Background: Previous studies had shown that short-term acute heat stress (HS) affected the host’s metabolism and intestinal microbiota independent of feed intake (FI) reduction, and long-term calorie restriction caused intestinal morphological injuries and gut microbial alterations. However, research on the effects of constant chronic HS on intestinal microbial composition and the roles of FI reduction played in is limited. This study aimed to investigate the effects of 7-day constant chronic HS on the composition of intestinal microbes in growing-finishing pigs, and its relationship with pigs’ performance, intestinal morphology, and ileal immune response. Twenty-four growing-finishing pigs (Duroc × Large White × Landrace, 30 ± 1 kg body weight) were randomly assigned to three treatments (n = 8), 1) thermal neutral (TN) conditions (25 ± 1 °C) with ad libitum FI, 2) HS conditions (35 ± 1 °C) with ad libitum FI, 3) pair-fed (PF) with HS under TN conditions to discriminate the confounding effects of dissimilar FI, and the FI was the previous day’s average FI of HS. The small intestinal segments (duodenum, jejunum, and ileum) and feces were collected on d 8. Results: Results indicated that HS drastically declined (P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI) (about 61%) in comparison with TN, and caused hyperpyrexia, meanwhile PF caused hypothermia. Morphological observation by light and electron microscopes showed that both HS and PF treatment decreased (P < 0.05) the villus and microvillus height compared with TN. Additionally, HS increased (P < 0.05) protein expression of heat shock protein 70 in the duodenum, jejunum, and ileum. Furthermore, the expression of tight junction protein zonula occluden-1 (ZO-1) in the duodenum and ileum, and Occludin in the ileum were enhanced (P < 0.05) compared with TN and PF. Moreover, HS significantly enhanced (P < 0.05) the mRNA relative expression of inflammatory cytokines (TLR-2, TLR-4, and tumor necrosis factor-α (TNF-α), IL-6, IL-8, PG1–5, β-defensin 2 (pBD-2)), mucins (mucin-1 and mucin-2) and P65 protein level in the ileal mucosa tissue. Intestinal microbiota analysis by 16S rRNA sequencing showed lower (P < 0.10) α diversity in both HS and PF, and a separated cluster of β diversity among groups. Compared with TN, HS but not PF mainly reduced (FDR < 0.05) Bacteroidetes (phylum), Bacteroidia (class) and elevated the proportions of Proteobacteria (phylum, FDR < 0.05), Bacillales (order, FDR < 0.05), Planococcaceae (family, FDR < 0.05), Kurthia (genus, FDR < 0.05), Streptococcaceae (family, FDR < 0.10) and Streptococcus (genus, FDR < 0.10). Notably, Lactobacillales (order) was decreased (FDR < 0.05) by PF alone. Furthermore, the Spearman correlation analysis indicated that the microbes prevalent in HS were positively (P < 0.05) associated with intestinal morphological injuries indicators and ileal immune response parameters, and the microbes reduced in HS were negatively (P < 0.05) with the performance data. Conclusions: Intestinal morphological injuries and ileal immune response caused by constant chronic HS independent of FI showed close connections with alterations in intestinal microbiota in growing-finishing pigs.

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 investigate the effects of diet supplementation with stevia residue extract (SRE) on growth performance, intestinal health, and antioxidant capacity of weaned piglets. A total of 144 weaned piglets (body weight 6.8 ± 0.5 kg) were randomly selected and allocated into four treatment groups with six replicates of six pigs/pen. The treatments consisted of a basal diet without SRE or basal diet supplemented with 100, 200, or 400 mg/kg SRE. The results showed that the addition of 200 mg/kg SRE to the diet significantly reduced (p < 0.05) the diarrhea rate of piglets compared with the control group. The supplementation of 400 mg/kg SRE in the diet significantly reduced the piglets’ serum MDA content and significantly increased (p < 0.05) the T-AOC, T-SOD, and GSH-PX activity in the serum. The dietary supplementation with 400 mg/kg SRE significantly increased (p < 0.05) the CAT and GSH-PX activity in the liver. Moreover, the supplementation of 400 mg/kg SRE in the diet significantly increased (p < 0.05) the relative abundance of Prevotellaceae (genus) and Roseburia (genus) beneficial bacteria compared to the control group. Spearman’s correlation analysis showed that Prevotella (genus) abundance was positively correlated with liver GSH-PX activity and acetic acid content of colon contents. In conclusion, the supplementation of 400 mg/kg SRE to the diet can improve piglet health by regulating antioxidant reduction homeostasis, which may also be associated with an increase in the relative numbers of potentially beneficial bacteria.

