GB2307840A

GB2307840A - Animal feed using whole grains

Info

Publication number: GB2307840A
Application number: GB9604476A
Authority: GB
Inventors: Thomas Hugh Crawford
Original assignee: Clow James & Co Ltd
Current assignee: Clow James & Co Ltd
Priority date: 1995-12-01
Filing date: 1996-03-01
Publication date: 1997-06-11
Anticipated expiration: 2016-03-01
Also published as: GB9604476D0; GB2307840B; GB9602656D0

Abstract

A process for preparing a grain-based particulate animal feed comprises the steps of: admixing grain with other ingredients, and passing the resultant mixture through a pressing apparatus to create the particulate feed, wherein the grain is wholly or partly whole grain. The process is based on the manufacture of a particulate feed using whole grain, which thus preserves such grain in its natural form, in contrast to the preparation of pellets which requires all the grain to be ground to a powder and then 'reformed'. The grain for use with the present invention is preferably completely unprocessed. Heat treatment to soften the grain prior to pressing may be used, and the pressing apparatus is preferably a die.

Description

ANIMAL FEED The present invention relates to a process for preparing a grain-based particulate animal feed and the animal feed therefrom, particularly but not exclusively for poultry.

Presently, the main feeds for poultry rearing, especially broiler chickens, are grain-based crumbs and pellets. The grain is present in an amount of up to 75%. The pellets are prepared as now described, flow charts for which are shown in Figs. la, 1 b and Ic of the accompanying drawings.

Fig. 1a is an example of a flow chart for a 'pre-grind mill'. Here, the grain and those other raw ingredients whose particle size must be reduced are pre-ground to a finer grist suitable for the pressing. The ground materials are then weighed and mixed with the other ingredients which do not need grinding, e.g. vitamins, minerals, soyabean meal, etc.

Fig. Ib is an example of a flow chart for 'post-grind mill'. In Fig. 1b the grain and all the other raw ingredients are weighed and mixed, and only then passed through a grinder. Fig. 1c is an example of a modified "post-grind" feed mill in which after weighing, the raw materials are passed through a blending conveyor to the grinder and then mixer.

Once mixed and ground in these flow charts, the material is then steam treated by passing it through a conditioner. Here the temperature is raised to a level which should kill any possible salmonella. The material is then pressed through a thick-walled die. The high pressures created by pressing the powderous mixture through the long holes in the die wall provide most if not all the necessary bonding needed to make and bond the pellets, which are then cut into desired lengths. The pellets are cooled, sieved for quality selection, and then fat-coated by spraying to increase the fat content of the pellets. The pellets are usually sieved again before distribution.

Crumbs are prepared by passing the pellets through rollers.

These processes have several disadvantages. Firstly, single or double sieving is required in order to ensure that the poultry farmer obtains as close to 100% perfect pellets as possible. Any poor performance of the growing poultry is usually attributed to a fault in the feed, which feed manufacturers often do not contest and regularly pay out compensation for. However, sieving creates a dust problem, and also creates about 10% of fine or loose material which has to be retumed for subsequent repelleting, with the possibility of cross contamination. The sieves are also expensive, but must be replaced regularly in view of the rigorous wear and tear they undergo.

Secondly, as fat is the highest form of energy for rearing poultry, high fat contents are desired. The material for pellet pressing normally has a maximum total fat content of about 5%. However, as fat is a lubricant, excessive amounts cannot be added to the material because of the need to have high pressure in the die to create hard pellets. Additional fat is therefore sprayed onto the pellets once formed to raise the final fat level to only approximately 10%. Accurate fat percentages are difficult as fat spraying is not a precise operation, despite accurate percentages being desired for quality reasons and because fat is one of the most expensive ingredients. Above about 10% fat, the coated pellets become sticky and do not flow freely, particularly in warm weather. Fat spraying is also a messy operation.

Thirdly, whilst the digestive system of a chicken is designed to digest whole grain, the pellets consist mostly of fine and finely ground ingredients, thereby reducing the gizzard function. Moreover, considerable amounts of water must be taken by the chicken to break down the pellets. The mode of digestion of pellets is not therefore in correlation with the chicken's natural digestive system, thereby reducing the function of the bird's digestive system.

Fourthly, the grinding of the grain (whether preground or postground) creates heat which drives off moisture from the grain, thereby producing a stock loss of up to 1%. This is a significant percentage reduction.

