Feed supplement for restoration of gastrointestinal balance

The invention relates to a feed supplement for restoration of the gastrointestinal balance.

For digestion the intestine comprises a natural gastrointestinal flora of, amongst others Lactobacillus spp. and Bifidobacterium spp. bacteria. This natural gastrointestinal flora is referred to as the so-called 'good' flora bacteria. The good flora bacteria flourish best at an optimal pH.

If the pH in the intestine deviates from this optimal pH, the number of bacteria decreases. In order to keep the pH at the optimal level, the good flora bacteria produce medium chain fatty acids, such as propionic acid, butyric acid, acetic acid, and lactic acid. These acids cause a pH in the intestine which is about optimal for the good flora bacteria. This is known as the gastrointestinal balance.

However, this balance is disrupted when the pH deviates from the aforementioned optimal pH. Such a deviation in pH can be induced by various factors, such as stress (reduced peristaltic movements), too much feed, too fast transit of the feed through the intestine, sudden diet changes, etc. In animal husbandry and in the nutrition of pets and game animals numerous factors that can disrupt the gastrointestinal flora are continuously present. In particular, deviation to higher pH causes an abundance of so-called "bad" flora bacteria. Typical bad flora bacteria are for example CoIi spp., Salmonella spp., and Clostridium spp. These bad flora bacteria are often pathogenic. If the gastrointestinal balance is disrupted, the good bacteria are suppressed and bad bacteria take over. The pathogenic bad flora bacteria produce toxins which can hamper the restoration of the natural physiological conditions and thus of the gastrointestinal balance.

Acids dissociate when the pH value of their environment is higher than their pK _a value. Acids associate when the pH value of the environment is lower than the pK _a value. Associated acids are able to penetrate the bacterial cells. Once penetrated, they dissociate if the internal pH value of the bacteria

is higher than the pKa value of the acid. If the acids dissociate in the bacterial cell, the proton concentration in the cell increases causing the proton pump of the bacterial cell to pump out protons. This is a highly energy consuming reaction. As a result the bacteria will exhaust (Lambert 1999). In particular, CoIi spp., Salmonella spp., and Clostridium spp. are extremely sensitive to an increased concentration of protons. Another effect of the dissociation of the acids inside the bacterial cell is that the ion concentration of the cell becomes much higher than its surroundings. Therefore, osmotic pressure will increase causing the cell to take up water. The bacterial cell will take up water from its surroundings to level the osmotic pressure until it will burst. Due to these effects, the acids can act as effective bactericides in the intestine.

In order to influence the pH in the stomach it has therefore been suggested to add acids to the food. A reduction of the pH in the stomach has a beneficial effect on the digestion of proteins in the stomach. However, it has been demonstrated that only in the case of application of a high dose of formic acid a pH reduction in the first part of the small intestine could be affected. Such an intestinal pH change could not be demonstrated for citric acid, fumaric acid, propionic acid, calcium formiate, sodium formiate, and sodium fumarate. Hence, although the mere addition of acid to the food has a beneficial effect on the digestion of proteins in the stomach, it has shown to be very hard if not impossible to influence the pH of the intestine. Moreover, the addition of acids to the food has a negative effect on the jugular flora that is pH sensitive as well.

NL-A-I 006 014 describes a feed supplement in which at least a strong acid is bound to at least one organic or mineral support. The support allows a slow release of the acid so that the acid is released in the entire digestive tract. There is no specific local release in the intestine. Also, the acidic nature of the feed supplement has a negative effect on the jugular flora that is pH sensitive as well.

It would be advantageously to provide a feed supplement that can effectively influence the pH in the intestines and that does not have a negative effect on the flora in the rest of the digestive tract. More in particular, it would be desirable to have a feed supplement that provides a controlled and specific local release of acid in order to influence the pH in the intestine such that a disturbed gastrointestinal balance can be restored. US 4,511,584 and WO 2004/112496 describe a food/feed supplement that contains a composition with a single acid (lactic acid and a hydroformate, respectively) wherein said composition can be coated with a lipid or fat. Although US 4,511,584 discloses such a supplement as acidulant only, WO 2004/112496 mentions the beneficial effects on the intestinal flora.

There is however still need for further alternatives. Object of the invention is therefore to provide an alternative, economical and safe feed supplement that can locally influence the pH in the intestine.

A further object of the invention is to provide a feed supplement that enables to induce the restoration of a disturbed gastrointestinal balance.

