Intermittent bolus feeding promotes greater lean growth than continuous feeding in a neonatal piglet model

Intermittent enteral nutrition shortens the time to achieve nutritional goals in critically ill patients

Nutritional support is associated with improved clinical outcomes in critically ill patients; however, loss of muscle mass during critical illness leads to weakness, delayed return to work, and increased healthcare consumption. Animal data have suggested that intermittent feeding decreases protein catabolism. This study was aimed at determining whether the mode of enteral nutrition administration might lead to differences in meeting nutritional goals, tolerance, and complications. A prospective, randomized, single-center clinical trial was conducted in four intensive care units in the Czech Republic. Critically ill adult patients with high nutritional risk were randomized to continuous or intermittent enteral nutrition administration through a tolerance-driven protocol. The primary outcome was the time to reach the energetic target. Secondary outcomes included assessment of tolerance (high gastric residual volume, vomitus, and diarrhea), complications (aspiration or ventilator-associated pneumonia), and 28-day mortality. A total of 300 patients were randomized, and 294 were analyzed: 148 in the continuous arm and 146 in the intermittent arm. Regarding the primary outcome, log-rank test indicated that the intermittent group, compared with continuous group, had a statistically significantly shorter time (p = 0.009) and greater diarrhea occurrence (7 (4.7%) vs. 16 (11%), p = 0.049). No statistically significant differences in ventilator-associated pneumonia incidence (18 (12.2%) vs. 18 (12.3%), p = 0.965), 28-day mortality (46 (31.1%) vs. 40 (27.4%), p = 0.488), and other secondary outcomes were observed between groups. Thus, intermittent enteral nutrition was superior to continuous enteral nutrition in terms of time to reach the energetic target with the tolerance-driven administration protocol but was associated with higher diarrhea incidence. No statistically significant differences in the other secondary outcomes were observed.

Time to Reach Full Enteral Feeding and Its Predictors among Very Low Birth Weight Neonates Admitted in the Neonatal Intensive Care Unit: A Follow-Up Cohort Study

Background

Feeding is crucial for very low birth weight neonates to grow and develop properly. This study aims to determine the time to achieve full enteral feeding and predictors among neonates admitted at Felege Hiwot Comprehensive Specialized Hospital.

Methods

An institutional retrospective follow-up study design was conducted among 332 very low birth weight neonates from July 1, 2018, to June 30, 2021. Samples were selected through a computer-generated simple random sampling method, and the data were entered into Epi data version 4.6 and then exported to STATA version 16 for analysis. Kaplan-Meier with the log-rank test was used to test for the presence of difference in survival among predictor variables. Model goodness of fit and assumptions were checked by the Cox-Snell residual and the global test, respectively. Variables with p value <0.25 in the bi-variable analysis were fitted to the multivariable Cox-proportional hazard model. Finally, the adjusted hazard ratio (AHR) with 95% CI was computed, and variables with a p value less than 0.05 in the multivariable Cox regression analysis were considered significant predictors of time to reach full enteral feeding.

Results

A total of 332 neonates were followed for 2,132 person days of risk time and 167 (50.3%) of very low birth weight neonates started full enteral feeding. The overall incidence rate of full enteral feeding was 7.8 per 100 person day observations. The median survival time was 7 days. Very low birth weight neonates delivered from pregnancy-induced hypertension-free mothers (AHR: 2.1; 95% CI: 1.12, 3.94), gestational age of ≥33 weeks (AHR: 5,; 95% CI: 2.29, 11.13), kangaroo mother care initiated (AHR: 1.4; 95% CI: 1.01, 2.00), avoiding prefeed residual aspiration (AHR: 1.42; 95% CI: 1.002-2.03), and early enteral feeding (AHR: 1.5; 95% CI: 1.03, 2.35) were significant predictors of full enteral feeding.

Conclusions

According to this study, the time to achieve full enteral feeding was relatively short. Therefore, healthcare professionals should emphasize achieving full enteral feeding and address hindering factors to save the lives of VLBW neonates.

Medium-Chain Fatty Acid Feeding Reduces Oxidation and Causes Panacinar Steatosis in Livers of Neonatal Pigs

BACKGROUND

Medium-chain fatty acids (MCFAs) are commonly used to enhance the caloric content of infant formulas. We previously reported that pigs fed MCFA developed hepatic steatosis when compared to those fed isocaloric long-chain fatty acid (LCFA) rich formula.

