WO2024111392A1 - Methane suppressant for reducing methane generation from ruminant digestive organs, methane suppressing feed and methane suppressing method - Google Patents

Abstract

Provided are a methane suppressant which is safe and steady supply of which is guaranteed; and a methane suppressant which is more efficacious in the effect of reducing methane generation than fumaric acid and malic acid. The methane suppressant, which is for suppressing methane generated from ruminant digestive organs, comprises as an active ingredient at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid and citric acid.

Description

Methane suppressant, methane suppression feed, and methane suppression method for reducing the amount of methane produced from the digestive tract of ruminants

The present invention relates to a methane suppressant, methane suppression feed, and methane suppression method for reducing the amount of methane produced from the digestive organs of ruminants (e.g., the first stomach of cattle).

In recent years, methane produced in the first stomach (also called the "rumen") of cattle, which are ruminant animals, has been cited as one of the causes of global warming. In order to reduce this methane, methane inhibitors that reduce the amount of methane produced are being added to ruminant animal feed.

　Conventionally, methane suppressants such as 3-nitrooxypropanol and the red algae Undaria pinnatifida have been known. However, the former is a chemically synthesized substance, which makes it difficult to dispel resistance from producers and consumers, and the latter is a natural product, which means it is difficult to secure sufficient quantities.

Therefore, organic acids derived from natural products, which are relatively inexpensive and easily available, are being used as methane inhibitors. For example, a methane production-inhibiting feed composition for ruminants that contains fumaric acid as an active ingredient has been proposed (see, for example, Patent Document 1). In addition to fumaric acid, there have been reported research examples that suggest that malic acid also has the effect of reducing the amount of methane produced by the digestive tract of ruminants (see, for example, Non-Patent Documents 1 and 2).

JP 11-46694 A M. D. Carro and M. J. Ranilla "Effect of the addition of malate on in vitro rumen fermentation of cereal grains" British Journal of Nutrition (2003), 89, 181-188 N. Mohammed, Z. A. Lila, N. Ajisaka, K. Hara, K. Mikuni, K. Hara, S. Kanda and H. Itabashi "Inhibition of ruminal microbial methane production by b-cyclodextrin iodopropane, malate and their combination in vitro" J. Anim. Physiol. Anim. Nutr. 88 (2004), 188-195

However, producers are calling for more options for methods to reduce methane emissions; methane inhibitors that are safe and can be expected to be in stable supply; and methane inhibitors that are more effective at reducing methane emissions than fumaric acid or malic acid.

The present invention has been made in consideration of the above-mentioned conventional techniques, and provides a methane inhibitor that is highly safe and can be expected to be supplied stably; a methane inhibitor that is more effective at reducing the amount of methane produced than fumaric acid or malic acid.

The inventors of the present invention have conducted intensive research to solve the problems of the conventional technology. As a result, they were the first in the world to discover that a specific organic acid is more effective at suppressing the amount of methane generated than fumaric acid or malic acid.

Then, they discovered that the specific organic acid could solve the problems of the prior art, and completed the present invention. The key point of the present invention is that at least one of maleic anhydride, itaconic acid, and citric acid is used as a methane inhibitor to suppress methane generated from the digestive organs of ruminants. In other words, the above problems are solved by the present invention described below.

[1] Methane inhibitor:
The methane inhibitor of the present invention is a methane inhibitor for suppressing methane generated from the digestive tract of ruminants, and contains as an active ingredient at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid.

The methane inhibitor of the present invention preferably contains at least one organic acid selected from the group consisting of itaconic acid and citric acid as an active ingredient.

The present invention increases the options for methods to reduce methane generation, is highly safe, has the potential for a stable supply, and is more effective at reducing methane generation than fumaric acid or malic acid.

The following provides a more detailed explanation of how the present invention can be implemented.

[1] Methane inhibitor:
The methane inhibitor of the present invention is a methane inhibitor for suppressing methane generated from the digestive tract of ruminants.

