Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR HANDLING WASTES FROM SMALL ANIMAL CAGES
This application is a division of Canadian application
Serial No. 253,766 filed May 31, 1976.
BACKGROUND OF THE INVENTION
Field of the Invention:
The present invention relates to a method and apparatus for
handling animal wastes from animals kept in cages with perforate
bottoms.
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Description of the Prior Art:
When small animals are kept in cages in which the animals
are not in contact with bedding, but rather are housed upon a
wire mesh or otherwise perforate floor, animal wastes-drop
through the floor and into a litter tray beneath the cage which
can be removed for cleaning. For hygenic and aesthetic reasons
a substance is provided in the tray which will absorb or suspend
liquid wastes and deordorize both liquids and solids, and which
can be disposed of when soiled. Many bulk litter materials have
been tried and have been used for this purpose, among them being
shredded alfalfa, shredded aspen, shredded peat moss, wood
shavings, and the like. Although these materials are absorbent,
they are bulky, messy to handle, and often constitute a fire
hazard in storage. Moreover, depending on the economic situation
of the moment, they are often either expensive or unobtainable.
Disposal of the soiled litter, which often constitutes a consid-
erable bulk, can be expensive, particularly in a vivarium.
Soiled wastes are often imperfectly suspended in the solid litter.
When the tray is emptied,lsome of the waste remains smeared on
- 20 the tray. The next batch of litter will then be inoculated
with odor-causing bacteria. To prevent this happening, each set
; of trays is commonly washed in a separate, remote facility,
while clean trays from a second set are installed in the cages.
Commercial substitutes have been offered for the bulk
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litter recited above. One is a fibrous pad impregnated with
- substances which control odors and bacteria. Though easier to
handle than ~ulk litter, the pads are relatively expensive, and
they do not solve the disposal problem. Another substitute for
bulk litter is a liquid. Although it controls odor and
bacteria, the liquid tends to slosh and spill out of the tray
when the tray is removed from the cage.
Some configurations of animal cages provide for a
continuous litter tray extending beneath a row of individual
cages, and in some cases the manure-receiving trays are slanted
to allow stacking of the cages and mechanical scraper blades are
provided to push the manure to the end of the tray. Other
arrangements provide reciprocating scraper apparatus with cut-
off limit switches for cleaning the trays. However, mechanical
lS scrapers inevitably leave a film of semi-dry manure stuck to the '
litter tray beneath the cages. This film or residue is an ideal
culture medium for bacteria, which, being ever present in the
tray, inoculate each successivè load of manure, thereby
generating noxious odors, particularly ammonia, often to the
extent of causing poor growth or production by the caged
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SUMMARY OF THE INVENTION
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The present invention as disclosed and claimed relates to a
new and improved method and means for handling the wastes from
small animal cages and provides a new and improved method and
apparatus for treating wastes produced by caged animals.
In place of solid fibrous litter, a long-lasting, aqueous
foam is provided ïn the litter tray. The foam has the property of
closing over the hole which an object or splash of liquid dropped
into it makes: that is to say, the hole "heals", so that a cont-
inuous, relatively air-tight surface of foam covers the tray
surface. Pieces of solid waste and splashes of liquid waste are
thereby largely sealed from the atmosphere: objectionable odors
cannot escape, and the shortage of oxygen at the surface of the
waste strongly inhibits the growth of microorganisms and the
processes of decomposition which cause odors.
When the foam has become soiled with animal wastes, it is
readily disposed of by flushing the soiled foam from the litter
tray into a suitable receptacle or into the sewer with a jet of
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water. A typical foam has an expansion of as much as twenty to
20 one: that is to say, the foam is composed of nineteen volumes of
air and one volume of foam composition. A small-volume jet of
relatively high pressure watex suffices to flush the foam from the
~ litter tray and to collapse the foam. When many cages are cleaned,
; the volume of the refuse-bearing foam is therefore relatively
; manageable: its volume is many times less than the volume of the
solid, fibrous type litter. Moreover, the refuse can be readily
disposed of in any convenient sewer, whereas solid, fibrous type
litters must be carted away from the premises to a suitable dis-
posable site, often at considerable expense.
one aspect of the invention as claimed comprehends an instal-
lation of a plurality of small animal cages disposed side-by-side
wherein a continuous litter tray common to all of the animal cages
contains a layer of semi-solid, long-lasting aqueous foam for
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receiving wastes from animals in the cages. Means are disposed
along the length of the litter tray for flushing the waste-
containing aqueous foam from the litter tray. The installation
may also contain means disposed along the length of the litter
tray for filling the litter tray with such aqueous foam.
