Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2011
Publication Date: 9/21/2011
Citation: Tekippe, J.A., Hristov, A.N., Heyler, K.S., Cassidy, T.W., Zheljazkov, V.D., Ferreira, J.F., Karnati, S.K., Varga, G.A. 2011. Rumen fermentation and production effects of Origanum vulgare L. leaves in lactating dairy cows. Journal of Dairy Science. 94:5065-5079. Interpretive Summary: Methane production by ruminants is not only of environmental concern due to the increase of greenhouse gases, but is also an energetic loss to the animal. Identifying plants that can reduce methane production by ruminants can offer the advantage of both increasing animal productivity and reducing methane emissions from the animal to the environment, the latter reducing impact on global warming. Lactating cows were fed oregano, a rich source of antioxidants, leaves (500 g/cow/day) mixed with their daily feed once daily for three weeks. Rumen methane production was reduced by an average of 40% in cows fed the oregano-enriched diet compared with the control diet. Oregano feeding did not affect animal feed intake, digestibility of nutrients, or the yield, fat content, taste, protein, lactose, and nitrogen concentration in the milk. However, cows fed oregano had higher fat-corrected milk yield and higher efficiency in converting dietary nitrogen into milk protein. Urinary and fecal nitrogen losses, and manure ammonia and methane emissions were unaffected by oregano feeding. Although the methane reduction results must be interpreted with caution due to the large animal-to-animal variation, oregano might help lactating cows reduce methane release into the environment with no adverse effect on their milk production and quality.
Technical Abstract: A lactating cow trial was conducted to study the effects of dietary addition of oregano leaf material (Origanum vulgare L.; 0, control vs. 500 g/d, OV) on ruminal fermentation, methane production, total tract digestibility, manure gas emissions, N metabolism, organoleptic characteristics of milk, and dairy cow performance. Eight primiparious and multiparious Holstein cows (6 of which were ruminally cannulated) were used in a switch-over design trial with 2, 21-d periods. Cows were fed once daily. The OV material was top-dressed and mixed with a portion of the total mixed ration. Cows averaged 80 +/- 12.5 days in milk at the beginning of the trial. Rumen pH, concentration of total and individual VFA, microbial protein outflow, and microbial profiles were not affected by treatment. Ruminal ammonia N concentration was increased by OV compared with the control (5.3 vs. 4.3 mM). Rumen methane production was reduced by OV (P = 0.004). Intake of DM (average of 26.6 +/- 0.83 kg/d) and apparent total tract digestibly of nutrients did not differ between treatments. Average milk yield, milk fat, protein, lactose, and milk urea nitrogen concentrations, and milk taste were unaffected by diet. Milk sensory parameters were also not affected by treatment. Fat-corrected (3.5%) milk yield and fat corrected milk feed efficiency were increased (P = 0.03 and < 0.001, respectively) by OV compared with the control (42.2 vs. 40.7 kg/d and 1.63 vs. 1.53 kg/kg, respectively). Urinary and fecal N losses, and manure ammonia and methane emissions were unaffected by treatment. Under the current experimental conditions, supplementation of dairy cow diets with 500 g/d of OV increased 3.5% FCM yield and feed efficiency. The sizable reduction in rumen methane production with the OV supplementation has to be interpreted with caution due to the large within and between animal variability in methane emission estimates.