High-starch Diet Research Articles

Metabolic influence of core ciliates within the rumen microbiome

Protozoa comprise a major fraction of the microbial biomass in the rumen microbiome, of which the entodiniomorphs (order: Entodiniomorphida) and holotrichs (order: Vestibuliferida) are consistently observed to be dominant across a diverse genetic and geographical range of ruminant hosts. Despite the apparent core role that protozoal species exert, their major biological and metabolic contributions to rumen function remain largely undescribed in vivo. Here, we have leveraged (meta)genome-centric metaproteomes from rumen fluid samples originating from both cattle and goats fed diets with varying inclusion levels of lipids and starch, to detail the specific metabolic niches that protozoa occupy in the context of their microbial co-habitants. Initial proteome estimations via total protein counts and label-free quantification highlight that entodiniomorph species Entodinium and Epidinium as well as the holotrichs Dasytricha and Isotricha comprise an extensive fraction of the total rumen metaproteome. Proteomic detection of protozoal metabolism such as hydrogenases (Dasytricha, Isotricha, Epidinium, Enoploplastron), carbohydrate-active enzymes (Epidinium, Diplodinium, Enoploplastron, Polyplastron), microbial predation (Entodinium) and volatile fatty acid production (Entodinium and Epidinium) was observed at increased levels in high methane-emitting animals. Despite certain protozoal species having well-established reputations for digesting starch, they were unexpectedly less detectable in low methane emitting-animals fed high starch diets, which were instead dominated by propionate/succinate-producing bacterial populations suspected of being resistant to predation irrespective of host. Finally, we reaffirmed our abovementioned observations in geographically independent datasets, thus illuminating the substantial metabolic influence that under-explored eukaryotic populations have in the rumen, with greater implications for both digestion and methane metabolism.

48 Disrupting hindgut microbiota through the diet alters strongyles infections in horses

Although little is known in horses, interactions between gut microbiota and intestinal parasites have been suggested in other species. Understanding how diet may affect these relationships could be a lead in the search for alternative anthelmintic solutions. In horses, the forage/cereal ratio can substantially influence the composition and functions of the hindgut microbiota. Additionally, polyphenols could carry natural anthelmintic activity. This study aimed at evaluating the effect of high-fiber or high-starch diets on the intestinal microbiota and strongyle infection in horses, and the impact of supplementation with sainfoin, a polyphenol-rich plant. Twelve naturally infected adult geldings (7 ± 2 years old,515 ± 53 kg BW) were enrolled in a 4 periods × 4 treatments Latin square design. Groups were formed based on fecal egg count (FEC) before the trial, age, and bodyweight. Experimental periods lasted 21 d (D0 to D21) and were separated by 21 d wash-out periods. The 4 iso-energy, iso-protein treatments consisted in high-fiber (HF; 18.5g DM hay/kg BW) or high-starch diets (HS; 8.0g DM hay+6.3g DM barley/kg BW; 1.9g starch/kg BW/meal), to which were added either control pellets (CONT; 3.1g DM sunflower meal+hay/kg BW) or sainfoin pellets (SF; 3.1g DM Equifolia [Multifolia]/kg BW). Feces were collected on D0, D7, D14, and D21 to assess strongyles excretion through FEC, and on D21 to investigatebacterial diversity and composition using both culture and sequencing technics. Mixed effect models were used to evaluate the effect of the day, the diet and supplementation on these parameters. A day*diet*supplementation interaction was found for FEC (P < 0.001): FEC did not differ between groups at D0, but horses fed the treatment HS CONT had higher FEC than the others at D21 (P < 0.01). Horses fed diet HS had a lower bacterial diversity (Shannon index; P = 0.03), higher relative abundances of Proteobacteria and Succinivibrionaceae (P < 0.01), and lower relative abundance of Lachnospiraceae (P < 0.001) than the horses fed diet HF. The Bacteroidota and Prevotellaceae were more abundant in horses supplemented with sainfoin (P < 0.01). Horses fed diet HS had a lower concentration of cellulolytic bacteria and higher concentrations of amylolytic and lactate-using bacteria (P < 0.001) than horses fed diet HF. These results show that diet and addition of sainfoin can impact both the hindgut microbiota and the intestinal parasitism in horses, which suggests existing relationships between them. Further microbiome analyses may provide data on the effects of specific bacterial taxa or microbial functions on intestinal parasitism.