Ruminants are animals that digest food by chewing it in their mouths, sending it to their stomachs, and then bringing it back into their mouths to chew it again (a process called rumination). A typical example of a ruminant is a cow, but goats, sheep, and deer are also ruminants.

Ruminants have four stomachs as their digestive organs, and methane is produced in the first stomach (also called the rumen). This methane is released into the atmosphere and is said to be a cause of global warming.

This production of methane not only contributes to global warming, but can also have a negative impact on dairy and meat productivity. If methane is produced during the digestive process, it is released into the atmosphere and is not used as an energy source by ruminants. If the amount of methane produced by ruminants over their lifetime could be reduced by 80% and used as an energy source by ruminants, it is estimated that dairy and meat productivity (e.g. feed costs) could improve by around 10%, which would enable producers to expect increased profits.

The methane inhibitor of the present invention contains as an active ingredient at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid. The structural formulas of each are shown in "Chemical formula 1" for maleic anhydride, "Chemical formula 2" for itaconic acid, and "Chemical formula 3" for citric acid.

　Conventionally, fumaric acid (see Chemical formula 4 below) and malic acid (see Chemical formula 5 below) have been known to reduce the amount of methane produced by the digestive tract of ruminants.

Although these substances have the effect of suppressing the amount of methane generated, the methane suppression effect (measured as the amount of methane generated) was only a 24% reduction for fumaric acid and a 19% reduction for malic acid, and further improvement in the effect was required.

The inventors have found that maleic anhydride, itaconic acid, and citric acid are compounds with a methane suppression effect superior to fumaric acid and malic acid. The methane suppression effect of these substances (in terms of the amount of methane generated) is surprisingly 97% reduction for maleic anhydride, 50% reduction for itaconic acid, and 30% reduction for citric acid, which is far greater than the methane suppression effect of fumaric acid or malic acid. Furthermore, these substances are produced and supplied stably in Japan, and there are no particular problems with securing the quantities.

Although the three compounds discovered this time are generally considered to be organic acids, they share no commonality or similarity in chemical structure, and it is difficult to predict that these substances will have a superior methane suppression effect compared to fumaric acid or malic acid.

The methane inhibitor of the present invention preferably contains as an active ingredient at least one organic acid selected from the group consisting of itaconic acid and citric acid. The above two compounds are effective in reducing the amount of methane generated, and also in converting the reduced amount into substances other than methane, which can be used as an energy source for ruminants, and are highly effective in improving dairy and meat productivity in livestock. In addition, these substances have a history of being used as food additives for humans, and it is expected that there will be little resistance from producers and consumers.

On the other hand, maleic anhydride has a significantly higher methane suppression effect than itaconic acid and citric acid, and although it is expected to have an effect in curbing global warming, experimental data does not deny the possibility that digestion and fermentation itself is inhibited. In terms of converting methane into an energy source and improving dairy and meat productivity in livestock, maleic anhydride is considered to be inferior to the other two compounds.

The phrase "as an active ingredient" means that at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid is contained, as long as the methane suppression effect is generated. The organic acid may be contained alone, or may be a mixture of the organic acid with other substances (e.g., additives, excipients, etc.).

[2] Methane suppression feed:
The methane-inhibiting feed of the present invention is a feed for inhibiting methane generation from the digestive tract of ruminants.

The feed contains at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid, and preferably contains at least one organic acid selected from the group consisting of itaconic acid and citric acid.

"Feed" generally refers to food given to livestock and other captive animals. There are no particular limitations on the type, but examples include roughage and concentrated feed. Examples of roughage include fresh grass, silage, hay, and straw. Roughage has a high fiber content, and is not as nutritious as concentrated feed, which will be described later. In contrast, concentrated feed is made from grains such as corn, barley, wheat, and rice; and legumes such as soybeans; and is characterized by being rich in protein and highly nutritious.

