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.

Conjugated linoleic acid (CLA) exerts anti-inflammatory and antioxidant bioactivities, yet its optimal hepatic anti-inflammatory dosage under lipopolysaccharide (LPS) stimulation remains unclear. This study aimed to screen the effective dietary CLA dose against LPS-triggered liver inflammation in mice. Twenty-four male mice were divided into four groups (n = 6): normal diet (ND), ND+0.5% CLA, ND+1% CLA and ND+2% CLA. After 49 days of feeding, all mice received LPS injection and were sacrificed 24 h later. Serum and liver tissues were collected to detect pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), the oxidative stress marker malondialdehyde (MDA), antioxidant indices (superoxide dismutase, SOD and total antioxidant capacity, TAC), hepatic inflammatory gene mRNA and liver histopathology. The 1% CLA group exhibited lower serum and hepatic pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and the oxidative stress marker MDA, higher SOD and TAC (p < 0.01), and reduced hepatic inflammatory infiltration. All CLA treatments downregulated hepatic CXCL1 mRNA and upregulated peroxisome proliferator-activated receptor γ (PPARγ) mRNA (p < 0.05). In conclusion, 1% dietary CLA elicited optimal anti-inflammatory effects in this acute LPS-induced liver inflammation model, while 1% and 2% CLA showed comparable antioxidant effects. This study was a short-term acute inflammation mouse model. The tissue distribution and lipid metabolic profile of CLA were not examined, and the CLA mixed isomers were used. Moreover, the PPARγ pathway was inferred based solely on mRNA levels, and further in-depth verification is still needed.