Search Results (77)

Intestinal diseases in nursery pigs harm health and performance and drive antimicrobial resistance. This study evaluated whether early probiotic inoculation helps piglets to cope with weaning-related gut challenges. The probiotic, containing Lacticaseibacillus rhamnosus, Enterococcus lactis, Bifidobacterium longum subsp. infantis, and Bifidobacterium breve, was given orally to newborn piglets daily until day 4 and then every other day until weaning at day 28 (at 4 × 10⁹ CFU/dose). The control piglets received a placebo. The results showed that the probiotic pigs had reduced fecal alpha-diversity on day 7 but greater Shannon diversity on day 28 (feces) and day 23 (intestinal contents) compared to those of the control pigs. Beta-diversity analysis showed microbial differences between the groups on day 35. Most zOTUs (zero-radius operational taxonomic units) found to significantly differentiate the two treatment groups were found pre weaning. Bifidobacterium breve, Ligilactobacillus salivarius, as well as Clostridium ramosum were significantly more abundant in the feces of the probiotic pigs more than once. The probiotic pigs had higher expression levels of mucin 2 (MUC2); solute carrier family 5, member 8 (SLC5A8); and interleukin 8 (IL-8) post weaning. In the early post-weaning period, the probiotic pigs had less diarrhea as well as lower cadaverine levels in digesta than the control pigs. In conclusion, early probiotic inoculation may induce lasting immunomodulation via microbial antigen changes, enhancing resilience during challenges, like weaning. Notably, the effects persisted beyond weaning and probiotic cessation. Full article

Galacto-oligosaccharides (GOS) are recognized prebiotics with extensive applications in animal nutrition. This study aimed to elucidate the effects of chlortetracycline (CTC) supplementation alongside GOS on growth performance, intestinal morphology, and microbiota composition in weaned piglets. A total of 72 weaned piglets [(Duroc × (Landrace × Yorkshire)] with an initial body weight of 7.64 ± 0.15 kg were randomly assigned to three dietary treatments: a corn–soybean meal-based diet (CON), a corn–soybean meal-based diet supplemented with chlortetracycline (CTC) at 75 mg/kg, and a diet with 1500 mg/kg GOS. The experiment spanned 14 days, divided into early (1–7 days) and late (7–14 days) stages. The results indicated that the GOS group exhibited a significant increase in body weight (BW) by day 14 and improved average daily gain (ADG) from day 1 to 14, alongside a decreased feed-to-gain ratio and diarrhea incidence (p < 0.05). Notably, GOS supplementation enhanced the villus height of the jejunum and increased the ratio of villus height to crypt depth compared to the CON group, although no significant differences were observed between GOS and AntB groups. Additionally, the number of goblet cells in the colonic crypts increased significantly with GOS supplementation. High-throughput 16S rRNA gene sequencing revealed an increased relative abundance of Firmicutes in the GOS group, coupled with a decrease in Bacteroidetes and Spirochaetota. Beneficial bacteria such as Lactobacillus and Faecalibacterium were significantly enriched, while potentially pathogenic bacteria, including Clostridium_sensu_stricto_1 and Treponema, were reduced. In summary, dietary GOS supplementation can enhance beneficial microbiota while diminishing harmful species, thereby improving intestinal morphology and growth performance in weaned piglets. Consequently, GOS emerges as a promising alternative to in-feed antibiotics in contemporary animal husbandry. Full article