52 Influence of Saccharomyces cerevisiae CNCM I-1077 on the intestinal environment, gut permeability, and markers of systemic inflammation in horses fed a high starch diet

Probiotics may balance the hindgut environment and relieve systemic inflammation in horses fed high starch concentrates to meet energy requirements. Therefore, 30 mature Quarter Horse geldings (545 ± 58 kg BW) were used in a randomized complete design for 32-d to test the hypothesis that supplemental live Saccharomyces cerevisiae CNCM I-1077 (SC; Levucell® SC Advantage) stabilizes the intestinal environment, reduces gut permeability, and decreases inflammation when horses are fed a high starch diet. Horses were stratified by BW, age, and body condition score (BCS) and randomly assigned treatments consisting of either a concentrate formulated with 2g starch • kg BW−1 • meal−1 (CON, n = 15) or the same concentrate top-dressed with 25 g/d SC(TRT, n = 15) containing 20 billion cfu. Horses were fed individually in stalls (3 × 3 m) every 12 h. Between meals, horses were housed in adjacent dry lots with ad libitum access to Coastal bermudagrass hay and water. On d 0 and 32, BW and BCS were recorded and blood samples were collected immediately before feeding (h 0) and at h 2, 8, 16, and 24 post meal. Samples were analyzed for serum D-lactate using a colorimetric assay, chemokine (CCL2) and cytokine (TNFα) concentrations were measured using a multiplex platform, and whole blood 16s rRNA sequencing was performedusing Illumina MiSeq. Fecal samples were obtained on d 0, 16, and 32 via rectal palpation before the morning meal and at h 8, 16, and 24 post meal. Fecal pH was determined using a portable pH meter and fecal starch was measured via concentration analysis. Data were analyzed using PROC MIXED of SAS v9.4. Non-normal data (CCL2) were log-transformed. From d 0 to 32 BW increased (P ≤ 0.01), independent of treatment, with no change in BCS (P = 0.97). Fecal starch was undetectable indicating nearly complete digestion of dietary starch regardless of treatment. On d 0, fecal pH declined to h 16 (P ≤ 0.01) in both groups and returned to baseline by h 24 post meal. At h 0, CON had lower fecal pH on d 32 than d 0 (P ≤ 0.01). D-lactate peaked at h 8 on d 0, and CON was greater (P ≤ 0.01) than TRT. On d 32, D-lactate tended to be higher in TRT (P = 0.10) at 16 h post meal compared with CON. LogCCL2 and TNFα declined (P ≤ 0.02) across treatments to d 32. Fold change of percent reads from d 0 in bacterial 16s rRNA was not different between treatment groups. A high starch diet initially reduced fecal pH and increased BW but after 32 d, there was no difference in intestinal inflammation or gut permeability, regardless of SC supplementation.

81 Measuring biomarkers to assess the effect of diet on the mucosal integrity of the equine large intestine

Alterations in the integrity of the intestinal mucosa can lead to severe health issues, which can manifest as an increase in mucosal permeability and/or in malabsorption of nutrients. In horses, the hindgut acidosis and the disbalance of the intestinal microbiota caused by excessive starch intake may jeopardize mucosal integrity. In other species, studies suggest that polyphenols could play a protective role for maintaining mucosal integrity. Thus, the objective of this study was to evaluate the integrity of the mucosa of the large intestineby measuring biomarkers of intestinal permeability and absorption in horses fed either a high-fiber or a high-starch diet, combined with a polyphenol-rich plant (sainfoin) supplementation. Twelve adult geldings (7 ± 2 years old,515 ± 53 kg BW) were enrolled in a 4 periods × 4 diets Latin square design, including 4 21 d experimental periods separated by 21 d wash-out periods. The 4 iso-caloric and iso-nitrogenous rations included either high-fiber (HF; 18.5g DM hay/kg BW) or high-starch meals (HS; 8.0g DM hay+6.3g DM barley/kg BW; 1.9g starch/kg BW/meal), and were supplemented with ether control (CONT; 3.1g DM sunflower meal+hay/kg BW) or sainfoin pellets (SF; 3.1g DM Equifolia [Multifolia]/kg BW). Feces and blood were sampled at theend of each experimental period to measure fecal and plasma acetate concentrations, and plasma lipopolysaccharides (LPS) concentration. Mixed effect models were used to assess the effect of the diet (HF vs HS), supplementation (CONT vs SF), and their interaction on these parameters. When horses were fed the diet HS, higher concentration of fecal acetate (P < 0.001) and lower concentration of plasma acetate (P = 0.007) were observed compared with diet HF. This might indicate a decreased absorption capacity through the intestinal wall with diet HS. However, no significant effect of the diet was observed on plasma LPS concentration which suggests that the permeability of the intestinal mucosa is not modified after 21 d with these diets. Adding sainfoin to the ration did not alter the monitored parameters related to mucosal integrity. The next step would be to monitor mucosal permeability and absorption for longer periods of time (longer that the 21-d monitoring done here). This might allow to have a better insight on the effect of diet on mucosal integrity.

