METHOD FOR IMPROVED ANIMAL HUSBANDRY USING LINEARLY POLARIZED LIGHT AND DEVICE FOR PRODUCING LINEARLY POLARIZED LIGHT
The subject of the invention is a method for improved animal husbandry during which animals are being reared in customary manner, but the animals are exposed - for given time periods - to linearly polarized light having given intensity. In conformity with this method the invention further relates to a device for producing linearly polarized light by means of which the polarized light can be emitted on a large surface with relatively high intensity in order to effectuate the method according to the invention. It is known that exposure to polarized light is used effectively for different therapeutic purposes. For the present invention investigations have been performed in order to find out whether polarized light has beneficial effects on a healthy organism. For this purpose mice were kept in a cage in a part of which complementary polarized light was used in addition to its normal lighting. Practically, about one fifth of the cage area was illuminated by polarized light the intensity of which corresponded to the intensity of the non-polarized light. It was experienced that mice preferred staying in that part of the cage which was illuminated by the polarized light. Further, it was also experienced that these mice behaved more lively without showing increased aggressiveness as compared to the reference population kept in a cage illuminated by non-polarized light. Attempts were made to perform the same investigation in case of animal breeds of a larger body, but it was realized that there is no light-source existing at a reasonable price which is suitable for the emission of polarized light on a surface of a sufficient size and generating an appropriate light intensity. The object of the present invention is to provide a method for improved animal husbandry during which animals are being reared in customary manner, but furthermore taking advantages of the exposure of living animal body to linearly polarized light. The further object of the present invention is to provide a device of reasonable cost of production by means of which polarized light can be emitted on a large surface with relatively high intensity. The problem to be solved was to choose a light-source which is suitable for light emission in the required spectrum with good efficiency, that is, which does not generate a quantity of heat which would cause difficulties during using such a device particularly in animal husbandry. Fluorescent tubes or LED devices
have been considered as the most suitable light-sources. A problem in connection with the use of fluorescent tubes or linearly arranged pinhole light sources is that there has not been yet found a solution by means of which the emitted light could be polarized with sufficient efficiency. The present invention provides a solution to this problem in two ways. According to a first solution the light emitted by a fluorescent tube or LED devices and partly collimated by means of cylindrical mirrors having parabolic profiles is polarized by Brewster mirrors. According to a second solution the light emitted by the fluorescent tube or LED devices is transmitted through a polarizing layer or a polarizing foil. The linearly polarizing layer may be placed on the fluorescent tube itself or on a cylindrical surface encircling the light-source, or it may be placed on a plate having a flat surface and positioned at a given distance from the light-source. The polarizing layer may constitute a part of a multi-layer structure, however, it should be noted that other optical layers being behind the polarizing layer or polarizing foil concerning the path of the light must not have characteristics which would considerably deteriorate the polarization. When self-adhesive, linearly polarizing foil is used as polarizing layer which is placed, for instance, on the fluorescent tube itself or on a surface encircling the light-source in such a manner that the transmission direction of the linear polarization corresponds to the longitudinal direction of the light-source, then the efficiency of polarization will not decrease, if cylindrical mirrors having parabolic profiles are used. The device according to the invention may be applied in an arrangement of multiple pieces. As a consequence linearly polarized light can be obtained economically from an optional large size emitting source area. It is also an object of the invention to create a device suitable for emitting polarized light within the visible and near infrared spectral range. It is a further object to provide lights of different colours, or in certain cases to change the colour of the light. This may be realized for example by using fluorescent tubes or LED devices which emit light in different spectral ranges, by combining fluorescent tubes or LED devices which emit white light in a wide spectrum with colour filter, or through colour blending i.e. by separately modulating the light intensity of several different coloured fluorescent tubes or LED devices which emit light in different spectral ranges. In this way for example three fluorescent tubes emitting light in different spectral ranges may be placed directly next to each other in the vicinity of the focus line of a single cylindrical mirror
