TECHNICAL FIELD

[0001] The invention relates to a feed additive for rumen comprising an ammonium source. BACKGROUND ART

[0002] Considerable research and development efforts have been devoted to developing feeds and/or feed supplements for ruminants like bovine and ovine (cattle and sheep), which may lower costs of total feed, reduce burden on valuable or expensive feed sources, but yet are effective as feed. Ovine and bovine can herd on relatively poor ground and feed supplements are useful for improvement in growth, milk production and the like.

[0003] Growth, wool and milk production are considered to be directly dependent on nitrogen availability from diet. Such nitrogen is often provided in the form of vegetable protein, like grass, maize and other common bulk feed. Further, soy bean meal is often used as supplementary protein source to promote growth, wool and milk production in ruminants.

[0004] Ruminants do not require dietary protein or amino acids per se, as proteins can be synthesized by microbes in the rumen of the ruminant from any hydrolysable nitrogen source. Hence, low molecular weight organic amine containing compounds, like urea, are hydrolyzed to ammonia by certain microbes in the rumen. The liberated ammonia is used by microbes to synthesize amino acids or other organic amine compounds suitable for further metabolism.

[0005] Low molecular weight amine comprising compounds (e.g. urea) are simple chemicals, and generally cheaper than dietary proteins. Furthermore, dietaiy proteins require agricultural land for production. It would be preferred to use this agricultural land to produce food for human consumption instead of feed for animal consumption.

[0006] Therefore, such low molecular weight amine compounds have been used as an alternative or supplement to dietary proteins for promoting growth, wool and/or milk production in ruminants.

[0007] However, the use of a feed or feed supplement comprising a low molecular weight nitrogen source like urea is associated with loss of ammonia, and even ammonia toxicity in ruminants. Once ingested by a ruminant, a low molecular weight nitrogen compound (e.g. urea) is rapidly converted by microbes residing in the rumen into, among other things, ammonia. Ammonia loss ensues as the rate at which ammonia is released as a sudden high peak in the rumen being greater than the microbe’s ability to convert the ammonia to amino acids. The excess ammonia, which is not utilized by the microbes will end up in the blood stream and be converted to urea in the liver, and largely excreted. The ammonia may be even released in such high levels, that they may be toxic to ruminants. Symptoms of ammonia toxicity (i.e. when peripheral blood exceeds about 1 mg

ammonia/100 ml of blood) include muscular twitching, ataxia, excessive salivation, tetany, bloat and respiration defects.

[0008] Significant efforts have been devoted to remedy the shortcomings associated with administration of low molecular weight compound like urea. For instance,

compositions comprising a low molecular weight nitrogen compound have been developed, which allow 'delayed release' of ammonia in the rumen. The 'delayed release' of ammonia in the rumen is intended to dampen the sudden peak of ammonia in the rumen, which typically occurs shortly after ingestion of feed or feed supplements comprising an immediate-release low molecular weight nitrogen compound like urea. Delayed release of ammonia from such a source is typically achieved by partially or fully coating a nitrogen compound with a so- called controlled release agent or coating.

[0009] For instance, US6231895B1 discloses a feedstock suitable for lactating ruminants comprising a urea encapsulated within a degradable polymeric coating, which is used as a controlled release agent.

[0010] Slow release formulation adds a process step, and it may be difficult to reliably administer such feed additives to ruminants, as the coated products will in part be chewed by the ruminant, destroying the slow release characteristics. Further, reliable slow release feed additives are relatively expensive.

[0011] Another composition includes liquid starch-urea mixtures sprayed on bulk feed (GB 1499624).

[0012] Another approach, disclosed in US3507662 is to provide a nitrogenous feed additive comprising an amine-compound, and protect this from hydrolysis by the microorganisms in the rumen by the addition of tannin, which would result in better use of the nitrogen in the crude protein. A comparable suggestion is made in Ann. Zootech. (1993) 42:127.

[0013] Providing an improved cheap but effective feed additive for ruminants would be desirable.

[0014] Therefore, there is a need in the art for compositions comprising a low molecular nitrogen compound that allows suitable nitrogen utilization, which limits ammonia toxicity or inefficient use of ammonia derived from such low molecular weight nitrogen compounds, by rumen microbes or microorganisms. SUMMARY OF THE INVENTION

[0015] It is an object of the invention to provide a low molecular nitrogen source as feed additive for ruminants, being effective in replacing protein feed for conversion in the rumen.

[0016] The present invention provides a feed additive for ruminants, comprising ammonium sulphate and a water extract of sweet chestnut wood.

[0017] The present invention furthermore provides a concentrated feed mixture comprising ammonium sulphate and water extract of sweet chestnut wood.

