Annatto concentrate supplementation improves systemic redox balance and modulates placental FGF-2 expression in ewes.

Annatto (Bixa orellana) carotenoids have antioxidant potential, but effects on placental biology and antioxidant parameters in ewes are unclear. We tested whether dietary annatto concentrate (ANC) in late gestation modulates immediate-postpartum blood oxidative markers and placental gene abundance. Thirty ewes were stratified by expected litter size (single/twin) and randomized within stratum to 0 %, 0.5 %, or 1.0 % ANC (dry-matter basis) from gestational day 100. ANC was a powdered concentrate, premixed into feed (1.5 % BW) and offered individually to ensure full intake. At lambing, we recorded maternal/neonatal descriptors (ewe weights, gestational length, time to placental expulsion, and lamb birth weight interpreted with litter size and sex), collected blood for FRAP, TBARS-MDA, H₂O₂, SOD, GPx, CAT, and -SH, and sampled placenta (cotyledon and intercotyledonary tissue) aseptically and froze it for RT-qPCR of VEGF-A, FGF-2, PAG1, GPX1, GSR, CAT, and SOD2. ANC produced marker-specific blood adjustments: lower H₂O₂ at 1.0 %, higher GPx in supplemented ewes, and lower -SH at 0.5 %, whereas FRAP, SOD, MDA, and CAT were unchanged. In placenta, cotyledonary FGF-2 showed higher relative abundance at 0.5 %, with no differences for VEGF-A, PAG1, GPX1, GSR, CAT, or SOD2 in either tissue. Ewe weights, gestational length, and time to placental expulsion were similar among groups; lamb birth weight showed no main effect of ANC. These results indicate that, in late gestation, ANC selectively increased the relative abundance of cotyledonary FGF-2 at 0.5 % and modulated peroxide handling in blood, supporting its use as a nutritional tool for antioxidant support near parturition.