Effect of Oregano Essential Oil Supplementation to a Reduced-Protein Diet on Meat Quality, Fatty Acid Composition, and Oxidative Stability of Longissimus Thoracis Muscle in Growing-Finishing Pigs

This study investigated the effects of reduced-protein diet supplementation with oregano essential oil (OEO) in pigs, from growing period to slaughter (98 days) , on meat quality, fatty acid composition and oxidative stability of longissimus thoracis (LT) muscle. A total of 36 barrows (Large White × Landrace) with an initial body weight (BW) of 29.0 ± 1.00 kg were obtained from a commercial farm in the Hubei province of China. Pigs were randomly allotted into 1 of 3 treatments based on BW in a randomized complete block design with twelve replicates of one pig per replicate. Pigs were penned individually. Three following experimental treatments were applied: 1) normal protein diet (NPD), 2) reduced-protein diet (RPD), and 3) identical reduced-protein diet supplemented (250 mg/kg feed) with OEO. The three diets were based on corn-soybean meal-dried distillers grains with soluble (DDGS). The pigs in the NPD group were offered diets which contained 17% and 15.6% protein during the growing (days 0–49) and finishing (days 51–98) periods, respectively, while the pigs in the RPD group were offered diets which contained 15% and 13.6% protein during their growing and finishing periods, respectively. Experimental diets were balanced with four amino acids (L-lysine, L-methionine, L-threonine, and L-tryptophan) to meet the requirements of growing-finishing pigs (NRC, 2012). Dietary RPD and OEO increased the Minolta b*_45min (?), tenderness, overall acceptance, and intramuscular fat (IMF) content of pork compared with dietary NPD (P < 0.05). The percentage of n-3 polyunsaturated fatty acid (n-3 PUFA) and the percentage of monounsaturated fatty acid (MUFA) in OEO muscle were higher (P < 0.05) and lower (P < 0.05) than those in RPD muscle, respectively. Dietary OEO improved oxidative stability, total antioxidative capacity and catalase (P < 0.01), but decreased drip loss in LT muscle compared with dietary NPD and RPD (P < 0.01). In our study, reduced-protein diet supplementation with oregano essential oil enhanced the sensory attributes and anti-oxidative status of pork meat by improving IMF and n-3 PUFA percentage and antioxidative capacity.