Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Animal and Food Sciences

First Advisor

Dr. Kyle McLeod


Greenhouse gas (GHG) emissions have been implicated in global warming and extreme climate change conditions. The Environmental Protection Agency (EPA) has identified agriculture, more specifically cattle production, as a major contributor to global GHG production. When expressed as liters of gas, CO2 is considered the primary GHG produced, however, in terms of global warming potential (GWP), CH4 has 25-times greater potential than that of CO2. Due to the elevated GWP of CH4, we have constructed a series of experiments to investigate the use of a halogenated CH4 analogue derived from kelp (i.e., bromoform) as an inhibitor of enteric CH4 production in cattle. In experiment 1, 12 Holstein steers were used in a randomized complete block design to test the hypothesis that kelp reduces enteric methane production. Dietary treatments included a corn-silage basal diet fed at 1.5x NEm, containing either no kelp (ground corn carrier only) or ground corn carrier plus kelp at 10% of carrier. Treatments were administered at 0.5% of total ration dry matter (bromoform content= 10 mg/g product). Steers were adapted to their respective diets for 14-d prior to placement into metabolism stalls fitted with stainless steel headboxes for continuous measurements of CH4 and CO2 production and O2 consumption over a 3-d period. Treatment had no effect (P > 0.11) on DMI (g/kg BW) during the adaptation or respiratory gas collection period. In contrast, steers receiving kelp had lower (P < 0.001) CH4 production (< 2.2L/d) compared to the control steers (88.7 L/d). Kelp substantially reduced methane production without altering DMI or oxidative metabolism. In experiment 2, 6 Holstein steers were used in a 17-d respiratory gas collection experiment to test the hypothesis that suppression of enteric CH4 would persist after removal of kelp from the ration. Dietary treatments contained either 0, 0.5 or 1% of diet DM as kelp (bromoform content= 2 mg/g product) top dressed to a corn silage-based diet provided at 1.5x NEm. All feed was consumed on all treatments throughout the adaptation, treatment, and recovery periods. Kelp was fed from d 1 through d 11 such that days 1 and 2 of the respiratory gas collection period represent the effects of bromoform on enteric CH4 production, and responses on subsequent days represent residual effects. On d 1, the 1% inclusion decreased production below the limits of detection, however, 0.5% was not different from the control. A treatment x day interaction (P ≤ 0.0003) was observed for enteric CH4 production (L/d) and yield (g/g DMI). Steers consuming 0.5% of DM did not differ from the control animals (P ≥ 0.3). Methane production and yield were not affected by day in control animals; however, a quadratic response was observed (P < 0.0001) for the 1% treatment and a cubic response was observed for the 0.5% treatment. In experiment 3, 12 Angus steers were used in a 30-d feeding trial to test the hypothesis that kelp would not contribute to differences in intake or measurable accumulations of bromoform residues in tissue. Dietary treatments included a corn-silage basal diet fed ad libitum, adjusted twice weekly for intake, and a top-dress composed of ground corn and distillers dried grain (DDG) and either no kelp (ground corn and DDG carrier), or carrier plus kelp (bromoform content = 2 mg/g product) at 10, or 20% of carrier. Treatments were administered at 0.5% of total ration dry matter. Steers were adapted to ad libitum intake of an 80% concentrate basal diet for a minimum of 14-d prior to introduction of the treatment. Treatment had no effect (P = 0.53) on DMI (kg/kg BW) following 30-d of kelp supplementation. Concurrently, treatment had no effect (P = 0.55) on ADG (kg/d) or growth efficiency (g/kg) (P = 0.82). In support of our stated hypothesis, kelp supplementation did not result in detectable bromoform residues in liver, kidney, adipose or muscle samples collected at harvest following the 30-d supplementation period.

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