JP7002068B2 - Ruminant breeding method - Google Patents

Description

The present invention relates to a method for breeding ruminants. In particular, the present invention relates to a technique for adjusting the water content of feces excreted from ruminants.

Generally, in the field of livestock, a concentrated feed having high nutritional value is often used together with a roughage such as pasture for the purpose of increasing the milk yield and weight of livestock. Concentrated feed contains a large amount of easily digestible carbohydrates (starch, etc.) such as corn, wheat, and soybeans, while roughage is fermented hay (hay, straw), which is dried grass, or green-cut grass. Mainly (silaged ones).

Ruminants are able to ingest and digest roughage because they have lumens (rumens). Rumen occupies the largest volume of multiple stomachs of ruminants and is rich in microorganisms (lumen microorganisms) capable of decomposing (lumen fermentation) indigestible polysaccharides such as cellulose and hemicellulose in forage. It has been.

However, cellulose and hemicellulose in the forage often bind to lignins and exist as a lignin-cellulose complex and a lignin-hemicellulose complex, respectively. Such a complex may not be sufficiently decomposed in rumen fermentation, and the roughage has a problem that the feed efficiency tends to be insufficient. In addition, it has been considered unfavorable in terms of the environment because a large amount of undigested material causes an increase in the amount of feces.

In addition, roughage is susceptible to grass yields and crops, and supply is unstable. Especially in Japan, since most of the roughage depends on imports, price fluctuations are generally large, and imports may be difficult due to various circumstances of the exporting country, which may put pressure on ranch management.

Therefore, there is a demand for a ruminant feed that can be replaced with grass, has excellent feed efficiency, is inexpensive, and is stably available.

Here, in order to increase the nutritional concentration in the feed, it is common practice to add a concentrated feed containing a large amount of easily digestible carbohydrate (starch) to the roughage. In order to maintain the milk yield of dairy livestock or to maintain the gain of meat livestock, it is necessary to increase the feed intake as well, but the energy requirement due to the increase in milk yield and the increase in physique is required. This is because the rate of increase exceeds the rate of increase in the amount of feed consumed. However, carbohydrates such as starch in concentrated feeds can sharply lower the pH of the rumen, resulting in rumen acidosis. Rumen acidosis is a type of ruminant disease caused by the rapid ingestion of carbohydrate-rich grains, concentrates, fruits and the like. In rumen acidosis, gram-positive lactic acid-producing bacteria, especially Streptcoccus bovis and Lactobacillus spp., Increase in rumen, resulting in abnormal accumulation of lactic acid or volatile fatty acids (VFA), resulting in pH in rumen. Decreases (pH 5 or less). As a result, it causes the reduction or extinction of protozoa (protozoa) in the rumen and certain bacteria. In particular, acute acidosis is extremely dangerous because it causes congestion and dehydration of the rumen (a large amount of fluid moves into the stomach with an increase in gastric osmotic pressure), as well as coma and death.

To prevent rumen acidosis, it is important to avoid sudden changes in feed composition, stabilize rumen fermentation, and reduce pH fluctuations. In addition, since saliva contains baking soda and contributes to pH regulation, it is also important to feed a feed capable of saliva secretion by sufficient rumination. However, there is also a concern that if the nutritional value of the feed is lowered due to fear of rumen acidosis, energy will be insufficient and milk production will decrease.

As a feed for preventing rumen acidosis, Patent Document 1 discloses a livestock feed obtained by applying a high impact force to a wood raw material and crushing it into fine particles. Further, regarding the pelletized feed, Patent Document 2 describes the production of feed by pelletizing the processed food residue, and Patent Document 3 (Japanese Patent Laid-Open No. 2013-518880) describes pelletizing lignocellulosic biomass. Proposed.

Further, Patent Document 4 discloses that feeding a feed containing neutral detergend fiber, starch and apple juice lees to a calf underdeveloped rumen alleviates rumen acidosis and improves fecal properties. There is.

Japanese Unexamined Patent Publication No. 2011-83281 Japanese Unexamined Patent Publication No. 10-75719 International release WO2011 / 097075 Japanese Unexamined Patent Publication No. 2013-255433

In general, feces excreted from ruminants such as cattle have a large amount of water, and it is difficult to directly perform treatment such as composting. In particular, when a ruminant is fed a concentrated feed, the excreted feces become moist. Therefore, it is necessary to concentrate the ruminant feces by a squeezing machine or the like and adjust the water content by mixing auxiliary materials (such as ogako), which requires a lot of cost. Especially in the summer when the environmental temperature is high, the water content of the feces becomes higher than usual, causing pests and other hygiene problems.

