MXPA97000670A - Cebo rodentic - Google Patents

Abstract

The present invention relates to a rodenticidal bait in the form of agglomerated granules comprising: a cereal base comprising a milled cereal, a rodenticide, and a soluble agglutinating film-forming binder.

Description

-_ RODENTICITY BAIT DESCRIPTION OF THE INVENTION This invention relates to rodenticidal baits; that is, edible compositions that are attractive to rodents (especially rats and mice), and which contain a rodenticide. Many types of bait are in commercial use and others have been proposed. These include grains; pellets usually prepared by extrusion or casting; wax blocks newly usually prepared by extrusion or casting, and wherein the edible material attractive to rodents is incorporated into the wax; and food baits that comprise 5 processed cereals in various forms. Cereal-based baits containing a rodenticide and a water-soluble film-forming binder are described in, for example, DE-A-2317285, DE-A-1929137, CH-A-348003, FR-A-2260948 and FR-A-2659194. These baits are in the form of grains, for example pellets, generally produced by compaction techniques under pressure. Such techniques include, for example, the use of a roller compactor (briquetting press) or a tablet forming press. In addition, Belgian Patent 847,653 discloses rodenticidal baits that consist of a core of an edible material coated with an outer film, which itself contains a rodenticide. None of these references suggests that the attraction of cereal-based baits for rodents can be improved by using cereal particles with different sizes in particular proportions. According to the present invention, a rodenticidal bait is provided in the form of agglomerated granules having an open texture comprising (1) a cereal base wherein from 2% to 10% of the particles of the cereal have a size in the scale of equal to or greater than 500μm to less than or equal to lOOOμm, and from 70% to 90% of cereal particles have a size on the scale equal to or less than 250μm, (2) a rodenticide, and (3) , a binder formed of water soluble film. Preferably, the rodenticidal bait contains an acceptor-appetite enhancing agent. The rodenticidal bait may contain other components, for example, a coloring agent, a preservative or a substance to prevent the consumption of the bait by a human being. The size of the agglomerated granules is preferably in the r of 0.20 mm to about 10 mm. and most preferably from 0.25 mm to 5 mm. In general, the agglomerated granules are generally round, but with minor irregularities, which provide attractive sites for rodents to graze. The granules can be prepared, applying conventional granulation methods to a mixture of components. The water-soluble film-forming binder is included in the granulation process as an aqueous solution. As the wet granules are formed in the drying process, the film-forming binder ,. Stabilizes the granules by joining together the particles '10 of the components. The film-forming binder also causes the individual granules to adhere together to form agglomerates or lumps having an open texture due to the gaps between the individual granules. (It could be mentioned that to a certain degree the The term "granulation" is used generically in the art as a convenient term to describe all the processes by which rodenticidal baits have been prepared. However, the present invention relates to a novel rodenticidal bait in the form of an agglomerated granule and processes for its preparation). This open texture may be more attractive to rodents than baits of the prior art. For example, open texture may be more attractive to rodents than solid block baits, such as pellets, since they are capable of separating small portions of the agglomerate from granules more easily than from a solid block or a pellet. Actually, the bait of the present invention, which is rough and irregular, can be contrasted with smooth and uniform prior art baits, particularly the pellet. The agglomerated granules of the invention may also be more acceptable to rodents than the baits hitherto proposed, since several non-acceptable ingredients, such as the dye and the rodenticide, are uniformly distributed throughout all the granules and unconfined, example, to a film on the surface of the bait, as in the bait described in Belgian Patent 847,653. As previously mentioned, a variety of processes can be used in the preparation of the bait to an agglomerated granule form; for example, mechanical agitation or fluidized bed granulation. Preferably, the mechanical agitation method is used. Examples of the machinery that can be used in said method of mechanical agitation are: Drum, tray and roller granulators, double-arm mixers, plow-gate mixers (Lodige), high-shear granulators, and strip mixers . Since operations may vary, depending on the particular process selected, a typical process could include the following steps: (a) Dry powder components (eg, ground cereals and optional enhancers of acceptability) are completely mixed together in a suitable mixer to form a premix. Typical mixing times could be 1 to 10 minutes depending on the machinery used. The mixer used for this operation can also be the means by which granulation is achieved (as assumed in the schematic process). (b) The rodenticide and the agent for preventing the consumption of the bait by the human being, if appropriate, both preferably in the form of a liquid concentrate, are added to the premix described in part (a), and the mixture is It combines until it becomes homogeneous. Typically, the concentrate could be sprayed onto the premix to aid in the production of even distribution. Typical mixing times could be of the order of 10 to 30 minutes. (c) An aqueous solution of the film-forming binder, optionally containing a preservative, is sprayed onto the mixture described in part (b), while the mixture is combined. Alternatively, the film-forming binder solution can be mixed with the concentrate of active ingredient and the only resulting liquid component sprayed onto the powder premix. (d) The wet mass is mixed for a required time until granulation is achieved and the required particle size scale is produced, typically this could be in the order of 1 to 5 minutes. (e) The granule mass is then dried at a specific moisture level, either in the granulator or in a separate apparatus (eg, a fluidized bed dryer). The typical moisture content could be in the range of 5 to 15%. Drying times may vary and depend on the initial moisture content, the drying temperature, the air flow, etc. The typical drying temperature could be 80-100 ° C and the drying times could be of the order of 30 minutes. (f) The granules are classified (for example by screening) at the required particle size scale. Typically, 0.20 mm, preferably 0.25 to 10 mm as previously mentioned. The agglomerated granules can be used to prepare other forms of bait. In this way, the wet granules prepared by the granulation process can be formed into blocks before drying. Alternatively, the granules, when dried, can be mixed with a fat or molten wax and then molded into blocks, which are allowed to cool and solidify. Such blocks can be prepared on a scale of sizes, for example, from 5 to 500 grams by weight. The baits according to the invention have these other advantages. (1) They can withstand high levels of moisture without breaking or becoming moldy; (2) They are highly acceptable by rodents; (3) During handling and application 'are not powdery; The cereals and other edible ingredients used in the bait are preferably of the highest available grade (ie, human food grade). In the bait, a wide variety of cereals can be used, for example, wheat, barley, corn, sorghum, oats, rice and millet. In the present invention, other cereals suitable for rodenticidal baits can be used, and one skilled in the art will know such cereals. It will be appreciated that one or more cereals may be used in the present invention. A proportion of the cereal can be replaced, if desired, by a ground pulse (eg, peas or ground beans). In order to obtain the required granule size, and to produce the open texture agglomerated granules described above, it has been found desirable to use cereals of a particular particle size regimen. The cereal is preferably not all reduced to the same particle size scale (ie, not all is ground to flour, or all in the form of coarse particles such as cut wheat kernels). Preferably a mixture of particle size scales is used, wherein a smaller proportion (less than 50%) of the cereal is in the form of relatively coarse particles (eg, as in the larger particles of the whole milled wheat), while that a larger proportion is in the form of relatively fine particles (for example, in wheat flour). Preferably, the size of the coarse particles is on the scale of or equal to or greater than about 500μm, but equal to or less than lOOOμm (lmm). The preferred amount of coarse particles used in the agglomerated granules is in the range of about 2% to about 10% by weight. Preferably, the size of the fine particles is equal to or less than 250μm. The preferred amount of fine particles used in the agglomerated granules is in the range of about 70% to about 90%. Obviously, there are combinations of the two proportions, coarse and fine, which add less than 100%. Any missing proportion could be made of intermediate particles, which preferably are in the range of 250μm to 500μm.

