Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Composition based on calcium sulphate hydrate and the use thereof for
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The present invention relates to an ecologically harmless composition based on
calcium sulphate hydrate and to the use thereof for destroying rats and/or
mice. The
composition preferably comprises a mixture of calcium sulphate hemihydrates,
baits
and optionally) in addition, extenders, flavourings and/or aromatic substances
and
colourings) the mixture of catcium sulphate hemihydrates being a mixture of
calcium
sulphate alpha-hemihydrate and calcium sulphate beta-hemihydrate.
Because of the damage they cause to food supplies as well as to electrical
installa-
tions, books, files, etc., and because of their role as carriers of disease,
rats and
mice are regarded as one of the main pests in rural and urban areas. Initially
they
were controlled using toxic compounds such as a-naphthylthiourea, see
DE-PS 919 617. Because of increased environmental awareness and ever more
strict iega) regulations, however, it is no longer desirable or permissible to
put down
such poisonous baits. Moreover, pets such as dogs and cats, which are nowadays
kept in large numbers, are also put at risk by such poisonous baits.
A newer agent uses an active ingredient that prevents the blood from clotting,
so
that the animals bleed to death at the slightest injury. However, this
encourages flies
and other pests in large numbers, so thak diseases and epidemics may be passed
on to humans. Such agents therefore had to be put aside after a test phase.
CH-PS 89 183 discloses non-poisonous compositions consisting of a mixture of
bread, calcined gypsum (CaS04 x xHtO), ground shells and an aromatic
substance.
No indication is given, however, either of the type of gypsum used or of the
ratio in
which the individual components are mixed. The use of the compositions as
agents
for destroying rats and mice is disclosed in CH-PS 89 183.
Conventional gypsum (calcium sulphate = CaSO,, x 2HZ0) is in the form of
calcium
sulphate dehydrate (hereinafter called "dehydrate"), which can be converted by
means of calcination into calcium sulphate hemihydrate (= CaSOa x 1I2 H20,
hereinafter called "hemihydrate") having two modifications (alpha and beta).
Herein-
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after, calcium sulphate hemihydrate (in both modifications) and calcium
sulphate
dihydrate are combined under the expression "calcium sulphate hydrate". In
addition, various calcium sulphate anhydrides can be obtained by further
calcination.
Furthermore, there are known from DE 41 33 382 A compositions consisting of
meat
and gypsum, but there is no indication of the type of gypsum that is used.
Those
compositions are used for destroying rats and/or mice.
Moreover, it is known to use non-poisonous compositions for destroying rats,
which
compositions consist of a mixture of 2I3 wheat meal and 1 /3 calcined gypsum,
see
DE-PS 832 359, or of a mixture of gypsum with sugar in a ratio of 2;1, see
C. Becher, Sch~diingsbek~mpfungsmittel, 1953, page 215. It has been found,
however, that such mixtures were not lethal even when the faeces were
completely
white and immediately became rock hard, see R. Koller "Das Rattenbuch" 1932,
page 79.
It has been found that the above-described methods are unreliable, are
extremely
cruel to the animals and therefore are unsuitable for destroying rats. (n
addition,
those mixtures have proved to be unsuitable for destroying rats because, owing
to
their behaviourally-conditioned "taster" system, the rats will not take the
compositions.
Accordingly, the problem underlying the present invention is to provide
compositions
based on calcium sulphate hydrate that do not have the above-described
disadvan-
tages. The compositions are to be non-poisonous to humans and pets and it is
to be
possible to put them down in areas in which poisons may not be used, such as,
for
example, where water is to be protected against pollution, in urban areas and
in the
immediate vicinity of foodstuffs. At the same time, the compositions are to be
effec-
tive agents for destroying mice and rats. To that end, compositions are
required that
lead to the death of the animals with a certain time delay, so that the rats'
"taster"
system is overcome. 1n addition, the animals are to suffer no unnecessary pain
after
eating the composition.
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That problem is solved by a composition
- that comprises from 30 to 60% by weight of calcium sulphate hydrate and from
40
to 70% by weight of one or more baits, especially meal)
- and that is characterised in that the calcium sulphate hydrate comprises a
mixture
of from 30 to 100% by weight of calcium sulphate alpha-hemihydrate and from 70
to
0% by weight of calcium sulphate beta-hemihydrate.
