Effects of Extract on Growth Performance, Nutrient Apparent Digestibility, Serum Parameters, and Fecal Microbiota in Finishing Pigs.

This study investigated the effects of extract (FAE) on growth performance, nutrient apparent digestibility, serum parameters, fecal microbial composition, and short-chain fatty acids (SCFAs) in finishing pigs. In total, 75 Duroc × Landrace × Yorkshire pigs (equally divided by sex), with an initial body weight of 79.49 ± 4.27 kg, were randomly assigned to three treatment groups. The pigs were fed either a basic diet (CON) or a basal diet supplemented with 500 mg/kg of FAE (FAE500) and 1000 mg/kg of FAE (FAE1000). The FAE1000 group exhibited a significantly higher final body weight (FBW) ( < 0.05), and the average daily feed intake (ADFI) showed an increasing tendency in the FAE500 and FAE1000 groups ( = 0.056) compared to the CON group. Additionally, the inclusion of FAE resulted in the significantly higher apparent digestibility of crude ash (Ash), gross energy (GE), and crude protein (CP) ( < 0.05), with a tendency to the increased digestibility of dry matter (DM) ( = 0.053). Dietary FAE supplementation led to elevated serum levels of reduced glutathione (GSH) and decreased levels of serum L-lactic dehydrogenase (LDH), along with a tendency to increase serum glucose (GLU) levels ( = 0.084). The FAE500 group demonstrated higher serum concentrations of motilin (MTL) and gastrin (GAS) ( < 0.05), and a tendency for reduced serum glucagon-like peptide-1 (GLP-1) level ( = 0.055) compared to the CON group. Furthermore, alpha diversity analysis revealed that the FAE500 group significantly increased the Chao 1 and Observed_species indexes ( < 0.05). Similarly, beta diversity analysis indicated that FAE feeding altered the fecal microbial structure ( = 0.083). Notably, compared with the control group, , , and displayed higher relative abundance in the feces of the FAE500 group, whereas Tenericutes showed a reduction in relative abundance ( < 0.05). Additionally, the relative abundance of Tenericute was negatively correlated with the digestibility of DM, GE, Ash, and CP ( < 0.05). Serum MTL and GAS levels correlated positively with the , , , and relative abundances ( < 0.05). Collectively, dietary FAE supplementation could enhance growth performance by boosting beneficial bacteria in feces, stimulating gastrointestinal hormone secretion, and improving nutrient digestibility.