Increase Fat Content of the Diet
System: Beef Cattle
Mainly applicable for: Zero- or low-grazing systems; animals in fattening and finishing phase or lactating (suckler/beef cows); low inititial fat content of the diet in order to be able to supplement substantial amounts of fat.
Not applicable or effective for: Full grazing systems without possibility for fat supplementation; young suckling animals. Also not applicable if the reference diet already has a 8% (concentrate-rich diets) or 7% (high-forage diets) fat content.
Description
Supplementing fats, oils, or free fatty acids (saturated or (poly)unsaturated) to the ration or to concentrate feed, in order to reduce the enteric methane emission in the rumen. It also delivers a high energetic source to the animal. Different types of lipid can be fed, such as coconut oil, sunflower oil, palm oil, or ingredients with a very high oil content such as crushed oilseeds. They can be applied in different forms; the so-called unprotected forms exerting an effect on rumen fermentation versus the protected forms with minimal impact and interaction with rumen fermentation. Exceeding the maximum level of usage, in particular of unprotected forms, increases dietary fat content too much and negatively impacts rumen function, fibre digestion, and dry matter intake.
Mechanism of effect
Increasing the lipid content reduces enteric methane emissions, mainly due to i) increased digestive efficiency, as lipids are high in energy (and low in fibres); ii) inhibition of methanogenesis, as lipids reduce the growth and activity of methane-producing microbes; iii) an effect on cell-wall degradation and the rumen fermentation profile (the type of volatile fatty acids and amount of hydrogen/methane produced) leading to less hydrogen production as substrate for methanogens. Adding lipids also leads to a lower nitrogen (N) content relative to the energy content of the diet, thereby reducing N excretion and N2O emission. Some lipids are associated with land use change (LUC) effects, such as palm oil or soybean oil from areas with deforestation risks.
Reference situation
Normal (low) fat content of diet, enabling supplementation with up to 5-6% of dietary dry matter in high-concentrate diets and 3-4% in high-forage diets.
Legend
| ● – Small effect (<5%) | o – No effect |
| ●● – Medium effect (5-20%) | ● – Unfavourable effect |
| ●●● – Large effect (>20%) | ● – ● – Variable effect (depending on farm characteristics or way/level of implementation) |
Effect on total greenhouse gas (GHG) emissions
| Mean effect and range in kg CO2-equivalents | per kg product | per farm | |||
| Mean | Min-Max | Mean | Min-Max | Level of evidence | |
| Fat supplementation | ●● | N/A – ●● | ●● | N/A-●● | High |
Effect per emission source
| Mean effect on emission from | Manure | Animal | Feed and forage production | Barn & farm inputs | |||
| CH4 | N2O | CH4 | CO2 | N2O | LUC | CO2 | |
| Fat supplementation | ● | ●● | ● | ● | |||
*risk of an adverse effect (see ’cause of variable or unfavourable effect’)
Cause of variable or unfavourable effect
Fat supplementation
The effect depends on the type of lipid, application form, inclusion rate, diet composition, animal characteristics, and degree of (un)saturation. The effect can be large up to a maximum of 6% supplemental fat in concentrate-rich diets and 4% supplemental fat in forage-rich diets, which may also depend on the form of supplemental fat (rumen-protected or non-protected) and the type of unsaturated fatty acids in the supplemented fat source. The potential methane reduction is greater in concentrate-rich rations compared to forage-rich rations, possibly because of lower rumen pH and less impact of potential decline in fibre digestibility. Exceeding the maximum usage of supplemented fat (maximum supplement of 6% of dietary dry matter, leading to a total of 8-9% dietary fat) may negatively impact rumen function, fibre digestion, dry matter intake and growth.
| Literature references | Lipid Supplementation |
|---|---|
| Wang, et al., 2018 | Mitigating Greenhouse Gas and Ammonia Emissions from Beef Cattle Feedlot Production: A System Meta-Analysis |
| Beauchemin et al., 2022 | Invited review: Current enteric methane mitigation options |
| Nayak et al., 2015 | Management opportunities to mitigate greenhouse gas emissions from Chinese agriculture |
| Almeida et al., 2021 | Meta-analysis quantifying the potential of dietary additives and rumen modifiers for methane mitigation in ruminant production systems |
| Zhang et al. 2021 | Combined effects of 3-nitrooxypropanol and canola oil supplementation on methane emissions, rumen fermentation and biohydrogenation, and total tract digestibility in beef cattle |
| Arndt et al., 2022 | Full adoption of the most effective strategies to mitigate methane emissions by ruminants can help meet the 1.5 °C target by 2030 but not 2050 |
| Yulianri Rizki Yanza et al., 2020 | The effects of dietary medium-chain fatty acids on ruminal methanogenesis and fermentation in vitro and in vivo: A meta-analysis |