IE64615B1 - Bedding for animals - Google Patents

Abstract

Pelleted straw is crumbled between closely-spaced rollers to provide a particulate composition useful as bedding (litter) for animals, especially poultry. Caustic alkali is added to the straw before pelleting. The processing reduces the risk that weed seeds and plant disease organisms will survive in the litter and be returned to the land if the waste litter is used as compost. The absorptive properties of the litter are also improved.

Description

BEDDING FOR ANIMALS This invention relates to bedding for animals, especially those housed in intensive rearing establishments.

The intensive rearing of poultry, and to a lesser extent other domesticated animals such as pigs, is often conducted in closed environmentally-controlled buildings (houses). It is necessary for the floor of the house to be covered with a material which provides satisfactory bedding for the animals. The term litter is sometimes applied to fresh bedding which is distributed on the house floor before the animals are admitted. More correctly, at least as far as the intensive rearing of poultry is concerned, the term litter applies to the bedding only at a later stage when the bedding has become contaminated with excreta (droppings) and other materials such as feathers, moisture and food particles. The litter develops in a complex process in which these various components blend together and undergo chemical, physical and microbiological changes. Current practice in poultry-rearing establishments typically involves the birds occupying the house for several weeks. During this period the composition of the bedding changes substantially. After the birds have been removed from the house, the litter is discarded and fresh bedding distributed on the floor in preparation for a new batch of birds.

A wide range of materials have been used as bedding. Chopped straw was popular historically, but more recently the favourite material has been wood in the form of shavings or sawdust. The rising cost of timber has now made it economically desirable to find an alternative to wood shavings.

For environmental reasons, the burning of straw and stubble is being discouraged or banned. There is a need to find further uses for straw.

Chopped loose straw became unpopular as a bedding material because it tends to be contaminated with weed seeds, mould spores, and plant disease organisms. Such contaminants remain viable in the litter, and farmers are understandably reluctant to return chopped straw litter to the land for fear that this may introduce or spread weeds and plant diseases. This could reduce the yield of subsequently planted crops, especially cereals.

Additionally, chopped straw of length greater than 50mm can produce a matted litter. The excreta is not mixed sufficiently with the bedding, and a wet surface develops. Chopped straw can adhere to concrete floors, making cleaning-out difficult.

There is a clear economic and environmental need for a bedding substitute to be found which can take advantage ί of waste agricultural materials such as straw, but which minimises the perceived disadvantages associated with * chopped straw bedding.

It has already been proposed to use crumbled pelleted straw and other fibrous materials as animal bedding.

Reference can be made to GB 2136263 and EP 310016. The mechanical action associated with the pelleting and crumbling can help to destroy some contaminants in the straw, such as weed seeds, but may not be sufficient to inactivate or destroy resistant microorganisms.

By the invention we have discovered that the usefulness of animal bedding material such as crumbled pelleted dry fibrous vegetable material (eg. straw) can be substantially enhanced if alkali is added during the manufacture of the bedding material.

The alkali can facilitate the inactivation or destruction of contaminants, eg. by attacking the outer coating of weed seeds and other natural biological contaminants.

The alkali enhances the ability of the granular product to absorb moisture present in excrement.

Surprisingly, the presence of the alkali in the bedding material of the invention does not apparently cause breakdown of ammoniacal compounds present in the litter. There is no observable release of ammonia.

By the invention we provide animal bedding comprising granules of compressed dry fibrous vegetable material. wherein the vegetable material has been -treated with alkali. Strong alkali, such as caustic soda (sodium hydroxide), is preferred. Generally, the alkali will be used in aqueous solution, preferable concentrated (saturated), to avoid raising the moisture content of the vegetable material unduly. Expediently, sufficient alkali is added to inhibit the activity of microorganisms present in the vegetable material, eg. by causing an exothermic reaction during the manufacture of the treated product.

Preferably, prior to compression, the vegetable material has been ground, eg. to pass a 7-lOmm screen.

Grinding by means of a hammer mill destroys or reduces the viability of many of the weed seeds vhich may be present.

Preferably the compression of the vegetable material is achieved by pelleting, eg. through the use of an animal-feeds ring-roll press, and the granules comprise the pelleted material that has subsequently been crumbled.

The presence of the alkali assists pelleting.

The moisture content of the granular bedding material should preferably not be greater than about 15% by weight, and generally will be in the range of about 10 to about 14% by weight.

