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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Research Project #439711

Research Project: 1890 Fellowship Research Regarding Enteric Methane Production by Cattle

Location: Livestock Nutrient Management Research

Project Number: 3090-31630-006-049-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: May 15, 2021
End Date: May 14, 2024

1) To learn modern molecular techniques to classify members for ruminant microbiome and to investigate the associations between the rumen microbiota and a large set of variables describing the production, metabolic and immunological state and behavioral attributes, in an attempt to describe possible functional interrelations and pathways. 2) Identification of methanogenesis pathways associated with CH4 emission and assess host-microbiome interactions when animals receive two different red seaweed supplementations (Asparagopsis taxiformis vs. A. armata).

The first in vitro experiment will quantify the anti-methanogenic effects from two species of red seaweed (Asparagopsis taxiformix and Mazzaella japonica) and two basal diets (grain-based and forage-based). Triplicated in vitro ruminal gas production will be measured continuously from 0 to 48 h period using an Ankom in vitro gas production system. Diet formulations are shown in Table 1. Ruminal gas production will be determined from an in vitro rumen incubation procedure in which 0, 1.0, and 2.0% DM ground seaweed will be added to both diets. Substrate (10 g DM) will be placed into each 250 mL fermentation vessel containing 50 mL of ruminal fluid (RF) and 50 mL of artificial saliva (AS; Table 1). Vessels will be saturated with CO2 gas and held at 39°C. Each treatment combination will be conducted in triplicate, with two blanks, for a total of 38 fermentation vessels. Gas samples will be collected from the in vitro rumen incubation attached with gas collection bags for CH4, CO2, H2S, and N2O gases for analysis. Gases will be determined after 48 h in vitro incubation, and gas samples will be analyzed for CH4, N2O and CO2 using a gas chromatograph equipped with a methanizer and electron capture and flame ionization detectors (SRI instruments, Torrance, CA). Two sub-samples (1.5 ml each) of the media culture from each vessel will be collected for measurement of VFA concentrations and methanogens. Following the collection of the supernatants samples, the in vitro DM disappearance (IVDMD) will be estimated on the contents of the incubation bottles. Ruminal bacteria (phylum levels), total methanogens and protozoa populations will be analyzed using qPCR techniques. Two different seaweed varieties (Asparagopsis Taxiformis vs. A. armata) as an active ingredient will be used to assess and validate CH4 emission and ruminal microbial community changes in ruminants. Calves (around 300-400 lbs.) will be trained to human contact and experimental procedures well before studies commence (around 60 days). Eight crossbred steers (Bos Taurus) will be randomly allocated to two different dietary treatments to evaluate the effect of sources of seaweed [Asparagopsis Taxiformis vs. A. armata in a total mixed ration (TMR)] on GHG emissions (CH4 and CO2) of steers using two different CH4 measurement tools including respiration chambers and Greenfeed methods. Animals will be adjusted to diets for at least 16 days before commenced experiments. Diets will be formulated to be isonitrogenous. Diets will be formulated to meet animal maintenance requirements for vitamins, and minerals.