[0018] The present invention furthermore provides a feed composition comprising bulk feed and a feed additive mixed therein, comprising ammonium sulphate and water extract of sweet chestnut wood.

[0019] The feed additive of the invention is effective in decreasing the requirement for crude protein in the diet. It is a further advantage that the feed additive of the invention may be effective in decreasing the requirements of sulphur containing amino acids in the feed.

DETAILED DESCRIPTION

[0020] The feed additive for ruminants according to the present invention, comprises ammonium sulphate and a water extract of sweet chestnut wood.

[0021] In one embodiment of the invention, the feed additive composition is in solid form, like powder or granules.

[0022] In another embodiment of the invention, the feed additive is in the form of a liquid.

[0023] The feed additive in the form of a solid can for example be mixed with other dry feed components, like feed concentrate or can be converted into a feed concentrate together with other common components of feed concentrates by extruding or pressing the ingredients into pellets. If in liquid form, the liquid can for example be sprayed on bulk feed, like hay or grass or silages (corn, grass, leguminosae) as silage preservative, or the feed additive can be mixed or dissolved in water supply. Preferably, the additive is in a solid form like powder or granules.

[0024] Nitrogen sources in the rumen are commonly divided into two categories; degradable crude protein and non-protein nitrogen. Both crude protein and non-protein nitrogen are hydrolyzed and utilized by rumen microbes. Crude protein is rapidly degraded into peptides and amino acids. Peptides can then be converted to amino acids or converted directly to microbial protein. Amino acids can be used directly by microorganisms for protein synthesis or can be further broken down. Overall, nitrogen in the rumen is known to promote the fermentation of carbohydrates and to improve fiber digestibility and microbial protein synthesis. Non-protein nitrogen generally is hydrolyzed to, or available as, ammonia, which can be used by rumen microbes. [0025] Under normal conditions (a standard ruminant diet), the rumen ammonia pool derived from the diet is typically very small (estimated to be around 5 - 20 mg/dl of ruminal fluid) and turns over rapidly, i.e. the ammonia not utilized by rumen microbes will normally be absorbed by the reticulo-rumen wall to ultimately reach the liver, where it will be converted into urea. Excess of rumen ammonia is therefore discarded in the urine after conversion to urea in the liver. Yet, the ammonia level in the rumen can be enhanced - if it would be low - by urea produced by the liver, which can return to the rumen by diffusion through the rumen wall and saliva.

[0026] Thus, ruminants are able to recycle systemic nitrogen back to the rumen. Nitrogen recycling typically occurs via blood and gut lumen exchanges of urea and ammonia. Nitrogen can re-enter the digestive tract, mainly through the rumen wall, where it can be absorbed again or be re-used for microbial protein synthesis. This allows nitrogen to remain longer in the body and increases the chance to utilize dietary nitrogen sources efficiently or to the fullest. Nitrogen recycling is maximized or enhanced when urea blood levels are high. In addition, products of ruminal fermentation (i.e., volatile fatty acids and C02) also contribute to the influx of urea from the blood stream into the rumen.

[0027] The use of low molecular nitrogen compounds (non-protein nitrogen) may disrupt the ruminal ammonia metabolism prevailing under normal conditions because of a sudden peak of liberated ammonia and cause substantial nitrogen loss by conversion to urea and excretion or may even cause ammonia toxicity.

[0028] Ammonia toxicity refers to a situation where ammonia levels in the blood exceed a certain ammonia threshold. It is generally accepted that when peripheral blood exceeds about 1 mg ammonia per 100 ml of blood, this may cause toxicity symptoms in a ruminant, e.g.

neurological symptoms.

[0029] The water extract of sweet chestnut wood comprises sweet chestnut tannins, which appear to aid the microorganisms in the rumen to quickly metabolize the free ammonia that is liberated from the ammonium sulfate and thereby capture the nitrogen in amino acids and other molecules. This was quite unexpected, as - according to US3507662 - tannins are suggested to only slow down the liberation of ammonia from biopolymers. By increasing the metabolism of free ammonia, the ruminant more efficiently utilizes the nitrogen source. Because of the efficient use of the nitrogen source, relatively low amounts of ammonium sulphate can be used such that the risk of ammonia toxicity is precluded. Without being bound to the theory, the inventors think that the relative low amount of tannins administered to the ruminant is instrumental in achieving the desired effect. [0030] The pH in the rumen is a further factor to take into account. The rumen has an optimal pH which is generally kept substantially constant. The pH typically ranges from pH 5.5 to pH 6.8, with fiber-digesting bacteria thriving best at pH 6.0-6.8 and starch-digesting bacteria at 5.5-6.0. Typically, the best balance of fiber and starch digestion occurs at a rumen pH of around 6.0.

