Botanical extracts are increasingly being explored for their potential benefits in the search for sustainable and natural solutions in livestock nutrition. In a three-run experiment, OXILEM, a polyphenol-rich commercial pine extract, was supplemented at 1% from day 106 of gestation through lactation in 10 sows (OX), while another 10 received a control diet (CON). At weaning, 229 piglets were assigned to one of four dietary groups based on maternal and post-weaning diets (CON/CON, CON/OX, OX/CON, OX/OX), with OX post-weaning diets containing 1% polyphenols. The study evaluated sow body weight and backfat changes during lactation, feed intake, milk composition (at day 3 and 17), piglet growth and feed intake from birth through early post-weaning. Sow performance was analyzed via ANOVA (R-studio software), considering the sow as the experimental unit. A linear mixed model assessed the effects of diet and parity (fixed factors) and run (random factor). Milk composition was analyzed using a model that incorporated diet, test day (day 3 vs. day 17), and their interaction as fixed effects, with run as a random factor. Post-weaning piglet performance was evaluated using a linear mixed model, with sow and piglet diets and their interaction as fixed effects, while run and box were random factors, with piglets nested within their foster mother. OXILEM supplementation had no significant impact on sow performance but increased total milk protein content at day 3 post-partum (5.58% in CON vs. 5.84% in OX, P = 0.04) with no differences observed at day 17. The sow diet significantly influenced piglet post-weaning growth, with higher body weight in piglets nursed by CON-fed sows and those fed the CON diet post-weaning (P < 0.05). However, the sow × piglet diet interaction was not significant. These findings indicate that while OXILEM supplementation may enhance total milk protein content, its direct application to piglets needs further investigations to optimize the supplementation strategy to balance sow benefits with optimal piglet development.