Another aspect of the invention in an installation having a
plurality of small animal cages disposed side-by-side beneath which
a continuous litter tray receives animal wastes is a method for
treating the wastes which comprises the steps of disposing a semi-
solid, long-lasting aqueous foam in the litter tray for a period
of time suf~icient to receive wastes from the animals in the
cages, and flushing the litter tray with a stream of water so
that the aqueous foam flows into a container.
The present invention, as well as further ob~ects and features
thereof, will be more fully understood from the following des-
cription of a preferred embodiment, when read with reference to the ;
accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a perspective drawing of a typical small animal
cage. The litter tray is shown partly withdrawn.
FIGURE lA is a fragmentary perspective view of a portion of `
the apparatus shown in Figure 1.
FIGURE 2 is a side elevational view of a litter tray washing
machine useful with animal cages in accordance with an embodiment
of ~he invention.
FIGURE 3 is a section taken along the line 3-3 of Figure 2,
; appearing with Figures 1 and lA.
FIGURE 4 is a partially schematic side elevational view
showing a row of animal cages set upon a rack in accordance with
another illustrative embodiment of the invention.
FIGURE 4A is a sectional view taken along the line 4A-4A.
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DESCRIPTION OF CERTAIN PREFE~RED EMBODIMENTS
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Discrete Litter Tray
In the accompanying drawings,
Figure 1 is a perspective view of a typical small animal
cage. 10 is the slatted floor of the cage. 11 is a rectangular ~ -
litter tray, containing aqueous foam, shown partly withdrawn
from the aperture in which it slides, formed by extensions 12 of
- the sides of the cage. Figure l-A is a magnified view of a
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corner of the tray 11 shown with a portion of the front edge cut
away to show the foam 13 in the tray. The depth of foam may be
from about 1/2" to 2".
In Figure 2 the side of the tray washin~ machine facing the
observer is shown removed to illustrate the interior. The tray
washing machine comprises a cabinet with spray apparatus mounted r ,
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upon a wheeled frame. Stainless stee:L is used for construction.
In other embodiments aluminum may be used. Steel may be used if
adequately protected from corrosion. The frame 14 of the tray
- washing machine is supported by castors 15. Compartment 16 is a
reservoir for rinsing water from which pump 17, in compartment
18, draws its intake through pipe 19. Pump 17 is driven by a
motor (not shown) which is controlled by a switch and timer
circuit (not shown) so that when the switch is activated, the
~ump will run for a preselected time and turn off. Compartment r~
18 also contains an air compressor and tank 20, to which a foam
gun 21 is attached by hose 220 The foam gun comprises a
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recepta_le for foam composition, a foal nozzle, and a valve for
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actuating it. (In another embodiment, the air compressor
may be replaced by a oam generator, such as the device sold
by Waukesha Foundry Company, Inc., 1300 Lincoln Ave.,
Waukesha, Wisconsin, 53186. In yet another embodiment, the
foam generating means may be pressurized containers, such as
shaving foam containers, separated entirely from the tray washing
machine.)
Pump 17 delivers rinsing water through pipe 23 which
penetrates, and is externally sealed to, divider 24, and
through flexible hose 25, to manifold 26. Manifold 26 is
rotatably mounted to the sides of tray supports 27, shown
supporting tray 11 in an inverted position. Spray nozzles -
28 are installed on manifold 26, facing upwards. Arm 29,
which is fixed to manifold 26, has a longitudinal slot to
which shaft 30 is pivotably connected. When handle 31,
attached to the other end of shaft 30, is moved laterally, ~-~
manifold 26 rotates through an arc, so that spray from nozzles
28 covers the interior surface of inverted tray 11. ;
Compartment 32 recelives wastes and collapsed foam
- 20 flushed from inverted tray 11. Pipe 33 and valve 34 provide
means for draining compartment 32.
In Figure 3 the location of the spray nozzles 28 can be
readily seen. Upper edges of the sides of the tray washing
machine are equipped with brackets 35 to receive a side of tray
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11.
In another embodiment, trays are rinsed into the same
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compartment which provides intake to pump 17, thereby eliminating
the need for a separate compartment, but necessitating provision
of a screen for pump inlet pipe 19.