having a parabolic profile, the light of which may be transmitted through the structural unit performing polarization. When this structural unit is a Brewster mirror, collimation of the light beams emitted from the three parallel fluorescent tubes can be improved if the three fluorescent tubes are encircled by a common, optically transparent optical diffuser cylinder. When the structural unit performing polarization contains polarizing foil, then also this polarizing foil may be placed on a common transparent cylinder of the same kind. If the fluorescent tube is white, that is, the radiation spectrum of the fluorescent tube contains spectral lines distributed within the visible and near infrared spectral range, then such a transparent cylinder may be used whose material is tinted or covered by a layer of colour filter. Farther out following the polarizing layer it is not allowed to apply any layer which would change or deteriorate the polarization. The layer of colour filter may be applied alternatively on the outer surface of the fluorescent tube, and it may be realized in the form of a transparent, coloured coat of paint, for example coloured lacquer. Naturally, also the lacquer may be applied on the surface, preferably on the inner surface of the cylinder encircling the fluorescent tube by means of spraying or immersion or using other known techniques. As an alternative to the fluorescent tubes other pinhole light-sources in a linear arrangement may also be used, for example discharge lamps, light emitting diodes (commonly known as LED devices). In respect of this invention the term LED devices is used for all high-efficiency light emitting semiconductor devices and structures currently manufactured in mass-production and available in trade. These devices and structures are continuously developed in order to reach higher and higher luminous efficiency. Such devices emit light within the visible and near infrared spectral range in the form of white light which may have different colour temperatures. In the present invention the term LED devices is used in a comprehensive meaning, especially for known high-intensity, high-power LED (Light Emitting Diode) or OLED (Organic Light Emitting Diode) devices. The latter renders possible to use a plane luminous foil which - theoretically - may be cut to an optional size. Also LEP (Light Emitting Polymer) devices may be used. To sum it up, according to the present invention all those devices may be regarded as LED devices which are known as SSL (Solid State Lighting) electronic devices in the state of the art. Current possibilities in trade make dominantly the use of discrete LED devices feasible. These so called high intensity LED devices are the most suitable for embodiments of units or panels emitting light from a plane and
which in a module system may be used for forming a lighting unit of a large surface according to the object of the invention. Experimental application of these devices emitting polarized light according to the present invention has been tested in various ways. On the basis of these tests a method for improved animal husbandry has been worked out in breeding of mammals and breeding of poultry as well. According to the method of the invention animals are exposed to polarized light of a given intensity for a certain period of time in certain phases of their life. In case of mammals illumination with polarized light proved to be particularly useful at the time after their birth, but it proved to be beneficial also in other critical periods (e.g.: pregnancy, nursing-milking). In case of poultry exposure to polarized light proved to be advantageous during incubation and also during the period immediately after hatching. A detailed description of some embodiments of the invention, as being selected examples only, will now be disclosed with reference to the accompanying drawings in which: Figure 1 is a perspective view of the device emitting linearly polarized light, comprising a fluorescent tube positioned at the focus line of a parabolic cylindrical mirror and a Brewster mirror; Figure 2 is the sectional view of the device of Figure 1 ; Figure 3 is a sectional view of an armature for emitting linearly polarized light comprising multiplication of the device of Figure 1 ; Figure 4 is a more detailed drawing of the Brewster mirror combination used in the device of Figure 1 ; Figure 5 is an illustration of an armature mounted on a stand; Figure 6 is a perspective view of a fragment of an exemplary lighting unit according to the invention; Figure 7 is a sectional view of the lighting unit of Figure 6; Figure 8 is a sectional view of a first example embodiment of the polarizing front unit; and Figure 9 is a sectional view of a second example embodiment of the polarizing front unit. According to the invention a method for improved animal husbandry is provided in which a device emitting linearly polarized light of sufficient intensity is used. Accord-