Only, by way of example, an analysis of the particle size scale of the two typical starting materials, mainly medium whole milled wheat flour and fine ground oat flour, is given below: Whole Ground Flour Half Size Aperture Percentage of sieve retained (μm) on sieve * 840 5 420 15 250 15 177 25 149 10 Passing 149 30 Fine Ground Oatmeal Aperture Size Percentage of sieve retention (μm) on sieve * 500 2 300 10 212 10 150 20 Passing 150 58 * Accuracy + 5% All sieve aperture sizes are classified as micrometers (μm). When mixtures of cereals are used, if desired, a cereal can be used to provide the coarse particles and another cereal to provide the fine particles. Examples of such mixtures include: finely ground corn with whole milled wheat; finely ground barley with whole milled wheat; whole ground wheat with finely divided oats; and finely ground wheat with whole milled barley. Baits that contain a mixture of two or more cereals may be more attractive to rodents than baits that contain only one cereal. Preferably, the rodenticidal bait includes an acceptability enhancing agent. The enhancer component of bait acceptability may include, for example, a sweetener. The sweetener may be, for example, sugar (sucrose), optionally in the form of molasses. Other sweeteners can be used and examples of which include acesulfame-K, alitame, aspartame, cyclamate, saccharin, sucrose, sorbitol, mannitol, xylitol, taumatin, monelin, isomalt, and isomaltulose. Many of these materials have a sweetening power greater than that of sucrose, and if they are used, they will be incorporated at an appropriate concentration to their sweetening power.

