**Background:** High-yielding sows often experience insufficient nutrient intake, excessive weight loss, prolonged weaning-to-estrus intervals (WEI), and metabolic disorders, which impair piglet growth. Fatty acids such as sodium butyrate (SB), medium-chain fatty acids (MCFAs), and omega-3 polyunsaturated fatty acids (n-3 PUFAs) have known benefits for metabolic regulation, intestinal barrier function, and immunity. However, the effects of combining these fatty acids with different chain lengths had not been systematically studied. This study aimed to compare the effects of different combinations of SB, MCFAs, and n-3 PUFAs on sow reproductive performance and the biochemical parameters, oxidative status, and intestinal health of suckling piglets.
**Methods:** Thirty third-parity sows (Landrace × Large White; 200 ± 15 kg) were randomly allocated to five treatments (6 per group) from day 85 of gestation through weaning (day 21 of lactation): (1) control basal diet (CON); (2) CON + 1 g/kg coated SB + 7.75 g/kg coated MCFAs (SM); (3) CON + 1 g/kg coated SB + 68.2 g/kg coated n-3 PUFAs (SP); (4) CON + 7.75 g/kg coated MCFAs + 68.2 g/kg coated n-3 PUFAs (MP); (5) CON + 1 g/kg coated SB + 7.75 g/kg coated MCFAs + 68.2 g/kg coated n-3 PUFAs (SMP). The n-3 PUFA source contained DHA, ALA, and EPA (20% purity). Reproductive performance, piglet growth, and diarrhea incidence were recorded. Colostrum composition (fat, protein, IgA, IgG, IgM) was analyzed. Plasma biochemical parameters (TP, ALB, HDL-C, GLU, TC, TG, BUN) and antioxidant markers (T-AOC, GSH-Px, MDA, T-SOD, CAT) were measured in piglets. Jejunal morphology (villus height, crypt depth), mRNA expression of tight junction proteins (CLDN-1, ZO-1, OCLN) and inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-10, TLR4, NF-κB, MyD88) were assessed. Colonic microbiota was profiled via 16S rRNA gene sequencing. Statistical analysis used ANOVA with Duncan's test (p < 0.05 significant).
**Key Results:** Sows fed SP, MP, and SMP diets had significantly shorter WEI than CON (p < 0.01). ADFI was higher in SM and SMP groups (p < 0.01). Piglets in the SMP group had the highest final body weight (6.48 kg vs. 5.36 kg in CON) and average daily gain (236 g vs. 186 g in CON) (p < 0.01). Diarrhea incidence was lower in SM, SP, and SMP groups vs. CON (p < 0.01). Colostrum fat and protein concentrations increased in all supplemented groups (p < 0.01). IgA and IgG in colostrum were higher in SM, SP, and SMP groups (p < 0.01). Plasma T-SOD and T-AOC activities increased in all supplemented groups (p < 0.01). CAT and GSH-Px activities increased in SM, SP, and MP groups (p < 0.01). Jejunal crypt depth decreased and VH/CD ratio increased in all supplemented groups (p < 0.01), with SMP showing the highest VH/CD ratio. mRNA expression of CLDN-1 and ZO-1 was upregulated in all supplemented groups (p < 0.01); OCLN was upregulated only in SMP (p < 0.01). TNF-α, IL-1β, and TLR4 mRNA were downregulated in all supplemented groups (p < 0.01). NF-κB was downregulated in SM, SP, and SMP (p < 0.01). Microbiota analysis showed increased relative abundances of Prevotella, Coprococcus, and Blautia in SM (p < 0.05); increased Faecalibacterium in SMP (p < 0.05); and increased Collinsella, Blautia, and Bulleidia in MP (p < 0.05). Bacteroidetes abundance increased in SMP (p < 0.05), while Firmicutes decreased in SM, MP, and SMP (p < 0.05).
**Clinical Implications:** Dietary supplementation with combinations of SB, MCFAs, and n-3 PUFAs during late gestation and lactation improved sow reproductive performance and piglet growth, immunity, antioxidant capacity, and intestinal health. The triple combination (SMP) showed the most consistent benefits, particularly for piglet weight gain, diarrhea reduction, intestinal barrier integrity, and anti-inflammatory effects, likely mediated through gut microbiota modulation (e.g., increased Faecalibacterium and Bacteroidetes). These findings support the use of combined fatty acid supplements as a strategy to enhance productivity in swine operations. Further research is needed to optimize dosages and elucidate synergistic mechanisms.