Another object of the invention is to provide a feed supplement that works as an effective bactericide in the intestine. Preferably, the feed supplement should be palatable and have no negative influence on the feed intake

Furthermore it would be desirable to decrease degradation of the microbial proteins and therewith the formation of NH3 in the intestine part of the digestive tract, resulting in a lower environmental contamination. These and other objects are met by providing a feed supplement according to the invention which comprises a composition of at least one support and at least two acids, of which one is chosen from the group of liquid acids consisting essentially of hydrochloric acid, sulphuric acid, propionic acid, formic acid, phosphoric acid, acetic acid, butyric acid, aqueous solutions of formaldehyde and/or mixtures thereof, and at least one acid is chosen from said group or the

group of acids consisting essentially of lactic acid, sorbic acid, citric acid, calcium propionate, calcium formiate, calcium citrate, fumaric acid, malic acid and/or mixtures thereof, wherein said composition is coated with a fat coating.

Alternatively, the feed supplement comprises a support on which acid-producing bacteria are provided, wherein said composition is coated with a fat coating.

A fat-coated, slow release composition which contains more than two acids is described in WO 2006/032958. However, in this composition no support and no addition of a liquid acid is mentioned. According to the invention, the composition of at least two acids and at least one support is coated with a fat coating. This fat coating serves as an enteric coating for the components of the composition. Only when the composition reaches the intestine, the local enzyme lipase gradually breaks down the fat coating of the composition and the acids are released. Then, the acids are able to induce a local change in pH. The fat coating comprises 20 to 80 % by weight of the final fat coated composition, preferably 40 to 70 %, and more preferably 45 to 65 %• In particular hardened vegetable fats and oils with a melting point above 55 °C are preferred. Either single fat or oil types or mixtures of them should be used. Examples of vegetable fats and oils are: palm olein, palm stearin, arachis oil, babassu oil, castor oil, coconut oil, cottonseed oil, grapeseed oil, maize oil, mustardseed oil, olive oil, palm oil, palm kernel oil, rapeseed oil, safflower seed oil, sesame seed oil, soya bean oil and sunflower oil.

An advantage of the fat coating is that the composition particles do not change the pH when dispersed in water. This can be used as a test to check if the composition is coated well. If the coating leaks, acid will be released and the pH of the water will drop. If the composition is coated well, the acid of the composition starts to become effective when released from the composition, viz. when the lipase breaks down the fat coating. Hence, when the feed supplement

is orally administered, the composition does not have a negative effect e.g. on the oral and jugular flora.

The support used in the invention may be any support that is compatible with the digestion of the animal and is able to take up liquid acid. The support may be inorganic such as silica, alumina, talc, clay, zeolites and/or mixtures thereof. Preferably, the support is silica and or other substances which can absorb a few times their own weight and have no negative influence on the animal.

The particle size of the support of the feed supplement depends on the dosage and target controlled release time. In a preferred embodiment the applied support has various particle sizes, and a broad particle size distribution. This enables a good spreading of the composition particles in the intestines, the bigger particles migrate further into the intestines than the smaller particles. The liquid acids used in the invention may be hydrochloric acid, sulfuric acid, lactic acid, propionic acid, formic acid, phosphoric acid, acetic acid and butyric acid, and/or mixtures thereof depending on the target group of so-called bad bacteria and the length of the intestine track of the respective animal species (Gedek 1998 internal communication). Also aqueous solutions of formaldehyde can be used. The choice of the acids is important if it is known which undesired microflora is present. For instance, formic acid is known to be an inhibitor of Salmonella (Izat, A.L. et al., 1990, Poultry Science, 69, 1876- 1882), while propionic acid has an excellent function against fungi (HA, S. D. et al. 1997, J. Rapid Meth. Autom. Microbiol. 5(4), 309-319). Phosphoric acid can be used for a rapid decrease of pH and as an additional diet phosphor source. Formaldehyde seems to act as a broad-spectrum antibiotic for veterinary pathogens (Aarestrup, F.M. and Hasman, H, 2004, Vet. Microbiol., 100, 83-89), while butyric acid is said to be active against Salmonella and nematodes.

The weight ratio between the support and the liquid acid applied in the composition typically ranges from 10:90 to 40:60, preferably from 20:80 to 35:65, more preferably from 25:75 to about 35:65, most preferable about 30:70. Additionally, dry acids can be added as active ingredient before the spray mixing fat coating process step of the feed supplement

Typical dry acids are for example sorbic acid, citric acid, calcium propionate, calcium formiate, calcium citrate, fumaric acid, malic acid and/or mixtures thereof. In general, the dry acids typically can be added to the active ingredient part of the feed supplement of the invention in a weight ratio of 10:1, preferably 5:1, and more preferably 2.5:1 of dry acids (and derivatives thereof) versus the liquid acids.

As mentioned above, an alternative embodiment is to use lactic acid bacteria in stead of acids. This has two advantages: first of all acid is produced, which will have the same beneficial effects as already mentioned, but secondly, lactic acid bacteria are provided to the intestine, which are bacteria which are normally part of the natural flora of the animal and thus already provide for a reconstitution of the normal intestinal flora. Lactic acid bacteria are known to produce lactic acid and acetic acid. Lactic acid bacteria also inhibit the growth of harmful putrefactive micro-organisms through other metabolic products such as hydrogen peroxide, carbon dioxide and diacetyl. It is also possible to use bacteria that produce butyric acid or a combination of lactic acid and butyric acid producing bacteria (see, e.g. US 5,143,845).

