Effect of long-term dietary probiotic Lactobacillus reuteri 1 or antibiotics on meat quality, muscular amino acids and fatty acids in pigs.

This study investigated effects of 175-d dietary treatment with Lactobacillus reuteri 1 (LR1) or antibiotics (olaquindox and aureomycin) on the longissimus thoracis (LT) of pigs. Results showed that antibiotics decreased pork quality by increasing drip loss, shear force, and altering myofiber characteristics including diameter, cross-sectional area and myosin heavy chain isoforms compared to LR1. Pigs fed antibiotics had lower muscle contents of free glutamic acid, inosinic acid, and higher glutamine compared to pigs fed the controls and LR1 diets (P ≤ .05). Furthermore, antibiotics decreased free isoleucine, leucine, methionine in LT compared to the control (P ≤ .05). Compared to antibiotics, LR1 likely improved protein synthesis by modulating expression of amino acid transport and ribosomal protein S6 kinase 1 (S6K1) genes, and altered fatty acid profile by regulating metabolic pathways. Overall, LR1 improved pork quality compared to antibiotics by decreasing drip loss and shear force, increasing inosinic acid and glutamic acid that may improve flavor, and altering muscle fiber characteristics.