[0031] Small changes, e.g. of pH, will easily disturb the fine symbiotic balance between various kinds of microorganisms, almost all of which have specific functions in the complex fermentation processes in the rumen. A change in pH will also decrease the metabolism of ammonia. Administering urea, and/or the release of ammonia from compounds like urea typically increases ruminal pH to values above pH 6.7. At such pH levels, rumen fermentation and ammonia metabolism is impaired.

[0032] A diluted ammonium sulphate solution typically has a pH in the range close to 6 (a 0.1M solution has a pH of 5.5). Hence, the feed additive of the present invention is instrumental in keeping the proper pH close to 6. This is contrasted with e.g. urea, which is basic, and/or with other compounds liberating ammonia that may increase the pH in an unwarranted way.

[0033] Ammonium sulphate is widely available as by product of several chemical or biochemical processes and is generally supplied as granules or powder.

[0034] A preferred type of ammonium sulphate is ammonium sulphate produced in biochemical processing. It is important that the ammonium sulphate is of feed grade, with no (or very low) amount of heavy metals.

[0035] Water extract of sweet chestnut wood comprises tannins. Tannins from chestnut wood are known as a food additive, leather tanning processes, feed additive and the like. Tannins are used as feed additive in poultry to lower bacterial pressure, with little effect on growth (see e.g. Poultry Science (2008) 87:521-527).

[0036] The amount of tannins in the water extract generally is about 40 wt% or more, preferably between 40-60 wt%, more preferably 45 and 55 wt% expressed as total polyphenols and with a dominant part as ellagic acid (or esters therefrom), calculated on dry matter. Higher concentrated extracts would be suitable as well. Tannins from sweet chestnut wood comprise gallic acid and ellagic acid, and hydrolysable esters therefrom with monosaccharides, like vescalin, castalin, vescalagin and castalagin.

[0037] The water extract of sweet chestnut wood for use in the feed additive according the present invention can be obtained by extraction of chestnut wood. Extraction is well known, and extracts are commercially available. Examples of suitable sources of tannin include: Silvafeed (Silva srl -Italy), Farmatan or Globatan (Tanin Sevnica - Slovenia), King Brown or Tanno-SAN (King Tree France, Sanluc Belgium). The product generally is supplied as powder or granule.

[0038] Lactating cows or full-grown cows eat about 30-50 kg weight of feed (on dry matter), mainly comprising hay, grass, maize and the like. Further, generally, concentrated feed supplement is given, often comprising a concentrated proteins source like soy bean meal. The concentrated feed supplement generally is given in an amount between 5 and 15 wt% relative to the total feed (calculated on dry matter), like 1-7 kg, also depending on the weight of the animal.

[0039] With the feed additive of the present invention, it is possible to replace 1 kg of concentrated protein source like soy bean meal (SBM) with about 120-150 grams ammonium sulphate and 5-7 gram of water extract of sweet chestnut wood (chestnut tannin; CT). Further, some additional grain source can be given to balance the amount of energy in the feed.

[0040] For example, 1 kg SBM can be exchanged with 130 grams AS, 5.5 grams CT and 1.1 kg barley.

[0041] Furthermore, the sulphur in ammonium sulphate can be converted by the ruminal flora to sulphur containing amino acids like methionine and cysteine. The ammonium sulphate therefore is also effective in increasing the availability of sulphur containing amino acids. This is important, as such amino acids may otherwise become limiting. Feed additives containing protected sulphur containing amino acids are available, for example as Smartamine of Addiseo or Mepron of Evonik. Such amino acid sources may be used for example with highly productive lactating cows, but the feed additive of the present invention obviates the need of these expensive additives.

[0042] For example, the amount of concentrated feed supplement fed to bovine may be 2-5 kg. and generally, a concentrated protein source may be 10-40% of the concentrated feed supplement. For example, bovine may, on average, receive 0.5, 1 kg or 2 kg of concentrated protein source like SBM per day. All or part of the crude protein source can be replaced with the feed additive of the invention.

[0043] The ammonia sulphate may be fed to a ruminant in an amount of about 50-300 g. This generally amounts to about 0.05 to 0.5% of the total dry weight of feed per day. Preferably, ammonium sulphate is fed in amounts of about 0.1 -0.3% of the total dry weight of feed per day. Suitable amounts include 50, 100, 150 or 200 grams per day per bovine animal.

[0044] The amount of sweet chestnut extract, comprising the sweet chestnut tannin, relative to ammonium sulphate generally will be about 3% - 6% of commercially available dry chestnut extract. Preferably, the amount is about 4-5 wt%. The sweet chestnut extract may be diluted with e.g. bulking material, in which case the amounts will be calculated relative to the chestnut extract only.

[0045] In general, the amount of dry sweet chestnut tannin comprising extract is about 3 to 6 grams per 100 grams of ammonium sulphate.

