P/00/011 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Invention Title: "LICK TROUGH" The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 LICK TROUGH This invention relates to a lick trough which is mainly used for feeding liquid nutritional supplements to cattle, sheep and other livestock. Such nutritional supplements may include molasses and/or urea which may 5 optionally include crude protein, minerals, vitamins, feed additives and intake limiters. Hitherto open troughs have been used for feeding such liquid nutritional supplements although this has the drawback of the feed being exposed to weather, birds and other animals. In addition cattle or calves 10 may be pushed into the open trough. Lick-wheel tanks have been utilised instead of open troughs because they can limit the intake of the liquid nutritional supplement. They are essential when feeding molasses mixtures which contain high levels of urea which may be toxic to livestock. The lick wheel tank also protects the 15 molasses mixture from impurities and contaminants. A conventional lick wheel tank includes a tank having a base or bottom wall, continuous side wall and a cover or top wall. In the cover there are provided wheels rotatably mounted within accommodating sockets of the cover which upon rotation contact a reservoir of liquid nutritional supplement 20 located within a hollow interior of the tank. The number of lick wheels that are utilised will vary according to the number of cows being serviced but generally a lick wheel for each 8-10 cows may be used as suggested in an article entitled "Molasses - Based Feeds and their Use as Supplements for Brood Cows", F.M. Pate and W.E. Kunkle, published by the Department of 3 Animal Sciences, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida (1989) published at http://edis.ifas.ufl.edu/BODY ANO50. Another type of lick trough or lick tank that has been proposed is the 5 use of a roller drum lick feeder as discussed in a World Animal Review article by G.I. Alexander entitled "Nonprotein Nitrogen Supplements for Grazing Animals in Australia" published at http://www.fao.org/DOCREP/004/X6512E/X6512E17.htm. Reference also may be made to an article by Bill McKiernan entitled "Urea Rollerdrum Mixes 10 for Cattle" from NSW Agriculture Australia Agnote DA1 -9, third edition, June 2001. Each of these references describes a roller drum feeder assembly comprising a drum supported on a welded axle rotating in a trough only slightly larger than the drum itself. Slots or holes are cut in the ends of the drum to give storage capacity. A supply of nutrient liquid is provided in the 15 base of the trough. Another type of lick tank or lick trough refers to a mobile assembly comprising a trailer and tank support frame which supports a circular tank having a peripheral base portion having a plurality of rotatable balls provided in corresponding sockets and a centrally located tank which was surrounded 20 by the peripheral base portion. However disadvantages of the aforementioned prior art include the following: a) the use of lick troughs having a number of lick wheels or rotatable balls located in a top cover of a trough or housing provided 4 an assembly that was complicated in construction and only provided a limited licking area for the livestock and thus limited access. b) the use of the roller drum assembly as described above was also large and cumbersome and did not have any means for limiting 5 the amount of nutrient fluid that could be ingested by the livestock. Accordingly it is an object of the invention to provide a lick trough that may alleviate the abovementioned disadvantages of the prior art. The invention provides a lick trough having a ball component of substantially spherical shape rotatably mounted in a trough of corresponding 10 cross sectional shape which in use contains nutritional fluid accessible to livestock for licking the nutrient fluid located on an external surface of the ball component. The ball component suitably has a number of holes which are disseminated uniformly over the external surface of the ball. This facilitates 15 the nutrient liquid to obtain a maximum height in the trough and also allows the nutrient fluid to be applied to the external surface as a thin film. The trough may be cylindrical having a base wall, continuous side wall and open top. However it is possible for the side wall to have a truncated or frusto-conical shape in side view. 20 The ball component may be rotatably mounted in the trough component by any suitable means such as the ball component having a pair of opposed stub axles or a single axle which extend from the ball component on diametrically opposite locations. Each outer end of the stub axle or the single axle may be mounted in a bearing, bush or