Effects of Marine and Freshwater Macroalgae on In Vitro Total Gas and Methane Production

Abstract

This study aimed to evaluate the effects of twenty species of tropical macroalgae on in vitro fermentation parameters, total gas production (TGP) and methane (CH4) production when incubated in rumen fluid from cattle fed a low quality roughage diet. Primary biochemical parameters of macroalgae were characterized and included proximate, elemental, and fatty acid (FAME) analysis. Macroalgae and the control, decorticated cottonseed meal (DCS), were incubated in vitro for 72 h, where gas production was continuously monitored. Post-fermentation parameters, including CH4 production, pH, ammonia, apparent organic matter degradability (OMd), and volatile fatty acid (VFA) concentrations were measured. All species of macroalgae had lower TGP and CH4 production than DCS. Dictyota and Asparagopsis had the strongest effects, inhibiting TGP by 53.2% and 61.8%, and CH4 production by 92.2% and 98.9% after 72 h, respectively. Both species also resulted in the lowest total VFA concentration, and the highest molar concentration of propionate among all species analysed, indicating that anaerobic fermentation was affected. Overall, there were no strong relationships between TGP or CH4 production and the >70 biochemical parameters analysed. However, zinc concentrations >0.10 g.kg−1 may potentially interact with other biochemical components to influence TGP and CH4 production. The lack of relationship between the primary biochemistry of species and gas parameters suggests that significant decreases in TGP and CH4 production are associated with secondary metabolites produced by effective macroalgae. The most effective species, Asparagopsis, offers the most promising alternative for mitigation of enteric CH4 emissions.

Reducing the carbon footprint of Australian milk production by mitigation of enteric methane emissions

“…Artificially synthesised halogenated chemicals are unlikely to be used in Australia because of their potential toxicity, the risk of residues in milk, their ozone-depleting properties and because there are strict laws governing their importation and use. However, some plants such as the red sea weed, Asparagopsis taxiformis, contain high concentrations of bromoform and other halogen compounds (Burreson et al 1976) and, in a recent in vitro experiment, Asparagopsis taxiformis was shown to reduce methane production by 99% (Machado et al 2014). Thus, the supplementation of ruminant diets with red sea weed may offer a natural means of methane mitigation.…”

“…Tropical marine algae (sea-weed) have been screened for their methane-mitigation potential. The brown algae (Cystoseira trinodis and Dictyota bartayresii), and the red algae (Asparagopsis taxiformis) were identified as having particularly potent methane-inhibiting effects in vitro (Dubois et al 2013;Machado et al 2014).…”

The potential of macroalgae for beef production systems in Northern Australia

“…Macroalgae are predominantly cultured for human nutrition and production of phycocolloids (Paul and Tseng 2012). However, many species have antibacterial, antiviral, antioxidant or anti-inflammatory properties that are used in nutraceutical and health markets and may also be used to manipulate livestock health and productivity (O'Sullivan et al 2010) and methane emissions (Machado et al 2014). Speciesspecific bioactive compounds in marine macroalgae and their characteristics and functions are well described by Holdt and Kraan (2011).…”

“…The use of A. nodosum as a supplement in intensive finishing systems for beef cattle was demonstrated as beneficial to carcass characteristics and meat quality (Braden et al 2007) and, as an additive in molasses blocks, increases ruminal organic matter and total tract crude protein digestibility (Leupp et al 2005). More recently, the work of Machado et al (2014) has generated a rich data set based on in vitro incubations with algae at an inclusion rate of 17 % organic matter (OM) basis. This work provides a basis for comparing the nutritional value of macroalgae relative to beef cattle requirements relevant to Australian conditions.…”

Seasonal composition of tropical C4 grasses, and its influence on rumen prokaryotic diversity in relation to methane production from beef cattle in the northern Australian rangelands

“…Promising data is emerging that macroalgae may have the potential to dramatically reduce 936 enteric CH4 production but also provide a significant nutritional support through provision of high 937 quality proteins and lipids to cattle in low planes of nutrition (Machado et al 2014 Particle attached microbes, the majority being cellulolytic, can be lost if inoculum is strained 1004 through cheesecloth which affects in vitro fibre degradation rates and GPP (Bueno et al 2005). 1005…”