OBJECTIVES

The objectives of this study were to investigate: 1) whether MCFA and LCFA feeding affect hepatic fatty acid oxidation, and 2) how fat type alters the expression of hepatic fatty acid metabolic genes.

METHODS

Twenty-six, 7-d-old pigs were fed a low-energy control (CONT) formula, or 2 isocaloric high-energy formulas rich in LCFA or MCFA for 22 days. Livers were collected for examining ex vivo fatty acid oxidation, fatty acid content, and mRNA expression of fatty acid metabolic genes.

RESULTS

Liver fat was 20% for pigs in the MCFA compared with 2.9% and 4.6% for those in the CONT and LCFA groups (P < 0.05). MCFA-fed pigs had greater amounts of hepatic laurate, myristate, palmitate, and palmitoleate (14, 34, 49, and 9.3 mg · g-1) than those fed LCFA and CONT (1.8, 1.9, 19, 1.5 mg · g-1) formulas (P ≤ 0.05). Hepatic laurate and palmitate oxidation was reduced for pigs fed MCFA (29 mmol · mg-1 · h-1) compared with those fed CONT (54 mmol · mg-1 · h-1) and LCFA (51 mmol · mg-1 · h-1) formulas (P < 0.05). Expression of fatty acid synthase 3 (FASN-3), fatty acid binding protein 1 (FABP-1), and acetyl-CoA carboxylase 1 (ACACA-1) were 8-, 6-, and 2-fold greater for pigs in the MCFA than those in the LCFA and CONT groups (P < 0.05).

CONCLUSIONS

Feeding MCFA resulted in hepatic steatosis compared with an isocaloric formula rich in LCFA. Steatosis occurred concomitantly with reduced fatty acid oxidation but greater mRNA expression of fatty acid synthetic and catabolic genes.

Pulsatile Leucine Administration during Continuous Enteral Feeding Enhances Skeletal Muscle Mechanistic Target of Rapamycin Complex 1 Signaling and Protein Synthesis in a Preterm Piglet Model

BACKGROUND

Continuous feeding does not elicit an optimal anabolic response in skeletal muscle but is required for some preterm infants. We reported previously that intermittent intravenous pulses of leucine (Leu; 800 μmol Leu·kg-1·h-1 every 4 h) to continuously fed pigs born at term promoted mechanistic target of rapamycin complex 1 (mTORC1) activation and protein synthesis in skeletal muscle.

OBJECTIVES

The aim was to determine the extent to which intravenous Leu pulses activate mTORC1 and enhance protein synthesis in the skeletal muscle of continuously fed pigs born preterm.

METHODS

Pigs delivered 10 d preterm was advanced to full oral feeding >4 d and then assigned to 1 of the following 4 treatments for 28 h: 1) ALA (continuous feeding; pulsed with 800 μmol alanine·kg-1·h-1 every 4 h; n = 8); 2) L1× (continuous feeding; pulsed with 800 μmol Leu·kg-1·h-1 every 4 h; n = 7); 3) L2× (continuous feeding; pulsed with 1600 μmol Leu·kg-1·h-1 every 4 h; n = 8); and 4) INT (intermittent feeding every 4 h; supplied with 800 μmol alanine·kg-1 per feeding; n = 7). Muscle protein synthesis rates were determined with L-[2H5-ring]Phenylalanine. The activation of insulin, amino acid, and translation initiation signaling pathways were assessed by Western blot.

RESULTS

Peak plasma Leu concentrations were 134% and 420% greater in the L2× compared to the L1× and ALA groups, respectively (P < 0.01). Protein synthesis was greater in the L2× than in the ALA and L1× groups in both the longissimus dorsi and gastrocnemius muscles (P < 0.05) but not different from the INT group (P > 0.10). Amino acid signaling upstream and translation initiation signaling downstream of mTORC1 largely corresponded to the differences in protein synthesis.

CONCLUSIONS

Intravenous Leu pulses potentiate mTORC1 activity and protein synthesis in the skeletal muscles of continuously fed preterm pigs, but the amount required is greater than in pigs born at term.

