Adding oregano essential oil to diet changed the muscle quality and composition and content of fatty acids and amino acids in Pingliang red cattle

This study aimed to investigate the changes in muscle quality, fatty acid composition, and amino acid content of Pingliang red cattle after long-term addition of oregano essential oil. Nine Pingliang red cattle geldings with good health and similar initial weight were selected and divided into three groups of three individuals each. The control group (CON) was fed basal feed, and the experimental groups were fed 10 (Group L) and 20 g·(head·d)⁻¹ (Group H) oregano essential oil, with a pre-test period of 14 d and a positive test period of 570 d. The semitendinosus muscle of the left half carcass was taken to measure the meat quality and fatty acid and amino acid contents. The results show: 1) When the acid excretion time was the same and the amount of added oregano essential oil was different, the water loss rate of the L group was significantly lower than that of the CON group at 0 h of acid excretion (P < 0.05). Additionally, the cooked meat rate of the H group was significantly higher than that of the CON group (P < 0.05), and the shear force of the L group was significantly lower than that of the CON group (P < 0.05). After 72 h of acid excretion, the brightness (L*) value of muscle in group H was significantly higher than that in group CON (P < 0.05), the loss of dripping water in the experimental group was significantly lower than that in group CON (P < 0.05), and the loss of cooking in group L was significantly lower than that in group CON (P < 0.05). In the CON group, when the amount of oregano essential oil added was the same and the acid excretion time was different, the L*, redness (a*) , and yellowness (b*) values, water loss rate, and cooking loss at 72 h were significantly higher than those at 0 h (P < 0.05), and the pH and cooked meat rate at 0 h were significantly higher than those at 72 h (P < 0.05). In group L, the L* and b* values and water loss rate at 72 h were significantly higher than those at 0 h (P < 0.05), and the pH at 0 h was significantly higher than that at 72 h (P < 0.05). In group H, the L* and a* values, water loss rate, and cooking loss at 72 h were significantly higher than those at 0 h (P < 0.05), and the pH and cooked meat rate at 0 h were significantly higher than those at 72 h (P < 0.05). 2) The levels of stearic acid (C18:0), oleic acid (C18:1n9c), and unsaturated fatty acid (USFA) in the test group were significantly higher than those in the CON group (P < 0.05), and the behenic acid in the L group (C22:0) was significantly higher than that of the CON and H groups (P < 0.05). 3) Threonine, valine, methionine, isoleucine, leucine, phenylalanine, lysine, alanine, aspartic acid, serine, proline, tyrosine, arginine, essential amino acids, nonessential amino acids, and total amino acids were significantly higher in the test group than in the CON group (P < 0.05), and glutamic acid content was significantly higher in the L group than in the CON group (P < 0.05). In summary, long-term feeding of oregano essential oil can improve muscle quality and raise the fatty acid and amino acid contents in the muscles of Pingliang red cattle during the late fattening stage.