Screening of Macroalgae Species for Enteric Methane Mitigation Effect in vitro
Open Access
- Author:
- Wasson, Derek
- Graduate Program:
- Animal Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 01, 2021
- Committee Members:
- Adele Turzillo, Program Head/Chair
Alexander Nikolov Hristov, Thesis Advisor/Co-Advisor
Kevin John Harvatine, Committee Member
Tara L Felix, Committee Member - Keywords:
- macroalgae
methane
ruminants - Abstract:
- The objective of this thesis was to discover the effects of multiple species of macroalgae on total gas production (TGP) and composition, volatile fatty acid (VFA) molar proportions, ammonia (NH3) concentration, and microbial populations during batch culture in vitro fermentation with buffered rumen inoculum. A total mixed ration (TMR) was supplemented with a low dose (2% of dry matter (DM)) of macroalgae to replicate a practical commercial dairy cattle ration. This work was conducted in response to recent research that identified the red macroalgae, Asparagopsis taxiformis (AT), as an effective enteric methane (CH4) mitigation supplement in livestock diets. While effective in decreasing CH4, several questions about the practical viability of AT remain, prompting the need for research on other possible native, sustainable, and CH4 inhibiting macroalgae species. A total of thirty-two incubations were conducted with 70 species of macroalgae that were harvested in waters surrounding North America, including a cultured AT. Treatments (2% of macroalgae on DM basis + TMR) were triplicated within incubation and compared with a Control (CON; TMR only) and were duplicated across incubations. Asparagopsis taxiformis decreased CH4 yield (mL CH4/g of substrate) by 99% when compared with CON. No other macroalgae investigated in this study decreased CH4 yield. Mastocarpus papillatus and Sargassum fluitans increased CH4 yield by 11 and 10%, respectively. Total VFA concentration was decreased 10% by AT and AT decreased molar proportion of acetate 9% and increased molar proportion of propionate 14%. In the confines of this series of incubations no other macroalgae were identified as potential inhibitors of methanogenesis.