Effects of Dietary Valine Levels on Production Performance, Egg Quality, Antioxidant Capacity, Immunity, and Intestinal Amino Acid Absorption of Laying Hens during the Peak Lay Period

The present study aimed to assess the impact of dietary valine levels on layer production performance, egg quality, immunity, and intestinal amino acid absorption of laying hens during the peak lay period. For this purpose, a total of 960 33-week-old Fengda No.1 laying hens were randomly divided into five experimental groups and fed with valine at the following different levels in a feeding trial that lasted 8 weeks: 0.59, 0.64, 0.69, 0.74, and 0.79%, respectively. Productive performances were recorded throughout the whole rearing cycle and the egg quality, serum indexes, and small intestine transporters expression were assessed at the end of the experiment after slaughter (41 weeks) on 12 hens per group. Statistical analysis was conducted by one-way ANOVA followed by LSD multiple comparison tests with SPSS 20.0 (SPSS, Chicago, IL, USA). The linear and quadratic effects were tested by SPSS 20.0. Egg mass, laying rate, broken egg rate, and feed conversion ratio were significantly improved with increasing dietary valine levels. However, the egg weight, eggshell thickness, albumen height, Haugh unit, and egg yolk color were significantly decreased with increasing dietary valine levels. Serum catalase (CAT), immunoglobulin A (IgA) and IgM levels, and malondialdehyde (MDA) levels were negative responses to valine-treated laying hens. Dietary supplemented valine enhanced the trypsin activity of duodenum chime and promoted the mRNA expression levels of ATB0,+, and LAT4 in the jejunum and corresponding serum free Ile, Lys, Phe, Val, and Tyr level. However, valine treatment significantly downregulated the mRNA expression levels of PePT1, B0AT1, LAT1, and SNAT2 in the small intestines and corresponding serum free Arg, His, Met, Thr, Ala, Asp, Glu, Gly, and Ser level. Our results suggest that 0.79% valine dietary supplementation can improve production performance by promoting amino acid nutrient uptake and utilization, and suggest a supplement of 0.79% valine to diet.

Walking exercise alters protein digestion, amino acid absorption, and whole body protein kinetics in older adults with and without COPD

Purpose: Gut symptoms and markers of gut dysfunction have been observed in patients with Chronic Obstructive Pulmonary disease (COPD). It remains unclear whether walking exercise induces disturbances in protein digestion and amino acid absorption and whole body protein kinetics in these subjects due to exercise induced hypoxia. Methods: Sixteen clinically stable patients with moderate to very severe COPD and 12 age matched control subjects completed the study. Protein digestion and amino acid absorption and whole body protein kinetics, in the postabsorptive state, were measured via a continuous infusion of stable tracers in combination with orally administered tracer sips during 20 minutes of walking exercise and up to 4 hours post-exercise. COPD patients completed one study day, walking at maximal speed, while healthy subjects completed two, one matched to the speed of a COPD patient and one walking at maximal speed. Results: The COPD patients tolerated 20 minutes of vigorous intensity walking despite elevated heart rate (P<0.001) and substantial desaturation (P<0.001). Relative to rest, protein digestion was increased during recovery from exercise (P<0.05) while amino acid absorption was reduced during (P<0.0001) and immediately after exercise (P<0.001). Whole body protein breakdown was reduced within 20 minutes after exercise (P<0.05) and stayed suppressed for four hours (P<0.0001). Whole body net protein breakdown was elevated for four hours post-exercise (P<0.001). Conclusion: Our data showed that 20 minutes of walking exercise is sufficient to cause substantial perturbations in gut function in older adults and COPD patients with hypoxia as a potential underlying factor.