ing to this method rearing of animals is conducted as it is customary, i.e. in line with the known agricultural technologies, with the difference that the animal or a part of its body is exposed to linearly polarized light of a given intensity for a given period of time at least in one selected period of its life which is of critical importance from the point of view of rearing. For this purpose, a device 10 shown in Figures 1 and 2 is advantageously adapted to produce and emit linearly polarized light. The device 10 contains a fluorescent tube 20 as a light-source and a polarizing unit 30 which is placed in the path of the light emitted by fluorescent tube 20. In the present example the polarizing unit 30 contains Brewster mirrors 31. Fluorescent tube 20 is placed at the focus line of a parabolic cylindrical mirror 40 which collimates at least a portion of the light emitted by fluorescent tube 20. Considering the fact that - for practical and economic reasons - the Brewster mirror 31 can be produced only in a relatively small size (e.g. 100 x 100 mm) therefore a Brewster mirror 31 containing e.g. twelve pieces of mirror packages 32 is attached to a single fluorescent tube 20 in this example. Consequently, the depth measure of the structure (its greatest expansion measured from fluorescent tube 20) can be decreased. It is particularly important because in this way a number of fluorescent tubes 20 together with the polarizing unit 30 may be placed easily into a single armature 50 as it is shown in Figure 3. The polarizing efficiency of Brewster mirror 31 can be improved if it is composed of mirror packages 32 containing five plane-parallel transparent glass plates 33 positioned parallel with each other, as it is shown in Figure 4. Glass plates 33 are set in frames 34, 35. The edge of a frame 34 is formed to a shape 36 along its edge in order to engage with a frame 35 of a similar mirror package 32, which frame 35 is formed to a complementary shape 37 along its edge. Thus frames 34 and 35 can be placed next to each other in an extensible manner. The polarizing unit 30 of the invention may alternatively comprise a polarizing foil. In Figure 5 an illuminating armature 50, such as illustrated in the preceding examples, mounted on an upright stand 51 is shown. The adjustable mounting junction between the armature 50 and the stand 51 allows the illumination to be directed more specifically to the target area of the body. To produce coloured polarized light a colour filter may be placed in between the
fluorescent tube 20 and the polarizing foil. The colour filter can be a coloured foil, but it can be realized also in the form of a transparent, coloured coat of lacquer applied on the surface of the fluorescent tube 20. In another embodiment three fluorescent tubes 20 having different colours e.g. red, blue and green are placed in the armature 50. By switching the proper fluorescent tubes 20 on and off and by setting their intensity the required perceptible colour can be obtained in a required spectral range. Advantageously, the polarizing foil is self-adhesive (available e.g. under product name NPF G1220 DUN by NITTO, Japan). It can be placed on the superficies of fluorescent tube 20; in certain cases colour filter may be interposed. The direction of polarization of the polarizing foil must be parallel with the longitudinal direction of fluorescent tube 20. Alternatively, in case of LED devices the longitudinal direction of their arrangement is relevant. Since fluorescent tube 20 is placed in the focus line of the parabolic cylindrical mirror 40 collimating at least a portion of the light emitted by the fluorescent tube 20, mirror 40 will not deteriorate polarization. Figure 6 is a perspective view of a fragment of an exemplary lighting unit according to the invention, in which a source unit 1 producing light in the visible and near infrared spectral range and an optically translucent polarizing front unit 4 providing protection against external effects can be seen. Source unit 1 and polarizing front unit 4 are included in a housing 8. Source unit 1 contains at least one panel 2 which has a number of high intensity LED devices 3 arranged in a predetermined pattern on one of its sides. In Figure 6 this pattern is a matrix, the geometry of which corresponds to a number of parallel fluorescent tubes. An electric cable (not shown) passing somewhere through housing 8 supplies energy for LED devices 3. The same source unit 1 may contain a number of separate panels 2 or these panels may be attached to each other in a releasable manner. According to Figure 7 the polarizing front unit 4 contains at least one optically transparent rigid carrier 5 and a polarizing filter foil 7 applied onto the carrier 5. At least a portion of housing 8 is made from heat conductive material, for example metal in order to reduce the heat developing during operation. To reduce the heat of the inner space 11 also any other known means, for example heat-insulating paint layer might be proper. Polarizing front unit 4 is fixed to housing 8 by means of a frame 9 so that they confine a hermetically closed in ner space 11. Panel 2 is positioned in a fixed way parallel with the polarizing front unit 4 within inner space 11 so that the high intensity