Enteral feeding strategies in patients with acute gastrointestinal injury: From limited to progressive to open feeding

Acute gastrointestinal injury (AGI) is very common in critically ill patients, and its severity is positively correlated with mortality. Critically ill patients with digestive and absorption dysfunction caused by AGI face higher nutritional risks, making nutritional support particularly important. Early enteral nutrition (EN) support is extremely important because it can promote the recovery of intestinal function, protect the intestinal mucosal barrier, reduce microbiota translocation, reduce postoperative complications, shorten hospital stay, and improve clinical prognosis. In recent years, many nutritional guidelines have been proposed for critically ill patients; however, there are few recommendations for the implementation of EN in patients with AGI, and their quality of evidence is low. The use of EN feeding strategies in critically ill patients with AGI remains controversial. The aim of this review was to elaborate on how EN feeding strategies should transition from limited to progressive to open feeding and explain the time window for this transition.

Branched-chain amino acid supplementation does not enhance lean tissue accretion in low birth weight neonatal pigs, despite lower Sestrin2 expression in skeletal muscle

Postnatal muscle growth is impaired in low birth weight (L) neonatal pigs. Leucine supplementation has been established as a dietary intervention to enhance muscle growth in growing animals. The aim of this study was to investigate the efficacy of supplementing L neonatal pig formulas with branched-chain amino acids (B) to enhance the rate of protein accretion. Twenty-four 3-day old pigs were divided into two groups low (L) and normal birth weight (N) based on weight at birth. Pigs were assigned to a control (C) or 1% branched-chain amino acids (B) formulas, and fed at 250 mL·kg body weight -1·d-1 for 28 d. Body weight of pigs in the L group was less than those in the N group (P < 0.01). However, fractional body weight was greater for L pigs compared with their N siblings from day 24 to 28 of feeding regardless of formula (P < 0.01). In addition, feed efficiency (P < 0.0001) and efficiently of protein accretion (P < 0.0001) were greater for L than N pigs regardless of supplementation. Pigs fed the B formula had greater plasma leucine, isoleucine, and valine concentrations compared with those fed the C formula (P < 0.05). Longissimus dorsi Sestrin2 protein expression was less for pigs in the L group compared with those in the N group (P < 0.01), but did not result in a corresponding increase in translation initiation signaling. Longissimus dorsi mRNA expression of BCAT2 was less for LB pigs compared with those in the LC group, and was intermediate for NC and NB pigs (P < 0.05). Hepatic mRNA expression of BCKDHA was greater for pigs in the L compared with those in the N groups (P < 0.05). However, plasma branched-chain keto-acid concentration was reduced for C compared with those in the B group (P < 0.05). These data suggest that branched-chain amino acid supplementation does not improve lean tissue accretion of low and normal birth weight pigs, despite a reduction in Sestrin2 expression in skeletal muscle of low birth weight pigs. The modest improvement in fractional growth rate of low birth weight pigs compared with their normal birth weight siblings was likely due to a more efficient dietary protein utilization.

Circulating direct infusion MS and NMR metabolomic profiles of post-gonadectomy kittens with or without additional dietary choline supplementation

Choline is beneficial for energy metabolism and growth in various species. Choline may work similarly in kittens at risk of obesity. Direct infusion MS (Di-MS) and NMR spectroscopy were used to investigate the metabolomic signatures of kittens supplemented with or without additional dietary choline for 12 weeks. Fifteen intact male kittens consumed a base diet (3310 mg choline/kg DM) to their daily metabolisable energy requirement (DER) over an 11-week acclimation. Kittens were gonadectomised and assigned, based on body weight, to the base diet (CONTROL, n 7) or the base diet with 300 mg/kgBW0·75 additional choline as choline chloride (CHOLINE, n 8) and offered three times their individual energy requirement divided into three meals. At weeks −1 and 12, fasted blood was sampled and serum analysed for 130 metabolites via Di-MS and fifty-one metabolites via NMR spectroscopy. Changes in fasted metabolites were assessed using a repeated-measures GLIMMIX procedure with time and group as fixed effects, and time as a repeated measure. Metabolites of one-carbon metabolism and lipids increased, and medium-chain acyl carnitines decreased from week −1 to 12 for CHOLINE (P < 0·05), but not CONTROL (P > 0·05). Increases in amino acid, biogenic amine and organic compound concentrations were observed in both groups (P < 0·05). The results suggest impacts of dietary choline at greater intakes than currently recommended on one-carbon metabolism and fatty acid oxidation, and these may promote healthy growth in post-gonadectomy kittens.