Therefore, an object of the present invention is to develop a technique for reducing the water content of feces discharged from ruminants.

As a result of diligent studies on the above-mentioned problems, the inventors of the present invention have found that the water content in feces can be reduced by feeding feed containing wood pulp to ruminants, and have completed the present invention.

The present invention includes, but is not limited to, the following aspects.
(1) A method for reducing the fecal water content of a ruminant, which comprises ingesting a feed containing 1 to 30% by mass of wood pulp to the ruminant.
(2) A method for breeding ruminants, which comprises feeding ruminants a feed containing 1 to 30% by mass of wood pulp and collecting ruminant feces.
(3) The method according to (1) or (2), wherein the ruminant is ingested a feed containing a concentrated feed but not containing wood pulp before ingesting the feed containing wood pulp.
(4) The fecal water content at the time when the feed containing wood pulp was ingested was 1% or more lower than the fecal water content at the time when the feed containing wood pulp was ingested (3). The method described in.
(5) The method according to any one of (1) to (4), wherein the fecal water content at the time when the feed containing wood pulp is ingested is 75 to 87%.
(6) The method according to any one of (1) to (5), wherein the ruminant is a cow.
(7) The method according to any one of (1) to (6), wherein the wood pulp is kraft pulp.
(8) The method according to any one of (1) to (7), wherein the wood pulp has a kappa value of 5 or more.
(9) The method according to any one of (1) to (8), wherein the wood pulp is a pulp treated with oxygen delignin.
(10) The method according to any one of (1) to (9), wherein the wood pulp is an oxygen-de-lignin kraft pulp obtained by treating unbleached kraft pulp with oxygen-derignin treatment and has a copper value of 5 to 15.

According to the present invention, it is possible to reduce the water content of feces discharged from ruminants such as cattle. Therefore, according to the present invention, it is possible to reduce the labor and cost required for the processing required for producing compost and the like.

The present invention reduces the fecal water content of a ruminant by ingesting a feed containing 1 to 30% by mass of wood pulp to the ruminant. The present invention is preferably applied to ruminants who are ingesting a feed containing a concentrated feed but not containing wood pulp before ingesting a feed containing 1 to 30% by mass of wood pulp. Further, it is preferable that the fecal water content at the time when the feed containing wood pulp is ingested is 1% or more lower than the fecal water content at the time when the feed containing wood pulp is ingested.

The ruminant feed of the present invention is applied to ruminants. Examples of ruminants include cows such as dairy cows and fattening cows, sheep and goats. When the feed of the present invention is fed to a ruminant, the age, physique, health condition and the like of the ruminant to be applied are not particularly limited, and for example, it can be used from a calf to an adult cow during the feeding period.

The feed of the present invention contains wood pulp, which is a pulp derived from wood, and preferably contains 1 to 30% by mass of wood pulp based on dry matter, more preferably 2 to 25% by mass, and 3 to 3 to. It is more preferably contained in an amount of 20% by mass.

Although the feed of the present invention contains wood pulp, pulp produced by a known pulping method can be used without limitation. For example, both mechanical pulp and chemical pulp can be applied. Examples of the mechanical pulp include crushed wood pulp (GP), refiner ground wood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP) and the like. Examples of the chemical pulp include kraft pulp (KP), melted kraft pulp (DKP), sulfite pulp (SP), melted sulfite pulp (DSP) and the like. Further, both bleached pulp and unbleached pulp can be used. Among these, chemical pulp treated with oxygen delignin, bleached chemical pulp and the like are preferable. Further, pulp having a copper value of 5 to 15 and kraft pulp are more preferable, and kraft pulp treated with oxygen delignin having a kappa value of 5 to 15 is particularly preferable.

In the feed for ruminants of the present invention, the pulp may be composed of one kind or a mixture of a plurality of pulps. For example, chemical pulp (broadwood kraft pulp, coniferous kraft pulp, melted broadleaf kraft pulp, melted coniferous kraft pulp) or mechanical pulp (crushed wood pulp, refiner groundwood pulp, thermomechanical pulp, chemothermomechanical pulp) with different raw materials and manufacturing methods. ), May be used as a mixture of two or more.

