Effects of Supplementation with Dimethylglycine Sodium Salt on Immunity, Intestinal Tissue Morphology, and Antioxidant Function in IUGR Lambs

This study investigates the regulatory effects of dietary supplementation with DMG-Na on growth performance, immunity, and intestinal development in IUGR lambs. A total of 45 lambs were used: thirty IUGR (3.10 ± 0.16 kg) lambs were randomly assigned to IUGR or IUGR + DMG-Na (0.1% in milk replacer from days 7–56) groups, with fifteen normal birth weight lambs as CON (4.32 ± 0.17 kg). At 56 days of age, eight lambs per group were slaughtered for sample collection. Compared to CON, IUGR lambs showed a significantly lower final body weight and average daily gain (ADG) (p < 0.01); IUGR also severely compromised intestinal structure, markedly decreasing villus height and villus height-to-crypt depth ratio across all small intestinal segments (p < 0.01); immune function was impaired, with highly significantly lower jejunal secretory IgA (sIgA) (p < 0.01); and antioxidant capacity was diminished, evidenced by reduced jejunal GSH, catalase (CAT) and glutathione reductase (GR) activities (p < 0.05) and increased jejunal MDA content (p < 0.01). Compared to IUGR, IUGR + DMG-Na group had highly significant increased final body weight and significant increased ADG (p < 0.01); it enhanced intestinal morphology, notably increasing villus height and villus height-to-crypt depth ratio in the duodenum and jejunum (p < 0.01); immune markers improved, with elevated jejunal sIgA (p < 0.05); and antioxidant status was restored, demonstrated by increased jejunal GSH and CAT activities (p < 0.05) and decreased jejunal MDA content (p < 0.01). In conclusion, DMG-Na effectively counteracted IUGR-induced deficits by promoting intestinal development, immunity, and antioxidant capacity, ultimately improving growth performance.