CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Divisional of U.S. application Ser. No. 12/812,947, filed Jan. 19, 2011, entitled “ PORTABLE AND COLLAPSABLE MODULAR CALF HOUSING SYSTEM,” which is a Submission Under 35 U.S.C. §371 for U.S. National Stage Patent Application of International Application Number PCT/CA2009/0000130 filed Jan. 14, 2009, and claims priority to U.S. 61/006,464 filed on Jan. 15, 2008, the entirety of which is incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to a calf housing system, particularly a system and method for housing calves individually. 
       BACKGROUND OF THE INVENTION 
       [0003]    Calves are born with a relatively immature immune system and, in particular, pre-weaned calves are susceptible to infectious pathogens that may be spread by the air-borne, fecal-oral or calf-to-calf transmission routes. Because transmission of enteric pathogens in calves is primarily through animal to animal contact, it has become common practice to isolate calves from others to reduce the risk of infectious diseases. 
         [0004]    It is important, however, to have appropriate housing isolation units to maintain a positive effect on the growth, health and well-being of a diary calf. Good design can provide a healthy environment that reduces environmental stress. For example, high levels of moisture, pollutants and air-borne pathogens may lead to respiratory problems that have long term effects. Thus, there has been an on-going need for management environments that provide calves with a clean, dry, well-ventilated space, especially in locations that may experience severe fluctuations in temperature. 
         [0005]    Several attempts have been made to provide appropriate housing for calves. For example, U.S. Pat. No. 6,964,245 provides a rigid pen, including an outer frame defining an open floor attached to a motorized vehicle. The vehicle is operated to raise the pen off the ground and deliver the raised pen to an area at which the calf and the mother cow are located. The vehicle then positions the raised pen over the calf. Finally, the pen is lowered such that the calf is inside of the pen and the mother cow is outside of the pen. The calf, in the pen, can then be housed in a manner in which the handler has access without interference from the mother. 
         [0006]    U.S. Patent application 20070178525 provides methods for managing livestock to improve performance and health of the general livestock population by reducing the impact of subclinical animals persistently infected with a contagious disease by separating animals into arrival groups, screening all animals for the pathogen of the contagious disease, promptly removing the pathogen positive animals from the general livestock population and feeding and managing the pathogen negative animals and pathogen positive animals separately. In preferred embodiments, the pathogen positive animals are removed from their arrival group within about 1.5-3 days after arrival. In preferred embodiments, the method of the present invention is applied in a cattle operation such as a seedstock operation, a cow-calf operation, a stocker operation, a backgrounding operation, a feedlot operation, a dairy operation, a farm of origin, such as a dairy farm, an auction facility, a gathering point or a buyer facility. 
         [0007]    Another type of calf housing system is marketed by Calf-Tel for Hampel products that can be used to house calves. While the Calf-Tel hutches provide a useful alternative to other types of hutches, they do not provide for adjustability as the calf grows. 
         [0008]    Thus, there was an unmet need for a calf housing system that addresses the requirements for good ventilation, isolation, disease reduction and adjustability in farm management practices. 
       SUMMARY OF THE INVENTION 
       [0009]    It is an object of the invention to provide an improved calf housing system. 
         [0010]    One aspect of the present invention relates to a method of isolating a calf from other calves and cows. The method includes providing a portable, rigid pen that provides systems for ventilation and for providing adequate nutrition to the calf as it grows with a minimum of environmental stress. 
         [0011]    In another aspect, the invention provides a portable pen for isolating a calf. The pen includes a frame that has a front, a back, and opposing sides that combine to define an interior pen area. In one preferred embodiment, the pen has an open floor and functions as a free standing pen that can be moved to various locations based on environmental conditions such as drainage, the direction of the prevailing winds or a temperature and humidity controlled facility. 
         [0012]    In another preferred embodiment, the includes a rear wall. 
         [0013]    In a further embodiment, the is adapted for attachment to a wall whereby the wall forms the rear of the enclosure. 
         [0014]    In yet another embodiment, the includes a floor. 
         [0015]    In a preferred embodiment, the pen includes a door hingedly attached to the front of the frame. Conventional hinges or pins may be used. The door or gate is preferably attached to the front such that the door can swing inwardly or outwardly relative to the frame. The gate preferably includes ventilation openings and locations for inclusion of optional features such as a headlock, a bottle holder, a wall bracket and a bottle. The opposing side panels are adapted for interconnection between multiple pens and also include channels in which the front of the frame fits. In a preferred embodiment, both the front panel and the side channels include apertures. 
