GB2139070A - Animal foodstuffs - Google Patents

Abstract

An animal foodstuff is made by mixing (i) aqueous waste material(s) having a dry matter content of less than 15% by weight and for other material(s) having the flow characteristics of a liquid or slurry, the waste & other materials having nutritional value, and (ii) at least one absorbent material when ingested, and incorporating a source of acidifying micro-organisms in the mixture and, if necessary, adjusting the content of fermentable carbohydrate to enables ensilage to occur. The absorbent material prevents or substantially reduces effluent formation during transport and storage of the mixture. The waste materials may be from the brewing industry and absorbent materials may include malt or barley dust, malt culms peat and vermiculite. The source of micro organisms may be brewers spent grains or unpasteurised whey. Protein- & carbohydrate-containing materials, such as yeast and molasses, can be added to the mixture.

Description

SPECIFICATION Animal foodstuffs The present invention relates to animal foodstuffs and, in particular, to a method of producing and storing animal foodstuffs utilising aqueous waste materials having nutritional value but too fluid and/or unstable to be stored individually using conventional methods of ensilage.

Much aqueous waste materials in the brewing,-distilling and certain food industries, whilst having good food value, have a low dry matter content, e.g. below 15% by weight. Such liquid materials, whether because of low dry matter content or because of a change to a flowable form are, therefore, uneconomical to transport and do not provide properties necessary for ensilage under normal farm conditions. Other materials, whilst initially of relatively high dry matter content, undergo a change from solid to a liquid form akin to a slurry, An example of such material is yeast which, when freshly pressed, has a dry matter content of about 25% and a putty-like consistency but quickly changes into a liquid "autolysed" yeast. Spent brewers grains can, under some circumstances, be in the form of a flowable slurry.As such, they are not a safe or economical source of food for livestock and have to be discharged to waste. Such discharge has its attendant problems since discharge of untreated waste can cause ecological problems and the necessary treatment is expensive.

It is an object of the present invention to provide a method of utilising such liquid material in the production of animal foodstuffs.

According to the present invention, this object is achieved by mixing together (i) one or more materials selected from aqueous waste materials having nutritional value but which have a dry matter content of less than 15% by weight and other materials which have nutritional value but which have the flow characteristics of a liquid or slurry and (ii) at least one absorbent material which has no deleterious effect on livestock when ingested, and incorporating a source of acidifying micro-organisms e.g. lactic acid producing micro-organisms in the mixture and, if necessary, adjusting the content of fermentable carbohydrate to the level required to provide a growth rate of the micro-organisms in the mixture which enables ensilage to be achieved under normally recommended farm conditions, the amount of absorbent material included being high enough to prevent or substantially reduce effluent formation during transport and storage of the mixture but not high enough to prevent effective anaerobic conditions being achieved in the mixture under normally recommended farm conditions for ensilage.

Examples of aqueous waste materials which can be utilized in the method of the present invention are Mashtun "last runnings" ca.1-3% oven-dry matter, spent grains drainings ca.3-5% oven-dry matter, filter runnings ca.1-5% oven dry matter ca.1-5% oven dry matter, spoilt beer and cask drainings ca.7-13% oven dry matter, whirlpool unseparated "trub" ca. 10-15% oven dry matter, storage tank "bottoms" and "barm yeast" ca.10-15% oven dry matter. Examples of absorbent materials are malt or barley dust-mill, malt culms and straw dust, all of which are themselves waste products or by-products, but which have nutritional value for livestock and have the added advantage particularly for ruminants that they are fibrous in structure.Other examples of absorbent materials which would have no deleterious effect on livestock are bakery waste, potato crisp waste, peat-moss and vermiculite.

The source of lactic acid producing microorganisms may be, for example, brewers' spent grains or unpasteurised cheese whey, such as that from the production of cottage cheese. Both these materials also have nutritional value which adds to the food value of the mixture. Other waste materials with relatively high dry matter content such as spent hops may also be incorporated if desired. The nutritional balance of the mixture can be adjusted by addition of materials rich in protein or carbohydrate. Thus, yeast may be added as a source of protein or molasses as a source of carbohydrate.

