diet are caused by increased delivery of specific AA to the kidney, ultimately stimulating MФs to promote cyst progression. Pkd1flox/flox mice with and without Cre (CAGG-ER) were given tamoxifen to induce global gene deletion (Pkd1KO). Pkd1KO mice were fed either a low (LP; 6%), normal (NP; 18%), or high (HP; 60%) protein diet for 1 week (early) or 6 weeks (chronic). Mice were then euthanized and tissues were used for histology, immunofluorescence and various biochemical assays. One week fed kidney tissue was cell sorted to isolate tubular epithelial cells for RNA sequencing. Chronic dietary protein load in Pkd1KO mice increased kidney weight, number of kidney infiltrating and resident MФs, chemokines, cytokines and cystic index compared to LP diet fed mice. Accelerated cyst growth induced by chronic HP were attenuated by liposomal clodronate-mediated MФ depletion. Early HP diet fed Pkd1KO mice had larger cystic kidneys compared to NP or LP fed counterparts, but without increases in the number of kidney MФs, cytokines, or markers of tubular injury. RNA sequencing of tubular epithelial cells in HP compared to NP or LP diet group revealed increased expression of sodium-glutamine transporter Snat3, chloride channel Clcnka, and gluconeogenesis marker Pepck1, accompanied by increased excretion of urinary ammonia, a byproduct of glutamine. Early glutamine supplementation in Pkd1KO mice lead to kidney hypertrophy. Chronic dietary protein load-induced renal hypertrophy and accelerated cyst growth in Pkd1KO mice is dependent on both infiltrating and resident MФ recruitment and subsequent inflammatory response. Early cyst expansion by HP diet, however, is relient on increased delivery of glutamine to kidney epithelial cells, driving downstream metabolic changes prior to inflammatory provocation.

A diet high in protein and fiber changes the gut microbiota of colorectal cancer rat model

Emerging evidence has suggested that gut microbiota dysbiosis may have a role in colorectal cancer (CRC) progression. Dietary intake high in plant protein and fiber has been associated with reduced risk of this cancer through modulation of gut microbiota. This study aimed to evaluate the effect of the soy protein and fiber diet on gut Lactobacillus and Bifidobacterium of azoxymethane/dextran sodium sulfate (AOM/DSS)- induced rat. A total of twenty-five Wistar rats aged eight weeks were randomly assigned into five groups: the normal control group (NC), the AOM/DSS group, the high protein diet +AOM/DSS group (HP), the high fiber diet +AOM/DSS group (HF), and the combination soy protein and fiber diet+ AOM/DSS group (PF). CRC was induced by injecting 12 mg/kg BW per week of AOM and adding 2% DSS into the drinking water. After four weeks, the rats were sacrificed, and the total DNA was isolated from the cecum. The relative abundance of Lactobacillus and Bifidobacterium was analyzed using quantitative real-time PCR. The fecal cecum samples analysis demonstrated that rats receiving a high soy protein diet (HP), high fiber diet (HF), or both diets (PF) have significantly higher Lactobacillus count compared with the AOM/DSS group that only received a standard diet. In the case of Bifidobacterium, both HP and PF diets showed higher abundance relative to AOM/DSS group, though it was not significant. In conclusion, dietary intake consisting of high soy protein, fiber, or a combination of the two diets modulates the gut microbiota of AOM/DSS-treated rats.

1610-P: Fatty Acid–Binding Protein 4 as a Biomarker for Remission of Type 2 Diabetes

