Technical Field

The present invention relates to a composition usable in the ensilage of green fodder, and a process for its production.

Background Art

During 1987, forage crops were cultivated in Sweden of an area of approx. 700 000 hectares, i.e. approximately 25 % of Sweden's total field acreage. Of these forage crops cultivated on the 700 000 ha, 17 % was ensilaged, which corresponds to approximately 720 000 tonnes of green fodder. Green fodder is the generic designation of the mass which is obtained by chopping forage crops such as grass, clover, lucerne, alf alfa etc. och possibly pressing them. Ensilage is a preservation method for int al green fodder and largely entails that the green fodder, either naturally or artificially, is subjected to fermentation in which bacteria strains and sugar varieties naturally occurring in the green fodder participate. Addition of bacteria and sugar also occurs. There exist substantially three preservation methods for green fodder. The commenest method is based on the addition of organic or inorganic acid with a view to rapidly reducing the pH of the green fodder in order thereby to reduce nitrogen losses and sugar losses via the degradation of proteins and cell breathing. A second preservation method which, however, is utilized to a lesser degree than acid treatment, is the addition of various preservative agents to the green fodder in order to minimize harmful microbial activity. These tv/o preservation methods account together for approximately 40 % of the total green fodder which is ensilaged. The remaining 60 % is ensilaged naturally. A number of basic precondi¬ tions must, in such instance, be met in order that natural ensilage is to be successful, i.e. the green fodder is not to be destroyed by harmful microorganisms such as various bacteria strains, yeast, mould, etc. These basic preconditions are as follows:

1. Anaerobity, i.e. the green fodder must be stored without air gaining access. If, during storage, the green fodder comes into contact with the oxygen of the air, the possibilities are immediately created for yeast and mould to grow uncontrollably, in which event the feed value of the ensilage disappears at the same time as a number of toxic substances are formed. Anaerobity is achieved, for example, by chopping the green fodder on har¬ vest, disposing it in a silo, as a rule of concrete, and packing the mass as hard as possible, often with the help of a tractor. Thereafter, the surfaces of the green fodder exposable to the oxygen of the air are covered with impermeable plastic which is then loaded with different materials.

2. For a natural ensilage, a bacteria flora is also required which can convert sugar varieties included in the green fodder into preservative lactic acid. Such a bacteria flora normally occurs in large volumes in green fodder, for which reason further additions in the form of bacteria preparations are not as a rule necessary.

3. One precondition for the ability of the lactic acid generating bacteria to grow is that there be present in the green fodder a sufficient amount of fermentable sugar vareties, such as glucose, fructose, saccharose, fructanes, etc. A sufficient amount of fermentable sugar is usually given as 25 g sugar per kg green fodder.

If the above three basic preconditions, viz. anaerobity, lactic acid generating bacteria and sugar content are satisfied, the requirements in order that the green feed may be converted into a fully satis¬ factory ensilage with high fodder value is satisfied. However, in practice, the situation is that the newly harvested green fodder is defective in one or more of the following respects. On storing in.

for example a silo, of directly harvested green fodder with a high aqueous content, large volumes of presswater are formed. This press water (as a consequence of its solubilizing nature) contains nutritive components dissolved from the green fodder such as nitrogen compounds, minerals, but also a large quantity of the sugar which is a basic precondition for the lactic acid generating microorganisms. Apart from being a considerable nutrient loss, this formation of presswater entails considerable environmental problems. As an illustrative example, it might be mentioned that 300 tonnes of ensilage with a relatively low total solids content corresponds to the same environmentally destructive effect as one day's production in the sewers from a town with a population of roughly 80 000.