The absorption capacity of the absorbent material or materials will determine the amount that needs to be incorporated. Each absorbent material will have a maximum absorption capacity beyond which liquid will tend to drain out on transporting the material or during storage. This may be termed the equilibrium point.

Such drainage can take with the liquid a proportion of the nutritional value of the mixture and is therefore to be avoided.

On the other hand, if the amount of liquid absorbed is too low to reach the equilibrium point, the voids remaining in the absorbent material may be too great to enable substantially anaerobic conditions to be reached under the normally recommended procedures for farm ensilage. It has been found to be essential to limit the remaining voids to a level which permit such anaerobic conditions to be attained. This is best achieved by adding sufficient aqueous waste such that the equilibrium point of the absorbent material or mixture of absorbent materials is substantially achieved.

The amount of lactic acid producing microorganisms present in the final mixture should be high enough to ensure proper ensilage, e.g., within 3 hours of preparation of the mixture there should be more than 10,000 viable cells per gramme of the moist material. Provided sufficient fermentable carbohydrate is present, preferably ca.5% of the DM, the amount of lactic acid producing organisms initially present can be comparatively low, since given their proper food and pH requirements and substantially anaerobic conditions their growth rate is high. Nevertheless, the initial fermentable carbohydrate content should not be so low that proper silage conditions (reduction to pH 4.2 or below) cannot be attained in 5 to 7 days, at normal atmospheric temperatures.

The following examples are the results of ensilage trials carried out in 60 litre 'Bowater International' plastic drums into which false bottoms had been inserted to allow drainage and which were fitted with venting arrangements so that any gas pressure could be relieved without allowing ingress of air. Whilst not providing totally anaerobic conditions at the start of ensilage, extensive experience of the Agricultural Developments Advisory Service of the Ministry of Agriculture, Fisheries & Food (ADAS) and others, which has been confirmed by our own trials, has shown that these containers give an excellent simulation of commercial ensilage on farms observing the recommended ADAS procedures.

Unless otherwise indicated, all the values for Metabolisable Energy (ME) and Crude Protein (CP) are those quoted for general reference in MAFF booklet 2087 "Nutrient Allowances of Composition of Feedingstuffs for Ruminants".

Example 1 A mixture was made up of whey, malt culins, crushed pellets of a nutritionally improved straw material sold under the Trade Mark Viton 10 and a small amount of molasses. Table l(A) below sets out the ingredients and their properties together with the amounts used in parts by weight:: TABLE l(A) Malt Vital Whey Culms 10 Molasses Total Gross Weight (kg) 74.0 19.0 5.0 2.0 100.0 Dry Matter (%) 6.6* 90.0* 86.0*** 75.0* 27.8 Weight of Dry Matter (kg) 4.9 17.1 4.3 1.5 27.8 ME(MJ/kgDM) 14.5* 11.2* 9.0*** 12.7 11.5 Crude Protein (%DM) 10.6* 27.1* 3.8*** 4.1 19.3 * From Booklet 2087 published by the Ministry of Agriculture, Fisheries and Food ** Estimated figures based on known calorific values and protein contents of typical beers Manufacturer's descriptive literature The mixture of Table í(A) was ensiled in two 60 litre containers.A mixture of one part by weight of the mixture of Table l(A) with three parts by weight of spent grains was ensiled in 4 containers of 60 litres capacity. As a control sample for comparison purposes, spent grains alone were ensiled in a further 60 litre container. The results of the ensilage are shown in Table l(B).