The invention is based, inter alia, on the finding that calcium sulphate
dihydrate on
its own is not suitable for destroying rats on account of its hardening time
and its
consistency in the animals' digestive system during hardening. It is excreted
by the
animals, and they suffer unnecessary pain.
Nor does the use of beta-hemihydrate on its own lead to the desired success:
The problem with compositions that contain as the calcium sulphate hydrate
only
beta-hemihydrate as the killing agent is that beta-hemihydrate is able to
absorb a
large amount of water and does not become sufficiently viscous in the animals'
digestive tract but hardens only partially, remains crumbly and is excreted
again in
that form. This causes the animals unnecessary pain, which also results in
their
refusing to eat such agents again, and the destructive action is impaired.
Such
compositions do not, therefore, lead to the desired death of the rats andlor
mice.
Only the use of compositions comprising at least 30~~ by weight of alpha-
hemihydrate leads to the rapid and reliable killing of the animals.
According to the invention it is advantageous to use a composition in which
the
calcium sulphate hydrate comprises from 30 to 80% by weight of calcium
sulphate
alpha-hemihydrate and from 20 to 70~~ by weight of calcium sulphate beta-
hemihydrate.
Such a composition is especially advantageous for the following reasons:
Calcium sulphate hydrate in the form of a mixture of alpha- and beta-
hemihydrate in
a mixing ratio that is in the range of from 30 to 80~~ by weight of alpha-
hemihydrate
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and from 70 to 20% by weight of beta-hemihydrate causes the calcium sulphate
hydrate to stiffen in the digestive tract as a result of water absorption
(percentages
by weight are based on the calcium sulphate hydrate content of the
composition). At
the same time, by adjusting the mixing ratios it is possible to make
stiffening of the
hemihydrate take place more quickly than the regular excretion of the animals,
but)
furthermore, death is delayed, so that the rats' "taste" system does not
react. As a
result, death is advantageously prevented from occurring too soon after consum-
ption in small, sick or weak animals (possibly after only one hour), and the
rats'
avoidance behaviour as a result of the "taster" system is prevented from
taking
effect.
lf, on the other hand, the content of beta-hemihydrate is greater than 70% by
weight, the removal of water is reduced and ii is possible that the ratslmice
will
survive consumption of the poison. By contrast, within the preferred mixing
range of
alpha- and beta-hemihydrate of the invention) a high degree of lethality is to
be
observed. At the same time, the death of the animals occurs sufficiently late,
so that
the "taster" system is not alerted even when the composition is consumed by
weak,
sick or particularly small animals.
When a preferred composition of the invention is ingested, the calcium
sulphate
hydrate adheres to the stomach wall as a result of the specifically adjusted
water-
absorbing capacity, causing the digestive tract to become dosed, especially
since
the hemihydrate mixture according to the invention, unlike a hemihydrate form
used
alone, is hydraulic in the relatively long term. The animals die twelve to
sixteen
hours after eating, so that the rats' warning system by means of the "taster"
does
not function.
A preferred embodiment relates to a composition that comprises as the calcium
sulphate hydrate component a mixture of from 40 to 80% by weight of calcium
sulphate alpha-hemihydrate and from 60 to 40~~ by weight of calcium sulphate
beta-hemihydrate.
An especially preferred embodiment relates to a composition that comprises as
the
calcium sulphate hydrate constituent of the composition a mixture of from 52
to 57%
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by weight of calcium sulphate alpha-hemihydrate and from 48 to 43% by weight
of
calcium sulphate beta-hemihydrate.
According to the invention, the two hemihydrates (alpha- and beta-hemihydrate)
are
prepared separately. To that end, calcium sulphate dehydrate as starting
material for
the preparation of the hemihydrate in question is calcined at least once,
preferably
several times, especially up to 12 times. The specific preparation conditions
for
alpha- and beta-hemihydrate are observed (Ullmann, Encyclopedia of Industrial
Chemistry, Volume 4, p. 557-573, 1985). In a subsequent preparation step, the
two
forms of hemihydrate are typically mixed in the desired mixing ratio and,
finally) the
mixture is mixed with the other components of the composition.
Stiffening of a composition according to the invention having a calcium
sulphate
hydrate constituent is advantageously promoted by including an extender in the
composition. Accordingly, in a preferred embodiment of the present invention
there
is claimed a composition that comprises as the calcium sulphate hydrate
constituent, in addition to the hemihydrate mixture, from 0 to 3% by weight of
calcium sulphate dehydrate. The dehydrate acts as a so-called extender which,
as an
accelerator additive, regulates the stiffening time of the calcium sulphate
hydrate.
