The present study was conducted to observe the protective effects of c9, t11- conjugated linoleic acid (CLA) on oxidative stress and inflammation in bovine mammary epithelial cells (BMECs) exposed to H₂O₂. The BMECs were treated with different concentrations of H₂O₂ for 8 h, 600 µmol/L was determined to be the damage concentration. Using different concentrations of c9, t11-CLA to process BMECs for 24 h, 50 and 100 µmol/L were determined to be the effective concentrations for subsequent analyses. Thus, four BMEC groups were established: Control group; H₂O₂ group; 50 µmol/L c9, t11-CLA + H₂O₂ group; 100 µmol/L c9, t11-CLA + H₂O₂ group. We observed that the H₂O₂ group exhibited significantly lower total antioxidant activity (T-AOC), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and significantly higher secretions of malondialdehyde (MDA), interleukin (IL)-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α and expressions of IL-1β, IL-6, and IL-8 than the control group (p < 0.05). Pretreatment with c9, t11-CLA enhanced SOD, CAT, and GPx activities and SOD mRNA expression and repressed IL-6 and IL-8 secretion and expression in H₂O₂-treated BMECs (p < 0.05). In conclusion, c9, t11-CLA treatment efficiently enhanced antioxidant capacity and decreased inflammation induced by H₂O₂ in BMECs.

This study evaluated the effects of dietary conjugated linoleic acid (CLA) on serum metabolites, antioxidant capacity, and immune function of transition ewes, as well as on growth performance, serum biochemical indices, and hormone levels of their suckling lambs. Forty healthy Ujumqin ewes (body weight 56.62 ± 5.30 kg) were randomly assigned to four groups (n = 10/group) at 28 d before expected parturition: control (basal diet), CLA-1 (basal diet + 10 g/d CLA), CLA-2 (basal diet + 20 g/d CLA), and CLA-3 (basal diet + 30 g/d CLA). Blood samples were collected from ewes at 21 d prepartum, at delivery, and at 21 d postpartum, and from lambs at 7 and 42 d postpartum. Serum metabolites, antioxidant enzymes, and inflammatory cytokines were measured. In ewes, CLA supplementation did not significantly affect serum AST, β-HB, GLU, TG, NEFA, SOD, GPX, MDA, or T-AOC (p > 0.05), although β-HB, GLU, SOD, GPX, and MDA changed with time. However, CLA markedly decreased serum TNF-α, IL-8, IL-6, and IL-1β (p < 0.05). In lambs, maternal CLA did not affect birth or final body weight. Maternal CLA decreased serum GH and the GH/IGF-1 ratio and increased IGF-1 (p < 0.05), especially at 30 g/d. Serum SOD, GPX, and MDA did not differ among groups, whereas T-AOC showed a significant group × time interaction (p = 0.004). Maternal CLA also decreased serum TNF-α, IL-8, IL-6, and IL-1β in lambs (p < 0.05). In conclusion, perinatal CLA supplementation did not significantly improve most energy metabolic or antioxidant enzyme indices under these conditions, but it alleviated excessive inflammatory responses in ewes and suckling lambs and activated the GH-IGF-1 axis in lambs. The 30 g/d CLA dose showed the strongest immunomodulatory and endocrine effects. These findings suggest that CLA may serve mainly as an immunomodulatory strategy in perinatal sheep, and dose optimization warrants further study.