Other acceptability-enhancing agents include animal and vegetable oils, for example, fish oil, and corn, peanut and soybean oil, and dry yeast. The concentration of the acceptability enhancing agent in the final composition of the bait will vary depending on its identity, but will typically be in the range of about 1 to about 5 weight percent. The amount to be used will be known to one skilled in the art or can be determined by routine experimentation. The bait according to the invention may contain one or more rodenticides. The rodenticide can be any known or developed rodenticide. Examples of commercially available rodenticides include brodifacoum; difetialone; flocoumafen; bromadiolone; arfarine; cholecalciferol; chlorphacinone; difenacoum; coumatetralyl; difacinona and fenindiona. The concentration of the rodenticide in the final bait may vary somewhat according to the particular active ingredient used, but is usually on the scale of about 5 to about 550 parts per million. (ppm), preferably in the range of about 10 to 500 ppm, preferably about 10 to 250 ppm, and most preferably in the range of about 10 to about 100 ppm. However, again, an appropriate amount of the rodenticide will be known to one skilled in the art or easily determined by routine experimentation. The water-soluble film-forming binder is used in the bait, according to the invention to help agglomerate the cereal base and the other ingredients to granules, and gives the granules their stress and resistance to environmental deterioration. Once the aqueous solution of the binder has evaporated from the granules, the binder film, which is left, is required to adhere strongly to the hydrophilic surfaces, which is flexible with a high mechanical strength, non-hygroscopic and non-sticky at high humidity, tasteless taste, and not repellent to rodents. Examples of binders include: cellulose ethers, for example, methylcellulose, ethylcellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; starches from various sources (eg potato, or wheat); polyvinyl alcohol; polyvinyl pyrrolidone; guar gum; carrageenan; jelly; xanthan gum; acacia gum; carob gum; karaya gum; tragacanth; pectin; and polyacrylates. Hydroxypropylcellulose is a preferred binder. Although binders are commercially available (usually in the form of a powder) they are soluble in water, in general, they do not readily dissolve in water, as they require mechanical agitation for a period to bring them into solution. When the binder solution is evaporated from the rodent bait, the binder film left on the surface of the particles is cured and becomes more resistant to dissolution in water, and is therefore capable of improving the physical structure of the binder. bait against degradation in high humidity conditions. The concentration of the binder in the bait can and will vary depending, for example, on the particular binder chosen for use, but in general will be from about 1 to about 10 weight percent and usually from 1 to 5 weight percent approximately. Again, an appropriate amount of the binder can be easily determined using routine experimentation.

The bait according to the invention may also contain a preservative to reduce or prevent the degradation of the bait by microorganisms, or an antioxidant to reduce the tendency of the bait to degrade by oxidation. Examples of preservatives include sorbic acid and its salts (eg For example, the potassium salt), propionic acid and benzisothiazolones. The concentration of the preservative may vary, depending, for example, on the identity of the preservative used, but in general it may be from about 0.05 to about 0.2 per cent per cent. weight. Examples of antioxidants include propyl gallate and butylated hydroxyanisole. The concentration of the antioxidant will usually be on the scale of 0.05 to 0.1 weight percent, approximately. The bait according to the invention may also have an agent to prevent the consumption of the bait by a human being, for example, the bitter agent denatonium benzoate another salt of the denatonium cation. Preferably this substance is used at a concentration of about 0.001 weight percent. The bait may also contain a coloring agent comprising a dye or pigment. The bait may also contain an additive to improve its resistance to moisture, for example, a wax. Examples of waxes include carnauba wax; waxes used in the food industry, (for example beeswax); and refined waxes used in the chemical industry (for example purified paraffin wax). The concentration of the wax is usually on the scale of 1 to 3 weight percent, approximately. Again, an appropriate amount of such optional components will be known to one skilled in the art or can be determined using routine experimentation. The granules can be used both inside buildings and other structures or outdoors. The granules can be placed in suitable places by transferring them from a bulky container. They can also be used in packages (ie packages containing a pre-measured dose) or in bait stations. They can also be used in a box or tube for mice or they can be distributed from a device designed to deliver a pre-measured dose. Other preferred aspects and embodiments of the present invention will now be illustrated by the following non-limiting examples, in which, unless otherwise specified, all parts are by weight. The liquid concentrate of brodifacoum referred to in the examples has the following composition: Ingredient Concentration (percentage by weight) Technical Brodifacoum x * Triethanolamine 6 Polyethylene glycol 200 4-x Durazol Blue BG 10 Powder "Bitrex" 0.1 Propylene glycol up to 100 * where x gives 0.5 percent by weight of active brodifacoum. Durazol Blue BG is a trademark for a composition containing a dye of trifendioxazine and Bitrex is a trademark for a bitter agent comprising a salt of the denatonium cation.

