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ARS Home » Plains Area » Bushland, Texas » Conservation and Production Research Laboratory » Livestock Nutrient Management Research » Research » Research Project #442659

Research Project: Assessing the Environmental Protective Benefits of a Tannin Containing Feed Ingredient for Finishing Beef Steers

Location: Livestock Nutrient Management Research

Project Number: 3090-31630-006-052-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2022
End Date: Aug 31, 2025

The objective of the proposed research project is to assess the effects of a tannin containing product or a tannin containing byproduct on enteric and manure greenhouse gas emissions of finishing beef cattle.

The primary objective for this agreement is to conduct a series of experiments to assess the ability of either a condensed and hydrolyzable tannin product or a tannin containing byproduct (such as peanut skins) to reduce enteric and manure emissions. The effects of tannins on ruminal fermentation patterns and greenhouse gas emissions will first be explored in vitro. For this experiment the ANKOM RF gas production system (ANKOM, Macedon, NY) will be used. This system includes a 250-mL incubation jar and a gas pressure module, which is fixed onto the top of the jar. The treatments will include 5 dietary inclusion levels of a tannin containing feed ingredient, depending on the concentration of tannins in the ingredient used. Overall, the target inclusion level of tannins will be identified, with selections made at: 0%, 0.5%, 1.0%, 1.5%, or 2.0% of dietary dry matter. This experiment will be conducted over 3 runs, where each treatment in each run is replicated 3 times. Ruminal fluid will be collected from cannulated steers that were consuming either a finishing diet (higher concentrate) or a starter diet (lower concentrate). The proposed basal substrate used will be the same diet fed to the cannulated steers. Fluid will be collected 1-2 hours following feeding. The in vitro incubations will last 48 hours, during which time cumulative gas production will be assessed every 10 minutes. Following the incubation, a sample of the ruminal fluid will be collected and analyzed for volatile fatty acids by gas chromatography and ammonia production using a commercial colorimetric assay kit. A sub-sample of gas will be analyzed for carbon dioxide (CO2) and methane (CH4) concentrations using a GHG gas chromatograph. The tannin inclusion level and two diets (either a high or low concentrate diet) will be analyzed as a completely randomized design in a 2 x 5 factorial arrangement. Once an optimum dose of tannin inclusion level from the in vitro trial has been identified, this level will then be applied in an in vivo experiment, with some animals receiving no tannins, representing a control treatment. For this experiment, 54 steers with an initial body weight range of 500 to 800 lbs. will be trained to use the Calan gate system (American Calan, Northwood, NH) and two GreenFeed systems (C-Lock inc., Rapid City, SD). The Calan gates allow for the direct measurement of individual animal intake. The GreenFeed systems allow for the assessment of enteric CH4 emissions from animals in their production environment. For data collection, animals will be weighed, blood will be drawn, and urine and fecal samples will be collected at the start of the feeding trial, on day 75 (approximately halfway through the trial), and at the end (prior to being shipped to a commercial packing plant). Animal live weight will be used to assess animal performance; blood will be analyzed for urea, as an indicator of daily urine nitrogen excretion; urine samples will be analyzed for nitrogen and creatinine content (as a secondary indicator of daily urine nitrogen excretion); and fecal samples will be analyzed for nitrogen and indigestible neutral detergent fiber.