The impact of maternal dietary restriction and hydroxytyrosol (HT) supplementation during the last third of gestation on plasma malondialdehyde (MDA) concentration, total antioxidant capacity (ABTS assay), and peripheral blood gene expression related to antioxidant defence, immune response, and energy metabolism was evaluated in beef cows and calves. Two feeding treatments in late gestation (T100% vs. T60% of nutrient requirements) and two HT levels (Control vs. HT at 180 mg/kg of diet) were evaluated during gestation (n = 46 cows) and lactation (n = 37 cows and calves). In pregnant cows, undernutrition led to inhibition of glucose oxidation (PDK4), decreased lipid synthesis (HMGCS1 and SCD) and TLR signalling; T60% cows showed higher plasma MDA (p < 0.05) with no positive effect of HT on antioxidant capacity. Contrarily, during lactation, earlier HT supplementation upregulated antioxidant capacity and modulated antioxidant gene expression (p < 0.05). In calves, there was an increase in SOD1, CAT, and GPX1, especially in the T60%-HT group (p < 0.05). Interestingly, HT supplementation increased glucose transport (SLC2A1/GLUT1) during pregnancy and lactation (p < 0.05). However, it caused different effects on immunometabolic regulation in both dams and calves, depending on maternal diet. Overall, maternal HT supplementation under restricted nutritional conditions promoted postpartum antioxidant capacity and modulated immune and metabolic gene expression in cows and calves.

Maternal nutrition during late gestation is critical for fetal development, neonatal resilience, and postnatal adaptation in beef cattle. This study aimed to evaluate the effects of nutritional restriction and supplementation of hydroxytyrosol (HT) in late pregnancy on behavioural, circadian, stress-related, and inflammatory responses in cows and their restricted nursed offspring. Pregnant cows were allocated to a 2 × 2 factorial experimental design (feeding level: T100% vs. T60% of nutrient requirements; HT: 0 vs. 180 mg/kg of diet). Cow behaviours were recorded during meals (from week −12 prepartum to term), and calf activities, body temperature, and mother–offspring interactions were assessed at 5 weeks postpartum. Nutritional restriction accelerated feed intake in cows and increased stress-related behaviours, while HT partially mitigated these effects. Molecular analyses in blood samples revealed dynamic prepartum upregulation of glucocorticoid-receptor NR3C1 in week −6, and downregulation of circadian (BMAL1, PER1, CRY1) gene expression in week 5 after parturition, both in T60%-HT cows. In calves, maternal HT supplementation promoted active exploratory behaviour, and counteracted behavioural and circadian (CRY1 and PER1) and inflammatory markers (IL8) gene expression resulting from prenatal nutrient restriction, leading to behavioural profiles and blood gene expression comparable to those observed in calves born to adequately fed dams.