GB2303043A - An enzyme supplement in dry pet food - Google Patents

Abstract

The use is provided of a non-starch polysaccharidase as a component of a dry pet food comprising 15% by weight or more of at least one cereal and less than 20% by weight of water. The effect of such a use is to decrease the viscosity of stools produced by an animal fed the food compared with an otherwise identical food lacking the non-starch polysaccharidase. The amount of non-starch polysaccharidase added to the dry pet food may be 1 x 10 -6 - 1% by weight of the dry pet food. The cereal may be any cereal ordinarily used in pet food such as wheat. The non-starch polysaccharidase may be any one or more of a xylanase, a * small Greek beta *-glucanase, a cellulase, a pectinase and a mannanase. The dry pet food may be formed by applying a solution of the non-starch polysaccharidase to extruded pellets of pet food. Alternatively, the non-starch polysaccharidase may be applied to a suitable carrier which is then mixed with other components of the food. This mixture is then extruded into pellets of dry pet food. The dry pet food increases nutrient digestibility and reduces stool volume. The food also results in higher stool dry matter, and the animal producing stools having improved consistency and appearance.

Description

Use Of An Enzyme Supplement In Dry Pet Food The present invention relates to the use of an enzyme supplement in a dry pet food, and in particular to such a use in which the enzyme supplement is capable of reducing the volume and improving the consistency of stools produced by an animal fed the food.

There is an increasing trend towards feeding pets, and in particular dogs, with complete dry food instead of canned moist or semi-moist food. A complete dry food is one which fulfils all of the dietary requirements of an animal when supplemented only with water. The share of complete dry dog food in the UK dog food market increased from 9.9% in 1988 to 17.8% in 1993. This market share is continuing to increase. The principal reasons for this are that complete dry foods offer the pet owner a more convenient and cleaner method of feeding their pets.

It is however well known that complete dry pet foods have a number of disadvantages. It has been observed that feeding complete dry food to a dog increases the volume of stools produced by the animal, and in addition these stools have a poor consistency. This poor consistency makes it difficult for the owner to scoop up and dispose of the stools. This is disadvantageous particularly bearing in mind that many towns and cities have by-laws which require an owner to remove and dispose of their animal's stools. It has been speculated by Sunvold et al in Petfood Industry, September 1994 that the undesirable poor stool consistency is caused by the relatively high level of fibre normally present in dry dog food. The fiber is present in the cereal which the food contains. In particular, dry pet foods presently marketed have a cereal content of at least 15% by weight.

Because of the amount of cereal contained in dry pet foods, the foods contain relatively large quantities of insoluble and soluble non-starch polysaccharides such as mixed-linked ss-glucans and arabinoxylans. These non-starch polysaccharides are present in the endosperm and aleurone layer of cereal grains, and are difficult for monogastric animals to digest because they are deficient in the appropriate enzymes. This results in trapping of the nutrients, for instance within the cell walls of the aleurone layer, which prevents these nutrients from being available to the animal. More importantly, the soluble high molecular weight non-starch polysaccharides cause the viscosity of the gut digesta to increase which inhibits access of endogenous enzymes to their substrates.As a result of all of these factors, the stools produced by an animal fed dry pet food have a relatively poor consistency. One reason for this is considered to be their relatively high viscosity and/or water holding capacity.

This latter problem is increased by the tendency to provide dry pet foods in the form of extruded pellets. The step of extruding the pellets causes cell walls in the cereal component of the food to breakdown. Whilst this has the benefit of releasing more of the bound nutrients, it has the disadvantage of increasing the solubility of the non-starch polysaccharides. This might cause an even greater increase in the gut digesta viscosity.

In the light of this problem, the present inventors considered that the problems of high stool volume and poor stool consistency might be caused by the non-starch polysaccharides present in the cereal component of the dry foods.

It is an object of the present invention to provide an enzyme supplement for a dry pet food which reduces the stool viscosity of an animal fed the food compared to unsupplemented dry pet food.

According to one aspect, the present invention provides the use of a nonstarch polysaccharidase as a component of a dry pet food comprising 15% by weight or more of at least one cereal and less than 20% by weight of water for decreasing the viscosity of stools produced by an animal fed the food compared with an otherwise identical food lacking the non-starch polysaccharidase.