Replacement water can be added during mixing of the ingredients, but extrinsic water is not comparable with the naturally held intrinsic moisture in the grain, and it is easily flashed off during the cooling process.

It is an intention of the present invention to obviate or mitigate these disadvantages.

According to one aspect of the present invention, there is provided a process for preparing a grain-based particulate animal feed comprising the steps of: admixing grain with other ingredients, and passing the resultant mixture through a pressing apparatus to create the particulate feed, wherein the grain is wholly or partly whole grain.

The process of the present invention is based on the manufacture of a particulate feed using whole grain. The term "whole grain" is used herein to mean grain which has not been ground at all, or ground only to a minor extent such that it retains its integrity (in comparison with the grinding action presently used to powderise grain). This process thus preserves such grain in its natural form, in contrast to the preparation of pellets which requires all the grain to be ground to a powder and then 'reformed'.

The term "particulate feed" is used herein to mean a feed made of particles whose shape and size vary, especially in comparison with the homogeneity of pellets. The particulate feed may also be described as "crumbly", "crunchy" or "gravelly", and it has a more open nature than pellets.

This process is not considered beneficial for preparing feed formulations which would involve less than possibly 10% of the total diet as whole grain, as this would not produce a satisfactory particulate feed. Any part of the grain requirement not added as whole grain can be ground as at present.

Preferably, the grain used is wholly or substantially whole grain. More preferably, all the grain used is whole grain, and the grain is completely unprocessed. The other ingredients correspond to those used in the prior art pellets, e.g. vitamins, minerals, soyabean meal, etc. They may be ground (prior to mixing) or not ground as desired or necessary. The grain and other ingredients may be added in the same amounts or ratios as currently used for the same animal feed.

The avoidance or reduction of grinding of the grain provides a significant reduction in the energy required for the overall process compared with prior art processes. Also, because there is reduced or no grinding of the grain, there is less or no reduction in the moisture content thereof and therefore less or no stock loss. Avoidance or reduction of grinding also eliminates or reduces the significant risk of fire or explosion inherent therewith.

Where necessary or desired, only part of the whole grain requirement is initially admixed with the other ingredients, with the remaining part being admixed with the pressed product to create the feed. However, preferably all the whole grain is initially admixed with the other ingredients such that only one mixing step is required.

The pressing apparatus may be any suitable apparatus able to compress the mixed ingredients together and thereby create some adhesion and bonding therebetween. Such apparatus includes a die having the same or a similar design to those currently used to create pellets, or an expander. An expander can also raise the temperature of the mixture and thus provide heat treatment to the mixture, heat treatment being a preferred embodiment further discussed below. However, the pressing apparatus is preferably a die, although any comments made hereinafter with respect to the use of a die may apply also to the use of other pressing apparatus.

With respect to the pressing of the mixed ingredients, because there is less or no grinding of the major ingredient, grain, (and possibly less or no grinding of one or more of the other ingredients previously ground), there is less surface area to be bonded (in the pressing) to create the particulate feed of the present invention, compared with the surface area of the completely powderous mixture pressed to form pellets. Also, as the size and shape of the particles created by the process of the present invention are intended to vary, lower pressures (e.g. a thinner-walled die) may be used for the pressing (compared with the high pressures needed to bond the prior art pellets). Thus the fat content in the mixture of the whole grain and other ingredients can be sufficient to provide the bonding required between the ingredients to produce the particulate feed.

Preferably however, at least a part, more preferably much or all, of the additional fat required for the desired fat content of the particulate feed being prepared is included with the ingredients during their admixture, as the limitation of fat for high pressure pressing is no longer necessary. Thus, whilst prior art fat-coated pellets may only have a fat content of up to 10%, the fat content of the particulate feed of the present invention may be up to 15-17% or more, and such fat is more integrated into the feed. Also, as the fat may be added during admixture of the ingredients, it can be added by systems which are more accurate than spraying. Fat being one of the most expensive ingredients, this allows savings to be made over the imprecise nature of fat spraying.

Any added fat may also help lubricate the pressing apparatus, especially a die. Thus, as the mixture of the present invention can have a much higher fat content during pressing, the rate of pressing may be significantly increased. As the rate of pressing is frequently the rate determining step of the overall process of animal feed production, extra lubrication and e.g. a thinner-walled die will significantly increase the rate of feed production, thereby dramatically reducing energy, labour and machinery costs.

