A new study led by Embrapa has been testing the use of detoxified castor meal as a soybean meal replacement in beef cattle diets and its potential to reduce methane emissions. The study is conducted at Embrapa South Livestock in Bagé, in southern Brazil, in collaboration with Embrapa Cotton and the Federal University of Santa Maria, and aims to assess consumption, digestibility, and safety of using castor meal in animal feed. Castor beans originally contain ricin, a toxic component. Nevertheless, through the detoxification performed by the industry, castor meal has large potential for ruminant nutrition, especially as it contains up to 45% crude protein (around 10% more than soybean meal) at a lower cost. Preliminary tests with small ruminants have shown the inexistence of adverse effects from using detoxified castor meal to feed such polygastric animals. Monogastric animals like poultry, fish and swine cannot tolerate castor meal and cannot consume the coproduct. According to Bruna Machado, the animal scientist who was responsible for the studies as part of her PhD thesis, castor meal is being tested to be safely introduced into the Brazilian animal market. “We are working to reach suitable and safe conditions to use castor meal in ruminant diets, to supplement the diets of both grass-fed and confined animals,” she explained. For Liv Severino, a researcher at Embrapa Cotton who has been working with castor oil plants for about 20 years, the tests with beef cattle represent a significant advance and entail great expectations from the castor oil industry worldwide. "India is the world's absolute top producer of castor beans, followed by China, and neither country has been able to use castor meal in animal feed. Thus the step we are taking is a global breakthrough", the researcher asserts, foreseeing expressive added value to the product based on the success of the experiments. Methodology The doctoral thesis is entitled “Uso seguro do farelo de mamona como alimento para animais ruminantes e para a redução das emissões de metano entérico” [Safe use of castor meal as feed for ruminant animals and to reduce enteric methane emissions]. The project was held in collaboration with UFSM's Pastures and Supplements Laboratory. The research was advised at Embrapa by the researcher Cristina Genro, and by professor Luciana Pötter at UFSM. On the whole, 20 one-year-old Brangus heifers were divided into four groups, each of which had access to a feed under a given treatment. The animals received a base diet for all treatments, composed of 1% cattle feed concentrate and 2% of pre-dried oat silage on demand. The treatments comprised different levels of castor meal inclusion as a replacement for soybean meal. The substitution levels of 10, 20 and 30%, were assessed against the control feed that had no added soybean meal. “Each animal only has access to one of the four troughs in the pen with its respective castor inclusion level. That is possible because each heifer is identified through an ear-implanted chip, which only gives access to their previously designated trough”, Bruna explains. New diet and reduced methane emissions One of the potential advantages of the castor meal tested in the study is reducing beef cattle enteric methane production and emissions. That is one of the factors being assessed alongside ruminant nutrition with the goal of making animal farming increasingly more competitive and sustainable. “One of the main sources that contributes to emissions of such gas is the process of enteric fermentation in ruminants, and methane is a very relevant gas for the goal of reducing global warming. As Brazil has one of the world's largest cattle herds, one of the ways that the country can meet the commitment to reduce methane emissions it has internationally pledged is through more efficient diet management and elaboration”, Bruna asserts. Detoxification of castor beans Castor oil plants are cultivated for oil extraction from their seeds or beans. The meal is left as a by-product, and so far it had only been used as an organic fertilizer due to its toxicity from the presence of ricin in its composition. The toxic protein ricin can inactivate ribosomes, impairing protein synthesis, and causing cell death. However, the oil extraction industry can efficiently detoxify castor meal, making its use in ruminant feed possible. When castor meal undergoes the suitable process, the by-product can be used as a replacement for soybean meal in ruminant diets, which benefit from its high crude protein content and lower cost.