Intermittent bolus feeding does not enhance protein synthesis, myonuclear accretion, or lean growth more than continuous feeding in a premature piglet model

Optimizing enteral nutrition for premature infants may help mitigate extrauterine growth restriction and adverse chronic health outcomes. Previously, we showed in neonatal pigs born at term that lean growth is enhanced by intermittent bolus compared with continuous feeding. The objective was to determine if prematurity impacts how body composition, muscle protein synthesis, and myonuclear accretion respond to feeding modality. Following preterm delivery, pigs were fed equivalent amounts of formula delivered either as intermittent boluses (INT; n = 30) or continuously (CONT; n = 14) for 21 days. Body composition was measured by dual-energy X-ray absorptiometry (DXA) and muscle growth was assessed by morphometry, myonuclear accretion, and satellite cell abundance. Tissue anabolic signaling and fractional protein synthesis rates were determined in INT pigs in postabsorptive (INT-PA) and postprandial (INT-PP) states and in CONT pigs. Body weight gain and composition did not differ between INT and CONT pigs. Longissimus dorsi (LD) protein synthesis was 34% greater in INT-PP than INT-PA pigs (P < 0.05) but was not different between INT-PP and CONT pigs. Phosphorylation of 4EBP1 and S6K1 and eIF4E·eIF4G abundance in LD paralleled changes in LD protein synthesis. Satellite cell abundance, myonuclear accretion, and fiber cross-sectional area in LD did not differ between groups. These results suggest that, unlike pigs born at term, intermittent bolus feeding does not enhance lean growth more than continuous feeding in pigs born preterm. Premature birth attenuates the capacity of skeletal muscle to respond to cyclical surges in insulin and amino acids with intermittent feeding in early postnatal life.NEW & NOTEWORTHY Extrauterine growth restriction often occurs in premature infants but may be mitigated by optimizing enteral feeding strategies. We show that intermittent bolus feeding does not increase skeletal muscle protein synthesis, myonuclear accretion, or lean growth more than continuous feeding in preterm pigs. This attenuated anabolic response of muscle to intermittent bolus feeding, compared with previous observations in pigs born at term, may contribute to deficits in lean mass that many premature infants exhibit into adulthood.

Intermittent Bolus Compared With Continuous Feeding Enhances Insulin and Amino Acid Signaling to Translation Initiation in Skeletal Muscle of Neonatal Pigs

BACKGROUND

Nutrition administered as intermittent bolus feeds rather than continuously promotes greater protein synthesis rates in skeletal muscle and enhances lean growth in a neonatal piglet model. The molecular mechanisms responsible remain unclear.

OBJECTIVES

We aimed to identify the insulin- and/or amino acid-signaling components involved in the enhanced stimulation of skeletal muscle by intermittent bolus compared to continuous feeding in neonatal pigs born at term.

METHODS

Term piglets (2-3 days old) were fed equal amounts of sow milk replacer [12.8 g protein and 155 kcal/(kg body weight · d)] by orogastric tube as intermittent bolus meals every 4 hours (INT) or by continuous infusion (CTS). After 21 days, gastrocnemius muscle samples were collected from CTS, INT-0 (before a meal), and INT-60 (60 minutes after a meal) groups (n = 6/group). Insulin- and amino acid-signaling components relevant to mechanistic target of rapamycin complex (mTORC) 1 activation and protein translation were measured.

RESULTS

Phosphorylation of the insulin receptor, IRS-1, PDK1, mTORC2, pan-Akt, Akt1, Akt2, and TSC2 was 106% to 273% higher in the skeletal muscle of INT-60 piglets than in INT-0 and CTS piglets (P  < 0.05), but phosphorylation of PTEN, PP2A, Akt3, ERK1/2, and AMPK did not differ among groups, nor did abundances of PHLPP, SHIP2, and Ubl4A. The association of GATOR2 with Sestrin1/2, but not CASTOR1, was 51% to 52% lower in INT-60 piglets than in INT-0 and CTS piglets (P  < 0.05), but the abundances of SLC7A5/LAT1, SLC38A2/SNAT2, SLC38A9, Lamtor1/2, and V-ATPase did not differ. Associations of mTOR with RagA, RagC, and Rheb and phosphorylation of S6K1 and 4EBP1, but not eIF2α and eEF2, were 101% to 176% higher in INT-60 piglets than in INT-0 and CTS piglets (P < 0.05).

