Effects of the macroalga Asparagopsis taxiformis and oregano leaves on methane emission, rumen fermentation, and lactational performance of dairy cows

Authors: STEFENONI, HANNAH - Pennsylvania State University; RÄISÄNEN, SUSANNA - Pennsylvania State University; CUEVA WELCHEZ, SERGIO - Pennsylvania State University; WASSON, DEREK - Pennsylvania State University; LAGE, CAMILA - Pennsylvania State University; MELGAR, AUDINO - Pennsylvania State University; FETTER, MOLLY - Pennsylvania State University; SMITH, PHILIP - Pennsylvania State University; HENNESSY, MEAGAN - University Of Pennsylvania; VECCHIARELLI, BONNIE - University Of Pennsylvania; BENDER, JOSEPH - University Of Pennsylvania; PITTA, DIPTI - University Of Pennsylvania; Cantrell, Charles; YARISH, CHARLES - University Of Connecticut; HRISTOV, ALEXANDER - Pennsylvania State University

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2020
Publication Date: 1/28/2021
Citation: Stefenoni, H., Räisänen, S., Cueva Welchez, S., Wasson, D., Lage, C., Melgar, A., Fetter, M., Smith, P., Hennessy, M., Vecchiarelli, B., Bender, J., Pitta, D., Cantrell, C.L., Yarish, C., Hristov, A. 2021. Effects of the macroalga Asparagopsis taxiformis and oregano leaves on methane emission, rumen fermentation, and lactational performance of dairy cows. Journal of Dairy Science. 104:4157-4173. https://doi.org/10.3168/jds.2020-19686.
DOI: https://doi.org/10.3168/jds.2020-19686

Interpretive Summary: Greenhouse gases (GHG) in the atmosphere have been steadily increasing since the industrial era but the current mixing ratios are unprecedented and identifying GHG mitigation practices is becoming increasingly important. One of the main sources of anthropogenic methane (CH4) in the United States and globally is enteric fermentation. Methanogenic archaea in the rumen are responsible for the production of enteric CH4, which is released into the atmosphere primarily through eructation with a small proportion being emitted from the hindgut with flatus. Various nutritional and animal management strategies were investigated, and some have shown promise at mitigating enteric CH4 in dairy cattle . Recently, seaweeds have emerged as a potential feed additive in ruminant diets as a CH4 mitigating strategy. The halogenated compounds produced by Asparagopsis spp. seaweeds have antifungal and antibacterial properties and of particular interest is the brominated halomethane, bromoform. Similar to the secondary metabolites produced in seaweeds, essential oils from plants have antibacterial properties and have been shown to reduce enteric CH4 through modification of rumen fermentation. Inclusion of Aparagopsis spp. seaweed at 0.50% in lactating cow diets has the potential to decrease methane emission, yield, and intensity by up to 80%. In this study, oregano leaves had no effect of enteric methane emission and animal production variables.

Technical Abstract: Asparagopsis taxiformis (AT) is a source of multiple halogenated compounds and has been shown to decrease enteric CH4 production in vitro and in vivo. This study consisted of 4 in vitro and in vivo experiments. Experiment 1 was aimed at establishing the effect of AT on total gas production and CH4 emission in vitro. Two experiments with lactating dairy cows were conducted to determine the antimethanogenic effect of AT in vivo. Experiment 2 was a short-term pilot study conducted with 6 Holstein cows with the objective of determining optimal dosages of AT for a consequent, longer-term experiment (Experiment 3). Treatments in Exp. 2 were background measurements (control) and 0.25, 0.50, and 0.75% AT (dry matter intake, DMI, basis). The objective of Exp. 3 was to determine the effect of AT and oregano leaves on enteric CH4 emission, rumen fermentation, and lactational performance of dairy cows. In Exp. 3, 20 Holstein cows were used in a replicated 4 × 4 Latin square design with 4, 28-d periods. Treatments were basal diet (control) or basal diet supplemented with (DMI basis): 0.25% AT (LowAT), 0.50% AT (HightAT), or 2.0% oregano leaves (Origanum vulgare). In both Exp. 2 and 3, enteric gas emissions were measured using the GreenFeed system and in Exp. 3, rumen samples were collected for fermentation analysis by the ororuminal technique. In Exp.1, relative to the control, AT decreased CH4 yield by 98%. In Exp. 2, AT decreased CH4 emission linearly, with 81% reduction at the 0.50% inclusion level, but DMI and milk yield were also decreased at the 0.75% inclusion rate. In Exp. 3, HighAT decreased average daily CH4 emission and CH4 yield by 65% and 55%, respectively, in experimental periods 1 and 2, but had no effect in periods 3 and 4. The differential response to AT among experimental periods was likely a result of a decrease in bromoform concentration in AT over time (up to 84% decrease in 4 mo of storage) observed in a separate experiment. In Exp. 3, hydrogen emission was increased by AT and, as expected, the proportion of acetate was decreased and that of propionate and butyrate were increased by HighAT, compared with the control. Compared with Control, HighAT decreased DMI, milk yield, and energy-corrected milk yield. Milk composition, nutrient digestibility, and N excretions were generally not affected by treatment. Concentrations of iodine and bromide were increased in HighAT milk, compared with control milk. Bromoform concentration and milk organoleptic characteristics were not different between control and HighAT milks. Oregano had no effect on CH4 emission or lactational performance of the cows in Exp. 3. Overall, AT included at 0.50% (DMI basis) in the ration of dairy cows can have a large mitigation effect on eneteric CH4 emission, but DMI and milk production may also decrease. There was a marked decrease in the CH4 mitigation potential of AT, likely resulting from bromoform decay over time. Milk composition did not substantially change due to AT supplementation, but milk iodine and bromide concentration increased significantly.