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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 Tannins and Fat Supplementation 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: Dec 31, 2025

The objective of the proposed research project is to assess the effects of: 1) fat supplementation and 2) a tannin containing product or a tannin containing byproduct on enteric and manure greenhouse gas emissions of finishing beef cattle.

Primary objectives are to conduct a series of experiments to 1) assess the effects of fat supplementation on greenhouse gas emissions (GHG) and 2) assess the ability of a condensed and hydrolyzable tannin product or a tannin containing byproduct (such as peanut skins) to reduce enteric and manure emissions. The profitability of the beef feeding industry in the Southern High Plains is threatened by the rising cost of fat supplementation. Data are needed to determine how and when finishing steers should be supplemented with fat and the associated effects on GHG. For this experiment, animal performance will be compared using four experimental diets: 1) no added fat fed throughout finishing; 2) added fat fed throughout finishing; 3) added fat fed during the first half of finishing; and 4) added fat fed during the second half of finishing. The effects of tannins on ruminal fermentation patterns and GHG 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. 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. Ruminal fluid will be collected from cannulated steers that were consuming either a finishing diet (higher concentrate) or a starter diet (lower concentrate). The 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, with cumulative gas production being assessed every 10 minutes. After incubation, ruminal fluid samples 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 (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 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 these two experiments, 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. Animals will be weighed, blood drawn, and urine and fecal samples collected at the start of the feeding trial, on day 75 (halfway), and at the end (prior to being shipped to a commercial packing plant). Animals will be assessed and samples analyzed for GHG products.