Supplementation of branched-chain amino acids (BCAA) has been demonstrated to promote skeletal muscle mass gain, but the mechanisms underlying this observation are still unknown. Since the regulation of muscle mass depends on a dynamic equilibrium (fasted losses–fed gains) in protein turnover, the aim of this study was to investigate the effects of BCAA supplementation on muscle protein synthesis and degradation in fed/fasted states and the related mechanisms. Fourteen 26- (Experiment 1) and 28-day-old (Experiment 2) piglets were fed reduced-protein diets without or with supplemental BCAA. After a four-week acclimation period, skeletal muscle mass and components of anabolic and catabolic signaling in muscle samples after overnight fasting were determined in Experiment 1. Pigs in Experiment 2 were implanted with carotid arterial, jugular venous, femoral arterial and venous catheters, and fed once hourly along with the intravenous infusion of NaH¹³CO₃ for 2 h, followed by a 6-h infusion of [1-¹³C]leucine. Muscle leucine kinetics were measured using arteriovenous difference technique. The mass of most muscles was increased by BCAA supplementation. During feeding, BCAA supplementation increased leucine uptake, protein synthesis, protein degradation and net transamination. The greater increase in protein synthesis than in protein degradation resulted in elevated protein deposition. Protein synthesis was strongly and positively correlated with the intramuscular net production of α-ketoisocaproate (KIC) and protein degradation. Moreover, BCAA supplementation enhanced the fasted-state phosphorylation of protein translation initiation factors and inhibited the protein-degradation signaling of ubiquitin-proteasome and autophagy-lysosome systems. In conclusion, supplementation of BCAA to reduced-protein diet increases fed-state protein synthesis and inhibits fasted-state protein degradation, both of which could contribute to the elevation of skeletal muscle mass in piglets. The effect of BCAA supplementation on muscle protein synthesis is associated with the increase in protein degradation and KIC production in the fed state.

This experiment aimed to study the effects of different proportions of Amaranthus hypochondriacus stem and leaf powder (AHSL) on the growth performance, apparent nutrient digestibility, carcass traits, meat quality, and blood biochemical parameters of broilers from day 1 to day 42. The experiment utilized a single-factor experimental design, with a total of 216 one-day-old male broilers (Ross 308) randomly assigned to three dietary treatment groups (eight replicate cages of nine birds per cage). The dietary treatments included a control diet, a 3% AHSL diet and a 6% AHSL diet for days 0–21. Then, the 3% and 6% AHSL diets were changed to 5% and 10% AHSL for days 22–42. The results showed that the inclusion levels of AHSL did not affect growth performance, carcass traits, or meat quality on days 21 and 42 (p > 0.05). However, the inclusion levels of AHSL decreased the apparent nutrient digestibility (AND) of dry matter (DM) (p ˂ 0.001) and neutral detergent fiber (NDF) (p ˂ 0.001) and increased the serum concentration of phosphorus (p ˂ 0.001) on day 21. On day 42, the inclusion levels of AHSL decreased the AND of DM (p = 0.025) and NDF content (p ˂ 0.001), but increased the AND of crude protein (CP) (p = 0.004). In particular, the diet containing 10% AHSL significantly increased the serum enzyme activity of alkaline phosphatase (ALP) (p = 0.046) and the serum concentration of total protein (TP) (p ˂ 0.001) on day 42. Overall, AHSL can be used as a new and effective feed ingredient in broiler diets. It can replace part of the corn–soybean meal diet without any adverse effects, which is beneficial for conserving feed resources. Additionally, AHSL can be included at a level of up to 10% during the broiler growth period.

