Milk Thistle Extract Enhances Lactational Performance in Primiparous Sows: A Comparative Screening of Plant-Derived Additives

Primiparous sows frequently fail to meet lactation nutrient demands, but direct comparisons of plant-derived feed additives are scarce. Eighty primiparous Yorkshire sows were assigned to four treatments from 14-day pre-farrowing to 21-day weaning: control (CON), milk thistle extract (MTE, 1% in 100 g/d), fenugreek seed extract (FSE, 1% in 100 g/d), and mannan oligosaccharide (MOS, 1.4% prepartum and 1.8% postpartum in 100 g/d). Production traits were recorded; mechanistic assays were confined to CON and MTE, the group that performed best in the production screen, and are reported as an exploratory, hypothesis-generating comparison. Lactation feed intake differed among groups (p = 0.047): MTE sows ate 4.16 kg/d compared to 3.51 kg/d for CON, while FSE (3.73) and MOS (3.47) were intermediate and similar to CON. Only MTE improved litter performance, raising weaning litter weight (+10.6%), piglet weight (+15.4%), and calculated milk yield (+13.1%) versus CON (p < 0.05); FSE and MOS showed no significant effects. MTE also increased prolactin (at farrowing and d-14) and catalase (at farrowing) but lowered d-14 cholesterol and HDL. In this two-step trial, MTE was the sole additive enhancing lactational performance, with endocrine and redox changes consistent with improved lactation.