According to a preferred embodiment of the present invention, the mixture is heat treated to soften the whole grains prior to pressing. The heat treatment should be sufficient to soften the grains to make them more malleable during pressing whilst maintaining the integrity of each grain pickle and grain particle such that they do not lose their form. The heat treatment may be any suitable form of treatment using direct or indirect heating. The heat treatment should not be so extensive or severe as to create a 'porridge'like mixture which would prevent the creation of a particulate feed according to the present invention.

The inter-relationship between the percentage fat and whole grain contents and the structure of the pressing apparatus (e.g. thickness of the die and diameter of the apertures in the die) may be varied to control the process and/or create various grades of feed products for different requirements. The invention enables the production of a wide range of physical characteristics for the finished feed.

As the pressing is the only force-acting part of the present process on the whole grains, many of the whole grains added are intended to remain whole in the finished feed, (especially those grains of smaller size than the exit hole(s) in the pressing apparatus). Around the pressing apparatus one or more blades or knives may be used to assist particularisation of the feed from the apparatus.

The particulate feed may then be cooled if required, e.g. by passing it through a cooler. Cooling is desirable from a hygiene point of view, especially if the mixture has been heat treated, but it is not essential to the creation of the feed of the present invention.

No sieving of the feed is necessary in view of its already particulate nature. Final fat coating is not essential, but may still be desired for e.g. high energy feeds. The addition of further fat in this invention is achievable due to the high surface area of the particulate feed. Should some of the particles created be of a size greater than desired or necessary size (e.g. for feed for young birds, layers, or breeders, and possibly because the pressing apparatus produced over-adhesion), the feed may be passed through rolls to produce a more even-sized grist.

The particulate feed is more gritty/gristly than prior art feed, and this is desirable for poultry in general. The more open nature of the feed and its grittiness encourage the bird's digestive tract to work more naturally and thus better. Also, less water (i.e. a more normal level) may be consumed and a drier dropping may be excreted producing drier litter which is healthier for the bird.

It can be seen that some of the process of the present invention can be carried out using equipment of the prior art processes, such that the processes of the prior art can be modified to use the present process. For instance, the delivery of all or part of the whole grain requirement into the mixing process can be made either by the grain by-passing an existing grinder or by the grain passing through an existing grinder which has been rendered ineffectual or ineffective.

According to a second aspect of the present invention, there is provided a grain-based particulate animal feed whenever prepared by a process as herein described. The animal feed of the present invention is suitable for feeding all types of poultry and game birds, more preferably laying or broiler chickens and turkeys. The process of the present invention may also be used, however, to prepare a particulate feed for other animals which can digest whole grains, e.g. sheep and goats.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings in which: Figs. 1a, ib and Ic are flow charts of processes for preparing prior art feed for chickens; Fig. 2 is a flow chart of a process for preparing a particulate poultry feed according to one embodiment of the present invention; and Fig. 3 is a diagrammatic perspective view of a die and rolls of a pellet mill.

Referring to the drawings, Figs. la, 1 b and 1 c show examples of prior art pre-grind and post grind processes for preparing feed for chickens, starting with a raw material intake. In Fig. 1a, those raw materials already in a powder form pass directly to the blending bins. Those not powderous pass to a pregrinding bin and then through one or more grinders. In Fig. Ib, all the (unground) ingredients are mixed and then passed through grinders. In Fig.

Ic, all materials are weighed, blended in a blending conveyor, ground and then passed through a mixer. As up to 75% of poultry feed can be grain, grinding either the grain fraction or the total mix is a significant energy using step.

After the mixing/grinding the mixture is passed to pre-press bins, heattreated in a conditioner, held in a retention vessel and then passed when required to a pellet mill for pressing, the essentials of which are shown in Fig.