CONCLUSIONS

The enhanced rates of muscle protein synthesis and growth with intermittent bolus compared to continuous feeding in a neonatal piglet model can be explained by enhanced activation of both the insulin- and amino acid-signaling pathways that regulate translation initiation.

Addition of dietary methionine but not dietary taurine or methyl donors/receivers to a grain-free diet increases postprandial homocysteine concentrations in adult dogs

Grain based ingredients are replaced in part by pulse ingredients in grain-free pet foods. Pulse ingredients are lower in methionine and cysteine, amino acid (AA) precursors to taurine synthesis in dogs. While recent work has investigated plasma and whole blood taurine concentrations when feeding grain-free diets, supplementation of a grain-free diet with various nutrients involved in the biosynthesis of taurine has not been evaluated. This study aimed to investigate the effects of supplementing a complete grain-free dry dog food with either methionine (MET), taurine (TAU), or methyl donors (choline) and methyl receivers (creatine and carnitine; CCC) on postprandial AA concentrations. Eight healthy Beagle dogs were fed 1 of 3 treatments or the control grain-free diet (CON) for 7 d in a 4 × 4 Latin square design. On d7, cephalic catheters were placed and one fasted sample (0 min) and a series of 9 post-meal blood samples were collected at 15, 30, 60, 90, 120, 180, 240, 300 and 360 min. Data were analyzed as repeated measures using the PROC GLIMMIX function in SAS (Version 9.4). Dogs fed MET had greater plasma and whole blood methionine concentrations from 30 - 360 min after a meal (P < 0.0001) and greater plasma homocysteine concentrations from 60 - 360 min after a meal (P < 0.0001) compared to dogs fed CON, TAU and CCC. Dogs fed TAU had greater plasma taurine concentrations over time compared to dogs fed CON (P = 0.02), but were not different than dogs fed MET and CCC (P > 0.05). In addition, most AA remained significantly elevated at 6 h post-meal compared to fasted samples across all treatments. Supplementation of creatine, carnitine and choline in grain-free diets may play a role in sparing the methionine requirement without increasing homocysteine concentrations. Supplementing these nutrients could also aid in the treatment of disease that causes metabolic or oxidative stress, including cardiac disease in dogs, but future research is required.

Serum ghrelin is associated with early feeding readiness but not growth in premature infants

BACKGROUND

Feeding tolerance among premature infants is unpredictable using clinical parameters. Ghrelin, a peptide hormone, acts on the hypothalamus to increase hunger and gut motility. It is present in fetal tissues, promotes intestinal maturation, and is secreted in milk. We hypothesized that higher serum ghrelin levels on days 0-7 are associated with improved feeding tolerance and growth in premature infants.

METHODS

Infants (<  1500 g birth weight, n = 36) were recruited on day (D) 0-7. Serum ghrelin was measured by ELISA on D 0-7, D 10-14, and D 24-32, and milk ghrelin in a feeding concurrent with each serum sample. Feeding tolerance was assessed as days to first and full enteral feeds. Growth was quantified as both weight and adipose and muscle deposition by ultrasound.

RESULTS

Mean serum ghrelin levels decreased from D 0-7 to D 24-32. Higher ghrelin levels on D 0-7 were correlated with shorter time to first enteral feeding, but not with time to full enteral feeds, rate of weight gain, or rate of accretion of muscle or adipose tissue. Milk ghrelin was not related to serum ghrelin or growth. Abdominal and suprascapular muscle and adipose increased during the first month, but weight gain correlated only with the rate of accretion of abdominal adipose.

CONCLUSIONS

Elevated serum ghrelin in the first days of life may contribute to gut motility and readiness to feed. Weight gain in premature infants may primarily indicate abdominal fat accumulation, suggesting that ultrasound measurement of muscle accretion is a better marker for lean body growth.

The Effect of Intermittent and Continuous Feeding on Growth and Discharge Time in Very Low Birth Weight Preterm Infants

Objectives

The aim of this study was to determine the effect of intermittent bolus feeding and continuous feeding models on early growth and discharge time in very low birth weight infants.

