title:  Effects of Biosynthesized Bromoform on Enteric Methane Production, Animal Performance and Tissue Residues in Cattle
Creators: name: Davis, Sydney 
Publisher: name: University of Kentucky Libraries
Year: 2023
Subjects: classificationCode: 4
subject: FOS: Agricultural sciences

description: 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.
description: © 2023 Sydney Davis