The weaning period is a critical phase for nursery pigs that is characterized by rapid growth and alterations in the intestinal microbiome associated with nutrient utilization. The present study aimed to investigate the efficacy of halquinol, when used as an antibiotic (ABO), on the growth performance, diarrhea incidence, coefficient of apparent total tract digestibility (CATTD), fecal volatile fatty acids (VFAs), and microbiota in pigs. A total of 210 healthy weaned pigs with an average initial weight of 6.9 kg and aged 28 ± 2 days were assigned to five treatments (six pens/treatment) in a complete randomized design, including a control group (T1, CON; feed with no ABO), a colistin group (T2, CLT; feed containing 120 ppm colistin), and three halquinol groups (T3 to T5, HAL; feed containing 180, 240, and 360 ppm halquinol, respectively). The experiment period lasted for 10 days. Field recordings, observation, and feces collection were performed on D1, D5, and D10. CATTD and VFA assessments were conducted on D10. The composition of the fecal microbiota was analyzed via 16S rRNA gene sequencing using the Illumina Miseq platform. The results demonstrated that the in-feed ABO groups exhibited a significantly lower ADFI (p < 0.01). Pigs fed the T3 and T4 diets had the lowest FCR (p < 0.01) on D5 and D10 and, thus, had reduced ADFI (p < 0.01). A quadratic contrast was found in ADFI and FCR on D5 and D10, indicating a negative correlation with HAL concentration (p < 0.01). Pigs fed CLT and HAL had significantly reduced levels of coliform (p < 0.01) and E. coli (p < 0.01). Moreover, pigs receiving ABO also had a lower fecal score compared to those on the CON diet (p < 0.01). Dietary in-feed ABO had no effect on all the parameters of the CATTD on D10 (p > 0.05), except for fat digestibility in pigs that received T4 (p < 0.01). Pigs fed the T4 and T5 diets had higher propionate concentrations and lower A/P ratios than pigs fed T1, T2, and T3 (p < 0.01). The microbial diversity shifted quickly through the early weaning period. The relative abundance of beneficial Enterococcus microbes increased in pigs fed in-feed ABO, whereas the relative prevalence of pathogenic bacteria, such as Escherichia and Klebsiella, decreased. Escherichia and Bacteroides were negatively correlated with carbohydrate digestibility and butyric and valeric acid production (p < 0.05). Overall, the appropriate HAL dosage was 240 ppm (T4), and this antimicrobial can potentially be characterized as an in-feed colistin replacer that improves feed efficiency and fat digestion, enhancing VFA production, alleviating post-weaning diarrhea, and protecting ABO-resistant piglets. Full article

The experiment was conducted to determine the interaction effects of parity and DFM supplementation from early gestation (G 21) to lactation (L 21) on reproductive performance, apparent total tract digestibility (ATTD), colostrum IgA and IgG, and mature milk composition. Three hundred pregnant sows were blocked by parity (2, 3, 4, 5, and 6–9) and randomly assigned to two experimental diets in a randomized complete block design, with a control (CON, n = 150) group and direct-fed microbial (DFM, n = 150) group. The DFM contained 5 × 10⁷ cfu/g of Bacillus subtilis and 2 × 10⁶ cfu/g of Lactobacillus spp. Reproductive traits recorded included total born (TB), born alive (BA), litter weight (LW), piglets born dead (PBD) weaning weight (WW), number of weaning pig (NWP), and PWM. Two separate 14 d ATTD trials were conducted on G86 to G100 and L7 to L21. Colostrum samples were collected at 0, 3, 6, 12, and 24 h post-partum and mature milks were collected at L7 and L14 for Ig and composition analysis, respectively. Total Ig concentrations were measured by an ELISA. The interaction between diet and parity was found on LW, colostrum IgG, milk lactose, and protein (p < 0.05). Regardless of parity, sows fed DFM had greater reproductive performance with higher BA, LS, LW, and lower in PWM (p < 0.05). DFM also improved the ATTD of organic matter (OM), crude protein (CP), and ether extracts (EE) (p < 0.05) at G100 and gross energy (GE), CP, and EE (p < 0.05) at L21. Entire IgG and 3 h post-partum IgA in colostrum were higher in DFM than in the CON diet (p < 0.05). Parity effects were seen on NWP, LW, CP, and EE, colostrum Ig at 12 and 24 post-partum, milk protein, and lactose at L7 (p < 0.05). Moreover, the parity showed linear effect on TB, BA, LW, litter size (LS), WW, total PWM, the ATTD of OM and EE, colostrum IgG at 12 h and IgA at 12 and 24 h post-partum, milk fat at L7 and L21, and milk lactose at L14 (p < 0.05). Stepwise prediction for average colostrum IgG (mg/mL) by using nutrient digestibility = −112.97 + 0.706GE(%) + 0.518CP(%) + 0.267EE(%) (n = 267, R² = 0.38, RSD = 6.7, p < 0.001). In summary, supplementing dietary DFM during early gestation through weaning had positive effects on production, the lifetime of sows, and better nutrient utilization, resulting in better milk quality and better piglet growth. Full article