The amount of accelerator added can be so chosen that the preferred stiffening
time is observed.
Stitfening of a hemihydrate mixture comprising alpha-hemihydrate and beta-
hemihydrate that have each been calcined several times begins typically after
from
10 to ~ 8 minutes, especially after 14 minutes. The end of the stiffening
process is
dependent on the specific mixing ratio of alpha- and beta-hemihydrate, on the
amount of extender and on the amount of calcium sulphate hydrate in the total
composition. A rapid onset of stiffening is advantageous especially because
the
animals excrete relatively frequently and hardening of the hemihydrate mixture
bEtween ingestion and excretion is therefore ensured. The high degree of water
absorption of the hemihydrate mixture according to the invention results in a
comatose state in the animals, so that they are spared any pain which they
suffer
on ingestion of conventional dehydrate or beta-hemihydrate on its own. In
addition,
the composition according to the invention, which may accumulate in the
intestine
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as a result of repeated ingestion, also causes mechanical pressure to be
exerted on
the heart, which likewise contributes to the state of shock.
Within the scope of the present invention, greatest preference is given to a
compo-
sition that comprises as the calcium sulphate hemihydrate a mixture of from
54.5 to
55.5% by weight of calcium sulphate alpha-hemihydrate, from 44.5 to 45.5% by
weight of calcium sulphate beta-hemihydrate and from 0 to 1 % by weight of
calcium
sulphate dehydrate.
Mixtures comprising approximately 54.7% by weight of alpha-hemihydrate,
approxi-
mately 44.7% by weight of beta-hemihydrate and approximately 0.6% by weight of
dehydrate have proved particularly effective for destroying rats (mice).
Within a
statistical inaccuracy range of t 0.3~r~ by weight, such a composition
corresponds to
the mixture "Spezial 52" manufactured by Heidelberger Zementwerk AG, Sulzheim.
In a further preferred embodiment, the composition additionally comprises as
further
components one or more additional flavourings and/or aromatic substances
andlor
one or more colourings andlor one or more other additives. In that case the
compo-
sition comprises from 0 to 15% by weight, preferably from 2 to 10% by weight,
of
one or more additional flavourings andlor aromatic substances andlor from 0
tol5%
by weight, preferably from 1 to 5% by weight, of one or more colourings andlor
one
or more other additives.
In order to identify mixtures having different flavours, it is advantageous to
add at
least one colouring. Coloured chalk has, of course, proved particularly
effective for
that purpose. Small amounts of only from 0 to 5% by weight, preferably up to
3% by
weight and especially up to 1 % by weight, are sufficient to achieve a slight
degree
of coloration, and in this case too the mixture as a whole is 100% natural in
origin.
Advantageously, coloured compositions of bait and calcium sulphate hydrate in
the
form of a hemihydrate mixture are used in order to provide a visible
indication of the
different flavours of the compositions in question.
According to a further preferred embodiment, the composition according to the
invention therefore comprises from 38 to 50% by weight of calcium sulphate
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hydrate, from 40 to 60% by weight of one or more baits, especially meal, from
0 to
10% by weight of one or more additional flavourings and/or aromatic substances
and from 0 to 5% by weight of a colouring and~or one or more other additives.
Greater preference is givQn to a composition comprising from 42 to 47% by
weight
of calcium sulphate hydrate, from 42 to 55% by weight of one or more baits,
espe-
cially meal, from 5 to i 0% by weight of one or more additional flavourings
and/or
aromatic substances and from 0 to 3% by weight of a colouring andlor one or
more
other additives.
Greatest preference is given to a composition comprising 459o by weight of
calcium
sulphate hydrate, from 44 to 50% by weight of one or more baits, especially
meal,
from 5 to 10% by weight of one or more additional flavourings andlor aromatic
substances and from 0 to 2% by weight of a colouring and/or sodium hydrogen
carbonate.
The above-mentioned composition is most preferred because, on the one hand,
the
taste of the calcium sulphate hydrate, especially of the mixture of alpha- and
beta-
hemihydrate, is masked by the other constituents to such an extent that the
composition is readily eaten by the animals. On the other hand, however, the
composition also contains a specific minimum amount of calcium sulphate
hydrate,
especially of hemihydrate mixture) since it is otherwise excreted by the
animals
without having a lethal effect.