other pivot joint which may 5 be attached to a peripheral flange of the trough component or a top surface of an outer edge portion of the trough component. In any event the use of a pair of stub axles or a single axle will mean that the ball component may rotate about a horizontal axis. However this is not essential and less 5 desirably the ball component for example may be mounted in the trough component so as to rotate or pivot universally such as by a ball and socket interaction. The ball component may also be releasably attached to the trough component and this may be achieved for example by outer ends of each 10 stub axle or the single axle being clamped or otherwise releasably mounted to the peripheral flange of the trough component. Reference may now be made to a preferred embodiment of the invention as shown in the attached drawings wherein: FIG 1 is a perspective view of a lick trough in accordance with the 15 invention; and FIG 2 is a side view of a lick trough assembly in accordance with the invention each comprising a pair of lick troughs as shown in FIG 1 interconnected by a housing containing nutrient liquid in flow communication with each lick trough. 20 The lick trough 10 as shown in FIGS 1 - 2 has a trough component 11 having an open top 12 which has a peripheral flange 13, continuous side wall 14 and base wall 15 as shown in FIG 2. The side wall 14 may be slightly frusto-conical as shown but also may be cylindrical if required. There is also provided a ball component 16 having a plurality of holes 17 which lead to a 6 hollow interior 18 as shown in FIG 2. The ball component 16 is provided with a pair of stub axles 19 and 20 which are each maintained in bearings 21. Each stub axle 19 and 20 has an end projection 22 which retains each stub axle 19 and 20 in bearing 21. There are also provided clamps 24 which 5 releasably attach bearings 21 to support ledge 25 of trough 11. The provision of stub axles 19 and 20 rotatably mounted in bearings 21 enables the ball component 16 to be rotated about horizontal axis 26 and the provision of holes 17 enables nutrient liquid to be coated on external surface 27 in a thin stream so that the stream may be licked off external surface 27. 10 The constant rotation of ball component 16 about horizontal axis 26 caused by impact on external surface 27 by tongues of livestock causes the coating of nutrient liquid on external surface 27 to be constantly replenished as required. In FIG 2 there is provided a lick trough assembly 28 comprising a pair 15 of lick troughs 10 in flow communication with housing 29 containing nutrient liquid 30. Each trough component 11 has conduits 31 which connect with housing 29 as shown. Housing 29 is also provided with cover or lid 32. Each ball component 16 is spaced from base wall 15 only by a relatively small distance as shown at 33. 20 FIG 2 also shows use of an optional roof 34 over lick trough 10 which is shown in phantom and also use of a single axle 35 also shown in phantom instead of stub axles 19 and 20. It will also be seen from the drawings that the trough may have a diameter or lateral dimension which is only slightly longer than the diameter 7 of the ball component so that the ball component extends into the trough to form a substantially hemispherical portion which extends above the trough and another hemispherical portion which is retained within the trough. The advantages of lick trough 10 and lick trough assembly 28 as 5 described in the preferred embodiment in FIGS 1-2 over the prior art includes the following: (i) the lick trough 10 of the invention is simple in construction and effective in use because the use of a single ball in a trough of complementary or corresponding shape avoids the adoption of a multiplicity 10 of lick wheels located in a single trough which only provides limited urea for the tongues of the livestock to gain access or the use of a large heavy drum which can only be rotated in effective manner when a number of livestock are licking the drum. (ii) the provision of clamps 24 or other suitable releasable 15 attachment means between the ball component 16 and trough 11 means that the lick trough 10 of the invention in a preferred embodiment is essentially modular and thus can be transported or stored with ball component 16 separate from trough 11; and (iii) the provision of holes 17 in ball 16 which is a preferred form of 20 the invention as clearly shown in FIG 2 for example means that nutrient fluid largely fills up trough 11 and this nutrient fluid can only be applied as a thin film to external surface 27 of ball 17. This enables the nutrient fluid to be taken up by each animal only in a limited amount and thus avoids the ingestion of toxic components of the nutrient fluid such as urea or sulphur. 25