Early weaning in intensive pig production induces stress, compromising gastrointestinal health. Poor fat digestion results from the piglets’ underdeveloped digestive system. Dietary emulsifiers can enhance fat utilization, and glyceryl polyethylene glycol ricinoleate (GPGR) has been shown to improve pig performance. This study evaluated GPGR’s effects on intestinal health in weaned piglets in a commercial production farm. A total of 380 just weaned (21 days old) piglets were divided in two groups of 190 animals each (in four replicates) that received either a basal diet (control) or a basal diet + 350 g/ton GPGR pharmaceutical formulation as top dress. Blood samples were collected at pre-established days, and intestinal sampling occurred 15 days post-weaning. Plasma cortisol, citrulline, intestinal morphology, mucus quality, enzymatic activity, volatile fatty acids (VFAs), and cecal microbiota were analyzed. GPGR did not alter plasma cortisol but increased citrullinemia (P: 0.024), suggesting greater enterocyte functional mass. GPGR piglets showed improved intestinal morphology (greater villus height, villus height:crypt depth ratio, and intestinal absorption area, p < 0.05) and higher enzymatic maltase activity (p ≤ 0.014). VFAs, bacterial adherence to mucus, and goblet cell counts were unaffected. Dietary GPGR increased Firmicutes and Actinobacteria (P: 0.014 and P: 0.045, respectively) while reducing Proteobacteria (p < 0.001). In conclusion, dietary GPGR promotes intestinal health in weaned piglets by improving epithelial structure, digestive function, and microbiota balance, representing a promising strategy to support piglets in overcoming the early nursery phase. Full article

Fifty-eight litters (16 from primiparous gilts and 42 from multiparous sows) were used, with a total number of 750 piglets involved in the study. Birth weight was stratified into three groups: low (<1.02 kg; LBW), normal (1.02–1.62 kg; NBW), and high (>1.62 kg; HBW). A creep feeding diet was offered to piglets in a creep feeder in 29 litters from day 7 until their weaning. Piglet mortality was recorded daily. Traceability was ensured up to the point of carcass splitting and subsequent meat analysis. Each carcass was eviscerated and weighed individually. Sixty-nine piglets were selected for the microbiome analysis (35 from the control group and 34 from the creep feeding group). Feces samples from the rectum were obtained at three time points (three days prior weaning, a week after weaning, and before the slaughtering of the pigs). Mortality during lactation was influenced by birth weight, with LBW piglets exhibiting a six-fold higher mortality rate than HBW. Creep feeding did not impact piglet mortality. Heavier piglets demonstrated greater weight gain when subjected to creep feeding, while the growth potential of lighter piglets was reduced. Variation in creep feeding consumption based on birth weight also affected microbiome composition, with high-birth-weight piglets displaying higher alpha diversity than low- and normal-birth-weight piglets seven days after lactation. Alpha diversity is indicative of gut health, with higher values suggesting greater stability and adaptability to different feed sources. In conclusion, the immediate impacts of creep feeding appear to be most prominent during lactation and potentially early postweaning. These short-term effects are modulated by birth weight, with HBW piglets demonstrating the greatest benefits from the implementation of creep-feeding practices. Full article