Meal is especially suitable as the bait because it is the preferred food of
rats and
mice and can be mixed with the hemihydrates in a simple manner without any
visible external change taking place. Various types of meal, for example wheat
meal, rye meat and barley meal as well as maize meal and mixtures thereof, may
be
used as the meal. Meal is preferably used in combination with aromatic
substances
andlor flavourings.
The composition may also comprise malt or a malt extract, such as wheat, rye
andlor barley extract or mixtures thereof, in an amount of from 3 to 8% by
weight,
preferably of approximately 5% by weight, with the result that the taste of
the
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calcium sulphate hydrate is masked even further and the animals will eat the
composition even more readily. There may additionally be used as baits one or
mote polypeptides, such as gelatin, bran and/or vegetable protein, such as
soya
protein.
According to the invention, therefore, some of the meal, preferably from 40 to
60%
by weight, more preferably approximately 50% by weight, may be replaced by
gelatin, bran andlor vegetable protein, such as soya protein. A bran content
is
especially advantageous when the composition is to be made into pellets.
When putting down the composition is it advantageous to vary the bait if the
composition is put down repeatedly or to change the taste or smell of the bait
by
means of an additive: it has been found that acceptance of the mixture is
inueased
further if, for example, a powdered flavouring andlor aromatic substance is
added.
The flavouring and/or aromatic substance masks the caste andlor smell of the
calcium sulphate hydrate, especially of the hemihydrate mixture, in the
composition,
in other words it serves to correct the taste and/or smell. A particularly
effective
flavouring has proved to be powdered sugar, optionally together with cocoa,
especially since powdered sugar, on account of its consistency) is not visible
In the
mixture and, in addition, is wholly biological in origin. Ground bacon fat is
also highly
suitable as a flavouring or aromatic substance. According to the invention
there are
used, based on the total composition, preferably at Fast 2% by weight,
preferably at
least 4% by weight, of powdered sugar and preferably at Least 4% by weight,
preferably at least 6% by weight, of cocoa or preferably at least 4% by
weight,
preferably from 6 to 8% by weight, of ground bacon fat.
Alternatively, fish meal Is used as the bait. Fish meal is simple to prepare)
or is a
waste product of the fishing industry) so that fish meal can be used
advantageously
especially in coastal regions.
Other additives that are preferred according to the invention are agents that
soothe
the mucous membranes of the rats and mice, such as dried milk, acid-binding
agents, such as patron (sodium hydrogen carbonate), andlor agents that promote
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secretion of saliva and/or gastric juices) such as burnt lime. preferably, 1 %
by
weight of patron is used in the composition.
The addition of dried milk soothes the mucous membranes of the rats and mice
so
that the animals do not suffer unnecessarily, and refusal to eat the
composition after
once tasting it is avoided.
It is preferable to add also at least one acid-binding agent, such as patron,
in order
to reduce or prevent colicky pain and heartburn. Otherwise, the animals may
refuse
to eat the composition when it is fed to them several times.
The addition of an agent that promotes the secretion of saliva andlor gastric
juices
leads to mare rapid and improved binding of the gypsum when the composition is
ingested) so that the activity of the composition is increased.
In one embodiment, water may additionally be fed to the animals in order to
accele-
rate binding of the calcium sulphate hydrate portion. In each composition
according
to the invention, the flavourings and/or aromatic substances and the baits,
such as
the meal, may be the same or different.
It has proved especially effective to use per rat an amount of at least 100 g,
preferably from 150 to 200 g, and per mouse a correspondingly smaller amount
of
the composition consisting of bait and calcium sulphate hydrate that comprises
a
hemihydrate mixture.
In order to prevent rain-water or moisture in the ground from rendering the
mixture
of bait and calcium sulphate hydrate ineffective from the outset, the bait
containing
a hemihydrate mixture of calcium sulphate alpha-hemihydrate and calcium
sulphate
beta-hemihydrate may, according to the invenkion, be put down in a container
that is
accessible only from the side. Moreover, the composition, as an agent for
destroy-
ing rats andlor mice, is thus inaccessible to larger pets. Since the
hemihydrate
mixture is very hygroscopic, it is preferably packaged, that is to say, for
example,
wrapped in paper) there being used, for example, biodegradable paper, such as
rape paper.