Preferably the fibrous vegetable material comprises straw. Wheat straw is preferred, but other types of straw can be used eg. from barley, oats or rye. Fibrous vegetable material from a wide range of other cultivated plants can also be used. Generally, such material will comprise stalks, leaves and/or chaff. Such material is presently regarded as low value waste. Plants that are convenient sources of such waste are maize, sunflower, rape, and legumes such as peas and beans.- The granular product of the invention can be derived from a mixture of such vegetable materials, if desired. A combination of straw and/or other vegetable fibres with sawdust or shavings is possible.

Preferably the granular material of the invention is of comparatively narrow particle size range (eg. l-10mm), and preferably is essentially free from dust. A relatively uniform particle size, and comparatively high density, facilitates the transport of the material, and the substantial absence of fines minimises potential health hazards caused by dust that may be experienced by persons handling the product and animals bedded on the product.

A preferred process for the manufacture of animal bedding in accordance with the invention, involves chopping and grinding the fibrous vegetable material, compressing the material to form pellets, and crumbling these pellets to provide granules of appropriate size. Preferably the compression is achieved by extruding the vegetable material through a die of suitable diameter to form pellets (cylinders) of compacted material. The diameter and length of these cylinders is dictated by the size of the die holes and other parameters that the skilled press operator can adjust as a matter of routine. Alkali is added to the fibrous material before it is compressed or extruded.

Crumbling of the resulting pellets can be achieved, for example, by passing them between closely-spaced rollers. .The optimum gap between the rollers will depend on the size (diameter) of the pellets, but the gap will generally be at least about 1mm, and generally not greater than about 10mm. For typical cylindrical - pellets of diameter about 8mm, an optimum roller gap will usually be in the range of about 3 to about 8mm. Preferably the rollers have a roughened rather than smooth surface, to promote passage of the pelleted material between the rollers. Fluted rollers are ideal. By crumbling a pelleted material such as straw between rollers, the cylindrical pellets tend to fracture into flakes or chips. In this physical form, the product of the invention constitutes an ideal bedding material. The presence of the alkali facilitates the production of an optimum crumbled product, which has a bulk density in the range 15 to 25 lb/cu.ft, and improves the absorptive properties of the product.

It may be necessary to dry the fibrous vegetable material, eg. to a moisture content in the range 10-15% before it is chopped or ground. This can be achieved, for example, using forced current airflow.

The pellets emerging from a ring-roll press are hot (typical temperature in the range 75-85°C) and comparatively soft. Moisture is lost as the pellets cool, and the cured” pellets are generally much firmer. Crumbling of the pellets can be performed before the pellets have cooled, which produces a small flake-like product, or after cooling which produces a higher proportion of larger fragments (chips).

During drying (if required in the process) the straw is usually subjected to air heated by a furnace, after chopping but before grinding. Extrusion subjects the vegetable material to elevated temperatures through friction. Mechanical working is applied to the material during these operations. In conjunction with the effects of the alkali, the process of the invention therefore generates conditions under which undesirable contaminants in the vegetable material, such as weed seeds and mould spores, can be severely damaged. The processing of the material therefore significantly reduces the risk that litter derived from the granulated product will contain viable contaminants which should not be returned to the land at a later stage.

The pelleting of caustic soda and straw to provide a straw-based material for use as an animal feedstuff ingredient is already well-known. Reference can be made to British patent No. l 366 138 (Unilever Limited). The co-extrusion of caustic soda and straw results in chemical breakdown of the straw and provides a product which is much more easily digested by ruminant animals. However, it has not previously been suggested that pelleted alkali-treated straw could be used in crumbled form as animal bedding.

The addition of alkali to straw or other fibrous vegetable material in the manufacture of a product according to the present invention is especially beneficial. The exothermic chemical reaction caused by the alkali helps to inactivate any contaminating weed seeds, spores or other micro-organisms present in the vegetable material. Although quite high levels of alkali can be included (to make a nutritionally improved straw feedstuff ingredient the optimum level of sodium hydroxide is typically about 4 to about 5% on a dry weight basis), the advantages in the present invention can be achieved with much lower alkali inclusion levels. Preferably, the alkali level is at least about 0.1% by weight. Alkali levels in the range of about 0.25% up to about 1.5% are - 8 ideal. Such low alkali levels would not-be expected to have significant impact on the nutritional value of straw.

During the period when animals are on bedding, biological changes continually take place in the litter.

An alkaline bedding material may contribute to litter which works more efficiently.

