Maternal Euglena gracilis supplementation alters sow and piglet gut microbiota, reduces diarrhea incidence, and enhances piglet growth.

Background: Gut microbiota plays a crucial role in swine health and performance, with diet as a key modulator. Euglena gracilis supplementation has shown immunomodulatory effects that benefit sows and piglets. However, its prebiotic effect on gut microbiota remains unclear. This study investigated the impact of maternal E. gracilis supplementation on gut microbiota, piglet body weight, and the incidence of diarrhea.

Methods: Sixty-one crossbred sows (Landrace × Yorkshire) were assigned to either a standard diet (Control; n = 30) or a standard diet supplemented with 1 g/sow/day of E. gracilis (E. gracilis; n = 31) from day 85 of gestation until day 21 of lactation. On day 109 of gestation, 30 sows (15/group) were randomly selected for performance assessment and fecal sample collection. After farrowing, one corresponding piglet per selected sow (15/group) was randomly chosen for fecal sampling. In total, 180 fecal samples were collected, 90 from sows and 90 from piglets. Sow samples (15/group/timepoint) were collected on day 109 of gestation and days 3 and 21 of lactation, while piglet samples (15/group/timepoint) were collected on days 3, 10, and 21 of age. Gut microbial composition was determined by 16S ribosomal RNA gene sequencing. Piglet body weight was measured from birth until weaning, while the incidence of diarrhea was monitored from days 1 to 21 of age.

Results: On average, the number of piglets alive at birth and weaning was 13.9 ± 2.4 and 10.9 ± 2.2 piglets/litter, respectively. Piglets nursed by E. gracilis-supplemented sows had greater body weight at weaning (+ 0.28 kg; P = 0.100) and a lower incidence of diarrhea on days 10 (P ≤ 0.05), 11 (P ≤ 0.10), and 12 (P ≤ 0.05) of age. For alpha diversity, E. gracilis-supplemented sows exhibited a lower Chao1 index on day 21 of lactation (P ≤ 0.05), while a higher Inverse Simpson index on day 3 (P ≤ 0.05) and both Inverse Simpson and Shannon indices on day 21 (P ≤ 0.05) of lactation. In piglets, the Inverse Simpson index was lower on day 10 of age in those nursed by E. gracilis-supplemented sows (P ≤ 0.10). Gut microbial composition revealed that E. gracilis-supplemented sows exhibited a higher relative abundance of Bacteroidetes (g_Prevotella and o_Bacteroidales) and Spirochaetes (g_Treponema), while lower Firmicutes (g_Clostridium and f_Peptostreptococcaceae) than control sows, during the lactation period. Similarly, piglets nursed by E. gracilis-supplemented sows had higher Bacteroidetes (g_Bacteroides) and Proteobacteria (g_Escherichia) but lower Firmicutes (g_Lactobacillus) during the suckling period than those nursed by control sows. The non-metric multidimensional scaling analysis showed a correlation between piglet gut microbiota in those nursed by E. gracilis-supplemented sows and their body weight on days 10 (P = 0.094) and 21 (P = 0.031) of age.

Conclusion: Maternal E. gracilis supplementation during late gestation and lactation exerts prebiotic effects, alters both sow and piglet gut microbiota, and potentially reduces piglet diarrhea incidence and tends to increase piglet body weight.