Effects of Phytosterols on Growth Performance, Serum Indexes, and Fecal Microbiota in Finishing Pigs

Phytosterols (PSs) are widely present in plants, particularly abundant in plant oils and seeds. PSs are reported to have various biological activities, such as lowering cholesterol, alongside antioxidant and antibacterial activities. This research examined the effects of PSs in finishing pigs, including growth performance, serum biochemistry, and fecal bacteria. Two treatment groups (each treatment group consisted of five biological replicates, and each replicate comprised five pigs housed communally) were randomly assigned to the fifty finishing pigs (equally divided by sex) of "Duroc × Landrace × Yorkshire" three-way cross with 79.76 ± 1.29 (kg) body weight. The control group (CON) was given basic food, while the experimental group was given basic food containing 300 mg PS/kg (PS). Dietary PS supplementation markedly raised the levels of average daily feed intake (ADFI) and apparent digestibility of dry matter (DM), crude protein (CP), ether extract (EE), and gross energy (GE) in comparison to the CON (<i>p</i> < 0.05). Additionally, PSs also significantly boosted the concentrations of high-density lipoprotein cholesterol (HDL-C), total protein (TP), catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), immunoglobulin G (IgG), motilin (MTL), and glucagon-like peptide-1 (GLP-1) (<i>p</i> < 0.05), and lowered the lactate dehydrogenase (LDH) level (<i>p</i> < 0.05). Both at the phyla and genus levels, the relative abundance of Firmicutes and <i>Streptococcus</i> increased significantly, and the relative abundance of <i>Acinetobacter</i> decreased significantly when adding phytosterols (<i>p</i> < 0.05). Overall, phytosterols dietary supplementation promotes immunity and antioxidant capacity in finishing pigs and boosts growth performance by improving nutrient digestibility.