Ingestion of Free Amino Acids as Opposed to Intact Protein Increases Amino Acid Absorption but Does Not Further Augment Postprandial Muscle Protein Synthesis Rates

Objectives The rate of protein digestion and amino acid absorption determines the postprandial rise in circulating amino acids and, as such, modulates postprandial muscle protein synthesis rates. This study compares protein digestion and amino acid absorption kinetics and the subsequent muscle protein synthetic response following ingestion of intact protein versus an equivalent amount of free, crystalline amino acids. Methods Twenty-four healthy, young subjects (age: 22 ± 3 y, BMI: 23 ± 2 kg·m−2, sex: 12 M/12F) ingested 30 g intrinsically L-[1–13C]-phenylalanine and L-[1–13C]-leucine labeled milk protein (PROT; n = 12) or an equivalent amount of free amino acids (AA; n = 12). In addition, subjects received primed continuous L-[ring-2H5]-phenylalanine, L-[ring-3,5–2H2]-tyrosine, and L-[1–13C]-leucine infusions. Blood samples and muscle biopsies were obtained frequently to assess protein digestion and amino acid absorption kinetics and subsequent muscle protein synthesis rates over a 6 h postprandial period. An unpaired t-test was used to compare overall exogenous phenylalanine release in plasma. For other parameters repeated measures ANOVA were applied to determine differences between groups over time (time as within, and group as between-subjects factor). Data are expressed as mean ± SD. Results Postprandial plasma amino acid concentrations and exogenous phenylalanine appearance rates increased after ingestion of PROT and AA (both, P &lt; 0.001), with a greater increase following ingestion of AA when compared to PROT (time*group interaction P &lt; 0.001). Exogenous phenylalanine release in plasma assessed over the 6 h postprandial period, was greater in AA (76 ± 9%) compared with PROT (59 ± 10%; P &lt; 0.001). Ingestion of AA and PROT strongly increased muscle protein synthesis rates based upon L-[ring-2H5]-phenylalanine (time effect P &lt; 0.001), with no differences between groups (from 0.037 ± 0.015 to 0.053 ± 0.014%·h−1 and from 0.039 ± 0.016 to 0.051 ± 0.010%·h−1, respectively; time*group interaction P = 0.629). Conclusions Ingestion of free amino acids as opposed to intact milk protein is followed by more rapid amino acid absorption and greater postprandial plasma amino acid availability, but this does not further augment postprandial muscle protein synthesis rates. Funding Sources This research did not receive external funding.

Probiotic Administration Increases Amino Acid Absorption from Plant Protein: a Placebo-Controlled, Randomized, Double-Blind, Multicenter, Crossover Study

The fate of dietary protein in the gut is determined by microbial and host digestion and utilization. Fermentation of proteins generates bioactive molecules that have wide-ranging health effects on the host. The type of protein can affect amino acid absorption, with animal proteins generally being more efficiently absorbed compared with plant proteins. In contrast to animal proteins, most plant proteins, such as pea protein, are incomplete proteins. Pea protein is low in methionine and contains lower amounts of branched-chain amino acids (BCAAs), which play a crucial role in muscle health. We hypothesized that probiotic supplementation results in favorable changes in the gut microbiota, aiding the absorption of amino acids from plant proteins by the host. Fifteen physically active men (24.2 ± 5.0 years; 85.3 ± 12.9 kg; 178.0 ± 7.6 cm; 16.7 ± 5.8% body fat) co-ingested 20 g of pea protein with either AminoAlta™, a multi-strain probiotic (5 billion CFU L. paracasei LP-DG® (CNCM I-1572) plus 5 billion CFU L. paracasei LPC-S01 (DSM 26760), SOFAR S.p.A., Italy) or a placebo for 2 weeks in a randomized, double-blind, crossover design, separated by a 4-week washout period. Blood samples were taken at baseline and at 30-, 60-, 120-, and 180-min post-ingestion and analyzed for amino acid content. Probiotic administration significantly increased methionine, histidine, valine, leucine, isoleucine, tyrosine, total BCAA, and total EAA maximum concentrations (Cmax) and AUC without significantly changing the time to reach maximum concentrations. Probiotic supplementation can be an important nutritional strategy to improve post-prandial changes in blood amino acids and to overcome compositional shortcomings of plant proteins. ClinicalTrials.gov Identifier: ISRCTN38903788