26 Hindgut microbiota fibrolytic efficiency may impact energetic metabolism and exercise performance in standardbred horses

Blood acetate originates from fiber degradation by the hindgut microbiota. In addition to glucose and fat, acetate represents an energy substrate for muscles during exercise. Compared with horses fed high-starch diets, it has been reported that high-fiber diets lead to higher plasma acetate concentrations prior and post-exercise, lower lactatemia during exercise, and lower glycogen depletion post-exercise. Fibrolytic efficiency of the hindgut microbiota could thus play a crucial role in energy metabolism during exercise by enhancing acetate availability, which could modulate performance. This study aimed at investigating the relationships between fibrolytic efficiency, energy metabolism, and exercise performance in Standardbred horses. Twenty-one elite 2-years old Standardbred horses (12 stallions, 9 mares) from Ecurie Hunter Valley with similar feeding (hay ad libitum + 6.8kg concentrates/day) and training regimen (3 very heavy works/week) were included in this experiment. An individual in vitro fermentation test was performed from fecal samples with hay as substrate. Gas production (GP) in the bottles was monitored during 48h and fitted to a generalized model using nonlinear regression. Dry matter (DM), cellulose, and hemicellulose were analyzed in substrate residues, and their disappearance was calculated. Two weeks after, horses performed an incremental exercise including 3 steps of 3 min duration at35km/h, 40km/h, and maximal velocity. Steps were separated by 1 min walking. Maximal speed was defined as the maximal velocity sustained for 1 min during the last step. Blood samples were collected before (T0), 5 min (T5), and 20 min (T20) after the incremental exercise to measure glucose, lactate, NEFA, and acetate concentrations. Maximal speed, blood parameters, and fermentation parameters were correlated with Pearson coefficients. No significant correlation was found between maximal speed and glycemia, lactatemia, or NEFA concentration. Maximal speed was correlated with asymptotic GP (P = 0.04; r = 0.46), DM (P = 0.01; r = 0.53) and cellulose (P = 0.02; r = 0.52) disappearance, and with acetate concentration measured at T5 (P = 0.03; r = 0.48). Higher in vitro fibrolytic activity of the hindgut ecosystem was associated with better performance, although resting acetate did not correlate significantly with maximal speed. These results suggest that the extra source of energy provided by fiber digestion could benefit muscle activity during high-intensity exercise in horses. Further work should monitor blood metabolites during exercise to evaluate acetate absorption from the hindgut and utilization by muscles.

Replacing ground corn with soyhulls plus palmitic acid in low metabolizable protein diets with or without rumen-protected amino acids: Effects on production and nutrient utilization in dairy cows

We previously observed that diets with reduced starch concentration decreased yields of milk and milk protein in dairy cows fed low metabolizable protein diets. Supplementation of reduced-starch diets with a lipid source may attenuate or eliminate production losses. Our objective was to investigate the effects of partially replacing ground corn with soyhulls plus a palmitic acid-enriched supplement on dry matter (DM) intake, milk yield and composition, plasma AA concentration, and N and energy utilization in cows fed low metabolizable protein diets (mean = -68 g/d balance) with or without rumen-protected Met, Lys, and His (RP-MLH). Sixteen multiparous Holstein cows averaging (mean ± standard deviation) 112 ± 28 d in milk, 724 ± 44 kg of body weight, and 46 ± 5 kg/d of milk in the beginning of the study were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Each period lasted 21 d, consisting of 14 d for diet adaptation and 7 d for data and sample collection. Diets were fed as follows: (1) high starch (HS), (2) HS plus RP-MLH (HS+AA), (3) reduced starch plus a palmitic acid-enriched supplement (RSPA), and (4) RSPA plus RP-MLH (RSPA+AA). The HS diet contained (DM basis) 26% ground corn and 7% soyhulls, and the RSPA diet had 10% ground corn, 22% soyhulls, and 1.5% palmitic acid. The HS diet averaged (DM basis) 32.6% starch and 4% ether extract, while starch and ether extract concentrations of the RSPA diet were 21.7 and 5.9%, respectively. All 4 diets had (DM basis) 40% corn silage, 5% mixed-mostly grass haylage, 5% grass hay, and 50% concentrate. Diets did not affect DM intake and milk yield. Contrarily, feeding RSPA and RSPA+AA increased yields of energy-corrected milk (47.0 vs. 44.8 kg/d) and milk fat (1.65 vs. 1.50 kg/d) compared with HS and HS+AA. Milk fat concentration tended to decrease when RP-MLH was supplemented to HS, but no change was seen when added to RS (starch level × RP-MLH interaction). Milk and plasma urea N increased, and milk N efficiency decreased in cows fed RSPA and RSPA+AA versus HS and HS+AA. Apparent total-tract digestibilites of crude protein and neutral detergent fiber, as well as urinary urea N and total N excretion, were greater in cows offered RSPA and RSPA+AA than HS and HS+AA. Plasma Met and His concentrations increased with supplemental RP-MLH. Intake of gross energy and digestible energy and the output of urinary and milk energy were all greater with feeding RSPA and RSPA+AA versus HS and HS+AA. In summary, partially replacing ground corn with soyhulls plus palmitic acid in diets supplemented or not with RP-MLH increased milk fat yield and fiber digestibility and maintained DM intake and milk yield, but with decreased milk N efficiency and elevated urinary N excretion.