3. In Fig. 3, the material is forced through a circular-walled die 2 by three serrated rolls 4 rotating around the inside of the die 2. For the preparation of pellets for chickens, the die 2 is up to possibly 100 mm thick. (The thickness of the die depends on the nature of the mix and the pellets being prepared). The die 2 has a number of transverse holes 6 therethrough of 3 1/2, 4 or possibly 6mm diameter. As the rolls 4 pass against the inside of the die 2 they press the material into the holes 6. By the time the material is pressed along the length of a hole 6, it forms a hardened line of material. Blades 8 are used around the outside of the die 2 to break the lines of material into whatever length of pellet is required, usually 4 mm.The material in the pellets is held together by the high pressures created by the thickness of the die 2 and hence the distance the material must travel therethrough. Limiting the amount of fat added to the mixture assists the creation of a high pressure (by minimising the degree of lubrication).

After pressing, the pellets are cooled and then sieved to remove those not of the right size and also to remove any loose material. The sieves may also create more loose material (by breaking up weak pellets). The sieves are also subject to significant wear and tear, and must be replaced regularly despite being expensive. Energy is also required for sieving.

After sieving, the pellets are usually fat-coated, especially if the feed is to be high energy feed. Although the pellets have already been sieved once, the quality demand from farmers is such that the pellets are usually sieved again prior to distribution. Crumbs are created by passing cooled pellets through rolls followed by sieving.

Figure 2 is a flow chart of a process for preparing a particulate poultry feed according to an embodiment of the present invention. Where the grain requirement is 100% whole grain, such grain may pass directly from the raw material blending bins into the mixer. The other raw materials (and any part of the grain requirement not being whole grain) may still be ground as before if desired or necessary, although for broiler chicken feed, those other raw materials currently ground may be added without having been ground also.

Additional fat may be added to the mixer to raise its percentage to up to 1517%.

Once mixed, the mixture is passed to pre-press bins, and then (if and when required) heat-treated. One method of heat-treatment is to pass steam through the mixture in a conditioner to raise its temperature to approximately 85"C, and hold it in a retention vessel, as is frequently done to remove any salmonella in prior art processes. In the present invention, the steam also softens the whole grains to make them more malleable for the pressing, whilst the integrity of each grain pickle and grain particle is maintained. Extended heat treatment or holding in an insulated vessel for some time may also be used.

The mixture is then pressed through a pressing apparatus being a pellet mill having a die and rolls similar to those shown in Figure 3. Because the pressure required of the die need not be as high as that used in the prior art processes of Figs. Ia-Ic, the width of the die may be considerably reduced, e.g. within the range 30 mm to 70mm. The width of the die depends on the nature of the mixed material, especially the fat content. Also, additional fat in the mixture assists lubrication of the mixture through the holes in the die. As this is frequently the rate-determining step of the process, the production rate of the process can be significantly increased by these two factors alone. The diameter of the holes in the die may be varied according to how much whole grain is required in the finished feed.

The fat in the mixture binds the ingredients together sufficiently strongly for the feed that emerges from the holes of the die to be gritty/crunchy/crumblyl particulate when at ambient temperature. One or more blades could be used around the outside of the die to help crumble (particularise) the feed. At least a significant portion of the whole grain added will still be in whole or segmented form, as shown by the test below. As the feed cools, it regains its hard gritty texture. The cooling is quicker than cooling of pellets due to the greater surface area of the particles of the feed. The feed is then ready for distribution.

No final sieving is required (eliminating associated dust and recycling problems). Fat coating is optional and not normally required unless very high levels of fat are desired (possibly up to 20% fat content). The feed may be passed through rolls to crack any particles of a greater than desired or necessary size.

The feed prepared by the process of the present invention more closely resembles a chicken's natural feed compared with the pellets produced by prior art methods. It is therefore more natural to the digestive system of the poultry.

Grinding of the major ingredient, grain, is avoided or reduced, making significant energy savings. The fat content of the feed can be increased to improve the energy content of the diet. The pressing step can be made faster.

By way of comparison, several steps of the prior art processes can be eliminated or reduced in scale making large savings in production costs. Feed produced by the prior art processes is also liable to deteriorate more rapidly in storage, whereas grain in its whole or particulate state may keep for longer.

TEST The following test was carried out on a standard James Clow & BR< Company Limited broiler starter feed "Product No. 43" made according to the flow chart of Fig. I a, and a particulate feed prepared according to the present invention and as shown in Fig. 2, including a heat treatment step. The ingredients of Product No. 43 and the particulate feed were the same and of the same ratio as follows.

