Effects of Late-Gestation Nutritional Restriction and Hydroxytyrosol Supplementation on Behavioural Responses and Neuroendocrine Blood Markers in Beef Cows and Their 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.