TABLE l(B) 25% Mixture Spent Mixture 75% Spent Grains Notes Alone Grains Alone In Vitro ME 9.9 In Vitro Crude Protein 17.9 pH before ensilage 5.6 4.6 4.0 pH after ensilage for 14 days 3.8 3.8 3.3 Visible mould growth -ve -ve -ve Observed evolution of gas -ve -ve -ve Loss of total weight after 14 days (%) 2.1 1.4 0.7 Weight of effluent after 14 days (%) 23.5 7.9 3.1 Specific Gravity of effluent 1044 1019 1014 Potential DM loss in effluent (%) 10.0 1.6 0.5 Loss DM in residual 'solids' (%) 6.2 0.5 0.5 The ME as shown in Table l(B) was measured by the Agricultural Development Advisory Service of the Ministry of Agriculture using 'In Vitro' laboratory methods which are valid for comparative purposes, one with another, but are not necessarily directly comparable with the values shown in Table l(A) which relate to 'In Vivo' methods. The In Vivo method involves drying of the sample so will not register the value of volatile substances. Thus the alcohol content of the mixture (which will be distinctly higher than that of the fresh spent grains) will not have been registered. Thus both the Table l(A) mixture and the 25% mixture of that with spent grains can be assumed to contain at least as much ME as spent grains. Similarly, the protein contents are at least as good as those of spent grains.

It is to be noted that the drop in pH of the mixture of Table l(A) is comparable to that of spent grains alone, the final pH being quite satisfactory for ensilage purposes.

Although no gas evolution was observed, it is believed that some must have occurred from the constituents of the mixture. The satisfactory drop in pH indicates that conditions remained anaerobic, so the loss of feeding energy would be insignificant because, e.g. ethanol has only about half the weight of the sugars from which it is formed, but has about double the energy density.

Addition of about 8kg more of either malt culms or Viton 10 would have virtually eliminated the effluent.

The apparent loss of dry matter (6.2%) from the mixture of Table l(A) is apparently high compared to the about 2% or 3% typical of spent grains, and is due mostly to loss of volatiles during the analysis. However, the amount of soluble matter shown by the high Specific Gravity of the effluent is also much higher than is typical for spent grains (about 1010); it would almost certainly be highly fermentable, with consequent formation of volatile substances which would not be recorded by the analysis.

Similar techniques can be applied to other wastes which, although of a higher dry matter content, carry excessive "free liquor" which at present becomes effluent either at the factory, in transit or on the farm unless separated by mechanical means. Addition of an absorbent material at the earliest practicable stage at the factory provides a novel means of reducing or avoiding the effluent.

Claims (10)

1. A method of producing an animal feedstuff comprising mixing together: (i) one or more materials selected from aqueous waste materials having nutritional value but which have a dry matter content of less than 15% by weight and other materials which have nutritional value but which have the flow characteristics of a liquid or slurry and (ii) at least one absorbent material which has no deleterious effect on livestock when ingested, and incorporating a source of acidifying micro-organisms in the mixture and, if necessary, adjusting the content of fermentable carbohydrate to the level required to provide a growth rate of the micro-organisms in the mixture which enables ensilage to be achieved under normally recommended farm conditions, the amount of absorbent material included being high enough to prevent or substantially reduce effluent formation during transport and storage of the mixture but not high enough to prevent effective anaerobic conditions being achieved in the mixture under normally recommended farm conditions for ensilage.

2. A method as claimed in claim 1 in which the ratio of aqueous waste and/or other material to the absorbent material is such that the absorbent material in the mixture is at or substantially at the maximum absorption capacity beyond which liquid will separate from the mixture during storage or transport.

3. A method as claimed in claim 1 or 2 in which within 3 hours of preparation of the mixture the amount of acidifying micro-organisms present in the mixture is greater than 10,000 viable cells per gramme of mixture.

4. A method as claimed in any of claims 1 to 3 in which the acidifying micro-organisms are lactic acid producing micro-organisms.

5. A method as claimed in any of the preceding claims in which the absorbent material is malt culms or malt or barley dust.

6. A method as claimed in any of the previous claims in which the protein content of the mixture is increased by the addition of a protein rich material to the mixture.

7. A method as claimed in claim 6 in which the protein coating material is yeast.

8. A method as claimed in any of the preceding claims in which the carbohydrate content of the mixture is increased by adding a carbohydrate rich material to the mixture.

9. A method as claimed in claim 8 in which the carbohydrate rich material is molasses.

10. A method as claimed in claim 1 substantially as hereinbefore described in any one of the Examples.