This study aimed to explore the effects of dietary fiber level and breed on the growth performance, nutrient utilization, intestinal morphology, slaughter performance, and meat quality of finishing pigs using fermented corn straw (FCS) as the fiber source. The experiment employed a 2 × 4 factorial design, selecting 96 Songliao Black (SLB) and Duroc × Landrace × Yorkshire (DLY) crossbred finishing pigs (a total of 192 pigs, with an initial body weight of 60.52 ± 4.59 kg) randomly assigned by breed to four dietary treatment groups (A: 2.92% crude fiber; B: 4.82% crude fiber; C: 6.86% crude fiber; D: 9.01% crude fiber). The results showed that DLY finishing pigs had higher final weight (FW), average daily gain (ADG), and average daily feed intake (ADFI) in both finishing stages 1 and 2 compared to SLB pigs (p < 0.05), while the ratio of feed to weight gain (F/G) showed no significant differences (p > 0.05). Compared to the basal diet, increasing the dietary fiber level to 4.82% improved FW and ADG in both SLB and DLY finishing pigs (p < 0.05) and reduced F/G (p < 0.05). Additionally, SLB finishing pigs had lower ether extract (EE) digestibility but higher crude fiber (CF) and acid detergent fiber (ADF) digestibility than DLY (p < 0.05). Dietary fiber level and breed exhibited an interaction effect on dry matter (DM) and crude protein (CP) digestibility in finishing pigs (p < 0.05). At a dietary fiber level of 4.82%, villus height, crypt depth in the jejunum, and cecal volatile fatty acid (VFA) concentrations were increased in both SLB and DLY finishing pigs (p < 0.05). Dietary fiber level and breed showed an interaction effect on cecal VFA production in finishing pigs (finishing stage 1; p < 0.05). The dietary fiber level of 4.82% increased loin eye area (LA) (p < 0.05) and decreased backfat thickness (BT) (p < 0.05) in both SLB and DLY finishing pigs. Dietary fiber level and breed had an interaction effect on LA in finishing pigs (p < 0.05). SLB pigs had higher muscle redness (a*), shear force, and contents of crude protein (CP), EE, saturated fatty acid (SFA), and polyunsaturated fatty acids (PUFA) than DLY (p < 0.05). Increasing the dietary fiber level improved pH_24h and reduced drip loss and shear force in both SLB and DLY finishing pigs (p < 0.05). Dietary fiber level and breed showed an interaction effect on pig meat color and drip loss (p < 0.05). In conclusion, FCS is a beneficial source of dietary fiber for SLB and DLY pigs. Its proper addition can enhance the growth performance, carcass traits, and meat quality in fattening pigs.

This study aimed to investigate the effects of dietary fiber (DF) levels and copper concentrations on the production performance and cecal microbial diversity of finishing pigs. A 2 × 2 factorial experimental design was used, with different levels of dietary fiber (low [23% DF]: L and high [30% DF]: H) and copper concentrations (normal [25 mg/kg]: N and supplemented [45 mg/kg]: S) resulting in four diets (LN, LS, HN, and HS). Forty-eight hybrid barrows (Duroc × Landrace × Yorkshire), with an initial body weight of 76 kg ± 1.5 kg, were randomly assigned to four groups: LN, LS, HN, and HS, with 12 replicates per group and one pig per replicate. There was a 7-day adaptation period followed by a 56-day feeding trial, after which all pigs were slaughtered for sampling. Results indicated that in finishing pigs, the low dietary fiber group exhibited a higher final weight, a higher average daily gain, and a lower feed-to-gain ratio compared to the high fiber group (p < 0.05). The LS group showed higher digestibility of dry matter, crude protein, crude fiber, ash, neutral detergent fiber, and DF than the HN and HS groups (p < 0.05). Blood total protein levels were higher in the high fiber group, whereas blood Cu levels were higher in the supplemented copper group (p < 0.05). High dietary fiber increased the activities of colonic carboxymethylcellulase and β-glucanase (p < 0.05). Concentrations of acetic acid, propionic acid, and total volatile fatty acids were elevated in the high fiber group (p < 0.05). Microbial α-diversity indices (observed species, Chao 1, and Shannon indices) increased with fiber but decreased with copper supplementation (p < 0.05). The Firmicutes/Bacteroidetes ratio increased with fiber levels, with a higher relative abundance of Lactobacillus in the LS group. In conclusion, appropriate copper supplementation in diets can mitigate the negative effects of high fiber levels on finishing pig production performance by enhancing nutrient digestibility, fiber-degrading enzyme activity, regulating the microbial community, and its metabolic products.

To investigate the regulatory effects of dietary fiber structure (β-glucan-to-arabinoxylan ratio, β/AX) and apparent viscosity (AV) on production performance in pigs, this study used a 2 × 3 factorial design, randomly assigning 36 growing pigs (47.2 ± 1.5 kg) to six dietary treatments (two AV levels and three β/AX ratios), and observed the growth performance, carcass traits, meat quality, intestinal microbiota, and liver lipid metabolism. The results showed that increased dietary β/AX and AV reduced subcutaneous fat deposition, improved meat tenderness and the nutrient content of meat, but decreased pig weight gain and dressing percentage. Increased dietary β/AX and AV selectively promoted the relative abundance of butyrate-producing bacteria and the concentration of butyrate in the middle colon, thereby regulating the expression of genes related to hepatic de novo lipid synthesis and oxidation, reducing serum glucose and total cholesterol levels, and increasing plasma glucagon-like peptide-1. These findings reveal the potential mechanism by which the physicochemical properties of dietary fiber mediate lipid metabolism to reduce weight gain and provide new insights for regulating fat deposition in pigs by controlling the structural and physical properties of dietary fiber.

Background: Placental angiogenesis is crucial for ensuring placental function and normal fetal development. It has been demonstrated that elevated plasma levels of homoarginine (hArg), an endogenous amino acid, during pregnancy correlate with enhanced vascular endothelial function. However, the effect of hArg in placental angiogenesis during pregnancy is still ambiguous. This study seeks to evaluate the impact of supplemental hArg during the rapid placental growth phase in early pregnancy, a key moment for placental angiogenesis, on ultimate pregnancy outcomes and placental angiogenesis in rats, as well as its potential processes. Methods: This study utilized thirty 8-week-old female Sprague Dawley rats as pregnant animals, which were randomly allocated to control and treatment groups (15 per group) and administered 20 mg/kg of hArg from embryonic day 0.5 (E0.5) to E13. The dams were euthanized on E21. Results: Maternal hArg dietary supplementation positively influenced pregnancy outcomes, resulting in a significant increase in the number of live-born offspring and total placental weight, alongside elevated maternal circulating reproductive hormone levels. Additionally, the upregulation of the amino acid transporter in the placenta of the treatment group established a basis for hArg accumulation in the placenta, hence promoting hArg-specific augmentation of eNOS-mediated NO production. The treated group simultaneously demonstrated an expanded labyrinthine zone, increased blood sinusoids area, enhanced vascular density, and raised levels of proangiogenic factors. Mechanistically, hArg enhanced the expression of proteins linked with the PI3K/AKT signaling pathway. Conclusions: Supplementation with hArg during the placenta’s rapid growth phase enhances placental angiogenesis, ultimately enhancing pregnancy outcomes. This effect may be attributed to the regulation of the PI3K/AKT signaling pathway.