Effect of Oregano Essential Oil and Canola Oil on Apparent Digestibility, Ruminal pH and Ammonia and Carcass Quality Characteristics of Fattening Dalagh Lambs

To investigate the effects of oregano essential oil and canola oil on digestibility, ruminal pH and ammonia and carcass quality of fattening Dalagh lambs, an experiment was conducted with 16 lambs with an average live weight of 25±2 kg in a completely randomized design with 4 treatments (Control diet based on barley grain and corn silage without canola oil and oregano essential oil, control diet supplemented with 2 % canola oil, control diet supplemented with 2 % canola oil and 0.2 % oregano essential oil and diet supplemented with 0.2 % oregano essential oil) and 4 replicates for 80 days. Results indicated that the NDF digestibility (60.06, 54.77, 52.56 and 55.73 respectively) was significantly decreased in lambs fed diet containing canola oil and oregano essential oil. Concentration of ruminal ammonia had significantly decreased with adding oregano essential oil in level 0.2% to the diet. The results also showed that pH and index of meat light color not affected by dietary treatments, whereas color parameters (yellowness–redness) appeared to decrease in control treatment. Amount of thiobarbituric acid was lower in thigh meat stored for 63 days after slaughtering in group received oregano essential oil. According to the results, use of oregano essential oil had favorable effect on ruminal ammonia concentration and the oxidative stability of meat in a long time so it would be considered for storing meat in fridges.