         [0016]    In a preferred embodiment of the invention, the frame includes at least one feed pail. The vertical location of the feed pail/front panel can be adjusted, as the calf grows, to facilitate feeding. In a preferred embodiment, the height, or vertical positioning, of the front panel is adjusted by sliding the panel in the channels of the side members and securing the panel at a specific height by inserting a pin in corresponding apertures in the front panel and the side panels. Other means of adjusting the height of the feeding pails, such as a spring loaded, ratcheting or hydraulic systems, are included within the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein: 
           [0018]      FIG. 1  is a view of one embodiment of a calf housing pen in accordance with one aspect of the invention; 
           [0019]      FIG. 2  is a view of another embodiment of a calf housing pen in accordance with the present invention; 
           [0020]      FIG. 3  is a front view of a complex of calf housing pens attached along their sides in accordance with one embodiment of the invention; 
           [0021]      FIG. 4A  is a front view illustrating how the feed buckets can be adjusted vertically; 
           [0022]      FIG. 4B  illustrates various confirmation in which the pens can be attached to each other; 
           [0023]      FIG. 5A  illustrates an optional headlock for use with the present invention; 
           [0024]      FIG. 5B  illustrates an optional quick release bottle holder for use with the present invention; 
           [0025]      FIG. 5C  illustrates an optional wall bracket for use with the present invention; 
           [0026]      FIG. 6  illustrates optional rotary vents for use with the present invention; and 
           [0027]      FIG. 7  illustrates how the front panel can be adjusted vertically to provide the calf with a feeding pail in position according to its height. 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    One embodiment of a portable pen unit  10  in accordance with the present invention is shown in  FIG. 1 . The pen unit  10  includes a frame  12  that comprises a rear panel  14 , two opposing side panels  16  and a front panel  20 . A door  22  is inserted in the front panel  20 . The door  22  is hingedly attached at one side  24  to the front panel  20 . The door  22  may be adapted to swing either inward or outward relative to the front panel  20 . The opposite side  26  of the door is releasably maintained in a closed position by a latching mechanism  28 . The latching mechanism  28  may comprise any type of known latching/securing mechanisms. For example, the hinges of the door  22  may be outwardly biased and the door  22  is latched by a simple stop member being rotated into position. Alternatively, the latching mechanism may incorporate a slide and bolt system or a click and fit system. In the embodiment illustrated in  FIG. 1 , the floor of the pen unit  10  is open and the pen unit  10  may be placed on any suitable surface. The door  22  typically includes openings  32 ,  34 ,  36 ,  38 ,  40  for feeding and ventilation and for insertion of optional items. The door  22  is equipped with at least one feeding pail receptacle  74  for receiving a corresponding feeding pail  42 ; the apertures  38 ,  40  in each door  22  provide access to the feeding pails  42  when received in the feeding pail receptacle  74 . As discussed in further detail below, the height or vertical positioning of the feeding pail receptacles  74  and the feeding pails  42  carried thereby can be adjusted as the calf grows by raising or lowering the front panel  20 ; in  FIG. 4A  the front panel  20  of the leftmost pen  10  is raised relative to the front panel  20  of the rightmost pen  10 . In a preferred embodiment, the front panel  20  is attached to the side panels  16  via a connector  50  on the side panel  16  which has a receiving channel  52  for the front panel  20  in the form of a tongue and groove mechanism. To raise the feeding pail receptacles  74  and thereby raise the feeding pails  42  the front panel  20  is moved up and a locking pin  72  is inserted into an aperture  70  ( FIG. 7 ) in the front panel  20 . This mechanism is discussed in greater detail below with respect to  FIG. 7 . 
         [0029]    In the embodiment illustrated in  FIG. 2 , the pen unit  10  is adapted for mounting on a wall  44  and the wall  44  to which it is attached forms the rear wall of the pen unit  10 ; thus the rear panel  14  is omitted. 