Growth Performance, Digestive Enzyme Activities, and Oxidative Stress Markers in the Proximal Intestine of European Sea Bass (Dicentrarchus labrax) Fed High Starch or Lipid Diets

The effect of different main dietary compositions on growth, anticipatory digestive enzyme activities, and oxidative status was studied in the proximal intestine of juvenile European sea bass. A control diet (C, 44% protein, 17.6% lipid, and 20% starch), three diets with increasing starch levels to test protein sparing (P36S36, P40S29, and P43S24), and two diets with high lipid content (L20S13 and L22S7) were tested. After 20 weeks, growth, digestive enzyme activities, lipid peroxidation, antioxidant enzyme activities, and G6PDH activity were measured after a 24-h fast. Sea bass fed P43S24 and L20S13 maintained an oxidative status like C fish, up-regulated CAT activity, and adjusted anticipatory protease activity. Instead, the lipid peroxidation increased in the L22S7 group, although CAT activity increased, whereas anticipatory total protease activity was downregulated. P40S29 also triggered LPO and CAT activity, but G6PDH levels diminished significantly. Moreover, an up-regulation in digestive enzyme activities was found. Finally, P36S36 fish showed less antioxidant enzyme activity and G6PDH, although their LPO tended to increase and their lipase and α-amylase activities were upregulated. In conclusion, the inclusion of carbohydrates up to 24% or lipids up to 20% is possible for this species if protein requirements are met without negative effects on growth.

Effects of dietary starch and metformin levels on the growth performance, body composition, hepatic glycolipid metabolism, and liver histology of juvenile largemouth bass Micropterus salmoides

In this study, an 8-week feeding trial was performed to evaluate the effects of dietary metformin inclusion on the growth performance, body composition, glucose homeostasis and liver histology of juvenile largemouth bass Micropterus salmoides (LMB) fed high starch diets. Using a 2 × 2 factorial design, four isoproteinic (50%) and isolipidic (13%) diets were formulated with two starch levels (9% and 14%) with or without 0.25% metformin inclusion at each starch level. Each diet was assigned to triplicate tanks of LMB with an initial body weight of 10.8 g. The results showed that an increase of dietary starch from 9% to 14% retarded the growth performance (weight gain ratio and specific growth rate) of LMB through impairing feed utilization (feed efficiency ratio, protein efficiency ratio and protein productive value). Though feed consumption increased, the growth performance of LMB did not benefit from dietary metformin administration as a result of the impaired feed utilization. Both the glucose homeostasis (fasting blood glucose) and glucose tolerance of LMB were impaired with increasing dietary starch from 9% to 14%. However, LMB metabolically adapted well to high starch diets through stimulating glycolysis and glycogen synthesis while inhibiting gluconeogenesis in the liver at the molecular level. Moreover, an increase of dietary starch from 9% to 14% upregulated hepatic lipogenic capacities while down-regulated fatty acid oxidation thereby promoting lipid deposition in the liver and whole fish. Dietary metformin improved the glucose homeostasis and glucose tolerance of LMB through promoting glycolysis and de novo lipogenesis rather than glycogen deposition in the liver. However, dietary metformin did not mitigate the liver injuries (the activities of alanine aminotransferase and aspartate aminotransferase in the plasma along with histological appearance) in LMB fed high starch diets. In conclusion, our results demonstrated that dietary metformin inclusion did not mitigate the growth retardation and liver injury of LMB fed high starch diets, but improved the glucose homeostasis and glucose tolerance through promoting the glycolytic and lipogenic pathways in the liver.

Integration of microRNA and mRNA analyses depicts the potential roles of Momordica charantia saponin administration in insulin resistance of juvenile common carp (Cyprinus carpio) fed with a high-starch diet.

Background: The regulation of target gene mRNA mediated by microRNA may play an important role in glucose metabolism in fish. Previous research findings of our research group revealed that Momordica charantia saponin (MS) administration in a high-starch diet could improve insulin resistance of common carp through renovating insulin signaling pathways, whose fundamental mechanisms have remained unknown by far. To reveal this potential mechanism, we aimed to investigate the difference in miRNA and mRNA expression profiles between common carp fed with high-starch diets containing MS (HS_MS1 and HS_MS2) and common carp fed with high-starch (HS) diets. Results: Through miRNA deep-sequencing, 10 significantly differentially expressed miRNAs in HC and HS_MS1, including one upregulated and nine downregulated miRNAs, were identified, whereas 10 significantly differentially expressed miRNAs in HC and HS_MS2, including four upregulated and six downregulated miRNAs, were identified. These miRNAs may not only be involved in the regulation of insulin signaling pathways and insulin resistance in common carp but also be the markers for liver insulin resistance in MS therapy for the remission of insulin resistance. This study identified 10 potential known miRNAs, namely, ccr-miR-10b, ccr-miR-122, ccr-miR-143, ccr-miR-146a, ccr-miR-155, ccr-miR-16c, ccr-miR-200a, ccr-miR-29a, ccr-miR-34, and ccr-miR-375, as candidates participating in modulating the liver insulin resistance. According to the biopathway enrichment analysis of the 252 target genes using the KEGG classical biopathway database, the relative expression levels of gsk3bb, pik3r1, and pik3r3b were analyzed using RNA-seq. Compared to the HC group, a significant decrease in the relative expression levels of pik3r1 and pik3r3b was observed in HS_MS1 and HS_MS2 groups (p < 0.05). This study raised a presumption of the presence of ccr-miR-29a targeting pik3r1 or ccr-miR-143 targeting pik3r3 playing likely roles in Momordica charantia saponins remitting the liver insulin resistance. Conclusion: The findings will further deepen the understanding of the carbohydrate metabolism of common carp and provide an important scientific basis for the application of Momordica saponins as functional nutrients to alleviate insulin resistance of fish in fish culture.

