Effect of Cinnamomum verum essential oil on performance, nutrients digestibility and ruminal fermentation in feedlot male lambs

Background and objectives: In recent years, due to human concerns about the emergence of antibiotic-resistant bacteria strain, especial attention has been paid to plant essential oil and extracts as replacer for growth promoter antibiotics. The results of in vitro studies have shown that essential oils and their constituents have the potential to alter ruminal fermentation and improve energy utilization in ruminants. One of the plants that has been recently considered is cinnamon with the scientific name of Cinnamomum verum. Therefore, this experiment was performed to investigate the effect of cinnamon essential oil on performance, nutrient digestibility and rumen fermentation in feedlot lambs.
Material and methods: This experiment was carried out in a repeated measurement design (three one-month periods) with four treatments in a completely randomized design with using 20 Kurdish male lambs (n=5, average weight of 26.15 ± 4.06 kg) in the research farm of the faculty of Agriculture at University of Kurdistan. Treatments were: 1) Basal diet without cinnamon essential oil (control), 2) Basal diet plus 0.5 ml of cinnamon essential oil per head per day, 3) Basal diet plus 1 ml of cinnamon essential oil per head per day and 4) Basal diet plus 2 ml of cinnamon essential oil. Lambs were fed 2x /d at 0730 and 1800 with the daily essential oil dose provided at the 0730 feeding. Lambs BW was recorded before the morning feeding on d 0 and again on d 24 of every period using a digital scale. To determine the amount of dry matter intake, the amount of supplied feed and its residue was measured daily for each animal during the last week of every period. Nutrients digestibility was measured by acid-insoluble ash as internal marker. On the 24th day of each period, 4h after morning feeding rumen liquid samples were taken from lambs to measure NH3-N, pH and volatile fatty acids concentration.
Results: Dry matter intake, final body weight and average daily gain did not affected by cinnamon essential oil supplementation. Apparent digestibility of dry matter, organic matter and NDF was not affected by the treatment (P> 0.05); while, total tract apparent crude protein digestibility in lambs fed one ml/d of cinnamon essential oil increased compared to those of the lambs fed 0.5 and 2 ml of cinnamon essential oil (P<0.05). Adding cinnamon essential oil had no significant effect on the total volatile fatty acids concentration and the molar proportion of acetate, propionate, butyrate and isovalerate. Rumen ammonia nitrogen concentration in lambs fed diets containing 1 and 2 ml of cinnamon essential oil increased compared to those of the control group (P<0.05).
Conclusion: The results of this study showed that cinnamon essential oil at used amount and in the condition of the present study could not affect performance, nutrients apparent digestibility (except for crude protein), and rumen fermentation (except for ammonia nitrogen) in feedlot mal lambs. The results suggested that in feedlot diets included cinnamon essential oil, it is better to use of protein sources with lower rumen digestibility.