The emergence of Japanese encephalitis virus (JEV) in eastern Australia in 2022 caused extensive reproductive disease in pigs and is a threat to public health. Groups of weaned piglets were experimentally infected with the Australian outbreak strain of JEV (genotype 4). All pigs challenged at 5 weeks of age were infected after an intradermal injection of 1 × 10^5.5 (n = 4) or 1 × 10^4.5 TCID₅₀/pig (n = 5). Intranasal instillation was less effective at this age, infecting 3/4 pigs with the same higher dose and 1/5 with the lower dose. Intradermal injection using 1 × 10^5.0 TCID₅₀/pig also infected 9/9 pigs at 11 weeks of age. Infection in all cases was confirmed by qRT-PCR of blood samples, which identified a viremia peak at 3–4 days and detected JEV-specific antibodies as early as 5 days after the challenge. The detection of JEV in oral and nasal swabs and in saliva from chew ropes was less consistent. JEV was detected in the tonsils of 21/22 infected pigs and was isolated from the tonsils of 9/9 pigs sampled 19 days after the challenge at 11 weeks of age. The infected pigs showed no clinical signs other than pyrexia on Days 4–6. Histopathology consistent with JEV infection was evident in the nervous tissues of all but two pigs sampled 28 days after the challenge and was characterized by meningitis, encephalitis and gliosis throughout the brain. Serological studies showed extensive cross-reactivity between JEV and Murray Valley encephalitis virus using blocking ELISAs. However, the determination of limiting-dilution titres allowed for the identification of the infecting virus. This in vivo infection model will be useful in evaluating JEV vaccines and for comparative pathogenesis studies with other JEV genotypes. Full article

There are different stress resistance among different breeds of pigs. Changes in intestinal stem cells (ISCs) are still unclear among various breeds of piglets after early weaning. In the current study, Taoyuan Black and Duroc piglets were slaughtered at 21 days of age (early weaning day) and 24 days of age (3 days after early weaning) for 10 piglets in each group. The results showed that the rate of ISC-driven epithelial renewal in local Taoyuan Black pigs hardly changed after weaning for 3 days. However, weaning stress significantly reduced the weight of the duodenum and jejunum in Duroc piglets. Meanwhile, the jejunal villus height, tight junction-related proteins (ZO-1, Occludin, and Claudin1), as well as the trans-epithelial electrical resistance (TEER) values, were down-regulated after weaning for 3 days in Duroc piglets. Moreover, compared with Unweaned Duroc piglets, the numbers of Olfm4⁺ ISC cells, PCNA⁺ mitotic cells, SOX9⁺ secretory progenitor cells, and Villin⁺ absorptive cells in the jejunum were reduced significantly 3 days after weaning. And ex vivo jejunal crypt-derived organoids exhibited growth disadvantages in weaned Duroc piglets. Notably, the Keap1/Nrf2 signaling activities and the expression of HO-1 were significantly depressed in weaned Duroc piglets compared to Unweaned Duroc piglets. Thus, we can conclude that ISCs of Duroc piglets were more sensitive to weaning stress injury than Taoyuan Black piglets, and Keap1/Nrf2 signaling is involved in this process. Full article

