Animal husbandry – Milkers – With fluid pressure regulator
Reexamination Certificate
2002-09-06
2004-11-09
Price, Thomas (Department: 3643)
Animal husbandry
Milkers
With fluid pressure regulator
Reexamination Certificate
active
06814028
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a milking apparatus for laboratory animals, and more particularly to a milking apparatus suitable for relatively small and prolific laboratory animals such as, e.g., rats and mice.
BACKGROUND ART
Recent years have seen the presence of substances responsible for environmental pollution and harmful to living bodies, such as carcinogenic substances and endocrine disrupting (chemical) substances, becoming a global problem. It is of concern how these harmful substances may affect living bodies through milk such as breast milk. If it becomes possible to collect milk from laboratory animals such as rats and mice by a simpler method, such a method would be a useful means of clarifying the influence of the above-mentioned harmful extrinsic substances on living bodies.
However, relatively small and prolific laboratory animals such as rats and mice have a small nipple and produce only a small amount of milk, and for this reason there has not been proposed an effective milking apparatus. For example, it is difficult to collect milk directly from the nipple of a rat. In laboratories, therefore, milk is usually collected from the stomach of a baby rat that has been fed with milk. In the milk collected from the stomach, however, the milk component may potentially be broken down and digested by having been mixed with saliva and gastric juice and stirred. It is, therefore, an open question whether such milk can be called authentic milk.
C. T. Rodgers proposes (Laboratory Animals (1995) 29, 450-455) an apparatus for directly milking a rat, as shown in FIG.
11
. In this apparatus, a milk-collecting test tube
61
is arranged in a glass container
60
, which is then closed by a lid
62
. One end of a flexible tube
63
is inserted into the milk-collecting test tube
61
in a communicated manner. The flexible tube
63
extends through the lid
62
to the outside of the glass container
60
, and its front end is attached to a teat cup
64
made of silicon. The lower part of the glass container
60
is provided with two openings
65
,
66
, to the latter of which is attached a tube connected to a negative pressure creating source (not shown).
When a rat is milked by using this apparatus, vacuum is drawn from one opening
66
by continuously operating the negative pressure creating source, while the experimenter closes and opens the other opening
65
by a finger to thereby produce a pulsation. The pulsation is transmitted to the teat cup
64
via the flexible tube
63
, and milk is collected by the teat cup
64
applied to the nipple of the rat. The above mentioned paper reports that 1.0-1.5 ml of milk was collected, by using the above apparatus, from all the nipples of mother rats on the fourteenth day of lactation.
The above milking apparatus shows that it is possible to directly milk from the nipple of a rat and the apparatus is therefore useful. This milking apparatus, however, requires two experimenters to operate. Namely, one experimenter must put the mother rat in place by one hand and operate the teat cup
64
by the other. The other experimenter must open and close the front end of the pressure-reducing opening
65
with his or her index finger in order to produce a pulsation. Further, since the beat is produced by the finger operation by the experimenter, errors tend to arise due to differences between individual experimenters. Thus, it is not easy to obtain data such as universal milked amount. Moreover, there has been no concrete report about the shape of the teat cup, and this remains an issue to be addressed in the future for better milking.
Accordingly, it is an object of the present invention to provide a novel milking apparatus for laboratory animals by which a single experimenter can perform a milking operation and which makes it possible to obtain milking data universally not influenced by individual differences among experimenters. It is another object of the present invention to provide a novel teat cup particularly suitable for a milking apparatus for laboratory animals.
DISCLOSURE OF THE INVENTION
The present invention provides a milking apparatus for laboratory animals comprising a milk-collecting container whose inside can be kept shut from the outside air, a first and second tubes having one of their ends inserted into an upper part of the milk-collecting container in such a manner as to communicate with the inside of the container, a teat cup replaceably attached to the other end of the first tube, a negative pressure creating source attached to other end of the second tube, and a pressure switching means for switching, in a pulsed manner, the state inside of the second tube between an atmospheric pressure state and a negative pressure state created by the negative pressure creating source.
In this milking apparatus for laboratory animals, the negative pressure creating source is continuously operated, and a negative pressure is developed inside the second tube by connecting it with the negative pressure creating source by means of the pressure switching means. The negative pressure is directly transmitted from the milk-collecting container to the teat cup via the first tube. As the pressure switching means opens the second tube to the atmosphere and the atmospheric pressure develops therein, the teat cup is brought under the atmospheric pressure. Thus, by operating the pressure switching means in a pulsating or cyclical manner, a continuous pulsation develops at the front end of the teat cup.
In that state, the experimenter can perform a required milking operation by putting the mother rat in place with one hand while applying the teat cup to the nipple of the laboratory animal with the other hand. This means that a continuous milking operation can be performed by a single experimenter. This is a great advantage provided by the present invention. Since the repetition of the negative pressure and the atmospheric pressure directly acts on the nipple of the laboratory animal via the teat cup, the milking operation can smoothly proceed even in the case of a small laboratory animal such as a rat.
The milk obtained from the laboratory animal by the pulsation of the teat cup is collected at the lower portion of the milk-collecting container via the first tube. For structural reasons, the milk collected in the milk-collecting container does not flow into the second tube, thereby preventing the pressure switching means and the negative pressure-creating source from being subjected to operational failure.
In the milking apparatus for laboratory animals according to the present invention, the negative pressure creating source may be of any type. In a preferred embodiment, however, a vacuum pump and a pressure controller for controlling the pressure inside the second tube are used as a single unit in constructing the milking apparatus for laboratory animals. By using a negative pressure tank such as an accumulator, a stable pulsation can be obtained. Alternatively, a negative pressure creating means using, as the operating source, the amount of motion of a fluid (such as tap water, air, vapour and the like) flowing at a substantially stable flow rate, such as an aspirator, may be used. In this case, the negative pressure can be easily adjusted to a desired value by adjusting the flow rate of the fluid by opening or closing the tap without using the pressure controller, thereby simplifying the apparatus.
The pressure switching means may comprise an open/close valve such as a two-way electromagnetic valve capable of switching the state inside the second tube between a state where the inside is opened to the atmosphere and a state where the inside is blocked therefrom, with the second tube being connected to the negative pressure source at all times. In another embodiment, the pressure switching means may comprise a first open/close valve for connecting and disconnecting the second tube to and from the negative pressure source and a second open/close valve for switching the state inside the second tube upstream of the first open/close v
Nihon University School Juridical Person
Price Thomas
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