The inclusion of the non-starch polysaccharidase in a dry pet food has the advantage that it breaks-down the non-starch polysaccharides within the animal's gut which reduces or even prevents the tendency of the polysaccharides to increase the gut digesta viscosity. This viscosity reduction enables the re-absorption of water into the gut which results in the animal producing stools having a higher content of dry matter, improved consistency and appearance, and reduced stool volume compared to an unsupplemented dry food. It is considered that non-starch polysaccharides, both soluble and insoluble, contribute towards the water holding capacity of the fibrous fraction of stools. Thus, a stool with high water holding capacity, which is indicated by high viscosity, will be more moist than a stool with a low water holding capacity and lower viscosity.As a result, stools having a lower water holding capacity or lower viscosity dry more rapidly than stools having a higher water holding capacity or higher viscosity making them more easy to scoop up and dispose of.

The water holding capacity of stools in the above context is not the same as their water content. Water content is found to decrease only by a very small relative amount when the non-starch polysaccharidase is added to the dry pet food. On the other hand, the viscosity of the resulting stools is found to be reduced by a substantial and surprising amount. Accordingly, water holding capacity is understood to describe the strength and ability of a stool to hold excess water, which evaporates quickly and easily into the environment.

Water content is a measure of the total amount of water contained in the stools, and can be measured for instance by heating a stool for around 15 hours at around 100"C to liberate all of the contained water.

Further benefits of the dry pet foods include improved nutrient digestibility compared to an unsupplemented dry pet food because of the reduction in the gut digesta viscosity. Also, stool odour is reduced whilst the scoop ability of the resulting stools is markedly improved. The dry pet foods provided by the use of the present invention also result in improved body weight gain and feed conversion ratio for puppies and growing dogs, and in improved milk yields of lactating bitches.

It is preferred that the dry pet food of the invention comprises 25-70% by weight of the at least one cereal, more preferably 40-60% by weight. This cereal can be any one or combination of wheat, triticale, barley, maize, sorghum, oats, rice, rye or a by-product or any of these. It is particularly preferred that the cereal is wheat or a wheat by-product.

It is further preferred that the moisture content of the dry pet food should be controlled such that the food comprises 5-15% by weight of water.

The non-starch polysaccharidase is included in the dry pet food preferably in an amount of 1 x 10.6 - 1% by weight, more preferably 1 x 105 - 0.5% by A weight, and most preferably 1 x 104 - 0.2% by weight based on the food as a whole.

The non-starch polysaccharidase may be any one or more of a xylanase, a glucanase, a cellulase, a pectinase or a mannanase.

In the case that the non-starch polysaccharidase is a xylanase, then it can be obtained from a bacterium such as Bacillus, Streptomyces, Clostridium, Thermonospora, Microtetraspora, or Ruminococcus. However, it is more preferred that the xylanase is obtained from a fungus such as Trichoderma, Aspergillus, Humicola or Neocallimastix. It is particularly preferred that the xylanase is the low pI xylanase (pI = 5.2) and/or the high pI xylanase (pI = 9.0) obtained from Trichoderma longibrachiatum obtainable by the method of Example 22 of WO 92/06209. It is particularly preferred that the xylanase is the high pI xylanase. The xylanase may be a modified xylanase obtained by inserting, deleting or replacing one or more different amino acid residues in any one of the above-mentioned xylanases.

In the case that the non-starch polysaccharidase is either a ss-glucanase or a cellulase, such an enzyme can be obtained from Trichoderma. If the nonstarch polysaccharidase is a pectinase, then it can be obtained from Aspergillus. A suitable mannanase can be obtained from Caldocellum, Aspergillus, Pseudo m onas, Trichoderma or Strep to myces.

In a further embodiment of the present invention, the dry pet food may further comprise at least one of a protease, an a-galactosidase, a lipase, an amylase and a phytase. Such additional enzymes possess further advantageous enzymic activities.

The dry pet food can be prepared in a number of ways. For instance, a solution of the non-starch polysaccharidase is applied to extruded pellets of dry pet food having a cereal content of at least 15% by weight and a water content of less than 20% by weight so that the resulting food comprises 1 x 104 - 1% by weight of the non-starch polysaccharidase. The solution of the non-starch polysaccharidase may be formed by dissolving the polysaccharidase in a suitable solvent such as water to an appropriate concentration of for example 5 mg of xylanase protein per ml of solvent.

