GB2124068A - Foodstuffs for ruminant animals - Google Patents

Abstract

A liquid feed supplement for ruminants, suitable for addition to straw or other roughage, comprises an acid solution of urea, possibly accompanied by other sources of non-protein nitrogen such as biuret and ammonium ions, sulphate ions to provide a source of sulphur and contains large, multivalent cations, such as those of magnesium or aluminium, which do not form an insoluble sulphate precipitate. The supplement can be relatively highly concentrated, containing for example between 35% and 65% urea by weight. The presence of the cations in acidic conditions has been found to prevent the crystallisation of the urea which would otherwise tend to occur on cooling. The supplement may also contain cations of trace elements such as zinc, manganese and copper. It may also contain molasses to sweeten the supplement and increase its stickiness.

Description

SPECIFICATION Foodstuffs for ruminant animals This invention relates to foodstuffs for ruminant animals. Roughage, such as barley straw, is often fed to ruminants as it is relatively cheap. Nevertheless, ruminants can normally digest only part of the roughage. In the case of straw, for example, ruminants are usually able to digest only between about 48% and 50% of it, the proportion digested depending on the plant variety from which the straw is derived and on other factors.

Straw, like much other roughage material, consists largely of fibre, mainly in the form of lignin and cellulose.

Lignin cannot be digested by ruminants but cellulose can be digested by them. However, the digestibility of the cellulose in straw and other roughage is reduced by the presence of lignin. Another disadvantage of roughages is that they normally lack a source of nitrogen such as is required by ruminant for conversion into proteins.

The addition to roughage of an aqueous solution of urea provides a source of nitrogen and improves the digestibility of the material. In the case of straw, such an addition of urea usually results in an increase of about four digestibility units (i.e. the percentage of the straw that can be digested increases by about 4%).

Another method of improving the digestibility of straw, and other forms of roughage, is to treat it with alkalis. Although the nature of the resultant chemical reactions is not fully understood, it is believed that the alkalis in some way react with the lignin and thus render the cellulose more available and therefore more digestible than it was before. One of the alkalis used has been sodium hydroxide but this is a relatively dangerous chemical requiring careful handling, and it adds no nitrogen to the roughage. Another alkali that has been used is ammonium hydroxide. Sometimes gaseous ammonia has been used. While ammonia and the ammonium ion are both sources of nitrogen, they also are relatively expensive and dangerous and require careful handling.In practice, therefore, the use of alkalis has generally been restricted to large, well-managed farms, and other establishments, that employ specialist personnel and equipment. As the use of alkalis is restricted, there is still an interest in the use of other additives such as urea and other non-protein nitrogen sources, which do not suffer from the disadvantages referred to above.

Ruminants are often fed with a diet consisting wholly or mainly of a relatively large proportion of straw and a smaller proportion of cereal. When urea has been used as an additive it has in the past usually been added to the cereal,though it has quite recently been shown that the addition of an aqueous solution of urea to the straw produces very beneficial results. This may result from the fact that the consumption of the treated straw is normally spread out over much of the day so that there is quite a steady intake of urea during a prolonged period. As urea is somewhat unpalatable it is sometimes used in conjunction with molasses, which is sweet, inexpensive and has a relatively high energy content.

It is desirable for the solutions of urea and other substances to be relatively strong, as it is both expensive and awkward to transport and apply dilute solution. Moreover, the use of dilute solutions tends to make the straw or other roughage unnecessarily wet. Problems arise, however, with the use of more concentrated solutions of urea as the urea tends to crystallise out of solution, its solubility decreasing with decreasing temperature. For example, a solution comprising 50% urea and 50% water by weight is saturated at 1 70C.

Some of the urea is therefore likely to precipitate out of such a solution at ambient temperatures lower than 1 7 C. Moreover, it is difficult to redissolve urea, as the dissolution of urea in water is a strongly endothermic reaction. A similar problem arises when a concentrated solution of urea is sprayed through a nozzle, for there is a tendency for the urea to form a precipitate and to clog the nozzle.

Now there is on the market an aqueous feed supplement containing a relatively high proportion of urea but which is sufficiently stable for urea not to be precipitated from the supplement either in cold weather or when it is sprayed through a nozzle. That supplement also contains calcium ions, trace elements and vitamins. The use of that supplement is to some extent restricted by the fact that the ratio of calcium and other metal ions to urea is predetermined and may be unsuitable for some stock. Moreover, in many cases this supplement will not provide the correct balance of mineral elements for the stock if it is the sole supplement to the diet of that stock. The use of additional supplements may therefore be necessary.