This study was carried out to investigate the effects of miscellaneous meal (rapeseed meal, cottonseed meal, and sunflower seed meal) as a replacement for soybean meal on growth performance, apparent nutrient digestibility, serum biochemical parameters, serum free amino acid contents, and gut microbiota of 50–75 kg growing pigs. A total of 54 healthy growing pigs (Duroc × Landrace × Yorkshire) with initial body weights (BWs) of 50.64 ± 2.09 kg were randomly divided into three treatment groups, which included the corn–soybean meal group (CON), corn–soybean–miscellaneous meal group (CSM), and corn–miscellaneous meal group (CM). Each treatment included six replicates with three pigs in each replicate. Dietary protein levels were maintained at 15% in all three treatment groups. Additional rapeseed meals, cottonseed meals, and sunflower seed meals were added to the CSM group’s meals to partially replace the 10.99% soybean meal in the CON group in a 1:1:1 ratio. Pigs in the CM group were fed a diet with a mixture of miscellaneous meals (7.69% rapeseed meal, 7.69% cottonseed meal, and 7.68% sunflower seed meal) to totally replace soybean meal. Our findings revealed that there was no significant impact of replacing soybean meal with miscellaneous meal on the ADG (average daily gain), ADFI (average daily feed intake), or F/G (feed-to-gain ratio) (p > 0.05) of growing pigs weighing 50–75 kg, nor on the crude protein, crude fat, or gross energy (p > 0.05) of the diet. On the other hand, compared to the CON group, the CM group exhibited significantly elevated serum alanine aminotransferase (ALT) and triglyceride (TG) levels (p < 0.05), while urea levels were significantly reduced (p < 0.05). No significant effect was observed on the serum free amino acid contents (p > 0.05) following the substitution of soybean meal with miscellaneous meal. A t-test analysis indicated that compared with the CON group, the CM group exhibited a significantly diminished abundance of Euryachaeota at the phylum level and augmented abundance of Desulfobacterota at the genus level. This study demonstrated that the miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower seed meal) as a substitute for soybean meal in the diet had no significant negative effects on the growth performance, apparent nutrient digestibility, serum amino acid content, or diversity of fecal microbiota in 50–75 kg growing pigs. These results can be helpful in developing further miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower seed meal) as functional alternative feed ingredients to soybean meal in pig diets.