Oedema disease (OD) in weaned piglets is caused by shigatoxigenic Escherichia coli (STEC), which produces the Stx2e toxin. The disease is controlled by early vaccination (for example, with Ecoporc Shiga^®). Iron-deficiency anaemia (IDA) and cystoisosporosis are the most common clinical conditions in piglets. These conditions are managed mainly by the intramuscular injection of iron and application of toltrazuril (for example, Forceris^®). In the present study, we sought to evaluate any effect on the efficacy of OD vaccination and iron/anticoccidial treatment resulting from a simultaneous application. An evaluation was carried out by measuring the development of neutralising antibodies against the Stx2e toxin, hematinic indices and oocysts shedding. Six litters from Stx2e-antibody-negative sows were included in the study, with 12 piglets in each litter. The piglets were randomly allocated into two groups on their second day of life (DOL): (T1) iron/anticoccidial treatment and vaccine were administered on different days, and (T2) products were administered simultaneously. Blood samples were collected to determine the levels of serum-neutralising antibodies, haemoglobin and haematocrit. Faecal matter was examined for the presence of oocysts of Cystoisospora suis. No differences were found between the two groups in terms of the development of neutralising antibodies. The levels of haemoglobin and haematocrit were lower (p < 0.05 and p = 0.08, respectively) when iron/anticoccidial treatment and vaccine were applied simultaneously but within the optimal range, based on current interpretive criteria for IDA. Oocysts were not detected in the faecal samples from the animals in either group. In conclusion, we found that, under the conditions of our study, the efficacy of OD vaccination and iron/anticoccidial treatment was not affected by the simultaneous use. Full article

The non-specific protective effects offered by the concept of “innate immune memory” might represent a promising strategy to tackle early-life threatening infections. Here we tested the potential of an in vitro selected β-glucan in inducing trained immunity using an in vivo porcine model. We assessed the leukocyte transcriptome using blood transcriptomic module (BTM), proinflammatory cytokines, and clinical scoring after a first “training” and a second “stimulation” phase. The possible induction of innate immune memory was tested during a “stimulation” by an LPS-adjuvanted Mycoplasma hyopneumoniae vaccine (Hyogen^®) one day after weaning. Following the “training”, no major group differences were found, with the exception of a plasma TNF that was only induced by Adj and Adj_BG treatment. After vaccination, all groups developed similar antibody responses. A significant induction of plasma TNF and IL-1β was found in groups that received Adj and Adj_BG. However, following vaccination, the expected early innate BTMs were only induced by the PBS group. In conclusion, the adjuvant alone, adjuvant-formulated β-glucan, or orally applied β-glucan were unable to enhance innate immune reactivity but rather appeared to promote innate immune tolerance. Such an immune status could have both positive and negative implications during this phase of the piglet’s life. Full article

Using 0.5% and 1.0% MGM-P, the objective of the present study was to determine a more appropriate additive level for early-weaned piglets as an alternative to the use of antibiotics. Thirty-six weaned piglets were allotted to one of four groups and given a basal diet (NC), with the basal diet containing either 0.5% (LT) or 1.0% (HT) MGM-P or antibiotics (PC). Diarrhea incidence, growth performance, hematology, blood biochemistry, and blood amino acid concentrations were monitored during the experimental period. Three piglets per group with a body weight nearest to the average level were slaughtered after the experiment to assess their organ index. The results showed that no diarrhea was observed either in the treatment groups or in the control group. The 0.5% group showed an upward trend in body weight and average daily gain at all stages. The WBC counts at 21 days of age were higher (p > 0.05) both in the MGM-P addition groups and the LT and HT groups. For some of the plasma amino acids, such as arginine, phenylalanine concentrations were significantly lower (p < 0.05) in the HT group at the end of the trial. The pathological examination of all organs confirmed no differences. Consequently, the 0.5% MGM-P addition level may be suggested as a potential alternative to the use of antibiotic additives. Even with additives as high as 1%, there is no negative effect on ADG and FCR. Full article

