Improvement of the Meat Quality of Holstein Bulls Fed a Diet Enriched with Oregano Oil

Beef is a dominant meat commodity produced mainly from beef cattle breeds. Dairy cattle breeds are reared for milk production, but their calves could be raised to produce high quality meat subject to designated feeding. The objective here was to investigate the role of oregano oil-enriched diets on the quality characteristics of meat produced by Holstein bulls. Fifty Holstein bulls, aged 12 ± 2 months and with an average weight of 365 ± 60 kg, were used. They were equally allocated in two experimental groups (n = 25). One group (group CON) was offered a basal diet and the other (group OREG) the same diet enriched with 50 mg/kg DM of oregano oil, for a period of 90 days. Afterwards, meat samples were subjected to microbiological (1 h after slaughter), physicochemical (1st and 15th day after slaughter), and sensory analyses (15th day after slaughter). The beef of group OREG is characterized with improved color parameters and a lower malondialdehyde (MDA) production rate and content (68.52 ng/g versus 105.91 ng/g, <i>p</i> = 0.01). The sensory evaluation of beef revealed higher scores for group OREG in flavor (3.88 versus 3.17, <i>p</i> = 0.0007) and color (3.87 versus 3.21, <i>p</i> = 0.001), as well as higher nutritional value, which was associated with significantly higher levels of alanine, arginine, aspartic acid, histidine, isoleucine, leucine, lysine, valine, and total amino acids (<i>p</i> < 0.05). Thus, the results suggest that the quality of the meat of Holstein bulls can be improved when they are fed a diet enriched with oregano oil.