Methods

The study was designed as a prospective, randomized, and controlled study. Infants born in our hospital with birth weight below 1500 g within a 1 year period were included in the study. The number of samples was determined by power analysis. Babies were randomized according to birth weight and fed with intermittent bolus feeding and continuous feeding models. Demographic characteristics, clinical findings, diagnosis, nutritional status, and length of hospital stay were compared.

Results

The study was conducted with 80 preterm infants, which consisted of continuous feeding (n=41) and intermittent bolus feeding (n=39). There was no significant difference in gender, gestational week, birth weight, height, and head circumference distribution of the babies between groups. The difference between the reach time to birth weight and maximum weight loss rates, parenteral feeding time, transition time to full enteral feeding, transition time to oral feeding, development of feeding intolerance, mechanical ventilation time, and hospitalization time in intensive care unit were not statistically significant. Necrotizing enterocolitis (NEC) Stage I and II developed in 34.1% of babies fed with continuous feeding model and 28.2% of babies fed intermittently; NEC was detected to start in 4.5±2.8 days in the continuous feeding group and in 2.8±5.2 days in the intermittent group. These differences were found to be insignificant between the two groups (p=0.634 and p=0.266, respectively).

Conclusion

There was no difference between growth parameters and discharge time of preterm babies who were applied continuous and intermittent bolus feeding model. Although there was no statistically significant difference on the development of NEC, it was determined that NEC developed earlier in the intermittent bolus feeding model.

Intermittent Bolus Feeding Enhances Organ Growth More Than Continuous Feeding in a Neonatal Piglet Model

BACKGROUND

Orogastric tube feeding is frequently prescribed for neonates who cannot ingest food normally. In a piglet model of the neonate, greater skeletal muscle growth is sustained by upregulation of translation initiation signaling when nutrition is delivered by intermittent bolus meals, rather than continuously.

OBJECTIVES

The objective of this study was to determine the long-term effects of feeding frequency on organ growth and the mechanism by which feeding frequency modulates protein anabolism in these organs.

METHODS

Eighteen neonatal pigs were fed by gastrostomy tube the same amount of a sow milk replacer either by continuous infusion (CON) or on an intermittent bolus schedule (INT). After 21 d of feeding, the pigs were killed without interruption of feeding (CON; n = 6) or immediately before (INT-0; n = 6) or 60 min after (INT-60; n = 6) a meal, and fractional protein synthesis rates and activation indexes of signaling pathways that regulate translation initiation were measured in the heart, jejunum, ileum, kidneys, and liver.

RESULTS

Compared with continuous feeding, intermittent feeding stimulated the growth of the liver (+64%), jejunum (+48%), ileum (+40%), heart (+64%), and kidney (+56%). The increases in heart, kidney, jejunum, and ileum masses were proportional to whole body lean weight gain, but liver weight gain was greater in the INT-60 than the CON, and intermediate for the INT-0 group. For the liver and ileum, but not the heart, kidney, and jejunum, INT-60 compared with CON pigs had greater fractional protein synthesis rates (22% and 48%, respectively) and was accompanied by an increase in ribosomal protein S6 kinase 1 and eukaryotic initiation factor 4E binding protein 1 phosphorylation.

CONCLUSIONS

These results suggest that intermittent bolus compared with continuous orogastric feeding enhances organ growth and that in the ileum and liver, intermittent feeding enhances protein synthesis by stimulating translation initiation.

Intermittent leucine pulses during continuous feeding alters novel components involved in skeletal muscle growth of neonatal pigs