EXAMPLE 1 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum liquid concentrate (toxicant) • '. •, • x Hard sugar coating (acceptability improver) 2.0 Hydroxypropylcellulose (first film) 2.0 Proxel GXL (preservative) 0.15 Whole ground wheat (acceptable base) for 100 where x gives 0.005% w / w of brodifacoum and 0.001% w / w of "Bitrex", Proxel GXL is a trademark for a preservative comprising 1, 2-benzisothiazolin-3 -one.

EXAMPLE 2 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum liquid concentrate (toxicant) x Hard sugar coating 2.0 Vegetable oil (acceptability improver) 2.0 Hydroxypropyl cellulose (first film) 2.0 Proxel GXL (conservative) 0.15 Whole ground wheat (acceptable base) for 100 where x gives 0.005% w / w of brodifacoum and 0.001% w / w of "Bitrex".

EXAMPLE 3 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum liquid concentrate (toxicant) x Hard sugar layer 2.0 Hydroxypropylcellulose 2.0 Proxel GXL (conservative) 0.15 Butylated hydroxyanisole (anti-oxidant) 0.1 Citric acid (anti-oxidant) 0.1 Whole ground wheat (acceptable base) for 100 where x gives 0.005% w / w of brodifacoum and 0.001% w / w of "Bitrex".

EXAMPLE 4 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum liquid concentrate x Hard sugar coating 2.0 Hydroxypropylcellulose 2.0 Potassium sorbate (preservative) 0.3 Carnauba wax (waterproof agent) 2.0 Whole wheat for 100 where x gives 0.005% w / w of brodifacourri and 0.001% w / w of "Bitrex".

EXAMPLE 5 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum liquid concentrate x Melasas 5. o Hydroxypropylcellulose 2.0 Colorant 0.1 Proxel GXL 0.15 Oatmeal (finely ground cereal) 37 Whole ground wheat (coarse ground cereal) for 100 where x gives 0.005% w / w of brodifacoum and 0.001% w / w of "Bitrex".

EXAMPLE 6 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum Liquid Concentrate x Hard Sugar Layer 5.0 Coloring 0.1 Hydroxypropylcellulose 2.0 Proxel GXL 0.15 Oat flour (finely ground cereal, acceptable base) 37 Whole ground wheat (coarse ground cereal, mixture of material) for 100 where x gives 0.005% w / w of brodifacoum and 0.001% w / w of "Bitrex" .

EXAMPLE 7 This example illustrates the composition of a rodent bait according to the invention.

Ingredient% p / p Brodifacoum liquid concentrate x Sacarin ', 0.1 Coloring 0.1 Hydroxypropylcellulose 2.0 Proxel GXL 0.15 Oatmeal (finely ground cereal) 37 Whole ground wheat (coarse ground cereal) for 100 where x gives 0.005% w / w of brodifacoum and 0.001% w / w of "Bitrex".

EXAMPLE 8 This example illustrates that the rodenticidal bait of the present invention provides good control of rodents. The test species were Welsh Farmstead Rattus norvegicus and Mus musculus. For each test, five males and five females were used and the animals were individually caged. The animals were conditioned to a laboratory diet for four days before the test. Before and after the analysis the animals were fed with control bait, which did not contain the active ingredient, which in these analyzes was brodifacoum. The amount of food ingested before and after the analysis provided an indication of the population of the rodents and can be used to determine the percentage of control. During the test with a agglomerated brodifacoum granule of the present invention, the animals were able to select between two test diets for three days. The water was available ad libitum during the analysis. The amount of each diet consumed was determined by weight daily, and at the end of the analysis, the amount consumed was summarized for 10 animals, of both sexes, during the three days and expressed as a percentage of total food consumption.

