Dietary supplementation of Lonicera macranthoides leaf powder improves amino acid profiles in serum and longissimus thoracis muscle of growing-finishing pigs

A 60-days feeding trial was conducted to determine the effect of dietary supplementation of Lonicera macranthoides leaf (LML) on growth performance, meat quality, and free amino acid profiles in growing-finishing pigs. L. macranthoides leaves were harvested, air-dried and milled to powder. A total of 288 crossbred barrows (Large White × Landrace) with an average initial BW of 54.0 ± 3.4 kg were randomly allocated to 3 treatment groups and fed either a basal diet or a diet supplemented with 0.5% or 1.0% LML powder. Results showed that diet supplemented with LML powder did not affect average daily feed intake (ADFI) and feed: gain ratio (P > 0.05) in growing-finishing pigs. Moreover, diet supplemented with LML powder showed no significant effects on carcass traits (P > 0.05) including dressing percentage, backfat thickness and loin muscle area, and meat quality traits (P > 0.05) including meat color, intramuscular fat and cooking loss. However, diet supplemented with LML powder significantly improved free amino acid profiles in serum and longissimus thoracis muscle in growing-finishing pigs. Most importantly, dietary LML powder increased total free amino acids content (P < 0.001) and essential free amino acid content (P < 0.001) in longissimus thoracis muscle. These results indicate that LML has the potential to improve the nutritional value of meat through improving free amino acid profiles.