The feed of the present invention can be any of the above feeds. It can be obtained by mixing these feeds with at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid (e.g., the methane inhibitor of the present invention).

[3] Methane suppression method:
The methane suppression method of the present invention is a method for suppressing methane generated from the digestive tract of ruminants.

In the method of the present invention, a methane inhibitor containing an organic acid as an active ingredient is administered to ruminants.

As already explained, the methane inhibitor used is one containing at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid as an active ingredient, preferably at least one organic acid selected from the group consisting of itaconic acid and citric acid.

The method for administering the methane inhibitor is not particularly limited, but an example would be to feed ruminants with a feed mixture that contains the methane inhibitor.

The present invention will be explained in more detail below using examples. However, the present invention is not limited to the forms of the following examples.

[Methane suppression effect of organic acids]
Various organic acids were used as methane inhibitors to evaluate their methane suppression effects. The evaluation was carried out by the following method.

Two dry cows under normal breeding conditions were prepared, and gastric juice was collected from each of the rumens. These gastric juices were mixed in a mass ratio of 1:1, and the same mass of artificial saliva was added to prepare a mixed gastric juice. The "artificial saliva" was prepared according to McDougall (Biochemical Journal. 43: 99-109.1948). Specifically, the mixture consisted of 1.00 liters of distilled water, 0.13 g of _MgCl2.6H2O , _{3.68 g} of _Na2HPO4 , 0.0530 g of CaCl2.2H2O, 0.570 g of KCl, 0.470 g of NaCl, and 9.80 g of _NaHCO3 . _The mixture _was bubbled with _CO2 gas before use and adjusted to pH = 6.8.

Separately, 0.2 g of Feed A and an organic acid as a methane inhibitor were added to a test tube at a predetermined molar concentration and mixed to prepare a feed containing a methane inhibitor. Feed A was prepared by mixing 0.067 g of dried grass (orchard grass) powder with 0.133 g of concentrated feed. A commercially available powdered concentrated feed (product name "Monster 18" (manufactured by Mercian Corporation)) was used as the "concentrated feed".

The mixed gastric juice (10 ml) was poured into this test tube, the gas phase was replaced with nitrogen gas, and the tube was then sealed with a butyl rubber stopper and screw cap, and anaerobic cultivation was carried out at a temperature of 39°C for 24 hours.

In this case, the amount of organic acid added was adjusted so that the final concentration in the culture vessel was 2.5 mM. For example, when maleic anhydride (molecular weight: 98.1) was used as the methane inhibitor, 0.0025 g was added to achieve a final concentration of 2.5 mM. For other organic acids, the amount added was calculated based on their molecular weight so that the final concentration would be 2.5 mM.

After the anaerobic cultivation was completed, the gas pressure in the gas phase was measured with a pressure gauge, and the total gas production was calculated. In addition, a portion of the gas in the gas phase was sampled with a syringe, and the amount of methane produced was calculated by gas chromatography. The methane suppression effect was evaluated by comparing with Comparative Example 1, in which no methane suppressant was added.

Furthermore, the culture fluid was subjected to short-chain fatty acid analysis by gas chromatography, and the bacterial flora was analyzed by next-generation sequencing. A gas chromatograph (model number: GC-14B, manufactured by Shimadzu Corporation) was used for gas chromatography, and a next-generation sequence analysis service (Hokkaido System Science Co., Ltd.) was used for next-generation sequencing, and the base sequence was deciphered using a desktop next-generation sequencer (product name: MiSeq system, manufactured by Illumina, Inc.).

(Comparative Example 1)
In the above evaluation method, a sample was prepared by adding only the feed A to a test tube without adding a methane inhibitor (organic acid), and evaluation was performed.

Example 1
In the above evaluation method, citric acid was used as the methane inhibitor and the evaluation was performed.

(Comparative Example 2-9, Example 2-3)
The evaluation was carried out in the same manner as in Example 1, except that the type of organic acid was changed to one shown in Table 1.