Effects of Macleaya cordata extract supplementation on digestive parameters of ponies

ABSTRACT High amounts of grains in the equine diet led to high starch intake, causing gut alterations. Aimed at reducing harmful effects, Macleaya cordata extract (MCE) is a phytogenic additive that stands out for its antibiotic and anti-inflammatory effects proven in different species. However, there is no useful information for horses. The objective of this study was to evaluate the effects of different levels of the inclusion of commercial MCE on body weight (BW), body condition score (BCS), total apparent digestibility (AD) of nutrients, faecal pH and fermentative products, on ponies fed a high-starch diet. Eight healthy gelding Mini Horse ponies were used. The study design was contemporary double Latin-square 4 × 4 in the experimental unit, with the animal inside each experimental period (n = 8 experimental units per group). The experiment was conducted over four 20-d periods. Basal diet attended 1.75% BW dry matter daily and starch intake was 2.2 g/kg BW/meal. The experimental groups were as follows: control – without food additive; S1–1 mg/kg BW MCE; S1.5–1.5 mg/kg BW MCE and S2–2 mg/kg BW MCE. The data were analysed by PROC MIXED of SAS (p < 0.05). Tendency was considered when 0.05 < p < 0.1. Our results showed higher ether extract (EE) AD for S2 group (63.75%) when compared with the control (54.55%) (p = 0.0377). Lactate was lower (p = 0.0391) in S1 (3.27 mmol/l) and S2 (3.24 mmol/l) groups, although pH was not different between groups. Iso-valerate was greater in S1 group (2.29 mmol/l; p = 0.0289), and a tendency of higher butyrate values was found for S1 and S2 groups (p = 0.0980). We concluded that MCE supplementation probably positively influences equine resident microbiota, improving EE AD and increasing iso-valerate concentration. It can also minimise harmful high-starch impact. We recommend further studies using MCE in horses for a better understanding of its local activity and possible benefits.

Effects of rumen degradable starch on growth performance, carcass, rumen fermentation, and ruminal VFA absorption in growing goats

The objective of the present study was to investigate the effects of dietary rumen degradable starch level (RDS) on growth and carcass performance, rumen fermentation, and rumen papillae development in growing goats. Forty healthy, weaned, 3-month-old male goats (BW=13.6 ± 0.23 kg) were randomly enrolled to receive either a low rumen degradable starch diet (LRDS, diet based on whole corn, RDS = 13.85 %, n = 20) or high rumen degradable starch diet (HRDS, diet based on crashed corn, RDS = 20.74 %, n = 20). After 90 d of feeding, 8 goats of each group were randomly selected and humanely slaughtered at 3 h after morning feeding. HRDS diet decreased the average daily weight gain, lean meat percentage of carcass, and the ratio of meat to bone (P < 0.05), whereas HRDS diet increased the feed conversion ratio (P < 0.05). HRDS diet decreased the plasma glucose level before morning feeding and 6 h postprandial (P < 0.05), and increasing the plasma glucose level at 2 h postprandial (P < 0.05). HRDS diet up-regulated rumen acetate proportion before morning feeding to 8 h postprandial (P < 0.05) and down-regulated the butyrate proportion before morning feeding to 4 h postprandial (P < 0.05). HRDS diet also increased the ratio of acetate to propionate during 6 h (P < 0.05) to 8 h postprandial (0.05 < P < 0.10). HRDS diet decreased the length and the surface area of rumen papilla (P < 0.05). Further, HRDS diet decreased the mRNA expression of HCO3-/volatile fatty acid (VFA) cotransporter SLC4A2 and SLC26A3, and Na+/HCO3- cotransporter SLC4A4 (P < 0.05). In summary, feeding HRDS diet to growing goats changed rumen fermentation, reduced rumen papilla development, rumen epithelial VFA absorption, and the capacity to maintain the rumen epithelial homeostasis, thereby decreasing the supply of precursors for hepatic gluconeogenesis and repressing the goats’ performance. These findings provided further insights for improving growth performance by reducing dietary RDS in goats’ diets.