The present study aims to determine the effect of miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower meal) replacing soybean meal in feed on growth performance, apparent digestibility of nutrients, serum biochemical parameters, serum free amino acid content, microbiota composition and SCFAs content in growing pigs (25–50 kg). A total of 72 (Duroc × Landrace × Yorkshire) growing pigs with initial weights of 25.79 ± 0.23 kg were randomly divided into three treatments. The pigs were fed corn–soybean meal (CON), corn–soybean–miscellaneous meals (CSM), and corn–miscellaneous meals (CMM). Each treatment included six replicates with four pigs per pen (n = 24, 12 barrows and 12 gilts). Soybean meal accounted for 22.10% of the basal diet in the CON group. In the CSM group, miscellaneous meals partially replaced soybean meal with a mixture of 4.50% rapeseed meal, 3.98% cottonseed meal, and 4.50% sunflower meal. In the CMM group, miscellaneous meals entirely replaced soybean meal with a mixture of 8.50% rapeseed meal, 8.62% cottonseed meal, and 8.5% sunflower. The results showed that compared with the CON, the CSM and CMM groups significantly improved the average daily gain (ADG) of growing pigs during the 25–50 kg stage (p < 0.05) but had no effects on average daily feed intake (ADFI) and average daily feed intake/average daily gain (F/G) (p > 0.05). Moreover, the CMM group significantly reduced nutrient apparent digestibility of gross energy compared with the CON group. The serum biochemical parameters results showed that the CSM group significantly improved the contents of total protein (TP) compared with the CON group (p < 0.05). The CMM group significantly improved the contents of total protein (TP), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) compared with the CON group in serum (p < 0.05). In comparison with the CON group, the CMM group also significantly improved lysine (Lys), threonine (Thr), valine (Val), isoleucine (Ile), leucine (Leu), phenylalanine (Phe), arginine (Arg), and citrulline (Cit) levels in serum (p < 0.05). However, the CMM group significantly decreased non-essential amino acid content glycine (Gly) in serum compared with CON (p < 0.05), while compared with the CON group, the CSM and CMM groups had no significant effects on the relative abundance, the alpha-diversity, or the beta-diversity of fecal microbiota. Moreover, compared with the CON group, the CSM group significantly increased butyric acid and valeric acid contents of short-chain fatty acids (SCFAs) in feces (p < 0.05). In contrast to the CON group, the CMM group significantly reduced the contents of SCFAs in feces, including acetic acid, propionic acid, and isobutyric acid (p < 0.05). Collectively, the results of the present study indicate that miscellaneous meals (rapeseed meal, cottonseed meal, and sunflower meal) can partially replace the soybean meal and significantly improve the growth performance of growing pigs during the 25–50 kg stage. Thus, miscellaneous meals are a suitable protein source as basal diets to replace soybean meals for 25–50 kg growing pigs. These results can be helpful to further develop miscellaneous meals as a functional alternative feed ingredient to soybean meal.

Our previous study has shown that replacing 100% inorganic trace minerals with 30% amino acid-chelated ones can enhance antioxidant capacity, improve nutrient digestibility, and reduce fecal excretion in growing-finishing pigs without compromising performance. This study aimed to further reduce the amino acid-chelated trace minerals content in pig diets and assess its impact. Seventy-two growing-finishing barrows (Duroc × Landrace × Yorkshire), with an initial average body weight of 67.04 ± 0.12 kg, were divided into four groups: negative control (NC, no additional trace minerals), high-dose inorganic trace minerals (HITM, 100% inorganic; 75 mg/kg Fe, 10 mg/kg Cu, 65 mg/kg Zn, 25 mg/kg Mn), and two low-dose groups (15 mg/kg Fe, 4 mg/kg Cu, 12.5 mg/kg Zn, 5 mg/kg Mn) receiving either inorganic sulfates (LITM) or amino acid-chelates (LOTM). The trial concluded when the body weight of pigs reached ~130 kg. Results showed that low-dose trace mineral substitution did not adversely affect growth performance, carcass traits, meat quality, or nutrient digestibility in growing-finishing pigs (p > 0.05). The LOTM pigs exhibited significantly higher serum glutathione peroxidase, liver total superoxide dismutase (T-SOD), and CuZn-SOD activities, muscle CuZn-SOD and catalase activities, and lower liver malondialdehyde content compared with LITM (p < 0.05). Muscle CuZn-SOD in LITM was lower than HITM (p < 0.05), but not in LOTM (p > 0.05). LOTM showed significantly higher muscle Fe content and lower muscle Mn content compared with HITM (p < 0.05), yet its muscle Mn level was higher than that of LITM (p < 0.05). Liver Zn content decreased in LITM compared with HITM (p < 0.05), but remained unchanged in LOTM (p > 0.05). Both LITM and LOTM significantly reduced fecal emissions of Fe, Cu, Zn, and Mn compared with HITM (p < 0.05), with greater reductions in Cu, Zn, and Mn in LOTM. In conclusion, low-dose substitution of inorganic or organic trace minerals did not negatively affect growth, carcass traits, meat quality, or nutrient digestibility in growing-finishing pigs, while it effectively reduced fecal heavy metal emissions. Organic trace minerals were more effective in enhancing antioxidant activity and trace mineral deposition.