This aqueous solution can then be sprayed on the extruded pellets so that the resulting pellets are dosed with the desired amount of polysaccharidase.

An alternative method of preparing the dry dog food is to firstly apply the non-starch polysaccharidase to a physiologically acceptable carrier. This polysaccharidase bearing carrier is then mixed with the other components constituting a dry pet food. The resulting mixture is then extruded into pellets of dry pet food having a cereal content of at least 15% by weight, a water content of less than 20% by weight, and 1 x 104 - 1% by weight of the non-starch polysaccharidase.

The physiologically acceptable carrier in the above embodiment may preferably be any one of milled wheat, maize, soya or a by-product of any thereof. The polysaccharidase bearing carrier is then mixed in an amount of e.g. 0.01 - 50g per kilo with the other components of the dry pet food, more preferably 0.1 - 10 g/kg.

The dry pet food provided by the use of the present invention is suitable for both cats and dogs, and in particular is suitable for dogs.

The present invention will now be further explained by way of the following Examples.

Example 1 The reduction of stool viscosity following treatment with a non-starch polysaccharidase was measured to demonstrate that the problems encountered with feeding complete dry dog food are at least in part related to gut digesta viscosity resulting from the presence of non-starch polysaccharides in the food.

A stool sample was collected from a male, 11 month old labrador fed only a commercial complete dry dog food which approximately comprises in terms of wt. %: cereals 50% meat and animal derivatives 20% vegetable derivatives 10% vegetable protein extracts 10% fats and oils 7% vitamins/minerals 2.5% colouring agents and other additives 0.5% The viscosity of the stool samples from the dog were measured by mixing the samples thoroughly with a spatula to obtain a uniform sample. Six 1.5 ml microcentrifuge tubes were filled with the stool samples and centrifuged for approximately 10 minutes at 5000 rpm. The supernatants from each tube were pooled and centrifuged for a further 2 minutes. 0.5 ml of the supernatant was extracted and placed into the cup of a Brookfield Viscometer (model no. DV-11), and the viscosity measured at 12 rpm at room temperature.

The viscosity of two samples was measured in this way until a constant viscosity reading was obtained. The control sample (without addition of a non-starch polysaccharidase) was allowed to run with the viscometer on for 1 hour to measure any loss of viscosity with time and friction from the spindle. The test sample, to which 5 1ll of the high pI xylanase obtained from Trichoderma longibrachiatum was added (corresponding to a 1.0% dilution by volume of the supernatant) directly into the supernatant in the viscometer cup, was also allowed to run for one hour. Readings were taken every ten seconds on the test sample. The results of these experiments are set out in Table 1.

Table 1

Time (mins) Faecal viscosity (cp) Faecal viscosity (+ control xylanase3 (cp) 0 4.19 4.11 60 3.91 3.65 Total reduction (cp) 0.28 0.59 Total reduction % 6.68 13.92 It should be noted that the viscosity readings in this Example were measured at room temperature (22.5"C). This is approximately 15"C lower than the normal body temperature of the dog. Accordingly, the effect of the enzyme in vivo would be expected to more rapid.

The above results demonstrate that the inclusion of a xylanase in a dry dog food reduces stool viscosity. The reduction of viscosity in the case of the control is believed to be due to friction inside the cup of the viscometer or the effect of bacteria naturally present in the stool sample. At least a 0.31 cp reduction in viscosity can be attributed to the addition of exogenous xylanase.

Example 2 Two feeding trials were performed to measure the effect of exogenous xylanase on stool volume and consistency from dogs fed complete dry dog food.

Trial details: Trial 1 Trial 2 number of dogs 12 12 breed of dogs mixed beagle life stage of dogs adult adult number of treatments 4 4 replicates per treatment 12 12 dogs per replicate 1 1 design of trials' latin square latin square diet form extruded extruded '6 This design places each dog on each treatment, therefore eliminating breed, age, sex and genetic differences.