Effects of hindgut acidosis on inflammation, metabolism, and productivity in lactating dairy cows fed a high-fiber diet

Hindgut acidosis (HGA) may cause or contribute to the inflammatory state of transition dairy cows by compromising the intestinal barrier. Previous experiments isolating the effects of HGA on inflammatory metrics have generated inconsistent results, which may be explained by acclimation to low- versus high-starch diets. Thus, study objectives were to evaluate the effects of HGA in cows acclimated to a high-fiber diet. Ten rumen-cannulated Holstein cows (38 ± 5 kg/d milk yield; 243 ± 62 d in milk; 1.6 ± 1.1 parity; 663 ± 57 kg of body weight) were enrolled in a study with 2 experimental periods (P). Before P1, all cows were acclimated to a high-fiber, low-starch diet (50% neutral detergent fiber, 15% starch) for 17 d. During P1 (4 d), baseline data were collected for use as covariates. During P2 (7 d), cows were assigned to 1 of 2 abomasal infusion treatments: (1) control (CON; 1.5 L of H2O/infusion; n = 4) or (2) starch infused (ST; 1 kg of corn starch + 1.5 L of H2O/infusion; n = 6). All cows were infused with their respective treatments every 6 h daily at 0000, 0600, 1200, and 1800 h, such that ST cows received a total of 4 kg of corn starch/d. Starch infusions successfully induced HGA, as indicated by a marked decrease in fecal pH (1.2 units) relative to CON. However, in contrast to our assumptions, infusing starch had no deleterious effects on milk yield, energy-corrected milk, or voluntary dry matter intake during P2. Milk protein, lactose, their yields, fat yield, and somatic cell score remained unaffected by starch infusions, whereas milk fat content and urea nitrogen were decreased in ST relative to CON (8 and 17%, respectively). Overall, circulating glucose and β-hydroxybutyrate concentrations remained similar between treatments, but starch infusions decreased nonesterified fatty acids on d 3 relative to CON. Blood urea nitrogen decreased throughout P2 in ST (38%) relative to CON. In contrast to our hypothesis, HGA did not alter circulating serum amyloid A or lipopolysaccharide binding protein, nor did it affect rectal temperature. In summary, HGA moderately altered metabolism but did not affect production or elicit an inflammatory response in lactating dairy cows previously acclimated to a high-fiber diet.

Starches of Varied Digestibilities Differentially Modify Intestinal Function in Rats

Starches of different digestibilities may enter the colon to different extents and alter colonic function. Male Fischer 344 rats were fed diets containing 25% cooked potato starch, arrowroot starch, high amylose cornstarch or raw potato starch for 6 wk. Fecal weight, transit time, colonic thymidine kinase activity (a marker for cell proliferation), and weight, starch content and pH of the cecum and proximal and distal colon were measured. Raw potato starch was much less completely digested than high amylose cornstarch, resulting in a 32-fold greater amount of undigested starch entering the cecum in the raw potato starch group. Both the high amylose cornstarch and raw potato starch diets significantly enhanced fecal weight and produced large intestinal hypertrophy, effects that were greatest in the raw potato starch group. Raw potato starch feeding was associated with the highest level of thymidine kinase activity, although the differences in thymidine kinase activity among the four groups were not significant. This diet also produced a 50% longer transit time. Entry of a large amount of raw potato starch into the colon resulted in greater luminal acidity, greater luminal bulk and slower transit. A much smaller amount of starch entered the colon in the high amylose cornstarch group and resulted in fecal bulking but no alteration in transit.

Eucommia ulmoides Oliver enhances the antioxidant capacity and protects Micropterus salmoides from liver damage and immune function impairment caused by a high starch diet

Eucommia ulmoides Oliver (EuO) is a traditional Chinese herb with effects on repairing disorders of liver lipid metabolism and enhancing immunity in mice. In this study, the effects of EuO on immune enhancement and liver protection of M. salmoides were tested by adding 3% EuO to a high-starch diet and were evaluated by histopathology, enzymology, flow cytometry, and molecular biology. The results showed that the high starch diet promoted hepatocytes apoptosis, damaged the liver, and led to impaired immune function. However, the integrality of liver was recoverd, innate response was enhanced, hepatocyte apoptosis was inhibited, and antioxidant capacity was improved after treatment with EuO. These findings reveal that EuO could improve the immune function while also repairing the M. salmoides liver injury induced by a high starch diet. This study provides a theoretical basis for EuO to solve the liver disease of M. salmoides caused by a high starch diet.