LED devices 3 face towards the polarizing front unit 4. Optionally, cooling flange 16 may be applied at the bottom part of housing 8 also in order to reduce the heat developing in the inner space 11. Figure 8 shows the cross-section of a possible structure of the polarizing front unit 4. The optically transparent rigid carrier 5 together with a similar carrier 6 form a sandwich structure surrounding the polarizing filter foil 7. This polarizing filter foil may be applied onto either carrier 5 or carrier 6. Application may be performed by sticking, self-adhesive foil, etc. It is also possible that polarizing filter foil 7 is simply kept in its place by exertion of a mechanical force. Polarizing filter foils are known and commercially available. Advantageously, the polarizing filter foil 7 is highly transparent, preferably it has a light-transmitting capacity of more than 40%. Advantageously, the carriers 5 and 6 are made of plexi-glass, transparent polycarbonate or similar plastic material, however glass or hardened glass may also be appropriate. According to Figure 9 only a single carrier 5 is used, in this case polarizing front unit 4 contains a polarizing filter foil 7 applied directly onto carrier 5 by using one of the applying methods previously described. Of course, polarizing filter foil 7 may be applied on carrier 5 either on the side facing the light-source or on its other side. The lighting unit according to the invention in its entirety may be disc-shaped or parallelepiped. Especially the latter has an advantage that the shape of a single separate armature of a lighting unit makes possible to extend it by further units, i.e. several armatures can be connected (both mechanically and electrically) to each other easily. Principally, lighting techniques shown in Figures 1-9 can be used for providing means applicable under the usual circumstances of animal husbandry, which can be installed easily and resist environmental effects. To this it is supposed that the animals are kept indoors for a certain time, and they are not allowed to move over a limited area during this time. Improvement in yield and hardiness resulting from the implementation of the method according to the invention has been proved by experimental investigations. In case of mammals, animals are exposed to linearly polarized light with an intensity of at least 2-40 mW/cm2 immediately after their birth, and thereafter for at least 10 minutes per day, and this procedure is continued till the body weight of the animals exceeds their birth weight at least by 10%. It is to be noted that the intensity of light is to be understood here and hereinafter as the intensity present on the target surface
being at a given distance from the light-source, and being perpendicular to the direction of the propagation of light. Another critical period in rearing mammals is the period of lactation. During this period the animal or a part of its body is exposed to linearly polarized light with an intensity of at least 2-40 mW/cm2 for at least 10 minutes per day. Particularly, in case of lactiferous animals e.g. cows, their udder and the surrounding area is exposed to linearly polarized light. As a result of this exposure increased milk yield was experienced, and also the incidence rate of the disease called mastitis decreased. This latter disease is a frequent problem in the case of lactiferous animals.
Experimental Example 1 From one of the cow-sheds of a dairy farm twelve cows having chronic bacterial contamination caused by bacteria Staphilococcus Aureus were put at our disposal for treatment with linearly polarized light according to the ivention. Six of these animals were treated with polarized light for four weeks. During this treatment the udders of the six animals were exposed to linearly polarized light for 20 minutes, twice a day. The armature emitting linearly polarized light was installed in the milking stall of the cow-shed in such a way that the usual life conditions of the cows were not changed and the animals could not cause any damage in the armatures. Polarized light emitted from the armature on a relatively large surface reached the body of the animals essentially from sidewards so that during the whole time of the treatment the surface of the udder was exposed to linearly polarized light with an intensity of at least 5-10 mW/cm2. During the four weeks of the treatment period and then for a further period of six weeks changes in the Somatic Cell Count and milk yield were examined as parameters of the test. The other six animals represented the control group in which changes of the Somatic Cell Count (SCC) and milk yield were examined for the experimental period of 4+6 weeks in the same way. When starting the experiment it was aimed to form light-treated/control pairs from the two groups of animals which were in the same phase of their lactation cycles and whose milk contained approximately the same Somatic Cell Count. Somatic Cell Count is indicative of the quality of the milk, it denotes the number