A wide range of additives can also be included in the product of the invention. Examples are mould inhibitors (fungicides) such as organic acids and their salts. Disinfectants such as quaternary ammonium compounds, biguanides, amphoterics and iodophores. Enzymes capable of promoting decomposition (composting) of the litter after use, such as cellulases. Compounds to assist in the suppression of ammonia release from litter such as Envistim (ex Finn Sugar) and extracts of yuka.

It can also be advantageous to incorporate a minor proportion of feed material such as intact or coarsely crushed feed grains in the bedding material. Feed grains will be noticed by poultry, and this will encourage the birds to scratch through the bedding in search of more grains. In so doing, the poultry will promote the mixing of the bedding components and contribute to satisfactory development of the litter. An animal welfare benefit is also conferred, because the birds can exercise a natural instinct.

In general, the total proportion of such minor ingredients in' the fresh compound bedding need-not exceed about 10% by weight.

Removal of fines from the product can be achieved by sieving. However, in a preferred process the fines are removed by aspirating the crumbled material, preferably while it is being cooled, eg. progressing through a fluid bed cooler or other aspiration apparatus. Air is passed through the flowing crumbled material at a velocity sufficient to lift the material and draw off the fines.

The drying, grinding and pelleting operations associated with the manufacture of a product of the invention will generally need to be conducted in a factory or similar well-equipped facility. The final crumbled product can also be manufactured in such a facility, and distributed therefrom to the livestock rearing customer in ready-to-use form. However, an alternative embodiment of the invention involves central manufacture of the pelleted product, followed by transport of the intact pellets to the customer and crumbling of the pellets to provide the granular bedding material on-site. Bulk transport of the material in the form on intact pellets will be more economic.

Production of the pelleted material in dedicated centralised facilities which are not directly involved in the handling of feed materials or livestock can minimise the risk of accidental contamination of the bedding material with livestock disease organisms such as salmonella.

The bedding material of the invention can be used as the sole bedding in a rearing facility. Alternatively, it can be used in combination with other forms of bedding, such as wood shavings.

The bedding material is ideal for poultry but is also suitable for pigs, horses, cattle, zoo animals, and dogs and cats. The product of the invention creates a litter which is particularly convenient to handle when cleaning out the house, due to its relatively small particle size. The litter is easily handled mechanically.

Additionally, litter based on the product of the invention is beneficial in slatted floor houses where long or chopped straw would tend to block the slats.

The spent litter can be used as a feed additive, eg. for ruminants. It can also be used as a compost substrate.

Example v The following trial demonstrates the practicality of using crumbled pelleted alkali-treated straw as a substitute for wood shavings as poultry bedding.

Commercially-available alkali-treated straw pellets were ground through a 5mm screen before laying as bedding for domestic poultry. The pellets had been prepared by blending ground dry wheat straw (moisture content less than 15% by weight) from a tub-grinder and hammer mill with concentrated caustic soda solution (sufficient to add about 3.8% by weight dry sodium hydroxide to the straw), and passing the blend through a conventional animal-feeds ring-roll press die to provide 8mm diameter pellets.

A 9000-bird house was divided into two floor areas to provide accommodation for 5000 birds on the crumbled treated straw and 4000 birds on wood shavings. 2 tonnes of treated straw were used.

Introduction, handling and feeding of the chicks was as per normal husbandry practise. The birds were free to move throughout the house.

Before commencement of the trial but after the bedding had been spread, problems were encountered with a leaking drinker unit. The treated straw bedding appeared to control the spread of the problem better than the shavings.

Animal performance in the trial house was compared to that in an adjoining house, also containing 9000 birds all on a shavings bedding.

TRIAL CONDITIONS Shavings/ treated straw DAYS LIVEWEIGHT 47 4.76 lbs FOOD CONVERSION 1.98 Shavings only 4.45 lbs 1.99 The difference in liveweight gain was not statistically significant. During the trial, 5 birds were extracted, slaughtered, and crop and gut contents examined. No abnormalities were found in any of the birds, and there was no evidence of excessive litter consumption. This confirmed that even at caustic treatment levels approaching 3.8% no adverse affects were found.

The litter development in both portions of the house was similar. The treated straw performed as well as shavings, in spite of adverse air humidity prevailing at the time of the trial. Birds showed no positional preference in the house. Samples of litter were collected and analysed.

Both bedding materials were comparable in the way they were behaving as litter. There was no evidence of ammonia release from the litter. The analytical results are shown below.

