GB2125698A

GB2125698A - Improved rumen bolus

Info

Publication number: GB2125698A
Application number: GB08318900A
Authority: GB
Inventors: Cyril Francis Drake; Mary Tripp
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1982-07-15
Filing date: 1983-07-13
Publication date: 1984-03-14
Also published as: GB2125698B; AU1671283A; GB8318900D0; NZ204879A; GB2124899A

Abstract

A rumen bolus for administration to a ruminant animal comprises a tubular body containing or incorporating an active material. The tubular shape of the body provides greater retention in the rumen than a conventional solid bolus.

Description

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GB2 125 698 A

1

SPECIFICATION Improved rumen bolus

5 This invention relates to animal husbandry and in particularto devicesforthe administration of medicaments to animals.

Ruminant animals, e.g. cattle and sheep, may be provided with medicaments by the administration of 10a rumen bolus. The bolus containing the medicament is administered orally and is intended to lodge in the rumen for a period sufficient for release of an active material into the digestive system of the animal. A major problem experienced with this technique is 15 that of lack of retention of the bolus in the rumen. In many cases the bolus is swept into the post rumen portion of the digestive system along with the rumen contents before sufficienttime has elapsed for effective medication to take place. Since passage 20 through the post rumen portion of the digestive system is relatively rapid very little further release of the medicament is effected. This is a particular problem where it is intended to supply a medicament to an animal over an extended period.

25 Attempts have been made to overcomethis problem by weighting the bolus, e.g. with iron weights, to provide gravity retention. This technique is however relatively costly and it is of course undesirable to introduce relatively large quantities of 30 free metal into an animal.

The object of the present invention is to overcome the disadvantages of the prior art by providing a rumen bolus with improved retention properties.

According to one aspect of the invention there is 35 provided a tubular rumen bolus.

According to another aspect of the invention there is provided a rumen bolusfor administration to an animal, said bolus comprising a wholly or partially soluble tubular body incorporating one or more 40 active materials.

We have found that the retention of a tubular rumen bolus, i.e. a hollow body having open ends, in the rumen of a ruminantanimal is significantly greaterthanthatofasolid bodyofsimilardensity. 45 Thus, the use of a tubular bolus obviates the need for the provision of metallic weights to ensure retention in the rumen for a reasonable period.

Typically the bolus comprises a water soluble glass, but other materials can of course be used. 50 Embodiments of the invention will now be described with reference to the accompanying draw-ingsinwhich:—

Fig. 1 isa plan view of a tubular rumen bolus;

Fig. 2 is a longitudinal sectional view of the bolus of 55 Fig. 1;

and Fig. 3 is a cross-sectional view of the bolus of Fig. 1.

Referring to the drawings the bolus comprises a hollow tubular body 11, typically of annularcross 60 section, which body is advantageously made of a water soluble glass composition. The dimensions of the bolus are by no means critical, but for maximum retention it is preferred thatthe wall thickness of the body should be significantly less than its radius. The 65 preferred ratio of wall thickness to outside radius is from 1/2 to 1/10.

Advantageously the entire body is soluble in the rumen fluids and incorporates one or more active materials released by dissolution of the body. The 70 configuration of the body is such that its surface area does not change significantly during dissolution both from the inner and outer surfaces. Thus the dissolution rate is substantially constant.

Typically the body material is a water soluble glass 75 incorporating one or more active materials, e.g. trace elements, in oxide form. These trace elements are released by dissolution of the glass which may be of the a phosphate type. The dissolution rate of the glass is determined by its composition and may be 80 controlled by the incorporation of furtherglass modifying oxides in the glass. Thus, for example, the addition of alkali metal oxide to the glass increases its dissolution rate whilst the addition of alumina or ferric oxide decreases the dissolution rate. Furth-85 ermore, by suitable choice of the glass modifying oxides, the dissolution rate characteristic of the glass may be controlled to give a desired dissolution rate underthe particular pH pertaining in the rumen. The techniques of glass dissolution rate control are more 90 fully described in our published specification No. 2,057,420 (C.F. Drake 70).

Field trials have demonstrated that tubular boluses 2.5cm in diameter, having a density of 2.4g/cc and lengths of 3,5,7 and 9 cm are retained in unfistulated 95 cattle for periods of at least 120 days thus demonstrating the efficiency of the technique. The mechanism whereby the tubular shape of the boluses provi des fo r its retenti onintherumenisnotfully understood but it is thoughtthatthe open ends may 100 provide a degree of frictional contact with the rumen wallsthus preventing the bolus from being swept along the digestive tract with the rumen contents.

The continuity of the rumen contents inside and outside the hollow cylinder may also be a contribut-105 ing factor in preventing loss of the bolus.

Three soluble glass compositions were used for these trails. These are listed in the following table, all concentrations being expressed in mole percent.