In order to manage the problem of nutrient losses and environmental destruction caused by the presswater, the green fodder which is to be ensilaged is often predried. The predrying implies that the cut crop (the green fodder) is left to lie in the field for a suitable time until its total solids content has risen so that presswater is not formed after the fodder is layed in the silo. Naturally, this creates a considerable dependence on the weather conditions and requires considerable attention on the part of the farmer since certain weather conditions may rapidly raise the total solids content so that the ensilage may be rendered more difficult because of an excessively high total solids content, or alternatively poor weather conditions ma very rapidly destroy or greatly reduce the feed value. This entails in its turn that the harvesting time will be extremely dependent upon weather, which may be disadvantageous from the feed point of view, since the green fodder is harvested in view of the weather conditions and not in view of the point in time when its ^" feed value is at its highest. If the weather conditions are such that the predrying can be carried out in an optimum manner, relatively large total solids losses will, however, occur in the field. Primarily, it is the valuable leaf fraction which may be lost at the same time as an admixture of earth into the green fodder cannot be avoided. Such an admixture of earth entails an unnecessary contamination of the green fodder with harmful microorganisms, a factor which may subsequently render the ensilage process more difficult. This apart, the total solids content increases on predrying and this

entails that presswater formation can be minimized or eliminated at the same time as the relative sugar proportion in the green fodder increases, which in itself creates conditions for the activity of the lactic acid generating bacteria during the ensilage.

A very promising and already utilized alternative to predrying is the addition of absorbing components. For example, it is previously known from EP-A-0 246 863 to add, on the ensilage of grass, a free-flowing composition including int al sugar beet pulp, cereals and molasses. In accordance with the above-mentioned publication, the cereals have partly an absorbing function and partly a feed value raising function. Hence, the purpose of the cereals is to increase the total solids content of the green fodder to such levels that no presswater is formed, at the same time as a feed value is added to the fodder via the cereals. The disadvantage inherent in the addition of cereals is that the farmer is forced into costly storage of the grain, at the same time as the cereals in themselves contain fermentable carbo¬ hydrates in such low concentrations that the total carbohydrate content of the green fodder is diluted.

By tradition, use has been made, in conjunction with ensilage, of a product which is marketed under the name BetforCv, which consists half of dried beet fibres (beet pulp) and half of molasses. In this context, Betfor possesses the properties of absorbing presswater corresponding to approx. 3 g per gram of added Betfor at the same time as the product adds to the green fodder fermentable sugar varieties.

One object of the present invention is to provide a composition usable in the ensilage of green fodder, the composition being considerably improved primarily in respect of its presswater absorbing capacity, the feed value, economy and the amount of composition in relation to the amount of green fodder, i.e. the dosage. These improvements are achieved by means of a composition of the type disclosed by way of introduction and with the characterizing features as set forth in appended claim 1.

The composition according to the present invention includes, as major components, beet fibre, which is also designated beet pulp, together with dried sugar beet slices and molasses. Each one of these three major components will be described and defined in greater detail below.

Beet Fibre

Beet fibre is a residual product in sugar manufacture and consists of beet slices which have been leached, i.e. freed of the major fraction of the sugar, pressed and dried. The total solids content or the dry content is approx. 25 % after the leaching and mechanical pressing. The total solids, below abbreviated to TS, is increased by drying from approx. 25 % to the norm value 90 % TS - but in practice this value may vary between 88 and 92 % TS. The sugar content in the beet fibre varies as a rule between 3 and 6 % but normally amounts to approx 4 % per kg TS. The mechanical pressing operation, whose purpose is to remove the major fraction of included water, is normally effected by means of a screw press. Drying normally takes place in a drum drier, and for the greater part, also employing hot air gases. Those properties of the beet fibre which are utilized in the composition according to the present invention are primarily a high liquid absorbtion capacity, which amounts to approx. 6 times the natural weight of the fibre, and a high feed value.

Dried beet Slices

Beet slices, which are the starting product in sugar manufacture, consist of washed and sliced sugar beets. The sugar content varies between GO and 75 % per kg TS. For use in the composition according to the present invention, the beet slices are dried, for example in a drum drier, under such conditions that they obtain a TS value of approx. 90 %. In practice, the TS varies, however, between 88 and 90 %. The dried beet slices have a high water absorption capacity, a high sugar content and a high feed value, making them eminently well suited as one of the components in the composition according to the invention.