         [0030]      FIG. 3  illustrates an embodiment in which several pen units  10  can be attached to each other. This provides additional stability and keeps the calves close enough to each other for easy handling, yet still separated. The pen units  10  can be attached to each other through the above-noted tongue and groove mechanism, with the edges of the front panels  20  received in the receiving channels  52  ( FIGS. 1 and 7 ) of opposed side panels  16 . As shown in  FIGS. 1 and 2 , the side panels  16  include connectors  50  with receiving channels  52  to receive the edges of the front panels  20  to form a plurality of tongues and grooves. The modular nature of the present invention including the interlocking tongue and groove system allows for quick and easy assembly and disassembly of pen units  10  in minutes. In a preferred embodiment the components are made of durable polyethylene and are light weight and easy to clean. The built-in calf dividers keep the calves apart to prevent the spread of disease and the built-in feeding pail receptacles  74  with pail divider prevents food contamination. The polyethylene surface of the component panels does not promote the growth of bacteria or the spread of infectious diseases. 
         [0031]      FIG. 4A  illustrates another configuration in which pen units  10  can be attached side to side and front to back.  FIG. 4B  illustrates schematically how the pen units  10  can be configured to fit one&#39;s needs. 
         [0032]      FIGS. 5A , B and C illustrate optional features which can be included with the calf housing pens.  FIG. 5A  illustrates how a headlock device  60  can be incorporated.  FIG. 5B  illustrates a quick release bottle holder  62  for feeding calves and  FIG. 5C  illustrates a wall bracket  64  for attaching the pen. All of the optional features may be provided in a kit which includes the basic building blocks of the pen  10  (i.e. rear panel  14 , side panels  16  and front panel  20  including door  22 ) as well as the quick release bottle holder  62  and the bottle  63  itself. 
         [0033]    As discussed previously, excellent air quality in a pen is essential to raising healthy calves. Different air exchange rates may be needed depending on the environmental conditions. The pen units of the present invention are preferably equipped with means for circulating air. In a preferred embodiment, rotary vents  66  are provided in the rear panel  14  as illustrated in  FIG. 6 . 
         [0034]      FIG. 7  illustrates how the front panel can be raised up and down in channels  50  associated with the side panels  16 . In the preferred embodiment illustrated in this figure, there are three apertures  70  located near the top of the front panel  20  on each side thereof. There is also an aperture  71  in each of the side panels that is adapted to receive a positioning pin  72 . In use, the pen  10  is usually initially set up with the front panel  20  secured in position at the lowest aperture, as shown in  FIGS. 1 and 2 . As the calf grows the front panel  20  can be raised by sliding it in the channels  52  of the connectors  50  of the side panels  16  and secured at the second aperture position  70  and then at the third aperture position  70 . This system provides a unique advantage for dairy farmers. Due to the adjustable pail height, the calves have greater comfort when feeding and thus may have improved growth profiles.  FIG. 7  also shows the apertured feeding pail receptacles  74  with the feeding pails  42  removed therefrom. 
         [0035]    In one embodiment, the frame of the pen unit  10  is square in transverse cross-section, having dimensions on the order of 8×8 ft. Alternatively, other shapes and dimensions are equally acceptable. Further, in one embodiment, the frame of the pen  10  has a fairly substantial height, on the order of about 3 ft to 6 ft. Other heights are equally acceptable, however, the frame preferably has a height greater than a height of an average cow. 
         [0036]    Prior to use, the pen  10  is provided as a kit for assembly. It includes in flat packing the front panel  20  and the side panels  16 . If not to be wall mounted, the rear wall panel  14  is also provided. The unique interlocking system allows for easy assembly. Optional features such as the bottle holder  62  and headlock  60  may be provided separately or as part of a “deluxe” kit. 
         [0037]    The pen and related method of use of the present invention provides a marked improvement over previous designs. Calves are easily isolated from other animals. The invention provides a structure and a farm management system that allows the farmer to easily gain access to the calf and, at the same time, to reduce the risk of transmission of infectious diseases among the herd. Furthermore the system is easy to assemble and to keep clean and is designed to adapt to the feeding needs of the calf as it grows. 
         [0038]    One or more currently preferred embodiments have been described by way of example. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.
A portable and collapsible modular calf housing system featuring at least one pen comprising a front panel and two side panels and optionally a rear panel forming a pen. The side panels include channels in which the front panel can slide vertically to adjust the height of a feeding pail attached thereto. The channels are disposed on either face of each side panel to enable a front panel from each one of adjacent pens to be joined to form a plurality of interconnected pens.