As the raw material wood, for example, hardwoods, conifers, miscellaneous trees, bamboos, kenafs, bagasses, and air chambers after squeezing palm oil can be used. Specifically, as broad-leaved trees, beech, cinnamon, white hippo, poplar, eucalyptus, acacia, oak, itayakaede, sennoki, elm, kiri, magnolia, yanagi, sen, ubamegashi, konara, kunugi, tochinoki, zelkova, mizume, mizuki , Aodamo and the like are exemplified. Conifers include Sugi, Spruce, Karamatsu, Black pine, Todomatsu, Himekomatsu, Ichii, Nezuko, Harimomi, Iramomi, Inumaki, Fir, Sawara, Togasawara, Asunaro, Hiba, Tsuga, Kometsuga, Hinoki, Ichii, Inugaya (Beihiba), Lawson Hinoki (Beihi), Douglas fir (Beimatsu), Sitka spruce (Beitohi), Radiata pine, Eastern spruce, Eastern white pine, Western larch, Western fur, Western hemlock, Tamarack and the like are exemplified.

Kraft pulp When kraft pulp is produced from wood chips, the wood chips are put into a cooking pot together with the cooking liquid and used for kraft cooking. Further, it may be used for cooking modified craft methods such as MCC, EMCC, ITC, and Lo-sold. Further, the cooking type such as 1 Vessel liquid phase type, 1 Vessel gas phase / liquid phase type, 2 Vessel liquid phase / gas phase type, and 2 Vessel liquid phase type is not particularly limited. That is, the step of impregnating and holding the alkaline aqueous solution of the present application may be installed separately from the conventional device or site for the purpose of permeation treatment of the cooking solution. Preferably, the unbleached pulp that has been cooked is washed with a washing device such as a diffusion washer after extracting the cooking liquid. The liquid ratio of the wood chip to the chemical solution can be, for example, 1.0 to 5.0 L / kg, preferably 1.5 to 4.5 L / kg, and more preferably 2.0 to 4.0 L / kg. ..

Further, in the present invention, an alkaline cooking liquid containing 0.01 to 1.5% by mass of the quinone compound per absolute dry chip may be added to the cooking kettle. If the amount of the quinone compound added is less than 0.01% by mass, the amount added is too small to reduce the copper value of the pulp after cooking, and the relationship between the copper value and the pulp yield is not improved. Furthermore, the reduction of lees and the suppression of the decrease in viscosity are also insufficient. Further, even if the addition amount of the quinone compound exceeds 1.5% by mass, further reduction of the kappa value of the pulp after cooking and improvement of the relationship between the kappa value and the pulp yield are not observed.

The quinone compound used is a quinone compound as a so-called known cooking aid, a hydroquinone compound or a precursor thereof, and at least one compound selected from these can be used. Examples of these compounds include anthraquinone, dihydroanthraquinone (eg, 1,4-dihydroanthraquinone), tetrahydroanthraquinone (eg, 1,4,4a, 9a-tetrahydroanthraquinone, 1,2,3,4-tetrahydroanthraquinone). , Methylanthraquinone (eg 1-methylanthraquinone, 2-methylanthraquinone), methyldihydroanthraquinone (eg 2-methyl-1,4-dihydroanthraquinone), methyltetrahydroanthraquinone (eg 1-methyl-1,4,4a). , 9a-Tetrahydroanthraquinone, 2-methyl-1,4,4a, 9a-tetrahydroanthraquinone) and the like, anthraquinone (generally 9,10-dihydroxyanthraquinone), methylanthrahydroquinone (eg, 2-methyl). Anthraquinone), dihydroanthrahydroanthraquinone (eg, 1,4-dihydro-9,10-dihydroxyanthracene) or an alkali metal salt thereof (eg, disodium salt of anthraquinone, 1,4-dihydro-9,10-). It is a hydroquinone compound such as dihydroxyanthracene disodium salt), and examples thereof include precursors such as anthraquinone, anthranol, methylanthron, and methylanthranol. These precursors have the potential to be converted to quinone or hydroquinone compounds under cooking conditions.