REF A REF B Treated REF C REF D Shavings and straw and Treated droppinqs droppinqs Straw Shavinqs ( % % % % Dry Matter 77.6 76.0 87.5 90.8 Ether Extract 1.8 1-7 1.0 1.9 Total Nitrogen 4.9 5.4 0.82 0.31 Non-protein 1.81 2.01 0.22 0.17 Nitrogen (NPN) True Nitrogen 2.09 3.39 0.60 0.14 Crude Fibre 12.3 10.1 34.2 65.0 Nitrogen-free 44.1 32.3 40.4 22.1 Extractives Ash 0.1 10.7 8.2 0.2 Sodium 0.27 0.33 2.12 75ppm NaOH 3.69 In Vitro: Organic Matter 58.0 72.1 60.7 7.1 Digestibility (%) D value 50.5 61.9 55.0 5.1 Metabolisable 7.59 / Energy (D+0.15) (MJ/kg dry basis) 9.29 8.25 1.07 where D value = Digestible organic matter (dry basis). These analyses suggest that the crumbled caustic-treated straw product retained the nitrogen (NPN) fraction of the droppings. If there had been a loss of ammonia then the result of (B - C) would have been smaller than (A - D) for NPN.

Claims (24)

1. 5 1. Animal bedding comprising granules of compressed dry fibrous vegetable material, wherein the vegetable material has been treated with alkali.

2. Animal bedding according to claim 1, wherein an amount of alkali is added in the course of the treatment which is sufficient to inhibit the activity of microorganisms 10 present in said material.

3. Animal bedding according to claim 1, wherein the alkali is concentrated aqueous caustic soda. 15

4. Animal bedding according to any preceding claim, wherein the granules comprise crumbled pellets.

5. Animal bedding according to any preceding claim, wherein the vegetable material comprises straw.

6. Animal bedding according to any preceding claim, wherein the granulated material contains a fungicide.

7. Animal bedding according to any preceding claim, wherein the granulated material 25 contains a disinfectant.

8. Animal bedding according to any preceding claim, wherein the granulated material contains an enzyme capable of promoting decomposition of the bedding after use.

9. Animal bedding according to any preceding claim, wherein the granulated material contains a minor proportion of feed grain. -1510. A process for the manufacture of animal bedding, wherein dry fibrous vegetable material, is chopped and/or ground, the chopped and/or ground material is compressed or extruded to form pellets, and the pellets are crumbled to form granules, and wherein alkali is added to the vegetable material prior to pelleting.

10. 11. A process according to claim 9, wherein said material is straw.

11. 12. A process according to claim 10 or 11, wherein an amount of alkali is added in the course of the treatment which is sufficient to inhibit the activity of microorganisms present in said material.

12. 13. A process according to claim 9 or 10, wherein said alkali is concentrated aqueous caustic soda.

13. 14. A process according to any of claims 10 to 13 wherein the alkali is added to the fibrous vegetable material at a level of at least about 0.1 % on a dry weight basis.

14. 15. A process according to any of claims 10 to 14, wherein the alkali is added to the fibrous vegetable material at a level in the range of about 0.25% to about 1.5% on a dry weight basis.

15. 16. A process according to any one of claims 10 to 15, wherein the granules are sieved or aspirated to provide a finished product essentially free from dust.

16. 17. A process according to any one of claims 10 to 16, wherein the fibrous vegetable materia] comprises straw and the pellets are crumbled between rollers to cause the pellets to fracture into flakes or chips.

17. 18. A process according to any one of claims 10 to 17, wherein one or more of the following minor components are blended with the fibrous vegetable material prior to -16pelleting: fungicide, disinfectant, enzyme and feed grain, the minor component or components comprising in total not more than about 10% by weight of the crumbled product.

18. 19. A process according to any one of claims 10 to 17, wherein the pellets are manufactured at a central location, transported intact to an animal rearing establishment, and crumbled on-site to provide animal bedding.

19. 20. Use of crumbled compressed dry alkali-treated fibrous vegetable material as bedding in granule form for animals, especially poultry.

20. 21. Use of crumbled, pelleted, compressed dry alkali-treated straw as bedding in granule form for animals, especially poultry.

21. 22. Spent litter based on animal bedding according to any one of claims 1 to 9.

22. 23. Animal bedding according to claim 1, substantially as hereinbefore described. ί

23.

24. A process according to claim 9, substantially as hereinbefore described.