Search

This review examines the current state of knowledge regarding the effectiveness of different dietary ruminant enteric methane mitigation strategies and their modes of action together with the issues discussed regarding the potential harms/risks and applicability of such strategies. By investigating these strategies, we can enhance our understanding of the mechanisms by which they influence methane production and identify promising approaches for sustainable mitigation of methane emissions. Out of all nutritional strategies, the use of 3-nitrooxypropanol, red seaweed, tannins, saponins, essential oils, nitrates, and sulfates demonstrates the potential to reduce emissions and receives a lot of attention from the scientific community. The use of certain additives as pure compounds is challenging under certain conditions, such as pasture-based systems, so the potential use of forages with sufficient amounts of plant secondary metabolites is also explored. Additionally, improved forage quality (maturity and nutrient composition) might help to further reduce emissions. Red seaweed, although proven to be very effective in reducing emissions, raises some questions regarding the volatility of the main active compound, bromoform, and challenges regarding the cultivation of the seaweed. Other relatively new methods of mitigation, such as the use of cyanogenic glycosides, are also discussed in this article. Together with nitrates, cyanogenic glycosides pose serious risks to animal health, but research has proven their efficacy and safety when control measures are taken. Furthermore, the risks of nitrate use can be minimized by using probiotics. Some of the discussed strategies, namely monensin or halogenated hydrocarbons (as pure compounds), demonstrate efficacy but are unlikely to be implemented widely because of legal restrictions.

Camelina seed or seed processing derivatives, i.e., cake, are cheap alternative protein feed ingredients for meat type poultry. Camelina is an oilseed crop containing 36.8% oil in seeds, while in the cake the oil content accounts for 6.4-22.7%. If compared with other Brassicaceae family plants, camelina is distinguished by a unique fatty acid composition, because the content of α-linolenic fatty acid (C18:3n-3; ALA) varies from 25.9 to 36.7% of total fatty acids. The total tocopherol content in camelina oil and cake are, respectively, 751-900 and 687 mg/kg. Addition of camelina to poultry nutrition increases the amount of n-3 polyunsaturated fatty acids (PUFA) in poultry meat and liver. The content of ALA in chicken muscles increases by 1.3-4.4, 2.4-2.9 and 2.3-7.2 times after supplementing chicken diets with, respectively, camelina cake (8-24%), seed (10%), and oil (2.5-6.9%) in comparison with the control group. Camelina cake (5-25%), seed (10%) and oil (2.5-4%) inclusion in chicken diets results in 1.5-3.9 times higher total n-3 PUFA content in muscles and liver. Meanwhile, supplementation of chicken diets with camelina oil (4-6.9%), seed (5-10%) and cake (5-25%) results in, respectively, a 1.8-8.4, 1.6-1.9 and 1.3-2.9 times lower n-6/n-3 PUFA ratio in muscles, and 3.29 times lower n-6/n-3 PUFA ratio in the liver. After inclusion of different amounts of camelina cake in chicken diets, a healthy for human nutrition n-6/n-3 PUFA ratio from 1.6 to 2.9 was found in chicken muscles.