Replacement of corn silage with shredded beet pulp and dietary starch concentration: Effects on performance, milk fat output, and body reserves of mid-lactation dairy cows

We aimed to evaluate the interaction between dietary starch concentration, varied by replacing wheat bran with dry ground corn, and replacement of corn silage (CS) with shredded beet pulp (BP) on production, milk fat output, milk fatty acid profile, and body reserves in dairy cows. Sixty-four Holstein dairy cows (140 ± 26 d in milk) were randomly assigned to 8 pens (8 animals per pen). Treatments were arranged in a 2 × 2 factorial arrangement with 2 concentrations of starch and 2 sources of fiber and were allotted to 8 pens (2 pens per treatment). Treatments were (1) 15% dry ground corn and 24% CS, (2) 15% dry ground corn and 24% BP replacing CS, (3) 30% dry ground corn and 24% CS, and (4) 30% dry ground corn and 24% BP replacing CS. The trial lasted for 47 d and final 7 d of experimental period was used for data and sample collection. Cows fed the BP-based diets had greater dry matter intake than those offered the CS-based diets, whereas no effects were observed with starch concentration. Milk yield increased by 1.8 kg/d with BP-based diets compared with CS-based diets and by 2.5 kg/d when cows received the high-starch compared with low-starch diets. Interactions between dietary starch concentration and forage substitution were detected for milk fat concentration and yield as BP inclusion lowered milk fat output with high-starch diet. Milk trans-18:1 concentration was lower with 15% dry ground corn and 24% CS compared with other diets. In conclusion, the effects of dietary starch concentration (22 and 32% dry matter) and forage substitution on production responses were independent except for milk fat output and milk trans 18:1 isomers. Substituting CS with BP is effective at increasing milk yield regardless of starch concentration; however, milk fat yield is lower when BP is used with high-starch concentration.

Overexpression of growth hormone improved hepatic glucose catabolism and relieved liver lipid deposition in common carp (Cyprinus carpio L.) fed a high-starch diet.

Growth hormone (GH) is important for regulating insulin secretion and carbohydrate metabolism, and its role in mammalian models of diabetes is relatively worked out. Although some fish species were used as models for diabetes research, the effects of GH on insulin and glucose catabolism and anabolism in these models remain to be clarified. In this study, we investigated the effect of GH on insulin and glucose catabolism and anabolism in an omnivorous fish using GH transgenic (T) common carp that consistently overexpressed GH and wild-type (WT) common carp. We compared the intestinal morphology, and digestive and absorptive capacity of fish fed commercial feed. We also analyzed the growth performance, insulin level, glucose catabolism and anabolism, lipid deposition, and lipid catabolism and anabolism in T carp and WT carp fed diets containing either 30% or 40% starch. In the intestine of T carp, α-amylase activity was enhanced, the number of goblet cells and intestinal villi surface area was increased, and the expression level of glucose transport protein-related genes (glut2 and sglt1) was upregulated when compared to these indicators in WT carp. When fed either a normal or high-starch diet, the growth performance of T carp was better than that of WT carp. Compared with WT carp, serum insulin was increased and glucose was decreased, hepatic expression level of igf-1 and glycolysis-related genes was increased, and the activity level of a hepatic enzyme related to glycolysis was enhanced in T carp. When fed with a high-starch diet, the serum alanine aminotransferase activity, hepatic lipid content, and malondialdehyde content were significantly lower in T carp than in WT carp. These results indicated that overexpression of GH (1) enhanced carbohydrate digestion and absorption in the carp intestine, (2) did not induce insulin resistance and improved glucose catabolism and utilization in carp, and (3) relieved liver lipid deposition. Our data might provide new insights into potential ways to improve glucose utilization in fish and diabetes treatments.

Transcriptome analysis provides insights into the molecular mechanism of liver inflammation and apoptosis in juvenile largemouth bass Micropterus salmoides fed low protein high starch diets

The present study was conducted to investigate the regulatory mechanism of liver injury in largemouth bass Micropterus salmoides (LMB) fed low protein high starch diets. Two isolipidic and isoenergetic diets were formulated with different protein and starch ratios, being named as diets P49S9 (48.8 % protein and 9.06 % starch) and P42S18 (42.4 % protein and 18.2 % starch). Each diet was fed to triplicate replicates of LMB (initial body weight, 4.65 ± 0.01 g) juveniles. Fish were fed to visual satiation for 8 weeks. The results indicated that though the P42S18 fish up-regulated the feeding ratio to meet their protein requirements, feeding efficiency ratio and growth performance were impaired in treatment P42S18 as compared to treatment P49S9. Periodic acid-Schiff (PAS) staining showed glycogen accumulated in the liver of LMB fed low protein high starch diets, and the reason should be attributed to down-regulated expression of the glycogenolytic glycogen debranching enzyme. Lower liver lipid level was associated with feeding low protein high starch diets in LMB, which should be resulted from the changes in hepatic glycerolipid metabolism regulated by lipoprotein lipase (representative of triglyceride synthesis, up-regulated) and diacylglycerol acyltransferase (representative of triglyceride breakdown, down-regulated). Though fasting plasma glucose level was comparable, treatment P42S18 performed inferior glucose tolerance to treatment P49S9. Hematoxylin-eosin (HE) and TdT-mediated dUTP Nick-End Labeling (TUNEL) staining suggested that feeding low protein high starch diets induced disruption of structural integrity, inflammation and apoptosis in the hepatocytes of LMB. As expected, KEGG pathways analysis indicated that many of the up-regulated differentially expressed genes were enriched in AGE (advanced glycation end product)/RAGE (receptor for AGE), Toll-like receptor and apoptosis signaling pathways. Our transcriptome data revealed that feeding low protein high starch diets might promote the accumulation of AGEs in LMB, which bound to RAGE and subsequently induced PI3K/Akt signal pathway. The activation of Akt induced NF-κB translocation into the nucleus thus releasing proinflammatory factors including tumor necrosis factor-α (TNF-α) and interleukin-8. The release of these inflammatory factors concomitantly induced T cell stimulation and natural killer cells chemotactic effects through Toll-like receptor signaling pathway. Besides mediating inflammation and immune response, TNF-α signal transduction participated in mediating apoptosis through the receptor of TNF (TNF-R1) pathway by up-regulating the expression of caspase 8 and cytochrome c. In conclusion, our results demonstrated that feeding low protein and high starch diets induced hepatocytes inflammation and apoptosis in LMB through the PI3K/Akt/NF-κB signaling pathway.