Species Experiment Conduction of bait consumption (g)% Control Before the After the experiment experiment Rattus 1 718 0 100% Rattus 2 3093 170 94.5% Mus 1 146 6 95.9% Mus 2 98 0 100% EXAMPLE 9 This example illustrates the preference of rats and mice for an agglomerated granule of the present invention. The acceptability of rats and mice for an agglomerated granule of the present invention, comprising 0.1% bromadiolone concentrate, 0.001% w / w Bitrex, sweetener, Proxel GXL, oatmeal and fine wheat, against the unformulated premix of the components (powder). In each test ten animals were used.

Bromadiolone (50 ppm) Rats 88.4% acceptance for the granule (11.6% powder) Mice 61.5% acceptance for the granule (38.5% powder) EXAMPLE 10 This example illustrates the preference of rats and mice for an agglomerated granule of the present invention. The acceptance of rats and mice for an agglomerated granule of the present invention against a commercially available wheat-based pellet was tested. Both formulations contained the same active ingredient, brodifacoum 50 ppm, along with 10 ppm Bitrex.

Rats 64.7% acceptance for the pellet (35.3% pellet) Mice 69.6% acceptance for the pellet (30.4% pellet)

Claims (13)

1. A rodenticidal bait in the form of agglomerated granules having an open texture characterized in that it comprises: a cereal base in which 2% to 10% of the cereal particles have a size on the scale of equal to or greater than 500μm, up to less than or equal to lOOOμm and from 70% to 90% of the cereal particles have a size on the scale equal to or less than 250μm; a rodenticide; and a water-soluble film-forming binder.

2. A rodenticidal bait according to claim 1, further characterized in that it comprises an acceptability enhancing agent.

3. A rodenticidal bait according to claim 2, characterized in that the acceptability enhancing agent is a sweetener, an animal oil, a vegetable oil or yeast.

4. A rodenticidal bait according to any of claims 2 and 3, characterized in that the rodenticidal bait contains from 1% to 5% by weight of the acceptability enhancing agent.

5. A rodenticidal bait according to any of the preceding claims, characterized in that the agglomerated granule is in the scale of size from 0.20 mm to 10 mm.

6. A rodenticidal bait according to claim 5, characterized in that each agglomerated granule is in the scale of size from 0.25 mm to 5 mm.

7. A rodenticidal bait according to any of the preceding claims, further characterized in that it comprises a coloring agent, a preservative, or a substance to prevent the consumption of the bait by a human being.

8. A rodenticidal bait according to any of the preceding claims, characterized in that the water-soluble film-forming binder is a cellulose ether, a starch, polyvinyl alcohol, polyvinyl pyrrolidone, carrageenan, gelatin, gum, tragacanth, pectin or a polyacrylate .

9. A rodenticidal bait according to any of the preceding claims, characterized in that the rodenticidal bait contains from 1% to 10% by weight of the water-soluble film-forming binder.

10. A rodenticidal bait according to any of the preceding claims, characterized in that the rodenticide is brodifacoum, difetialone, flocumafen, bromadiolone, warfarin, cholecalciferol, chlorphacinone, difenacou, coumatetralyl, difacinone or phenindione.

11. A rodenticidal bait according to any of the preceding claims, characterized in that the rodenticidal bait contains from 5 ppm to 550 ppm by weight of the rodenticide.

12. A rodenticidal bait according to any of the preceding claims, characterized in that the milled cereal is wheat, barley, corn, sorghum, oats, rice or millet.

13. A method for the production of a rodenticidal bait according to any of the preceding claims, characterized in that it comprises mixing, by mechanical agitation, or by fluidized bed granulation, a cereal base wherein from 2% to 10% of the particles of the cereal have a size on the scale of equal to or greater than about 500μm to less than or equal to lOOOμm and from 70% to 90% of the cereal particles have a size on the scale of equal to or less than about 250μm; a rodenticide and a water-soluble film-forming binder.