20.5 Soyabean Meal 3.0 Meat & Bone Meal 3.5 O'Kane Meat Bone Meal 1 4.0 O'Kane Meat Bone Meal 2 2.5 Fishmeal 0.42 Di-calcium Phosphate 0.16 Sodium Bicarbonate 0.2 Synthetic Lysine 0.15 DL Methlonine 0.43 Fine Limestone 0.64 Soyabean Oil 1.5 Poultry Blend (fat) 20.0 Barley 42.59 Wheat 0.39 Mineral Vitamin Supplement 100.00 Total grain 62.59%, remainder 37.41% non grain materials. For the Product No. 43, the grain was ground down to a 2.5 mm screen size.

In the test, 1009 of each feed were added to 200 ml of water in a flask and left to stand for 10-15 minutes, or at least until the pellets broke down by the dissociation action of the water. Each flask was then shaken to encourage dissociation, and then the contents rinsed through a 1.4 mm screen. The collected matter was dried to 0% moisture and weighed and then corrected to 13% moisture (corresponding to the approximate moisture of Product no. 43).

The percentage retained by the 1.4mm screen for Product No. 43 was 12. 10%, whereas the percentage retained for the particulate grain of the present invention was 50.73%, over four times greater.

Variations and modifications can be made without departing from the scope of the invention described above.

Claims

1. A process for preparing a grain-based particulate animal feed comprising the steps of: admixing grain with other ingredients, and passing the resultant mixture through a pressing apparatus to create the particulate feed, wherein the grain is wholly or partly whole grain.

2. A process as claimed in Claim 1 wherein the grain is wholly or substantially whole grain.

3. A process as claimed in Claim 2 wherein the grain is wholly whole grain.

4. A process as claimed in any one of Claims 1, 2 or 3 wherein the whole grain is not ground.

5. A process as claimed in any one of Claims 1 to 4 wherein the grinding of one or more of the other ingredients normally ground for the preparation of pellets is not required.

6. A process as claimed in Claim 5 wherein the grinding of any or all of the ingredients soya bean meal, corn gluten meal and US corn distillers meal when used is not required.

7. A process as claimed in any one of Claims 1 to 6 wherein only part of the whole grain requirement of the feed is admixed with the other ingredients prior to pressing, and the remaining part of the whole grain requirement is subsequently admixed with the pressed product.

8. A process as claimed in any one of the preceding Claims wherein the pressing apparatus is a die.

9. A process as claimed in Claim 8 wherein the die has a wall thickness in the range 30-70 mm.

10. A process as claimed in any one of the preceding Claims wherein the mixture is heat treated prior to pressing.

11. A process as claimed in Claim 10 wherein the heat treatment comprises passing steam through the mixture.

12. A process as claimed in any one of the preceding Claims wherein all or a substantial proportion of the additional fat requirement of the particulate feed is admixed with the grain and other ingredients prior to pressing.

13. A process as claimed in any one of the preceding Claims wherein the particulate feed is fat coated.

14. A process as claimed in any one of the preceding Claims wherein the fat content of the particulate feed is in the range 5-20%.

15. A process as claimed in any one of the preceding Claims wherein the particulate feed is cooled after pressing.

16. A process as claimed in any one of the preceding Claims wherein the particulate feed is passed through rolls to produce a more even-sized grist.

17. A process as claimed in any one of the preceding Claims wherein a significant portion of the initial whole grain remains whole or in segmented form in the particulate feed.

18. A grain-based particulate feed wherever prepared by a process as claimed in any one of Claims 1 to 17.

19. A feed as claimed in Claim 18 for feeding poultry, game birds, sheep or goats.

20. A feed as claimed in Claim 19 for feeding laying or broiler chickens or turkeys.

21. A process for preparing a grain-based particulate feed substantially as hereindescribed with reference to Fig. 2.

Amendments to the claims have been filed as follows

1. A process for preparing a grain-based particulate animal feed comprising the steps of admixing grain with other ingredients and passing the resultant mixture through a pressing apparatus to create the particulate feed, wherein the grain added and the grain in the resultant feed is wholly or partly whole grain, whole grain being grain which has not been ground at all, or ground only to a minor extent such that it retains its integrity.

2. A process as claimed in Claim 1 wherein the grain added is wholly or substantially whole grain.

3. A process as claimed in Claim 2 wherein the grain added is wholly whole grain.

17. A process as claimed in any one of the preceding Claims wherein a significant portion of the initial whole grain remains whole grain in the particulate feed.