Further, the use of at least on liquid acid enables a better performance in establishing the desired acidity, because a liquid acid is able to lower the pH more effective than a dry acid, which often is available as a less acid Ca-salt.

All sorts of lactic acid bacteria can in principle be used. However, preferred are bacteria that are known to reside naturally in the intestine, such as Lactobacillus bifidus (Bifidobacterium bifidum), L. acidophilus , L, casei, L. fermentum, L. salivarius, L. brevis, L. leichmanii, L. plantarum and L.

cellobiosus. Especially preferred are L. bulgaricus, L. acidophilus, Streptococcus thermophiles and L. sporogenes which is also named Bacillus coagulans. The lactic acid bacteria can be applied to the support by dipping the support in a lactic acid bacteria culture medium, whereby the support is able to absorb the medium containing the bacteria. The support plus bacteria may then be coated with fat as described above.

The enzyme lipase, which is present in the intestine, gradually breaks down the fat coating of the composition. As a consequence, the acid is set free, can penetrate into the cell walls of the bacterial cells and kill them. This will stop the production of the toxins by the bad flora bacteria. This is essential to give the good flora a chance to restore the normal microflora. A second effect of the released acid is that the pH of the intestine is lowered towards the optimal pH for the flourishing of the good flora bacteria. The thus stimulated good flora bacteria grow in number and start producing their medium chain fatty acids again. These acids preserve the optimum pH that is needed to keep up the bactericidal effect and make the pH gradually move in the direction of the pH optimum which makes the good flora bacteria thrive better at every gradual change. As a result, the gastrointestinal balance is restored Although the entire content of the intestine is relatively large with respect to the composition particles, the composition of the invention is nevertheless effective. This is due to the fact that the local concentration of acid in the immediate vicinity of the composition increases substantially, thereby creating a starting of focal point of the cascade reaction. Because of the steady supply of compositions new focal points gradually develop, which get bigger towards the end of the intestines and step by step the good flora takes over. It is believed that this principle of focal points with high local concentration of acid in the immediate vicinity of the compositions enables an effective influencing of the intestine pH. In general non-coated products are lost in the relatively enormous mass of the intestine content .

The invention further relates to a method for preparing a feed supplement as described hereinabove comprising the steps of:

- providing a support;

- adding liquid acid to said support thereby making a composition; and - providing the composition with a fat coating.

In a preferred embodiment the acid is applied on the support by spray mixing into the final product.

The production of the feed supplement is exemplified in the flowchart (see Fig. 1). In this chart a plurality of acid storage tanks (1-9) is available, from which the acid(s) can be supplied in the desired amount(s) through a weighing and mixing tank (11). Also a tank (10) for any liquid that needs to be supplied (could also be an acid) is available. The acid mixture is further mixed in a spray mixer (25) with the carrier material, which is supplied from a powder silo (12-14) via a weighing hopper (15). Additional micro-components can be added to said mixture via a weighing and dosing system (16). When the above ingredients are thoroughly mixed, lipids or oils, which are stored in heated tanks (17-21) are added via a weighing tank (22) and sprayed to coat the acid-carrier mixture. The primary conglomerate is sprayed within the mixer to prevent the so-called sheering effect, which would lead to poor free flowing properties of the feed supplement. The spray mixer (25) can be heated or cooled by a heating (24) or cooling (23) system, respectively, to adjust the temperature of the mixing and spraying processes in the spray mixer (25). After sufficient coating the mixture is put in bags through a bagging system (27) after sieving (26). Alternatively, the feed supplement is stored in silos for bulk dispatch.

Feed supplement example 1

21 weight% (based on the final feed supplement weight) active acids (mixture of formic, phosphoric, propionic and lactic acid each for 5.25%) and 9

weight% mineral support are mixed. Coating is performed with 70% hardened palm fat.

The result is a feed supplement with excellent free flowing properties, which in a concentration of 0.5% in water, after 5 minutes stirring with a magnet unit, has a pH of 6.2 at 20°C (but this value depends on the pH of the water used) and a pH of 2.78 at 80°C.

Feed supplement example 2

A food supplement is made as in Example 1 with in total 33.5% active acids (comprising the liquid acids lactic acid (12%), phosphoric acid (12%) and formic acid (4.5%) and the dry acids sorbic and citric acid (2.5% each)), the mineral support (12.2%) and 55.3 % hardened rapeseed oil The result is a feed supplement with very good free flowing properties, which in a concentration of 0.5% in water, after 5 minutes stirring with a magnet unit, has a pH of 6.2 at 20°C and a pH of 2.48 at 80°C.