Our previous study demonstrated that moderate inhibition of intestinal autophagy was beneficial to alleviate early weaning stress in piglets, but the detailed mechanism behind this was unclear. Microbiota-mediated enterocyte autophagy helps maintain intestinal homeostasis. This study investigated the effects of inhibition or activation of autophagy in intestinal microbial community compositions and metabolite profiles in piglets. Eighteen 24-day-old weaned piglets were divided into three groups (each treatment of six piglets) and treated daily with rapamycin (RAPA), chloroquine (CQ) or a control volume of normal saline (CON group). Before the formal trial, the piglets were allowed to acclimatize for 3 days, and then the trial period was 14 days. Collected samples from the ileum and colon underwent 16S rRNA gene sequencing and metabolite analysis. Significant differences in microbial composition were observed in both the ileum and colon of the RAPA and CQ groups compared to the CON group (p < 0.05). In addition, the relative levels of abundance of Peptostreptococcus, Fusobacterium, Dialister, Selenomonas and Oceanobacillus in the ileum and Porphyromonas, Bacteroides, unidentified_Lachnospiraceae, Akkermansia, Sharpea, Peptococcus, Pseudoalteromonas, Peptoclostridium and unidentified_Acidobacteria in the colon were improved in piglets fed the RAPA diet, whereas the relative levels of abundance of Turicibacter, Rickettsiella and Sarcina in the ileum and Roseburia and Kroppenstedtia in the colon were enhanced in the CQ group (p < 0.05). Meanwhile, metabolomic analysis showed that there were significant differences in metabolites among all groups (p < 0.05), and KEGG enrichment analysis revealed that differential metabolites were mainly enriched in the ABC transporters and biosynthesis of amino acids pathways. Furthermore, these metabolites were closely related to differential microorganisms (p < 0.05). Overall, autophagy inhibition regulates the composition of intestinal microorganisms and their metabolites, and these differential metabolites are significantly correlated with differential intestinal microorganisms, which may in turn affect the production performance of weaned piglets. Full article

(1) Background: Weaning is a challenging and stressful event in the pig’s life, which disrupts physiological balance and induces oxidative stress. Microbiota play a significant role during the weaning process in piglets. Therefore, this study aimed to investigate key gut microbiota and metabolites associated with weaning stress in piglets. (2) Methods: A total of ten newborn piglet littermates were randomly assigned to two groups: S (suckling normally) and W (weaned at 21 d; all euthanized at 23 d). Specimens of the cecum were dehydrated with ethanol, cleared with xylene, embedded in paraffin, and cut into 4 mm thick serial sections. After deparaffinization, the sections were stained with hematoxylin and eosin (H&E) for morphometric analysis. Cecal metagenomic and liver LC-MS-based metabolomics were employed in this study. Statistical comparisons were performed by a two-tailed Student’s t-test, and p < 0.05 indicated statistical significance. (3) Results: The results showed that weaning led to intestinal morphological damage in piglets. The intestinal villi of suckling piglets were intact, closely arranged in an orderly manner, and finger-shaped, with clear contours of columnar epithelial cells. In contrast, the intestines of weaned piglets showed villous atrophy and shedding, as well as mucosal bleeding. Metagenomics and metabolomics analyses showed significant differences in composition and function between suckling and weaned piglets. The W piglets showed a decrease and increase in the relative abundance of Bacteroidetes and Proteobacteria (p < 0.05), respectively. The core cecal flora in W piglets were Campylobacter and Clostridium, while those in S piglets were Prevotella and Lactobacillus. At the phylum level, the relative abundance of Bacteroidetes significantly decreased (p < 0.05) in weaned piglets, while Proteobacteria significantly increased (p < 0.05). Significant inter-group differences were observed in pathways and glycoside hydrolases in databases, such as the KEGG and CAZymes, including fructose and mannose metabolism, salmonella infection, antifolate resistance, GH135, GH16, GH32, and GH84. We identified 757 differential metabolites between the groups through metabolomic analyses—350 upregulated and 407 downregulated (screened in positive ion mode). In negative ion mode, 541 differential metabolites were identified, with 270 upregulated and 271 downregulated. Major differential metabolites included glycerophospholipids, histidine, nitrogen metabolism, glycine, serine, threonine, β-alanine, and primary bile acid biosynthesis. The significant differences in glycine, serine, and threonine metabolites may be potentially related to dysbiosis caused by weaning stress. Taken together, the identification of microbiome and metabolome signatures of suckling and weaned piglets has paved the way for developing health-promoting nutritional strategies, focusing on enhancing bacterial metabolite production in early life stages. Full article