Elevated levels of circulating Fatty Acid Binding Protein 4 (FABP4), also named adipocyte FABP (A-FABP), are associated with obesity, diabetes mellitus, insulin resistance, hypertension, and cardiovascular risk. FABP4 is a protein found in high levels in both macrophages and adipocytes. Release of FABP4 from adipocytes via lipolysis, and release from macrophages during inflammation, plays a key role in development of insulin resistance and diabetes mellitus. We studied the effect of a high protein (HP; 30% protein, 40% carbohydrate, 30% fat) diet vs high carbohydrate (HC;15% protein, 55% carbohydrate, 30% fat) diet in patients recently diagnosed with Type 2 Diabetes (T2D). We determined the levels of circulating FABP4 and metabolic parameters in the HP vs HC groups at baseline and 6 months after consuming the respective diets. Participants (14) were randomized to a HP or HC diet for 6 months. All food was provided and designed for weight loss. After 6 months on the HP diet, 100% of the subjects had remission of T2D to Normal Glucose Tolerance (NGT), whereas only 16.6% of subjects on HC diet had remission of T2D. The HP diet group exhibited significant improvement in a) insulin sensitivity (p=0.001), b) inflammatory cytokines (p=0.001), C) cardiovascular risk factors (p=0.004) compared to the HC diet group at 6 months. Although weight loss in both groups was around 10% at 6 months, the HP group lost % fat mass, whereas, the HC group lost both % muscle and fat mass. Average level of FABP4 decrease after 6 months was 12,831 pg/ml in the 8 participants on the HP diet, compared to only a 1183 pg/ml average decrease after 6 months for the 6 HC participants. Conclusions: These data showed a significant decrease of circulating FABP4 in the HP but not HC diet group and suggests that a high protein diet could be an optimal way to reduce FABP4 levels in the blood. This could subsequently lower the risk of development/progression of insulin resistance, T2D, inflammation and cardiovascular risk conditions and serve as a biomarker. Disclosure F.B.Stentz: None. Funding AD Baskin

Xylo-oligosaccharides improve the adverse effects of plant-based proteins on weaned piglet health by maintaining the intestinal barrier and inhibiting harmful bacterial growth.

Piglets are more susceptible to weaning stress syndrome when fed high levels of plant-based proteins that contain abundant food antigens and anti-nutritional factors. Xylo-oligosaccharides (XOS) are a potential prebiotic that may improve the tolerance of weaned piglets to plant-based proteins. The aim of this study was to investigate the effects of XOS supplementation in high and low plant-based protein diets on growth performance, gut morphology, short-chain fatty acid (SCFA) production, and gut microbiota of weaned piglets. A total of 128 weanling piglets with an average body weight (BW) of 7.63 ± 0.45 kg were randomly allocated to one of the four dietary treatments in a 2 × 2 factorial arrangement, with two levels of plant-based proteins (d 1-14: 68.3 or 81.33%, d 15-28: 81.27 or 100%) and XOS complex (0 or 0.43%) over a 28-day trial. The growth performance of piglets did not differ significantly among groups (P > 0.05). However, the diarrhea index of weaned piglets fed a high plant-based protein diet (HP) was significantly higher than that of those fed a low plant-based protein diet (LP) at days 1-14 and throughout the experimental period (P < 0.05). XOS treatment tended to reduce the diarrhea index at days 1-14 (P = 0.062) and during the whole experiment period (P = 0.083). However, it significantly increased the digestibility of organic matter at days 15-28 (P < 0.05). Moreover, dietary XOS supplementation increased ileal mucosa mRNA expression of occludin and ZO-1 (P < 0.05). Furthermore, the concentration of butyric acid (BA) in the cecal contents and in the concentrations of BA and valeric acid (VA) in colon contents were significantly elevated in the XOS groups (P < 0.05). Additionally, XOS optimized the gut flora by lowering the number of pathogenic bacteria such as p_Campylobacterota, thereby stabilizing the gut ecosystem. In conclusion, the HP diet aggravated diarrhea in weaned piglets while the XOS diet alleviated it by improving nutrient digestibility, protecting intestinal morphology, and optimizing the gut flora.

Pyrroloquinoline quinone promotes growth and intestinal health and alleviates tris(1,3-dichloro-2-propyl) phosphate-induced hepatic oxidative stress in zebrafish

Pyrroloquinoline quinone (PQQ) is a newly discovered redox coenzyme possessing multiple biological activities, whose role in nutritional and physiological regulation in fish remains elusive. In this study, we explored how the dietary PQQ influenced the growth, intestinal health and oxidative stress of liver triggered by tris(1,3-dichloro-2-propyl) phosphate (TDCPP) in zebrafish, which was accomplished through a long-term feeding trial (experiment 1) and a short-term stress trial (experiment 2). In experiment 1, two-month-old zebrafish were fed experimental diets either involving 0.4 mg/kg (low PQQ, LP) or 1.6 mg/kg PQQ·Na2 (high PQQ, HP), or a basal diet (CNT) for four weeks. It showed that compared to the zebrafish in the CNT group, those in the LP and HP groups exhibited remarkably improved growth performance, whose feed conversion ratio was lower, while specific growth rate and weight gain rate higher. No significant intestinal pathological symptoms were found among groups, albeit the prominently increased villus height of zebrafish in LP and HP groups than the CNT zebrafish. Dietary PQQ led to great phylum- and genus-level modulation of intestinal microflora and made it more balanced. In experiment 2, four-month-old adult zebrafish were fed a basal diet (control group), a basal diet under TDCPP exposure (TDCPP group), a HP diet under TDCPP exposure (TDCPP+PQQ group), or a HP diet (PQQ group) for one week. After the stress trial, significant intrahepatic pathological symptoms were found in the TDCPP group, while TDCPP+PQQ and PQQ groups exhibited no significant stress injury. Further analysis implied that dietary PQQ significantly alleviated the TDCPP-triggered intrahepatic oxidative stress of zebrafish by elevating the antioxidation-related gene levels, potentiating the antioxidant enzyme activities and maintaining appropriate level of apoptosis. Taken together, this study suggested that PQQ could improve growth performance and intestinal health and alleviate the TDCPP-induced liver oxidative stress in zebrafish.