The aim of this study was to determine the effects of dietary supplementation with mannose oligosaccharide (MOS) on the condition of the body and the reproductive and lactation performances of sows. Eighty pregnant sows were randomly assigned to four groups with a 2 × 2 factorial design: with or without MOS (1 g/kg) and with or without heat stress (HS) challenge. The temperature in the HS groups (HS and HM group) was controlled at 31.56 ± 1.22 °C, while the temperature in the active cooling (AC) groups (AC and AM group) was controlled at 23.49 ± 0.72 °C. The weight loss of sows in the AC group was significantly lower than that of sows in the HS group (p < 0.01). The weight and backfat thickness loss of sows supplemented with MOS displayed a downward trend. The average birth weight of the litter significantly increased in the HM group (basic diet + MOS) compared with the HS group (p < 0.05). The milk protein of sows significantly decreased under the HS condition at 2 and 12 h after delivery (p < 0.05). However, the milk immunoglobin G (IgG) of sows in the HS group increased significantly compared with that of sows in the HM group (p < 0.05) at 12 and 24 h after delivery. The levels of serum urea nitrogen (UREA) and glucose (GLU) decreased significantly under the HS condition (p < 0.05), while the level of interleukin-6 (IL-6) increased significantly under the HS condition (p < 0.05). Dietary supplementation with MOS also significantly reduced TNF-α under the AC conditions (p < 0.05). In conclusion, HS significantly affected the body condition, lactation performances and their offspring of sows. However, dietary supplementation with 1 g/kg MOS did not result in statistically significant changes.

Amaranthus hypochondriacus is rich in nutrients and represents a feed resource with significant potential. This experiment aimed to study the effects of different proportions of Amaranthus hypochondriacus stem and leaf powder (AHSL) on intestinal digestive enzyme activities, cecal volatile fatty acids, and the microbiota of broilers. A total of 288 one-day-old male broilers (Ross 308) were randomly assigned to the control diet group and the 3%, 6%, and 9% AHSL diet group for days 0–21. Subsequently, the 3%, 6%, and 9% AHSL diets were switched to 5%, 10%, and 15% AHSL diets for days 22–42. The results demonstrated that the dietary inclusion of AHSL significantly affected sucrase activity in the jejunal mucosa (p < 0.05). The 5% AHSL group exhibited the highest sucrase activity, followed by the control group, both of which showed significantly higher activity compared to the 10% and 15% AHSL groups (p < 0.05). The cecal pH in the 5%, 10%, and 15% AHSL groups was significantly lower than that in the control group (p < 0.05). The contents of acetate, propionate, butyrate, and valerate in the cecum of the 10% and 15% AHSL groups were significantly higher than those of the control group (p < 0.05). The addition of AHSL had no significant effect on the alpha diversity of cecum microorganisms. The relative abundance of Ruminococcaceae_UCG_005 and Lactonifactor was significantly higher in the 10% AHSL group compared to the control group, whereas the 15% AHSL group had a significantly higher relative abundance of Clostridium_sensus_tricto12, Peptoclostridium, Anaerofilum, and Peptococcaceae. In summary, the inclusion of 5% AHSL in the diet enhances sucrase activity in the jejunum of broilers, while 10% or 15% AHSL increases the volatile fatty acid content and reduces the pH value in the cecum, without adverse effects on the cecal microbiota.

Intrauterine growth restriction (IUGR) in newborn animals is linked to impaired intestinal health, yet the characteristics of their gut microbiota and circulating exosomal miRNAs remain incompletely understood. This study compared the cecal microbiota composition and serum exosomal miRNA profiles to characterize differences between IUGR and normal birth weight (NBW) piglets. Compared to NBW piglets, IUGR piglets displayed significant reductions in body and organ weights (heart, liver, kidney) as well as shorter jejunal and ileal lengths ( p < 0.05). Microbial diversity, reflected by the Chao1 and Shannon index, was significantly reduced in IUGR piglets ( p < 0.001). Taxonomic analysis revealed decreased abundances of Bacteroidetes, Fusobacteria , and Fusobacterium ( p < 0.05), alongside increased abundances of potential pathogenic taxa, including Proteobacteria, Escherichia-Shigella , and Sutterella ( p < 0.05). Moreover, three serum exosomal miRNAs (ssc-miR-16, ssc-miR-19b, and ssc-let-7c) emerged from the analysis as potential key regulators of IUGR. Functional enrichment analysis revealed that ssc-miR-16 and ssc-miR-19b were significantly increased in IUGR piglets, mainly targeting genes involved in cellular signaling, metabolism, and immune regulation, including the mTOR and infection-related pathways. In contrast, ssc-let-7c was significantly downregulated and linked to metabolic processes such as protein digestion and absorption. Collectively, these findings demonstrate that IUGR disrupts intestinal barrier development and microbial homeostasis, while identifying three serum exosomal miRNAs as potential biomarkers and mechanistic contributors to the pathological processes underlying IUGR.