As explained above, where feedstuffs for ruminants have a low nitrogen content it is advantageous to add non-protein nitrogen to them. It is believed that much of the nitrogen in what is eaten by a ruminant is incorporated in microbial protein in the rumen, but as proteins also include sulphur, a source of usable sulphur must also be available for this to occur. For the formation of microbial proteins there is a requirement for one part of sulphur for about every eighteen parts of nitrogen by weight. A traditional method of incorporating sulphur is to add soluble sulphates to feed-stuffs for ruminants. It would, of course, be impossible to add sulphates to the commercially available supplement referred to above, as the calcium ions and sulphate ions would combine to form a precipitate of insoluble calcium sulphate.

An aim of the present invention is to provide a formulation for a feed supplement for ruminants enabling at least some of the disadvantages outlined above to be overcome or reduced.

From one aspect the present invention consists in a liquid feed supplement for ruminants comprising an acid solution of urea containing sulphate ions and large, multivalent cations that do not give rise to the formation of an insoluble sulphate precipitate.

The acidity of the solution and the concentration of said cations is preferably such as to prevent the solution forming a precipitate when its temperature is reduced to - 150C. Th is is particularly desirable in the case of a supplement embodying the present invention that is likely to be stored in unheated premises or out of doors. The supplement may, of course, be such that no precipitate is formed when an even lower temperature is reached. Nevertheless the criterion expressed above, namely that no precipitate should form when the temperature of the supplement is reduced to -1 5 C may be excessively stringent in some circumstances. All the same it is usally desirable for the solution to be such that it can be cooled, at least to some extent, without a precipitate forming.Thus the supplement may be such that no precipitate is formed when its temperature is reduced to a certain temperature above - 1 50C, such as - 1 0 or - 5"C or even only 0 C. In each case, of course, the solution would be such that it did not freeze at the temperature specified.

The invention is particularly, though not exclusively, applicable to solutions in which the urea content is between 35% and 65% by weight. Thus, the urea content is preferably not less than 35% by weight and is preferably not greater than 65% by weight.

The invention is based on the discovery that the presence of hydrogen ions and of large, multivalent cations inhibits the crystallisation of urea from an aqueous solution. Calcium ions cannot be used for, as pointed out above, they form an insoluble precipitate with the sulphate ions. Magnesium ions are preferred.

Aluminium ions may also be used in addition to magnesium ions or intead of them. Zinc is generally unsuitable for use as the sole or principal source of cations as it could be toxic at the concentrations required.

Nevertheless the large, multivalent cations may include the cations of one or more trace elements in non-toxic quantities. Thus cations of at least one of the following metals may be included: zinc, manganese and copper. Such trace elements are essential for the well-being of ruminants.

In the formation of the solution, the cations would usually be introduced in soluble salts. In particular they are preferably introduced as chlorides or sulphates. Magnesium chloride is a preferred salt.

The urea in the supplement constitutes a source of non-protein nitrogen. If desired one or more other sources of non-protein nitrogen may also be included. For example the solution may include biuret and/or one or more ammonium salts such as ammonium sulphate.

The solution may be rendered acidic with the aid of sulphuric acid, which then provides some or all of the necessary sulphate ions. Another acid that could be used is hydrochloric acid. If hydrochloric acid is the only acid used, it is necessary for soluble sulphate salts to be added to provide the sulphate ions. An increase in the acidity of the solution (i.e. a decrease in the pH) is generally found to increase the solubility of the urea in the solution. Simple experiments can be undertaken to enable suitable ranges of pH to be found for any particular concentration of urea. The concentration of large multivalent cations also affects the solubility of the urea, but here again suitable concentrations of these cations can readily be determined by experiment.

The solution would usually be such that the content of sulphur in a form available to the microflora in the rumen would be less than the content of nitrogen in a form available to the microflora in the rumen. For the reason outlined above, however, the content of sulphur in that form is preferably no less than about one eighteenth of the content of nitrogen in that form.

In order to mask the taste of the urea and thus increase the palatability of the solution, sweetners and/or flavouring additives may be incorporated in the solution. Molasses may be added, both to sweeten the solution and to increase the stickiness of the solution, enhanced stickiness increasing the extent to which the solution sticks to straw or other roughage to which it is applied. One or more other substances may be included which serve to increase the stickiness of the solution and/or to thicken the solution. For example, one or more gums, such as Guar gum or Xanthan gum, may be included for either or both of these purposes.

In addition, or alternatively, one or more surfactants may be added to the solution in order to assist in the dispersion of the solution when it is being applied.