When neonatal pigs continuously fed formula are supplemented with leucine pulses, muscle protein synthesis and body weight gain are enhanced. To identify the responsible mechanisms, we combined plasma metabolomic analysis with transcriptome expression of the transcriptome and protein catabolic pathways in skeletal muscle. Piglets (n = 23, 7-day-old) were fed continuously a milk replacement formula via orogastric tube for 21 days with an additional parenteral infusion (800 μmol kg^-1 h^-1) of either leucine (LEU) or alanine (CON) for 1 h every 4 h. Plasma metabolites were measured by liquid chromatography-mass spectrometry. Gene and protein expression analyses of longissimus dorsi muscle were performed by RNA-seq and Western blot, respectively. Compared with CON, LEU pigs had increased plasma levels of leucine-derived metabolites, including 4-methyl-2-oxopentanoate, beta-hydroxyisovalerate, β-hydroxyisovalerylcarnitine, and 3-methylglutaconate (P ≤ 0.05). Leucine pulses downregulated transcripts enriched in the Kyoto Encyclopedia of Genes and Genomes terms "spliceosome," "GAP junction," "endocytosis," "ECM-receptor interaction," and "DNA replication". Significant correlations were identified between metabolites derived from leucine catabolism and muscle genes involved in protein degradation, transcription and translation, and muscle maintenance and development (P ≤ 0.05). Further, leucine pulses decreased protein expression of autophagic markers and serine/threonine kinase 4, involved in muscle atrophy (P ≤ 0.01). In conclusion, results from our studies support the notion that leucine pulses during continuous enteral feeding enhance muscle mass gain in neonatal pigs by increasing protein synthetic activity and downregulating protein catabolic pathways through concerted responses in the transcriptome and metabolome.

The daytime feeding frequency affects appetite-regulating hormones, amino acids, physical activity, and respiratory quotient, but not energy expenditure, in adult cats fed regimens for 21 days

The effects of feeding frequency on postprandial response of circulating appetite-regulating hormones, insulin, glucose and amino acids, and on physical activity, energy expenditure, and respiratory quotient were studied in healthy adult cats. Two experiments were designed as a 2 x 3 replicated incomplete Latin square design. Eight cats, with an average body weight (BW) of 4.34 kg ± 0.04 and body condition score (BCS) of 5.4 ± 1.4 (9 point scale), were fed isocaloric amounts of a commercial adult maintenance canned cat food either once (0800 h) or four times daily (0800 h, 1130 h, 1500 h, 1830 h). Study 1 consisted of three 21-d periods. On day 14, two fasted and 11 postprandial blood samples were collected over 24 hours to measure plasma concentrations of ghrelin, GLP-1, GIP, leptin, PYY, insulin and amino acids, and whole blood glucose. Physical activity was monitored from day 15 to 21 of each period. In Study 2 indirect calorimetry was performed on the last day of each period. Body weight was measured weekly and feed intake recorded daily in both experiments. No effect of feeding regimen on BW was detected. Cats eating four times daily had lesser plasma concentrations of GIP and GLP-1 (P<0.05) and tended to have lesser plasma PYY concentrations (P<0.1). Plasma leptin and whole blood glucose concentrations did not differ between regimens (P>0.1). Cats fed once daily had a greater postprandial plasma amino acid response, and greater plasma ghrelin and insulin concentrations (P<0.05). Physical activity was greater in cats fed four times (P<0.05), though energy expenditure was similar between treatments at fasting and in postprandial phases. Finally, cats eating one meal had a lower fasting respiratory quotient (P<0.05). Overall, these data indicate that feeding once a day may be a beneficial feeding management strategy for indoor cats to promote satiation and lean body mass.

Protein delivery in intermittent and continuous enteral nutrition with a protein-rich formula in critically ill patients-a protocol for the prospective randomized controlled proof-of-concept Protein Bolus Nutrition (Pro BoNo) study

Background

Critically ill patients rapidly develop muscle wasting resulting in sarcopenia, long-term disability and higher mortality. Bolus nutrition (30–60 min period), whilst having a similar incidence of aspiration as continuous feeding, seems to provide metabolic benefits through increased muscle protein synthesis due to higher leucine peaks.

To date, clinical evidence on achievement of nutritional goals and influence of bolus nutrition on skeletal muscle metabolism in ICU patients is lacking. The aim of the Pro BoNo study (Protein Bolus Nutrition) is to compare intermittent and continuous enteral feeding with a specific high-protein formula. We hypothesise that target quantity of protein is reached earlier (within 36 h) by an intermittent feeding protocol with a favourable influence on muscle protein synthesis.

Methods

Pro BoNo is a prospective randomised controlled study aiming to compare the impact of intermittent and continuous enteral feeding on preventing muscle wasting in 60 critically ill patients recruited during the first 48 h after ICU admission. The primary outcome measure is the time until the daily protein target (≥ 1.5 g protein/kg bodyweight/24 h) is achieved. Secondary outcome measures include tolerance of enteral feeding and evolution of glucose, urea and IGF-1. Ultrasound and muscle biopsy of the quadriceps will be performed.

