Effects of Conjugated Linoleic Acid on Antioxidant and Immune Functions of Perinatal Ewes and Lambs

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.