Diet: whole barley 11.5 maize whole feed 4.8 meat meal 48% 4.8 meat meal P 4.2 soybean meal 48% 7.6 whole wheat Bulk 33.5 wheatfeed bulk 23.9 dye 0.04 chicken fat 1.5 chicken digest 3 sugar beet pulp 2.4 vitamin/mineral premix 2.9 dry matter 84.4 moisture 15.6 crude fat 5.01 The same xylanase as used in Example 1 was applied by hand spray to the extruded dry dog food in an amount to provide foods having an amount of xylanase protein/kg of food of 0.0025, 0.0050 and 0.0075g.

Methodology: Dogs were housed individually for the duration of the trial. Each dog was randomly assigned a diet, three dogs on each diet at all times. Dogs were fed for one week acclimation period to the diet during which they were offered 0.5 kg per day (or sufficient above that to maintain body weight). Rejected food was measured daily. During the second week of feeding, the stools were collected every day, weighed for each dog, and then frozen. At the end of seven days, the stool collections from each dog were pooled and dry matter analysis was performed in triplicate for each dog. Dogs were then rotated on to the next diet and the cycle repeated until each dog had been fed each diet.

Dry Matter analysis: 5 g of each stool sample was placed into a dried, desiccated, cooled and preweighed metal dish. This was placed in an oven for 15 hours at about 100"C.

When removed, the dish was placed in the desiccater to cool, then reweighed. Dry matter was calculated as a percentage of wet weight.

In the final week of the trial, stool viscosity, consistency and appearance were measured. Viscosity was measured in accordance with the method described in Example 1 above (viscometer rpm adjusted as required), except that the addition of exogenous enzyme was omitted, and a reading was taken when a consistent value of viscosity had been reached.

Stool consistency and appearance were visually scored according to the following scale: 1: : firm, matt appearance, slightly crumbly 2 : firm consistency, slightly moist, glossy appearance 3 : slightly soft, shiny appearance 4 : appearance of wet cement 5 : consistency of thick custard The results of these tests are set out in the following Table 2.

Table 2

g xylanase Stool Dry * Stool Mass: Stool Stool Dry Matter protein/kg Matter Feed Consistency Viscosity Digestibility food (wt. %) Consumed Score (cp) Control 0 28.7 84 2.6 73.8 72.0 Xylanase 0.0025 29.8 72 1.8 42.6 75.5 Xylanase 0.0050 29.3 76 1.7 no 73.7 extractable supernatant Xylanase 0.0075 28.4 79 1.3 ~ 50.7 ~ 75.2 Stool Mass : Feed Consumed - Stool Volume collected in 1 week (kg)/Feed Consumed voluntarily in 1 week (kg).

The above results show that there is a significant reduction in stool volume even for foods including the lowest level of enzyme inclusion. There was also a positive effect of xylanase on increasing dry matter, reducing stool viscosity and improving the stool consistency score.

Claims (10)

ClAIMS:

1. The use of a non-starch polysaccharidase as a component of a dry pet food comprising 15% by weight or more of at least one cereal and less than 20% by weight of water for decreasing the viscosity of stools produced by an animal fed the food compared with an otherwise identical food lacking the non-starch polysaccharidase.

2. The use according to Claim 1, wherein the dry pet food comprises 1 x 10 6 1% by weight of the non-starch polysaccharidase.

3. The use according to Claim 2, wherein the dry pet food comprises 1 x 10~5-0.5% by weight of the non-starch polysaccharidase.

4. The use according to Claim 3, wherein the dry pet food comprises 1 x A 104-0.2% by weight of the non-starch polysaccharidase.

5. The use according to any preceding Claim, wherein the dry pet food comprises 25-70% by weight of the at least one cereal.

6. The use according to any preceding Claim, wherein the cereal is at least one of wheat, triticale, barley, maize, sorghum, oats, rice, rye, and/or a by-product of any thereof.

7. The use according to any preceding Claim, wherein the dry pet food comprises 5-15% by weight of water.

8. The use according to any preceding Claim, wherein the non-starch polysaccharidase is at least one of a xylanase, a -glucanase, a cellulase, a pectinase and a mannanase.

9. The use according to Claim 8, wherein the xylanase is the low pI xylanase and/or the high pI xylanase obtainable from Trichoderma longibrachiatum.

10. The use according to any preceding Claim, wherein the dry pet food further comprises one or more of a protease, an a-galactosidase, a lipase, an amylase and a phytase.