Discussion

The Basel Pro BoNo study aims to collect innovative data on the effect of intermittent enteral feeding of critically ill patients on muscle wasting.

Trial registration

ClinicalTrials.gov NCT03587870. Registered on July 16, 2018. Swiss National Clinical Trials Portal SNCTP000003234. Last updated on July 24, 2019.

Compound Lactobacillus sp. administration ameliorates stress and body growth through gut microbiota optimization on weaning piglets

The composition of bacteria in the gastrointestinal tract of piglets is easily affected by environmental changes, particularly during the weaning period. Compound strains of Lactobacillus reuteri and Lactobacillus salivarius were supplemented to piglets during pre- and post-weaning to determine their effects in improving the growth performance and ameliorating the diarrhea rate and stress caused by antioxidation in piglets. A larger number of L. reuteri and L. salivarius colonized the distal segment of the ileum and the total numbers of Lactobacillus spp. and Bifidobacteria were higher in the ileal mucous membrane and cecal lumen with probiotics supplementation. The numbers of antioxidants and immune molecules increased, levels of cortisol and endotoxin reduced, and growth hormone and insulin-like growth factor 1 improved in the plasma following compound bacteria (CL) supplementation. Spearman's and KEGG analysis of the bacterial operational taxonomic unit and antioxidative and immune indices and metabolic genes indicated that the body growth modulation by CL supplementation could be attributed to optimization of the intestinal bacterial composition; functional strains of L. delbrueckii, L. salivarius, L. formicilis, L. reuteri, and L. mucosae were positively correlated with body antioxidation and immunity derived by CL supplementation. Strains of L. agilis and L. pontis were diverse and negatively correlated with body antioxidation and immunity. Collectively, these results suggest that supplementation with CL could reduce stress and improve the growth performance of piglets during weaning by optimizing the intestinal bacterial composition. KEY POINTS: • The colonization of L. reuteri and L. salivarius in ileal mucous membrane optimize bacterial composition of GIT, mainly some functional strains of Lactobacillus, L. delbrueckii, L. salivarius, L. formicilis, L. reuteri, and L. mucosae. • The optimized bacterial composition of piglets in both ileal mucous membrane and cecal content improves body growth hormone level, immunity, and antioxidation, which is helpful to defend the stress. These benefits induce to increased growth performance of animal model piglets during weaning.

Decreased abundance of eIF4F subunits predisposes low-birth-weight neonatal pigs to reduced muscle hypertrophy

Muscle hypertrophy is limited in low-birth-weight (LBWT) neonates, suggesting a reduction in protein synthesis and increased protein degradation. Sixteen pairs of 1-d old normal-birth-weight (NBWT) and LBWT littermates (n = 16) were euthanized and the longissimus dorsi (LD) was sampled for protein abundance and kinase phosphorylation profiles measures. Eukaryotic initiation factor (eIF) 4E and eIF4G abundance, and assembly of the active eIF4E-eIF4G complex was less for LBWT than for NBWT pig muscles. Similarly, eIF3f abundance was reduced in muscle of LBWT compared with NBWT pig and was associated with diminished ribosomal protein S6 kinase 1 (S6K1) phosphorylation. This decrease was linked to a lower phosphorylation of programmed cell death protein 4 (PDCD4) in LBWT pig muscle. By contrast, PDCD4 abundance was greater in muscle of LBWT than NBWT group, suggesting lower release and availability of eIF4A from PDCD4-eIF4A complex. Moreover, protein abundance of eIF4A was lower in LBWT muscle, which is expected to further impair the formation of eIF4F translation initiation complex. Microtubule associated light chain 3 (LC3) II to total LC3 ratio was greater in LBWT LD lysates yet P62 abundance was similar between the two groups suggesting no difference in autophagy. Muscle atrophy F-box (atrogin-1) abundance was less in LBWT LD lysates, suggesting decreased degradation through the ubiquitin-proteasome system. In conclusion, limited eIF4F subunit abundance and downregulated translation initiation are plausible mechanisms for diminished muscle growth in LBWT compared with NBWT neonatal pigs.