The results of Comparative Examples 1-9 and Examples 1-3 are shown in Table 1.

(evaluation)
As shown in Table 1, the organic acids shown in Examples 1 to 3 (citric acid, itaconic acid, and maleic anhydride) exhibited excellent methane suppression effects and were effective as methane suppressants compared to the organic acids shown in Comparative Examples 2 to 9. Furthermore, the organic acids shown in Examples 1 to 3 exhibited high methane suppression effects even compared to malic acid (Comparative Examples 6 and 7) and fumaric acid (Comparative Example 9), whose methane suppression effects have already been reported.

Table 2 shows the results of the analysis using next-generation sequencing.

As shown in Table 2, clear changes in the bacterial flora were confirmed in Comparative Example 1, which did not use a methane inhibitor, Example 1, which used citric acid, and Example 2, which used itaconic acid. It is believed that this change in the bacterial flora contributes to the improvement of the methane inhibition effect.

Lactobacillus is a species of bacteria that produces lactic acid, Megasphaera produces propionic acid and butyric acid, and Streptococcus produces lactic acid.

From this, it is believed that by adding citric acid or itaconic acid, the hydrogen process leading to methane production changes to hydrogen process through the production of propionic acid or butyric acid via lactic acid, resulting in the production of lactic acid, propionic acid, etc., and suppressing the production of methane. Since lactic acid, propionic acid, and butyric acid are metabolized as energy sources for ruminants, it is expected that this will improve the dairy and meat productivity of livestock, which will ultimately lead to increased profits for producers.

[Differences in methane suppression effects depending on feed type]
An evaluation was performed to see whether there was a difference in the methane suppression effect depending on the type of feed. The evaluation was performed in the same manner as in Comparative Example 1.

(Comparative Example 10, Examples 4-6)
Anaerobic culture was carried out in the same manner as in Comparative Example 1 and Examples 1-3, except that the type of feed was changed from feed A, which was mainly made of concentrated feed used in Example 1, etc., to feed B, which was mainly made of dried grass powder. As feed B, the same dried grass powder and concentrated feed used in feed A were used, but the ratio was reversed, and a mixture of 0.133 g of the grass powder and 0.067 g of the concentrated feed was used. The material powder was added to the culture solution to a concentration of 10 mM. The results after culture are shown in Table 3.

(evaluation)
As shown in Table 3, even if the type of feed was changed from a feed mainly composed of concentrated feed to a feed mainly composed of dried grass powder, no change was observed in the methane suppression effect. In other words, it is considered that the organic acids shown in Examples 1 to 3 have a methane suppression effect regardless of the type of feed.

The methane inhibitor of the present invention has a higher effect of reducing the amount of methane generated from the digestive tract of ruminants (methane suppression effect) than the conventionally known fumaric acid and malic acid. Therefore, it can be suitably used as a methane inhibitor for livestock used to produce dairy and meat.

Claims (6)

A methane suppressant for suppressing methane generated from the digestive tract of ruminants, comprising:
The active ingredient is at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid and citric acid. 2. The methane inhibitor according to claim 1,
The active ingredient is at least one organic acid selected from the group consisting of itaconic acid and citric acid. A methane suppression feed for suppressing methane generated from the digestive tract of a ruminant, comprising:
Contains at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid and citric acid. The methane-suppressed feed according to claim 3,
Contains at least one organic acid selected from the group consisting of itaconic acid and citric acid. 1. A method for reducing methane emissions from the digestive tract of a ruminant, comprising:
A methane inhibitor containing an organic acid as an active ingredient is administered to ruminant animals.
The methane inhibitor used in the present invention contains, as an active ingredient, at least one organic acid selected from the group consisting of maleic anhydride, itaconic acid, and citric acid. 6. The method for suppressing methane according to claim 5,
The methane inhibitor used in the present invention comprises, as an active ingredient, at least one organic acid selected from the group consisting of itaconic acid and citric acid.