Anti-corrosive agents may be included in the solution. As indicated above, minor quantities of substances containing trace elements essential for the well-being of ruminants may be included. Minor quantities of other nutrients, salts and/or growth promoters may also be included.

The solution is preferably added to straw or other roughage which is later fed to ruminant animals, and from another aspect the present invention consists in a foodstuff for ruminant animals comprising straw or other roughage to which a solution of the kind outlined above has been added. The solution may be applied to the roughage in any suitable manner. For example it may be poured onto the roughage or sprayed on to it.

The solution is preferably applied to the straw or other roughage at harvest-time. It may, for example, be applied when the material is about to be made into bales. The treated material can then be stored before use.

It is preferably stored for at least one month and may be stored for a longer period. During storage some of the urea decomposes to form ammonia, which acts in a manner similar to that described above.

Alternatively the solution may be applied to the straw or other roughage at some other time; it may, in particular, be added shortly before the roughage is fed to the ruminants.

Ruminant animals fed with the treated roughage are also preferably fed with a separate supplement which incorporates one or more of the following constituents: minerals such as calcium and phosphorus, trace elements and vitamins. The formulation of this separate supplement may be varied as required. The requirements generally vary with different types of stock; further, the soil in different neighbourhoods may lack certain minerals and include sufficient quantities of others. Vitamins are preferably excluded from solutions in accordance with the invention, for they tend to deteriorate during storage; in particular, roughage treated at harvsst-time with a solution containing vitamins would be likely to have a much reduced vitamin content by mid-winter when the treated material would most probably be consumed by the ruminants.

There now follow two Examples illustrative of the present invention.

Example Urea 41% Molasses 10% MgC121/26H20 14% to 20% MgSO41/27H2O 3.0% H2SO4(98% strength) 2.0% Trace elements 0.9% Water remainder The percentages are proportions by weight. As the proportion of magnesium chloride increases, so the temperature at which the urea crystallises out decreases.

The solution may be poured or sprayed onto straw or other roughage which is subsequently fed to ruminant animals as described above.

Example II Urea 55% MgCI2 solution (8.2% Mg) 26% H2SO4 (77% strength) 5.6% Water 13.4% The percentages are proportions by weight. The solution may be poured or sprayed onto straw or other roughage which is subsequently fed to ruminant animals as described above.

Claims (18)

1. A liquid feed supplement for ruminants comprising an acid solution of urea containing sulphate ions and large, multivalent cations that do not give rise to the formation of an insoluble sulphate precipitate.

2. A liquid feed supplement according to claim 1 in which the acidity of the solution and the concentration of said cations is such as to prevent the solution forming a precipitate when its temperature is reduced to -15"C.

3. A liquid feed supplement according to either of claims 1 and 2 in which the urea content is not less than 35% by weight.

4. A liquid feed supplement according to any one of the preceding claims in which the urea content is not greater than 65% by weight.

5. A liquid feed supplement according to any one of the preceding claims in which the large, multivalent cations consist entirely or partially of magnesium ions.

6. A liquid feed supplement according to any one of the preceding claims in which the large, multivalent ions consist entirely or partially of aluminium ions.

7. A liquid feed supplement according to any one of the preceding claims in which the large, multivalent cations include the cations of one or more trace elements in non-toxic quantities.

8. A liquid feed supplement according to claim 7 in which the large, multivalent cations of trace elements include the multivalent ions of at least one of the following metals: zinc, manganese and copper.

9. A liquid feed supplement according to any one of the preceding claims which has been rendered acidic with the aid of sulphuric acid.

10. A liquid feed supplement according to any one of the preceding claims in which the content of sulphur in a form available to microflora in the rumen of a ruminant animal is no less than about one eighteenth of the content of nitrogen in that form.

11. A liquid feed supplement according to any one of the preceding claims which incorporates molasses.

12. A liquid feed supplement according to any one of the preceding claims in which one or more substances is included to increase the stickiness of the solution and/or to thicken the solution.

13. A liquid feed supplement according to any one of the preceding claims in which one or more surfactants are added to the solution.

14. A liquid feed supplement which contains a source of non-protein nitrogen additional to urea.

15. A liquid feed supplement according to claim 1 4in which said source of non-protein nitrogen comprises biuret and/or one or more ammonium salts.

16. A liquid feed supplement substantially as hereinbefore described in Example I.

17. A liquid feed supplement substantially as hereinbefore described in Example II.

18. A foodstuff for ruminant animals comprising straw or other roughage to which has been added a liquid feed supplement in accordance with any one of the preceding claims.