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The composition according to the invention can be prepared by mixing the
individual
components in any order.
The composition according to the invention can be used in powder form, in the
form
of granules or compressed, for example, to form pellets. Pellets in particular
are
preferred by rats.
The present invention is illustrated in more detail by the Examples which
follow:
Example 1
450 g of calcium sulphate hydrate, which is used in the form of a mixture of
(51.5%
by weight) 231.75 g of alpha-hemihydrate, (47.5% by weight) 213.75 g of beta-
hemihydrate and (1 % by weight) 4.5 g of dihydrate,
4A.0 g of meal
40 g of powdered sugar and
70 g of cocoa
are added together and mixed uniformly. The composition is fed to the rat.
The described composition is eaten by the rat and has a lethal effect.
Depending on
the age and constitution of the rat, death occurs after 92 hours at the
earliest. The
rats' "taster" system is thus overcome.
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Example 2
450 g of calcium sulphate hydrate, which is used in the form of a mixture of
(51.5%
by weight) 231.75 g of alpha-hemihydrate, (47.5% by weight) 213.7S g of beta-
hemihydrate and (1 % by weight) 4.5 g of dihydrate,
520 g of fish meal
10 g of patron and
20 g of burnt lime
are added together and mixed uniformly. The results are identical to those
accor-
ding to Example 1
Example 3
450 g of calcium sulphate hydrate, which 1s used in the form of a mixture of
(51.y0
by weight) 231.75 g of alpha-hemihydrate, (47.5% by weight) 213.75 g of beta-
hemihydrate and (1 % by weight) 4.5 g of dihydrate,
390 g of meal
80 g of ground bacon fat
50 g of dried milk
20 g of burnt lime and
10 g of patron
are added together and mixed uniformly. The results are identical to those
accor-
ding to Example i.
Example 4
450 g of calcium sulphate hydrate, which is used in the form of a mixture of
(51.59'o
by weight) 231.75 g of alpha-hemihydrate, (47.S% by weight) 213.75 g of beta-
hemihydrate and (1 % by weight) 4.5 g of dihydrate,
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470 g of fish meal
50 g of dried milk
20 g of burnt lime and
10 g of patron
are added together and mixed uniformly. The results are identical with those
accor-
ding to l=xample 1.
Example 5
450 g of calcium sulphate hydrate, which is used in the form of a mixture of
(89.5%
by weight) 402.75 g of alpha-hemihydrate, (9.5% by weight) 42.75 g of beta-
hemihydrate and (1% by weight) 4.5 g of dehydrate,
and S50 g of fish meal
are added together and mixed uniformly. The composition is fed to the rat.
The rat eats the composition, and death occurs approxtrnately 6 hours after
the
composition was fed to the rat.
Comparison example
4S0 g of calcium sulphate hydrate, which is used in the form of a mixture of
(9.5%
by weight) 42.75 g of alpha-hemihydrate, (89.5% by weight) 402.75 g of beta-
hemihydrate and (1% by weight) 4.5 g of dehydrate,
and 550 g of fish meal
are added together and mixed uniformly. The composition is fed to the rat.
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The rat eats the composition but excretes it again in the form of lumps. The
compo-
sition does not, therefore, harden sufficiently after water absorption. Death
of the rat
does not occur.
The present invention also discloses the use of the above-described
composition for
destroying rats andlor mice.
The composition according to the invention has the following advantages over
the
cited prior art: Because it is composed of calcium sulphate hemihydrate,
preferably
substantially in the form of a hemihydrate mixture of alpha- and beta-
hemihydrate,
and one or more baits, especially meal, and optionally one or more additional
flavourings and/or aromatic substances, optionally an extender and optionally
one
or more colourings and optionally one or more other additives, it is
completely non-
poisonous and accordingly can be used in any area in which the use of poisons
Is
ruled out. Therefore, the composition according to the invention presents no
problems at all for pets. Dogs and cats will not eat the mixture anyway, and
in the
case of birds, especially hens, their digestive system, which is different
from that of
rodents, will ensure that the constituents are broken down immediately.
Even when mice or rats have eaten the composition, no disadvantageous side-
effects are caused. Once they have eaten the pest-control preparation
according to
the invention) the rats or mice withdraw into their underground labyrinth
system. And
it is there that death finally occurs, so that rotting in the open, with
insect infestation,
the transmission of germs, etc., is avoided.
