Enteric methane emissions are the single largest source of direct greenhouse gas emissions (GHG) in beef and dairy value chains and a substantial contributor to anthropogenic methane emissions globally. In late 2019, the World Wildlife Fund (WWF), the Advanced Research Projects Agency-Energy (ARPA-E) and the Foundation for Food and Agriculture Research (FFAR) convened approximately 50 stakeholders representing research and production of seaweeds, animal feeds, dairy cattle, and beef and dairy foods to discuss challenges and opportunities associated with the use of seaweed-based ingredients to reduce enteric methane emissions. This Perspective article describes the considerations identified by the workshop participants and suggests next steps for the further development and evaluation of seaweed-based feed ingredients as enteric methane mitigants. Although numerous compounds derived from sources other than seaweed have been identified as having enteric methane mitigation potential, these mitigants are outside the scope of this article.
The present study evaluated the effects of a feed additive (synthesized from Yucca schidigera) on some fermentation variables. In the first of two experiments, seven concentrations of the feed additive were evaluated using the in vitro batch culture technique to determine the optimum dose to use in the second experiment. The substrates used were a total mixed ration (TMR) and alfalfa hay. The levels of inclusion were 0 (control), 0.5, 1, 2, 4, 6, and 8 g/head/d. After this initial evaluation, 2 g/head/d was selected for the second experiment. For the second study, four dietary substrates (two corn silages and two TMR; collected from different dairy farms in the Piedmont, North Carolina, area) were used. Incubation times were 3, 6, and 24 h and treatments were 0 (control) and 2 g/head/d of the feed additive. Inclusion of the feed additive did not affect (p > 0.05) in vitro dry matter disappearance. Additionally, the feed additive had no effect (p > 0.05) on short-chain fatty acid concentrations, microbial mass, and efficiency of microbial production. Methane production was reduced by 22.7% with feed additive inclusion. Similarly, lower (p = 0.013; 18%) carbon dioxide concentration was observed in the feed additive treatment. Ammonia and hydrogen sulfite concentrations were similar (p > 0.05) for both treatments. Inclusion of the feed additive at 2 g/head/d decreased methane and carbon dioxide concentrations in most of the diets. The energy saved by reducing the amount of methane produced was not partitioned into valuable products such as short-chain fatty acids and microbial mass.
Certain enzymes have improved fiber digestion of low-quality forages. Our objective was to determine the efficacy of a combination of a protease and Aspergillus oryzae and A. niger fermentation extracts on fiber digestion and rumen fermentation of bermudagrass hay supplemented with different energy concentrates. Bermudagrass hay was chopped and offered for ad libitum consumption to 20 ewes per study (33.1 ± 10.65 kg BW; Exp. 1; 36.0 ± 11.10 kg BW; Exp. 2) housed individually in 1 × 1.5-m pens (n = 5/trt). In Exp. 1, hay supplemented with DDGS at 0.25% BW, 1% BW, 1% BW + 2.3 g enzyme, or 1% BW + 3.5 g enzyme. In Exp. 2, hay was supplemented with cracked corn at the same levels as used in Exp. 1. Each experiment consisted of a 14-d dietary adaptation followed by 7 d of total fecal collection. On d 21, rumen samples were taken at 3 h intervals from each ewe for analysis of pH and VFA concentrations. Data were analyzed using PROC MIXED of SAS and orthogonal contrasts compared 0.25% vs. 1% BW, no enzyme vs. 2.3 g/d enzyme and 2.3 g/d vs. 3.5 g/d enzyme. In Exp. 1 NDF digestibility was greater (P < 0.05) from 1% vs. 0.25% BW supplement. Ruminal acetate and the acetate:propionate ratio were greatest (P < 0.05) from 0.25% BW vs. the other diets. Exp. 2, DM and OM intake were greater (P < 0.05) from the 1% BW diets and tended (P = 0.08) to be greater from 1% BW alone vs. 1% BW + 2.3 g enzyme. Ruminal acetate concentrations were greatest (P < 0.05) from 0.25% BW. Therefore, the blend of A. oryzae and A. niger fermentation extracts and a protease was not effective under the conditions of this study.
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