Table 6.
Summary of seaweeds with CH4 mitigation effects in vivo.
| Seaweed | Seaweed Dose (% of Dry Matter (DM)) and Animal Trial Used | CH4 Decrease vs. Control | Effects of TGP, TVFA and Digestibility | Reference |
|---|---|---|---|---|
| Asparagopsis taxiformis (R) | <2% OM | Asparagopsis inclusion resulted in a consistent and dose-dependent reduction in enteric CH4 production in sheep over time, with up to 80% CH4 mitigation at the 3% offered rate compared with the group fed no Asparagopsis spp. (p < 0.05). | Sheep fed Asparagopsis had a significantly lower concentration of total volatile fatty acids and acetate, but higher propionate concentration. No changes in live weight gain were identified. Supplementing Asparagopsis in a high-fibre diet (<2% OM) results in significant and persistent decreases in enteric methanogenesis over a 72 d period in sheep. | [141] |
| 0.05–0.20% feed | Asparagopsis spp. was included in the feed of Brahman-Angus cross steers at 0.00%, 0.05%, 0.10%, and 0.20% of feed organic matter. Emissions were monitored in respiration chambers fortnightly over 90 d of treatment. Asparagopsis demonstrated decreased CH4 up to 40% and 98%. | Asparagopsis resulted in weight gain improvements of 53% and 42%, respectively. | [15] | |
| 5% inclusion rate in OM | Feeding cows a 1–2% dry mass supplement of Asparagopsis per day reduced CH4 release by up to 95% without altering fermentation processes. | No negative impact on milk taste. No obvious negative impacts on volatile fatty acid production. | [14] | |
| Ascophyllum nodosum (B) | 2% of diet dry matter (DM) | Limited effect on rumen microbiome. | Feeding 8 Canadian rams with sun-dried seaweed extract (Tasco; Acadian Seaplants Ltd., Dartmouth, NS, Canada) containing a mixture of polysaccharides and oligosaccharides and derived from Ascophyllum nodosum resulted in decreased faecal shedding of E. coli. | [76] |
| Seaweed-derived beta-glucans and marine omega-3 oils (fish oil) | 5 L (120 g/L) per day of milk replacer (MR) and one of the following: (1) 40 g n-3 PUFA per day; (2) 1 g β-glucans per day (GL) and (3) 40 g n-3 PUFA per day and 1 g/d β-glucans in a 2 × 2 factorial design. | Improved immunity. | 44 Holstein Friesian bull calves pre- and post-weaning. | [142] |
B, brown; DM, dry matter; OM, organic matter; R, red; TGP, total gas production; TVFA, total volatile fatty acids.