Weaning is a challenging period for piglets, characterized by stress-related growth checks, compromised immunity, and gut dysbiosis. Purslane (Portulaca oleracea L.), known for its rich content of antioxidants, has potential as a functional feed ingredient. This study investigates the effects of feeding fermented purslane (FP) on the growth performance, immune function, intestinal microbiota, and metabolic profiles of weaned piglets. Forty-eight weaned piglets were randomly divided into two groups, with eight pens in each group and three pigs in each pen: a control diet (CON group) and a diet supplemented with 0.20% FP (FP group). The experiment lasted 28 days. The results show that FP supplementation did not affect the average daily feed intake (ADFI) but significantly increased the average daily gain (ADG) during the initial 14 days post-weaning. FP supplementation decreased diarrhea occurrence, with a pronounced reduction from days 10 to 13 (p < 0.05). Immunologically, the FP group had a trend towards reduced serum IgA levels on day 14 (p < 0.10). Importantly, the serum concentrations of the pro-inflammatory cytokine IL-6 were significantly reduced on both days 14 and 28 post-weaning. The antioxidative analysis showed increased serum superoxide dismutase (SOD) and decreased catalase (CAT) activities on day 14 (p < 0.05). In addition, FP supplementation significantly decreased serum diamine oxidase (DAO) activity and D-lactate levels by day 28, indicating a potential improvement in gut integrity. Fecal microbiota assessment demonstrated a distinctive clustering of microbial communities between the FP and CON groups, with an increase in the abundance of Clostridium_sensu_stricto_1, Tyzzerella, and Prevotellaceae_NK3B31_group and a decrease in Lactobacillus, Bacillus, and Subdoligranulum in the FP group (p < 0.05). Functional predictions suggested that the relative abundance of microbial butyrate synthesis enzymes (EC 2.7.2.7 and EC 2.3.1.19) was significantly enhanced by FP treatment. This modulation was further corroborated by elevated fecal butyrate levels (p < 0.05). In summary, dietary supplementation with FP promotes early-growth performance and has beneficial effects on immune function and intestinal health in weaned piglets. The enhancements may be attributed to distinct microbiota compositional changes and targeted modulation of microbial butyrate metabolism, which are crucial for piglet post-weaning adaptation and overall health. Full article

Early socialization during lactation is advocated as a feeding strategy to reduce the weaning stress of piglets. However, early socialization has often been accompanied by more frequent aggression between individuals, and its effect on the immune system of piglets has yet to be evaluated. In this study, 89 piglets were raised separately under conventional feeding and early socialization environments. Based on differences in the aggressive behavior of the piglets in different environments during lactation, we further investigated the effects of early socialization on oxidative stress in the spleen of the piglets and the inflammatory responses involved in the canonical nuclear factor kappa-B (NF-κB) signaling pathway. The results revealed that early socialization led to a higher aggression level between individuals (p < 0.01), increased malondialdehyde (MDA) and H₂O₂ levels and inducible nitric oxide synthase (iNOS) activity, and inhibited glutathione (GSH) levels and the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX) in the piglet spleens (p < 0.05). The mRNA expression levels of the protein kinase A (PKA), inhibitor of kappa B kinase-α (IKK-α), inhibitor of kappa B kinase-β (IKK-β), inhibitor of NF-κB-α (IκB-α), NF-κB(p65), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX2), iNOS, and heat shock protein (HSP) genes were significantly up-regulated, as well as the protein levels of P-p65, IKK-β, P-IkB-α, pro-IL-1β, and TNF-α. In summary, early socialization caused oxidative stress and inflammatory responses in the spleen of the piglets by inducing ROS production and the activation of the canonical NF-κB pathway. Our study revealed that early socialization significantly increased the ROS level in the piglet spleens and activated the canonical NF-κB signaling pathway, which induced a high expression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and COX2) and HSP genes regulated by NF-κB signaling, leading to oxidative stress and the inflammatory response. Full article