The cooking liquid preferably has an active alkali addition rate (AA) of 10 to 35% by mass per weight of dry wood chips. If the active alkali addition rate is less than 10% by mass, the removal of lignin and hemilulose is insufficient, and if it exceeds 35% by mass, the yield and quality are deteriorated. Here, the active alkali addition rate is obtained by converting the total addition rate of NaOH and Na ₂ S as the addition rate of Na ₂ O, and multiplys NaOH by 0.775 and Na ₂ S by 0.795. This can be converted into the addition rate of Na ₂ O. Further, the sulfurization degree is preferably in the range of 20 to 35%. In the region where the sulfurization degree is less than 20%, the delignin property is lowered, the pulp viscosity is lowered, and the meal rate is increased.

Craft cooking is preferably carried out in a temperature range of 120 to 180 ° C, more preferably 140 to 160 ° C. If the temperature is too low, delignin (decrease in copper value) is insufficient, while if the temperature is too high, the degree of polymerization (viscosity) of cellulose decreases. The cooking time in the present invention is the time from when the cooking temperature reaches the maximum temperature to when the temperature starts to decrease, but the cooking time is preferably 60 minutes or more and 600 minutes or less, and 120 minutes or more and 360 minutes or less. Is even more preferable. If the cooking time is less than 60 minutes, pulping does not proceed, and if it exceeds 600 minutes, the pulp production efficiency deteriorates, which is not preferable.

Further, in the craft cooking in the present invention, the treatment temperature and the treatment time can be set by using the H factor (Hf) as an index. The H factor is a guideline for expressing the total amount of heat applied to the reaction system in the cooking process, and is expressed by the following formula. The H factor is calculated by integrating the time from the time when the chips and water are mixed to the time when the cooking is completed. The H factor is preferably 300 to 2000.

Hf = ∫exp (43.20-16113 / T) dt
[In the formula, T represents the absolute temperature at a certain point in time]
In the present invention, the unbleached (unbleached) pulp obtained after cooking can be subjected to various treatments, if necessary. For example, unbleached pulp obtained after kraft cooking can be bleached.

The pulp obtained by kraft cooking can be subjected to oxygen delignin treatment. As the oxygen delignin used in the present invention, a known medium concentration method or high concentration method can be applied as it is. In the case of the medium concentration method, the pulp concentration is preferably 8 to 15% by mass, and in the case of the high concentration method, the pulp concentration is preferably 20 to 35% by mass. Sodium hydroxide and potassium hydroxide can be used as the alkali in oxygen delignin, and oxygen from the cryogenic separation method, oxygen from PSA (Pressure Swing Adsorption), and VSA (Vacuum Swing Adsorption) can be used as the oxygen gas. ) Can be used.

The reaction conditions for the oxygen delignin treatment are not particularly limited, but the oxygen pressure is 3 to 9 kg / cm ² , more preferably 4 to 7 kg / cm ² , and the alkali addition rate is 0.5 to 4 mass per pulp dry weight. %, The treatment temperature is 80 to 140 ° C., the treatment time is 20 to 180 minutes, and other known conditions can be applied. In the present invention, the oxygen delignin treatment may be performed a plurality of times. Further, the kappa value of the kraft pulp after being subjected to oxygen delignin treatment or the like is preferably 5 to 15.

For the purpose of further lowering the copper value and improving the whiteness, the pulp subjected to the oxygen delignin treatment is, for example, then sent to a washing step, washed, and then sent to a multi-step bleaching step for multi-step bleaching. It can be carried out. The multi-stage bleaching treatment of the present invention is not particularly limited, but acid (A), chlorine dioxide (D), alkali (E), oxygen (O), hydrogen peroxide (P), ozone (Z), and the like. It is preferable to combine a known bleaching agent such as hydrogen peroxide with a bleaching aid. For example, the chlorine dioxide bleaching stage (D) and the ozone bleaching stage (Z) are used for the first stage of the multi-stage bleaching treatment, the alkali extraction stage (E) and the hydrogen peroxide stage (P) are used for the second stage, and the third and subsequent stages are used. A bleaching sequence using chlorine dioxide or hydrogen peroxide is preferably used. The number of stages after the third stage is not particularly limited, but considering energy efficiency, productivity, etc., it is preferable to finish with three or four stages in total. Further, a chelating agent treatment stage with ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) or the like may be inserted during the multi-stage bleaching treatment.