Molasses

Molasses consists of residual sugar and minerals, i.e. that product which is left after crystallization of the major fraction of the sugar in the solution which is formed on leaching of the beet slices, to a certain economical level. The molasses has a norm value for sugar content of 46 % (in Sweden) at TS 78 %. Normally, however, the sugar content varies somewhat. The TS content for Swedish molasses (RT figure) is 78 %. This value is often higher in production but is adjusted to the correct level on sales. Molasses can be derived from both beet and cane sugar. The RT figure varies greatly and is, among other things, dependent on source and use. Among the properties of the molasses utilized in the composition according to the present invention, mentioned might above all be made of its relatively high sugar content, its attractive flavor and the fact that the molasses in feed ration mixtures has a favourable influence on the pelletiza¬ tion capacity, int al because of its tacky effect.

By combining the above three components it has proved possible to realize a product usable in ensilage with a high energy content (of the order of magnitude of 12.5 MOME/kg), a high sugar content of the order of magnitude of 20 weight , and a high water absorption capacity, v/hich amounts to approx. 7 times its own weight or more. The relatively high water absorption capacity is a consequence of the pelletizing process which is employed for producing the composition (product) and which will be described in greater detail below. All of these three parameters are of crucial importance in ensilage.

It will be clearly apparent from the discussion below that, having perceived the importance of the presence of the above-mentioned three components in the composition, those skilled in the art will find no major difficulties (essentially requiring no inventive work) in determining the proportions between the three components so that an optimum composition in respect of the above-described three parameters will be obtained. Hence, of primary importance to the present invention, and its characterizing features, is the presence of the above-described three major components, while their relative proportions may readily be established by a person skilled in the art.

Reference has been made above to three major components. However, the presence of these three major components in the composition according to the present invention does not preclude the presence of other components which may possibly be added for other purposes than those disclosed above in connection with the present invention, viz. for realizing an improved water absorption capacity, a higher sugar content and an improved animal feed value. Examples of such other components are vitamins, minerals, salts, nutrients etc. Such additions are of a purely conventional type and are not, therefore, germane to the spirit and scope of the present invention.

A theoretical admixture of beet fibres may amount to between 40 and 100 %. The higher degree of admixture can be motivated with respect to the superior water absorption capacity. On the other hand, such a product adds an extremely limited amount of fermentable sugar varieties. There are, therefore, grounds for reducing the admixture of beet fibre. A 90 % admixture improves the situation given that the sugar-containing products dried beet slices and molasses are admixed. Hov/ever, this is not sufficient to realize an adequate sugar addition to the ensilage. At an 80 % admixture of beet fibre, an acceptable sugar level may be obtained if the remainder (20 %) exclusively consists of dried beet slices. However, in terms of cost, this is more onerous than molasses, at the same time as molasses is needed in the composition for reasons of pelletization technology. If the beet fibre is included in the composition in an amount of 40 % (lower limit), 60 % will, naturally, consist of a mixture of molasses and dried beet slices. In such case, the admixture of molasses must, for technical reasons, be set at a maximum of approx. 25 %, of which the remaining 35 % v/ould then be constituted by dried beet slices. However, this mixture "looses out" water absorption capacity, at the same time as the sugar content will become unnecessarily high. It will be apparent from the foregoing reasoning that acceptable quantity ranges for the three major components are as follows: 40-90 % beet fibre, 5-25 % molasses and 10-35 % dried beet slices. Results from tests undertaken in the development of the present invention have shown that preferred ranges are 65-80 % beet fibre, 5-20 % molasses and 10-20 % dried beet slices, these percentages being based on dry weight. It may generally be noted that an

increased admixture of beet fibre at the expense of molasses and dried beet slices satisfies the requirement of water absorption capacity, at the same time as adequate quantities of sugar can be added to the green fodder. With the above-described preferred quantity ranges, the requirements of high-water absorption capacity and high-sugar content in combination with a high feed value will be satisfied in an optimum manner.

