The imbalance of redox biology and oxidative stress leads to intestinal barrier injury and mitophagy. However, much uncertainty still exists about the role of mitophagy in oxidative stress and intestinal function. Here, we showed the effects of hydrogen peroxide (H₂O₂)-induced oxidative stress on intestinal epithelial cell oxidation balance, intestinal barrier function and mitochondrial energy metabolism and its underlying mechanism. In this study, we found that H₂O₂-induced oxidative stress activated adenosine monophosphate-activated protein kinase (AMPK) and enhanced mitophagy in intestinal porcine epithelial cells (IPEC-J2). While compound C (AMPK inhibitor) and mdivi-1 (mitophagy inhibitor) significantly reduced the activity of superoxide dismutase (SOD) and increased mitochondrial reactive oxygen species (ROS) levels in H₂O₂ treated cells. Moreover, compound C and mdivi-1 significantly reduced the trans-epithelium electrical resistant (TER) and increased the fluorescein isothiocyanate-dextran (FD4) flux in H₂O₂ treated IPEC-J2. Furthermore, compound C and mdivi-1 significantly reduced the activity of mitochondrial complex II. Seahorse XF96 data showed that compound C + mdivi-1+ H₂O₂ treatment significantly reduced maximum respiratory oxygen consumption and spare respiratory capacity. Additionally, compound C or mdivi-1 treatment reduced the formation of mitochondrial autophagosomes. These results unveiled that AMPK and PINK1/Parkin mediated mitophagy is necessary for alleviating oxidative stress induced intestinal epithelial barrier damage and mitochondrial energy metabolism dysfunction in IPEC-J2.

This study aimed to systematically evaluate the effects of low-protein (LP) diets and their associated nutritional interventions on growth performance and intestinal health in weaned piglets through a meta-analysis. Following the PRISMA guidelines, 21 studies were selected from an initial set of 1720 to construct a database. A random-effects model was employed to assess the growth performance and intestinal health of weaned piglets, comparing LP diet with control diet, and LP diet + additive with LP diet alone. Heterogeneity was assessed using the I² statistic, and its sources along with publication bias were explored through meta-regression, subgroup analysis, and Egger’s linear regression. The results show that LP diets (crude protein < 18%) reduced final body weight (p < 0.001), average daily gain (p < 0.001), and gain-to-feed ratio (p < 0.001) of weaned piglets. Additionally, forest plot data show that LP diet (crude protein < 18%) decreased villus height and crypt depth in the jejunum and ileum of weaned piglets (p < 0.05). To mitigate these adverse effects, plant extracts, amino acids (AAs), fatty acids, vitamins, enzymes, and carbohydrates are commonly used as additives. Among these, the results show that LP diets supplemented with AAs and plant extracts increased average daily feed intake (p < 0.001) and ileal crypt depth (p < 0.05). Network meta-analysis further identified AAs and plant extracts as the most effective additives for improving growth performance of weaned piglets. In conclusion, dietary protein levels below 18% negatively affect the growth performance of weaned piglets, and supplementation with AAs or plant extracts represents a promising strategy to counteract these adverse effects.

Background/Objectives: Calcium–phosphorus metabolism is critical for skeletal development in weaned piglets. This study evaluated the effects of dietary 25-hydroxyvitamin D₃ (25-OH-VD₃) in combination with phytase and probiotics on mineral metabolism, bone development, and related molecular mechanisms in weaned piglets. Methods: Sixty 28-day-old weaned piglets (7.1 ± 1.30 kg) were randomly assigned to four dietary treatments for 31 days (including 3 days of acclimation): CON (basal diet + 50 µg/kg 25-OH-VD₃), HI (CON + 50 mg/kg phytase), CY (CON +10 mg/kg probiotics), HICY (CON + 50 mg/kg phytase + 10 mg/kg probiotics). Apparent calcium digestibility, serum biochemical indices, bone mineral density (BMD), and mRNA and protein expression of calcium–phosphorus transport- and metabolism-related genes in jejunal mucosa and kidney were assessed. Results: Compared with CON, piglets in the HI, CY, and HICY groups showed higher apparent calcium digestibility (p < 0.05). Serum transforming growth factor-β was elevated in CY and HICY (p < 0.05). HI enhanced metatarsal and toe BMD (p < 0.05) and upregulated jejunal solute carrier family 34, member 2 (SLC34A2) and SLC34A3 mRNA expression (p < 0.05). In contrast, HICY reduced mRNA expression of transient receptor potential cation channel subfamily V member 6 and calcium-binding protein D28k, as well as of calcium-binding protein D9k and cytochrome P450 27B1 in the kidney (p < 0.05). Renal calcium-sensing receptor protein abundance increased in CY (p < 0.05). Conclusions: Supplementation of 25-OH-VD₃ with phytase and/or probiotics improved calcium utilization and modulated key transport pathways, contributing to enhanced bone development in weaned piglets. These findings highlight coordinated nutritional regulation of mineral metabolism during early post-weaning growth.