Preparation and Feeding of Feed The feed of the present invention may be prepared by preparing wood pulp together with other feed components, and the prepared compound feed can be fed to ruminants. Other feed components include roughage (eg grass), concentrates (eg cereals such as corn and wheat, beans such as soybeans), bran, rice bran, okara, proteins, lipids, vitamins, minerals and additives (preservation). Agents, coloring agents, fragrances, etc.), etc.

When a concentrated feed is added to the feed of the present invention, for example, grains such as corn, wheat, barley, and polished rice can be used. In the feed of the present invention, for example, grains such as rice, wheat, barley, barley, mylo, and corn can be used as the main starch source.

In the present invention, it is preferable to mix the roughage at a certain level, for example, it is preferably contained in an amount of 5 to 50% by mass, more preferably 15 to 48% by mass, and may be 25 to 45% by mass in terms of dry matter. .. Raw materials for roughage include, for example, soybean, soybean meal (including soybean meal that has been subjected to sweetened heat treatment or humidified heat treatment, etc.), rapeseed meal, flaxseed meal, corn gluten meal, concentrated soy protein, wheat gluten, and wheat gluten enzyme. Decomposables and the like can be mentioned. In particular, soybean-derived crude protein feedstocks such as soybean meal (excluding those that have been subjected to sweetened heat treatment or humidified heat treatment) are fed with a large amount of soluble protein to increase the digestibility of fibers in the rumen. From the viewpoint of improving the growth of calves, and to prevent the content of crude fat in the feed from becoming excessively high due to the formulation of NDF feedstock with a relatively high content of crude fat such as DDGS, the feed It is preferable to blend in.

In the present invention, sugars may be added to the feed, and for example, glucose, fructose, sucrose, lactose, maltose and the like can be preferably added.

In addition to the above-mentioned raw materials, the feed of the present invention includes seasonings, minerals, vitamins, organic minerals, grasses, feed raw materials for gramineous plants, crystalline amino acids, fats and oils, fatty acids, fatty acid calcium, adsorbents, minerals, and plants. It may contain extracts, fermented products, flavoring agents, organic acids, antibiotics, animal feeds, microbial components, herbal medicines, enzyme preparations, oligosaccharides, woody feeds, binders, other plant processing by-products, etc. ..

Examples of pasture include orchardgrass, timothy, oatshay, alfalfa, Italian ryegrass, red clover and the like, and examples of feed raw materials derived from gramineous plants include sorghum, wheat straw and rice straw. Can be mentioned. However, feed raw materials derived from grass and grasses are not easy to digest for calves under 3 months of age, for example, so they are supplied as roughage as needed for the purpose of stimulating the stomach wall of rumen. The calf feed of the present invention is preferably not contained, or even if it is contained, it is preferably contained in a small amount.

In a preferred embodiment, wood pulp and other feed components may be compression molded into pellet-like form. The feed used in combination with the feed pellets of the present invention may be in the form of pulp, powder, or fluff, but it may be in the form of cubes, pellets, or the like, or in the form of cut sheet. It is preferable because it can be easily mixed with other feeds such as grass, and can be easily transported and handled.

When compression molding into a cube shape, it is preferable to form a cube having a length of 5 to 50 mm, a width of 5 to 50 mm, and a height of 5 to 50 mm. In the case of compression molding into pellets, it is preferable to form a cylinder having a diameter of 5 to 50 mm and a length of 5 to 80 mm. The device for performing compression molding is not particularly limited, but a briquette (manufactured by Kitagawa Iron Works), a ring die type pelletizer (manufactured by CPM), a flat die type pelletizer (manufactured by Dalton) and the like are desirable.

In the case of a sheet-like form, it is preferable to use a sheet piece having a basis weight of 300 to 2000 g / m ² and a thickness of 5 to 50 mm × 5 to 50 mm.

The ruminant feed of the present invention preferably has a water content of 15% or less. By setting the water content to 15% or less, transportability can be improved and putrefaction by microorganisms can be reduced. The water content of the feed may be, for example, 1% by mass or more, or may be adjusted to 5% by mass or more.

The ruminant feed of the present invention can have, for example, the total amount of digestible nutrients (TDN: Total Digestible Nutrients) of 50 to 95%, but may be 60 to 85%, and further may be 65 to 80%. The crude protein (CP: Crude Protein) can be, for example, 5 to 40%, but may be 10 to 30%, and further may be 13 to 25%.