Body Weight Development in Adult Dogs Fed a High Level Resistant Starch Diet.

This study investigated the effect of Dodamssal rice, which has a high content of resistant starch, on obesity and hematologic properties in dogs. In Experiment 1, 24 spayed dogs were divided into three feeding groups: normal-fat basal diet (control), high-fat diet with 12% normal amylose type rice (hNAR), and high-fat diet with 12% high amylose type rice (Dodamssal rice; hHAR). In Experiment 2, 8 spayed dogs were assigned to a normal amylose type rice (NAR) group and a high amylose type rice group (HAR) with a normal-fat basal diet. After 24 weeks, an increase in weight and blood cholesterol was observed in both high-fat diet groups for Experiment 1. Specifically, an increase in serum alanine aminotransferase was observed over time in the hNAR group compared with that of the control; however, no such patterns were present in the hHAR group. Further, a significant weight-loss effect was observed in the HAR group in Experiment 2 at 4 weeks. The effect on body weight was due to the reduced digestibility of amylose and thereby lower dietary ME content. Overall, this confirmed that Dodamssal rice had a positive effect on weight loss in dogs, and these results suggest that Dodamssal rice has potential value as a raw ingredient for preventing obesity in dogs.

Diet Influences the Gut Microbial Diversity and Olfactory Preference of the German Cockroach Blattella germanica.

The gut microbiota of insects has been proven to play a role in the host's nutrition and foraging. The German cockroach, Blattella germanica, is an important vector of various pathogens and causes severe allergic reactions in humans. Food bait is an effective and frequently used method of controlling this omnivorous insect. Thus, understanding the relationships among diet, gut microbiota, and olfactory preferences could be useful for optimizing this management strategy. In this study, B. germanica was exposed to different foods, i.e., high-fat diet, high-protein diet, high-starch diet, and dog food (as control). Then their gut microbial and olfactory responses were investigated. 16S rRNA gene sequencing confirmed that the gut microbiota significantly differed across the four treatments, especially in relation to bacteria associated with the metabolism and digestion of essential components. Behavioral tests and the antenna electrophysiological responses showed that insects had a greater preference for other types of diets compared with their long-term domesticated diet. Moreover, continuously providing a single-type diet could change almost all the OR genes' expression of B. germanica, especially BgORco, which was significantly repressed compared to control. These results indicate that diet can shape the gut microbiota diversity and drive the olfactory preference of B. germanica. The association between gut microbiota profiles and diets can be utilized in managing B. germanica according to their olfactory preference.

Insulin sensitivity is preserved in mice made obese by feeding a high starch diet.

Obesity is generally associated with insulin resistance in liver and muscle and increased risk of developing type 2 diabetes, however there is a population of obese people that remain insulin sensitive. Similarly, recent work suggests that mice fed high carbohydrate diets can become obese without apparent glucose intolerance. To investigate this phenomenon further, we fed mice either a high fat (Hi-F) or high starch (Hi-ST) diet and measured adiposity, glucose tolerance, insulin sensitivity, and tissue lipids compared to control mice fed a standard laboratory chow. Both Hi-ST and Hi-F mice accumulated a similar amount of fat and tissue triglyceride compared to chow-fed mice. However, while Hi-F diet mice developed glucose intolerance as well as liver and muscle insulin resistance (assessed via euglycaemic/hyperinsulinaemic clamp), obese Hi-ST mice maintained glucose tolerance and insulin action similar to lean, chow-fed controls. This preservation of insulin action despite obesity in Hi-ST mice was associated with differences in de novo lipogenesis and levels of C22:0 ceramide in liver and C18:0 ceramide in muscle. This indicates that dietary manipulation can influence insulin action independently of the level of adiposity and that the presence of specific ceramide species correlates with these differences.