To use the tray washing machine, the operator fills
;~ 5 compartment 16 with rinse water (which may contain a small
- amount of silicone foam collapsing compound), wheels it to the -
site of the animal cages to be cleaned, and plugs its power cord
into an electrical outlet. He withdraws a litter tray, with
its load of soiled foam, from an animal cage, and rests its long -
side on the brackets 35. Using the brackets for support he in-
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; verts the tray, resting it on tray supports 27, activates the
switch controlling the pump motor, pulls out handle 31 and pushes -
; it back in. After the pump motor stops, he turns the tray right
side up on the tray supports 27, and with the foam gun 21,
refills the tray with clean foam. He replaces the tray in its
cage and proceeds to the next one. When a number of trays
has been cleaned, he pushes the tray washi.ng machine to a sewer
drain and, by opening valve 34, empties compartment 32 into the
sewer.
Continuous Litter Tray
In Figure 4, a plurality of animal cages 40 are shown
mounted on a rack 41 above a continuous litter tray 42, àlso
supported by rack 41. Tray 42 is pitched to drain through
drain pipe 43.
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Three manifol~s are associated with tray 42. Manifold 44
is attached to rack 41 beneath the cages and above the tray.
Spray nozzles 45 in the manifold are directed into the tray.
The end of manifold 44 is connected to a water supply line -
through valve 46. Just downstream of valve 46 an aspirator -~
47 is installed in the manifold and connected to a supply of
silicone foam-killer.
Beneath the tray and supported by rack 41 upon which lt
rests, manifold 48 is connected to foam nozzles 49 which are -
installed down the length of the tray in the center of its
bottom. The end of manifold 48 is connected to a source of
compressed air (not shown) through valve 50.
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Also beneath the tray and similarly supported, manifold
51 is connected to the same foam nozzles 49. The end of
manifold 51 is connected through valve 52 to a supply of foam
composition (53).
In another embodiment, a single manifold is provided be- -
neath the tray, connected to foam outlets (which must be larger
than foam nozzles 49), the other end being connected to a foam
generating machine such as that provided by Waukesha Foundry
Company. Foam composition, in this embodiment, is fed directly
into the foam generator and expanded into foam. The foam is -
pumped by the foam generator down the manifold and out of the
foam outlets into the tray. In yet another embodiment,
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foam generating means and foam composition is provided
on a portable cart. The operator draws the cart the length
of the tray, filling it with foam by means of a hose
connected to the foam generating means.
The preferred embodiment of aqueous foam in a contin-
uous tray is used as follows. The operator opens valve 46,
providing water containing foam killer drawn through
aspirator 47 to spray nozzles 45. Spray from the nozzles
collapses the foam and flushes the load of waste down tray
42 and out drain pipe 43. When the tray is clean and
empty, the operator shuts valve 46, stopping the spray.
He then opens valve 50 supplying air to manifold 48, and
opens valve 52, allowing Eoam composition to flow through
manifold 51. Air pressure at the foam nozzles makes foam
; and extrudes it through the nozæles to fill the tray
with clean foam. Since the tray is wet from the previous
cleaning, foam from one nozzle tends to slid down the tray
- until it encounters foam from the next nozzle, so that a
flat, continuous bed of foam is left in the tray.
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~ The Foam Co~position
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In a preferred embodiment it is important that the foam
provided be stiff and long-lasting in the environment
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in which it is used. Certain foam compositions
useful at low temperature
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e.g. for insulating crops from frost, will collapse at
temperatures of 70F and above, such as exist where small
animals are caged. Though not to be construed as limiting of
the invention, foam compositions found to be useful with this
invention comprise mixtures of water, sorbitol, a fatty acid, a
polyhydric alcohol, and an amine. The following formulation
represents a particularly yood formulation in this situation:
First, mix the following ingredients, heat the mixture to 200F,
and hold the mixture at that temperature:
218 lb. of water
29.25 lb. of sorbitol
19.35 lb. of triethanol amine
Next, separately mix and heat until all dissolves:
18.50 lb. of stearic acid, thrice processed
7.75 lb. of coconut oil
Finally, combine the first mixture with the second, mix them
thoroughly, and cool. When cool, add:
8.75 lb. of water, and
- 8.75 lb. of propylene glycol.
; 20 This formula makes 310 pounds, or about 35 gallons of foam
composition, sufficient to generate 100 cubic feet of stiff,
long-lasting foam when intermixed with gas or air. The
formulated composition is made and sold by Skyline Industries,
Inc., Route 29 North, Charlottesville, Virginia, 22901.
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The terms and expressions which have been employed
are used as terms of descrïption and not of limitation, and
there is no intention in the use of such terms and expressions ~;
of excluding any equivalents of the features described or
portions thereof, it being recognized that various modifications
are possible within the scope of the invention.
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