The present invention will be described in more detail with reference to specific examples, but the present invention is not limited to the following specific examples. In the present specification, the concentration and% are based on mass unless otherwise specified, and the numerical range is described as including the end points thereof.

Experiment 1: Production of feed containing wood pulp Based on the formulations shown in the table below, feeds used in the control group and the test group were prepared. The feed of the control group and the feed of the test group (containing 10% of hardwood kraft pulp by dry weight) were mixed so that the total amount of digestible nutrients (TDN) and crude protein (CP) in the dry matter were almost the same (TDN). : Approximately 71 kg, CP: Approximately 13 kg).

(Roughage)
・ Corn silage (produced in-house at Kyushu Okinawa Agricultural Research Center)
・ Italian wrap silage (produced in-house at Kyushu Okinawa Agricultural Research Center)
(Concentrated feed)
・ Corn (purchased from Kumamoto Dairy Federation and Livestock Federation)
・ Soybean meal (purchased from Kumamoto Dairy Federation and Livestock Federation)
・ Compound feed (Kumamoto Dairyen, Kumadai P & F74C)
-Wood pulp Eucalyptus chips were kraft-melted with an active alkali addition rate of 16.0%, sulfide degree of 25%, and H factor of 800 to obtain unbleached kraft pulp (copper value: 21.1, ISO whiteness: 24). .8%).
After washing the above unbleached kraft pulp with tap water and preparing it to a concentration of 10%, the oxygen addition rate is 2.1% (per absolute dry pulp weight), 1.4% sodium hydroxide (per absolute dry pulp weight), and 100 ° C. , Oxygen delignin treatment was carried out in 60 minutes to obtain oxygen delignin kraft pulp (copper value: 8.6, ISO whiteness: 47.3%).
The obtained oxygen-de-lignin kraft pulp was washed with tap water and then dehydrated with a screw press (SHX-200 type, manufactured by Togoku Kogyo) to adjust the water content to 28.8% by mass.

(Additive)
・ Calcium phosphate for feed (manufactured by Onoda Chemical Industry Co., Ltd.)
・ Calcium carbonate for feed (manufactured by Iida Kogyosho)
・ Salt for feed (made by Dia Solt)

Experiment 2: Feeding test for ruminants At the Kyushu Okinawa Agricultural Research Center (Koshi City, Kumamoto Prefecture), the compound feed produced in Experiment 1 was fed to 14 lactating cows. The test was conducted from the end of May, and the compound feed of the control group was first fed, and then the compound feed of the test group was fed for 2 weeks. The details of the lactating cows fed the compound feed are as follows. In general, the milk yield of cows gradually increases after calving and reaches the peak milk yield about 3 months after the start of lactation.

In this experiment, rectal feces were collected from the anus of lactating cows, and the water content of the collected rectal feces was measured. Specifically, the collected rectal feces sample (about 50 grams) is dried at 55 ° C. for 3 to 4 days, and when the weight does not change even after half a day or more, it is regarded as a dry weight, and the following formula is used. The water content of rectal feces was calculated in.
・ Rectal fecal moisture content (%) = (pre-drying feces weight-post-drying feces weight) / pre-drying feces weight x 100

As shown in the table, the water content of rectal feces (average value of 14 animals) in the control group (before feeding the pulp-containing feed) was 87.6 ± 1.1%, whereas it was 2 after feeding the pulp-containing feed. The water content of rectal feces at the weekly stage was 85.3 ± 1.7%, and the present invention was able to significantly reduce the water content of feces (p <0.05).

Claims (5)

1-30% by mass of wood-derived kraft pulp, corn silage, Italian wrap silage, and soybean meal-containing feed for 2 weeks against ruminants consuming a feed containing concentrated feed but not wood pulp. It is a method of reducing the fecal water content of corn, including feeding the above .
The above method, wherein the kraft pulp derived from wood is oxygen-deliginized kraft pulp obtained by treating unbleached kraft pulp with oxygen delignin, and has a copper value of 5 to 15. The method according to claim 1 , wherein the total amount of digestible nutrients in the feed is 50 to 95% and the amount of crude protein is 5 to 40%. The method according to claim 1 or 2 , wherein the feed contains 3 to 20% by mass of wood-derived kraft pulp. The method according to any one of claims 1 to 3 , wherein the ruminant is a cow. The method according to any one of claims 1 to 4 , wherein the kraft pulp is a kraft pulp derived from hardwood.