Glass Batch MgO Cao Na20 cuo P205

1 15.8 - 41.2 - 43

2 - 26.6 26.9 - 46.4

3 - 0.7 21.9 33.4 44.0

In these and other suitable glass compositions the

110 principal glass forming oxide is phosphorus pentox-ide. The glass also contains glass modifying oxides, e.g. alkali metal oxides and/or alkaline earth metal oxides, whereby the glass dissolution rate, in the pH conditions in the rumen, is determined. Typically the 115 glass contains36to 48 mole % phosphorus pentox-ide, although phosphorus pentoxide contents outside this range can also be used. A proportion of this glass forming oxide, typically upto 10 mole %, may be replaced by other non-toxic glass formers such as 120 B203,Si02orS03.Furthersuitableglasscomposi-

The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy.

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GB 2 125 698 A

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tions are described in ourco-pending application Nos. 38222/78 (C.F. Drake 64); 49600/78 (C.F. Drake-M. Tripp 68-2; and 8025964 (C.F. Drake-M. T ripp 72-3).

A variety of active elements may be incorporated in 5 the glass for release at a controlled rate into the rumen of an animal. These elements include, but are not limited to, copper, selenium, boron, magnesium, iron, iodine, zinc, cobalt, manganese and molybdenum.

10 The glasses may be formed by melting quantities of the constituent oxide materials, or where appropriate their precursors such as carbonates which break down on heating to form the corresponding oxides, to form an homogeneous melt from which the bolus 15 may then beformed. Composition control maybe effected by using accurately measured quantities of the constituent materials or, preferably, by chemical analysis of the finished glass. If the former method is employed due allowance must be madeforthe loss 20 by volatilisation of one or more of the constituents, particularly phosphorus pentoxide.

In a further application the hollow axis of the tubular body may be packed with a highly soluble material, e.g. an antibiotic or an anthelmintic com-25 position, to provide additional medication priorto dissolution of the body. This material dissolves on ingestion to free the bore of the bolus and does not therefore inhibit retention. Alternatively a low solubility active material may be provided as a pellet 30 retained in the central portion of the bolus.

The bolus may be made by a variety of methods. The body may be cast, pressed, drawn or moulded. Advantageously the body may be cast by the process described in ourco-pending application No. (J. R. 35 Brocklehurst-V. Baker-C.T. Millikin 6-1 -1).

In a further embodimentthe bolus may comprise a pressed or moulded body of a composite material formed from a particulate water soluble glass and a polymeric resin. Such composite materials are de-40 scribed in our copending application No. 8134751 (C.F. Drake-R. Jones 82-2).

In another embodimentthe bolus 11 may be formed from two or more different materials, 11a, 11b and 11c (Fig. 3). Such a structure may be 45 employed where the substances to be released on dissolution are difficult to provide in a single material or are incompatible in a single material. This overcomes the problem, sometimes experienced with glass composition, of devitrification or phase separa-50 tion where certain combinations and concentrations of materials are used. The technique also provides for the separate dissolution rate control of the various active materials.

Claims

CLAIMS 55 1. Atubularrumen bolus.
2. A rumen bolus for administration to an animal, said bolus comprising a wholly or partially soluble tubular body incorporating one or more active materials.

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3. A bolus as claimed inclaim 1 or2,and comprising a water soluble glass composition.
4. A bolus as claimed in claim 3, wherein said glass incorporates one or more trace elements in oxideform.

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5. A bolus as claimed in claim 4, wherein said glass incorporates copper, selenium, boron, magnesium, iron, iodine, zinc, cobalt, manganese, molybdenum or mixtures thereof.
6. A bolus as claimed in claim 3 or4, wherein the

70 principal glass former of the glass is phosphorus pentoxide.
7. A bolus as claimed in claim 6, wherein the glass includes 36 to 48 mole % phosphorus pentoxide.
8. A bolus as claimed in claim 6 or7, wherein a

75 proportion not exceeding 10 mole % of the phosphorus pentoxide is substituted by one or more further glass modifying oxides.
9. A bolus as claimed in claim 6,7 or 8, wherein the glass includes one or more alkali metal oxides,

80 one or more alkaline earth metal oxides or mixtures thereof.
10. A bolus as claimed in any one of claims 1 to 9 and comprising a plurality of water soluble glass compositions.

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11. A bolus as claimed in claim 1 or2 and comprising a composite material.
12. A bolus as claimed in claim 11, wherein said composite material comprises a particulate water soluble glass and a polymeric resin.

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13. Abolusasclaimedinanyoneofclaims1to12, wherein the ratio of the wall thickness to the external ratios is from 1/2 to 1/10.
14. A bolus as claimed in any one of claims 1 to 13 and containing a medicament having a relatively high

95 solubility.
15. A bolus as claimed in any one of claims 1 to 13 and containing a medicament in the form of a pellet retained in the core of the bolus.
16. A bolus as claimed inclaim 14or 15, wherein

100 said medicament includes an anthelmintic.
17. A rumen bolus substantially as described herein with reference to the accompanying drawings.

PrintedforHerMajesty'sStationery Office byTheTweeddale Press Ltd., Berwick-upon-Tweed, 1984.

Published at the Patent Office, 25 Southampton Buildings, London WC2A1 AY, from which copies may be obtained.