The ensilage composition according to the present invention is prepared according to one embodiment, by first grinding and carefully mixing beet fibre and dried beet slices in a quantity within the above-indicated quantity ranges in a separate blender. The thus obtained mixture is subsequently added to a mixer which is disposed in direct association with a pellet press. In the mixer, molasses is added, possibly together with steam to increase the plasticity of the material, in an amount within the above-indicated range and the thus obtained three component mixture is pelletized and cooled. The obtained pellets are suitable for delivery in sacks or in bulk. In order to obtain the correct total solids content in the final product, the beet fibre and/or the dried beet slices must, in certain cases, have a higher total solids content than 90 %, since a certain amount of heat is generated in the pelletizing process which is utilized for removing a certain volume of water. Naturally, account must be taken of this factor in adjusting the total solids content of the included components. According to one preferred embodiment, the total solids content in the final product is 88-92 weight-%.

According to one alternative and preferred embodiment according to the present invention, wet beet fibres or beet pulp (TS = 20-30 %) is mixed with molasses in proportions within the above-mentioned quantity ranges and dried with hot air (exhaust air temperature 100-150°C) in a drum drier, for example of the same type as employed for drying the leached beet slices after mechanical dewatering. Standard values and normal distribution of the total solids content will be the same as for beet fibre, as was mentioned above. This dried product consisting of beet fibre and molasses is subjected to pelletization so as to increase volume v/eight. Dried beet slices are added to this product, which is then ground and blended for subsequent pelletization.

According to the above preferred embodiment the ratio (weight) between the molasses and wet beet fibre is usually within the range of 0.18 - 0.25, and preferably within the range of 0.20 - 0-23. The ratio (weight) between the beet slices and the pellets comprising beet fibre and molasses is usually within the range of 0.13 - 0.20, preferably 0.15 - 0.18.

The diameter of the pellets should be as small as possible, since the distribution and absorption capacity will be greater the smaller the diameter. Pellet diameters of between 3 and 5 mm have proved to be ideal. The length of the pellet should be as a maximum twice the diameter, since the material then "flows" more easily in spreader equipment, etc. At the same time volume weight is increased.

EXAMPLE

Molasses and wet beet fibre (TS 25 %) in a weight ratio of approx. 0.20 are mixed in a separate blender and dried in a drum drier to TS approx. 90 _.. This blend is thereafter ground and a fraction is removed with a maximum particle size of approx. 6 mm (the major part of the fraction has a particle size of 4-6 mm) and this fraction is batched in a mixer which is disposed in direct association with ^' a pelletization press of the ring matrix type and Matador make. The mixer is supplied with pressurized steam (approx. 4.5 bar) and is at such temperature that the material in the mixer assumes a temperature of 60-70°C. The ground mixture of beet fibre and molasses disposed in the mixer is subsequently subjected to pelletization in the press and pellets are obtained of a diameter varying between 3 and 5 mm and a length of at most 10 mm. Beet slices and pellets (in the approx. ratio of 0,16) are ground in a mill and fractions with a maximum particle size of 6 mm are removed and added to the above-mentioned mixer (once this has possibly been cleaned). Steam is once again supplied under substantially the same conditions as above and the mixture is once again subjected to pelletization. Pellets are obtained with a mean diameter of 4 mm and with a TS-content of approx. 90 %. The pellets have a water absorption capacity exceeding 7 times their own weight.

The present invention has been described with reference to preferred embodiments thereof, but it will be obvious to those skilled in the art that many variations and modifications are conceivable without departing from the spirit and scope of the inventive concept as herein disclosed and claimed.