of bacteria being present in the milk. If the Somatic Cell Count is more than 400,000, then the milk is inedible for humans. Therefore reduced or low level Somatic Cell Count is required. Lactation cycle starts immediately after calving, this cycle follows the volume of the milk yield. In the first phase of this cycle the milk yield is increasing, then reaches a maximum volume, and from this time on it slowly decreases. Each of the twelve animals under investigation was i n the descending phase of the lactation cycle. The same conditions of life and feeding were provided for them. Our experiences show that in case of the control animals the average milk yield decreased in accordance with the usual physiological phenomena, while in case of the animals treated with polarized light this average volume slightly increased. A difference of 10.7% was experienced between them at the end of the experiment. The Somatic Cell Count (SCC) measured in the milk of the animals treated with polarized light was 49% less than in the case of the contro I animals at the end of the experiment. Another critical period in the lifetime of mammals is the period of pregnancy. According to the invention the animal is exposed to linearly polarized light with an intensity of at least 2-40 mW/cm2 for at least 10 minutes per day at least in the last third of the pregnancy. The usefulness of the method for animal husbandry according to the invention was proved in case of pigs by the treatment of newly-born piglets in the following manner. One of the most difficult problems of the large-scale animal husbandry is to decrease the death rate of the newly-born animals. Newly-born piglets were treated with polarized light immediately after their birth. Piglets under investigation were crossbred of the brands: "Magyar Nagy Feher" X "Magyar Lapaly' ' X "Duroc". In our first and second series of experiments all the piglets of 18 sows were treated with linearly polarized light one hour after their birth (after leaving the caul) for 15 minutes. Piglets of other 18 sows represented the control group. Death rate within each litter of pigs was examined till the ablactation which took place on the 30th day, when also the weight of each piglet was registered, as it appears from the following Table !
Table 1
As it can be seen, a great number of piglets were under investigation during which a significant difference in death rates could be noticed. While only 4.0% of the piglets perished between 0-7-days in the treated group, this value in the control group was 12.4%. This difference later became even greater, since by the time of the ablactation (when the piglets were 30 days old) only 5.6% of the treated animals died, while in the control group this value reached 18.7%. On the basis of our data it can be stated, that the decrease of the death rate in the group treated with polarized light was due to the fact that the number of piglets starving or suffering from cachexy decreased significantly, and also less piglets were squeezed to death by the sows. On the basis of our results it can be stated that the hardiness of the newly-born animals can be increased considerably by treating the animals with linearly polarized light within a short time after their birth, and as a consequence of this their chance of survival is enhanced. Means needed for the treatment can be adapted to the technology, they do not require modifications or significant additional means in the usual process of rearing animals. In case of appropriate arrangement (dropping-boxes, hatcher) the process of the treatment with linearly polarized light can be automatized easily. In case of poultry-farming, immediately after hatching in a period which is critical in respect of rearing, the animal is exposed to linearly polarized light with an intensity of at least 2-40 mW/cm2 for at least 10 minutes. Advantageously, this procedure is continued till the body weight of the animals exceeds their birth weight at least by 10%. Another critical period in rearing poultry is the period of incubation. During incubation, before the eggs hatch out, at least in the last third of the incubation period the eggs are exposed to linearly polarized light with an intensity of at least 2-40 mW/cm2 at least once a day for 2 minutes, and preferably this is done for seven days. The usefulness of the method for animal husbandry according to the invention
was proved in the case of poultry in the following manner.
Experimental Example 2 Young geese were treated with polarized light after hatchin g. Treatment took place after a two-hour rest being necessary for the development of the passive immunization against the so called Derzsy disease. 336 goslings were exposed to polarized light for 10 minutes. The treated animals were marked by cutting th ir web, and 4540 geese represented the control group. On the day following the treatment geese were taken to a goose farm, where they were kept together with the geese of the control group in the same place and under the same conditions. The following Table 2 contains the data of observation in case of the young geese treated with polarized light and in case of the control group:
Table 2
On the basis of these data it can be stated that the death rate decreased by nearly 40% due to the treatment. This improvement is due to the effect of the exposure to the linearly polarized light, by which the chance of the animals to survive and their ability to develop are enhanced. Possibilities of treatment with polarized light were examined during incubation with a relatively low number of goose eggs. In the course of incubation eggs are checked in any case by candling, and the treatment with polarized light was performed during one of these candlings. Our results of the experiments in this field give the conclusion that the exposure to linearly polarized light can reduce significantly the number of heatings during the incubation and hatching.