Protein Content in the Diet Influences Growth and Diarrhea in Weaning Piglets.

The aim of this research has been to assess the effect of the dietary protein level on piglet growth and post-weaning diarrhea (PWD) incidence. Piglet fecal microbiota and feces composition were also assessed. The experiment was carried out on 144 weaned piglets (Duroc × Large White; 72 piglets per treatment) and lasted from weaning (at 25 days of age) until the end of the post-weaning phase (at 95 days). Two dietary protein levels were compared: high (HP; 17.5% crude protein on average, during the experiment) and low (LP; 15.5% on average). Lower (p < 0.01) average daily gain and feed conversion ratio were observed in LP piglets in the first growth phase. However, at the end of the post-weaning period, the growth parameters were not significantly different in the two diets. Diarrhea scores were lower in piglets fed LP diets than in piglets fed HP diets (28.6% of the total vs. 71.4% in the HP piglets). Fibrobacteres, Proteobacteria, and Spirochaetes were more abundant in the feces of the piglets fed LP diets. Feces nitrogen content was lower in piglets fed LP diets. In conclusion, low protein levels in the diet can reduce the incidence of PWD while only marginally affecting growth parameters.

Effects of dietary tryptophan and threonine supplementation above nutritional recommendations on performance, diarrhoea, and intestinal health parameters in weaned piglets

Pigs may have an enhanced need for the amino acids (AA) tryptophan (Trp) and threonine (Thr) around weaning. This study aimed to evaluate the effect of additional dietary Trp and Thr above nutrient requirements; on performance, the probability of diarrhoea, intestinal permeability, and morphology in weaned pigs. A total of 120 piglets (7.20 ± 0.26 kg), weaned at day 28, were randomly allocated to five dietary treatments and individually housed. A standard diet with maximum crude protein (CP) according to Danish nutrient recommendations was used as control diet (HP). The other dietary treatments consisted of the HP diet with additional 20% Thr (THR), 20% Trp (TRP) or 20% of both (THR+TRP) relative to the recommendations for these AA (standardised ileal digestible (SID); 7.8 g SID Thr/kg and 2.6 g SID Trp/kg). Finally, a low-protein diet according to recommendations was included as a negative control (203 g CP/kg DM; LP). Diets were designed to be isoenergetic and fed ad libitum from 0 to 4 weeks post-weaning. Faecal consistency was evaluated daily using a 4-scale visual scoring system. Blood was collected on day 4, 14, 21, and 28 and small intestinal and colonic tissue were obtained from HP, LP, and THR+THR pigs at day 28. Average daily gain and feed intake were unaffected by diet (P > 0.10), whereas the feed conversion ratio was increased with 11% in LP compared with HP pigs (P < 0.05). Additionally, Thr and Trp did not affect the probability for diarrhoea (P > 0.10), neither in separate weeks nor across the entire period. The number of antibiotic treatment days were 3.92 days higher for TRP compared with THR+TRP pigs (P = 0.01), with the other three diets being intermediate. The concentration of the intestinal permeability markers diamine oxidase and d-lactate in blood was unaffected by the diets. The systemic inflammatory markers haptoglobin and C-reactive protein did not differ between feeding groups. The THR+TRP diet increased the area of neutral mucin-producing cells in the colon with 83% compared with the HP diet (P = 0.02), but other intestinal morphology measurements were unaffected by the diets. In conclusion, supplementation with Thr and Trp together stimulated neutral mucin production in the large intestine and reduced the number of days where antibiotics treatments against diarrhoea is necessary.