[0046] Suitable amounts are 2-20 gram of sweet chestnut extract per bovine animal per day. Preferably, the amount of water extract of sweet chestnut fed to a bovine per day is about 10 mg or lower, and even more preferable about 9 mg or lower. Preferred amounts include 3-9, more preferably 3-8, like for example 5, 6 or 7 mg per day.

[0047] The above described amounts are for bovine (cow). For sheep or goats, the amounts can be scaled down relative to the amount of total feed as consumed by sheep or goat. As - for example - sheep generally weight between 30 and 50 kg, the amounts can be calculated to be about 4-10% of the amounts given for bovine.

[0048] The feed additive of the invention may be fed to a ruminant as such, but preferably is fed in admixture with other ingredients such as minerals, vitamins, other feed additives, and the like. For example, the feed additive of the invention may be incorporated in a feed composition or a feed supplement composition.

[0049] In an embodiment, the feed additive of the invention is fed to a ruminant in an amount of about 0.005 % to about 0.06% of the animal body weight. In a preferred embodiment, said feed additive is fed to a ruminant in an amount of 0.01-0.04% such as for example about 0.02 or 0.03% of the animal body weight.

[0050] In an embodiment of the invention, the feed additive of the invention is fed to a ruminant in an amount ranging between about 10 grams per day to about 500 grams per day, e.g., about 20 grams per day to about 400 grams per day, or about 30 grams per day to about 300 grams per day.

[0051] In a preferred embodiment, the feed additive is used in an amount ranging from about 50 grams per day to about 200 grams per day.

[0052] Generally, the feed additive of the invention is used in feed for a ruminant once every 3 days, preferably once every 2 days, more preferably once a day.

[0053] Preferably, the feed additive of the invention is used over an entire season.

[0054] Optionally, the feed additive of the invention is fed in portions and fed more than one times a day for instance 5 times per day, 4 times per day, 3 times per day or 2 times per day.

[0055] The feed additive of the invention may be fed to a ruminant, simultaneously with other conventional ruminant feeds and/or feed supplements (e.g. com silage, alfalfa silage, mixed hay, grains, and the like) or the feed additive may be fed separately, i.e. as a supplement offered in the pasture or compound feed offered during milking.

[0056] Preferably, the feed additive of the invention is fed to a ruminant separately from other conventional ruminant feeds and/or feed supplements.

[0057] The feed additive of the invention may be fed to a ruminant that may be held outside for periods of time, for example, at least two weeks, 1 month, two months, three months, four months, or five or more months, in an environment suitable for grazing, such as pastureland or other fields with grass or other types of vegetation suitable for ruminants or cattle animals, during the rest of the day. The feed additive may also be fed to a ruminant held in an agricultural building (e.g. bam) or farm enclosure for periods of time, for example at least one week, two weeks, three weeks, 1 month, two months, three months, four months, or five or more months.

[0058] Generally, the ruminant is allowed to graze or feed ad libitum.

[0059] The ruminant preferably is a ruminant selected from the group consisting of bovine, ovine, and caprine.

[0060] The bovine, ovine, or caprine preferably is a domestic animal and may be a male or a female (particularly a lactating female).

[0061] Preferably, the bovine is selected from the group consisting of cows, bulls, steers, stags, heifers, oxen, calves, and the like. In a preferred embodiment, the bovine is a bull, steer or heifer (beef). In another preferred embodiment, the ruminant is a bovine, preferably beef and/or a lactating cow.

[0062] In another preferred embodiment, the bovine is a cow, preferably a lactating cow.

[0063] In an embodiment, the ovine is sheep, or a lamb. In another preferred embodiment, the ovine is an ewe, preferably a lactating ewe.

[0064] The descriptions above and examples below are intended to be illustrative and not limiting. It will be apparent to the person skilled in the art that alternative and equivalent embodiments of the invention can be conceived and reduced to practice, without departing from the scope of the claims set out below.

EXAMPLES

Example 1; formulation A:

[0065] A granular mixture of 5.5 grams CT (Tanno-SAN), 130 grams AS and 1.0 kg barley (as energy carrier), was used to replace the 0.8 - 1 kg soybean meal (which may be intact, toasted, extruded or protected) in a grass-maize ration for high producing dairy cows.

Example 2; formulation B: [0066] A granular mixture of 6.0 grams of CT (Tanno-SAN) and 150 grams of AS was used to replace 130-150 grams of protected urea (which was coated to obtain slow release properties) in dairy cows.

Example 3; formulation C

[0067] A powdery mixture of 5-6 grams CT (Tanno-SAN) and 135 grams of AS was used to replace about 100 grams protected urea and 20 grams protected sulphur amino acids (cysteine, methionine) in dairy cows or fattening beef.