the surface of a pellet 1 with an active substance core 2 is completely covered by a coating 3 . the coating 3 may include a filler 11 , which is preferably in the inner layer near the active substance core 2 . the end walls 4 of the pellet are concave , thus forming two circular edges 5 with the angle α ( dotted lines in fig2 ). in the area of these edges 5 , the coating 3 is considerably thinner than in the other areas of the pellet 1 , so that a predetermined rupture site 6 is formed . the formation of the predetermined rupture site 6 and the breaking open of said site is favored by the edges 5 which form an acute angle α with their adjacent areas ( i . e ., in the given example , the curved surface 7 and the corresponding end wall 4 of the pellet 1 ). the angle α is determined by the curved surface 7 and the tangent of the end wall 4 to the edge 5 . likewise , the radius r of the edge 5 and the length l of the areas 7 and 4 adjacent to the edge 5 ( measured perpendicularly to the edge 5 ) are responsible for the function , that is the breaking open of the predetermined rupture site 6 . the length l is measured up to the next considerable change of the corresponding area , i . e ., for the given example in the case of the curved surface 7 up to the other edge and in the case of the end wall 4 up to the opposite part of the corresponding circular edge 4 . if these lengths l are too small , the predetermined rupture site will be especially thickly coated , so that the desired effect cannot occur . fig3 shows the pellet of fig1 where the endwall is broken open . at the end wall 4 , the coating 3 is broken open like a lid my mechanical action or by partial dissolution of the coating 3 in the area of the predetermined rupture site 6 , so that the active substance is released from the core in the area 10 . 3 , 600 g dl - methionine and 400 g of the sodium salt of carboxymethylcellulose are placed in a receiver and combined with intensive mixing with 870 g water . the mixture is pressed in an annular grind - and - mix press with 1 . 5 mm matrix bore to pellets which are cut to a length of approximately 2 mm and dried at 60 ° c . 100 g of these pellets are sprayed in a coating device , at first with a solution of 0 . 5 g ethyl cellulose in 25 ml ethanol in which 2 . 5 g sodium aluminum silicate ( particle size 3 . 5 μm ) are suspended . then , a solution of 3 . 5 g ethyl cellulose in 95 ml ethanol is sprayed on . the particles coated in this manner are dried under reduced pressure at 60 ° c . their methionine content , determined by bromatometric titration , is 83 . 6 % and the undissolved portion of the methionine 75 % / 63 % / 18 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 4 g ethyl cellulose ( inside 1 g , outside 3 g ) and 1 . 5 g sodium aluminum silicate . the methionine content is 84 . 6 % and the particular undissolved portion of the methionine 70 % / 56 %/ 13 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g sodium aluminum silicate . the methionine content is 83 . 0 % and the particular undissolved portion of the methionine 77 %/ 64 %/ 21 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 8 g ethyl cellulose ( inside 2 g , outside 6 g ) and 5 g sodium aluminum silicate . the methionine content is 79 . 5 % and the particular undissolved portion of the methionine 93 %/ 87 %/ 47 %. the pellets produced according to example 1 are treated in such a manner in a customary apparatus suitable for this purpose , e . g . in a rounding device , that the edges and webs of the invention are ground off to a large extent . then , 100 g of the pellets rounded in this manner are coated as in example 1 using a total of 4 g ethyl cellulose ( inside 0 . 5 g , outside 3 . 5 g ) and 2 g sodium aluminum silicate . the methionine content is 84 . 8 % and the undissolved portion of the methionine 94 %/ 91 %/ 74 %. this reference test shows that after the edges and webs have been ground off , thus eliminating predetermined rupture sites , by far the greatest part of the methionine still remains undissolved even after 24 hours . 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g ammonium alginate as filler . the methionine content is 84 . 1 % and the undissolved portion of the methionine 86 %/ 76 %/ 34 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g magnesium carbonate as filler . the methionine content is 83 . 4 % and the undissolved portion of the methionine 91 %/ 82 %/ 43 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g starch as filler . the methionine content is 83 . 4 % and the undissolved portion of the methionine 84 %/ 75 %/ 31 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g gum arabic as filler . the methionine content is 83 . 8 % and the undissolved portion of the methionine 91 %/ 83 %/ 40 %. 100 g of the pellets produced according to example 1 are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g sodium stearate as filler . the methionine content is 82 . 9 % and the undissolved portion of the methionine 78 %/ 65 % / 18 %. the same method is used as in example 1 , but 400 g starch are used instead of the sodium salt of carboxymethylcellulose in the production of the active - substance pellets . 100 g of these pellets are coated as in example 1 using a total of 5 g ethyl cellulose ( inside 1 . 25 g , outside 3 . 75 g ) and 2 . 5 g sodium aluminum silicate as filler . the methionine content is 84 . 2 % and the undissolved portion of the methionine 80 %/ 69 %/ 29 %. the same method is used as in example 1 , but 360 g starch and 40 g sodium stearate are used instead of the sodium salt of carboxymethylcellulose in the production of the active - substance pellet . 100 g of these pellets are coated using a total of 3 . 5 g ethyl cellulose ( inside 1 g , outside 2 . 5 g ) and 2 g sodium aluminum silicate as filler . the methionine content is 85 . 5 % and the undissolved portion of the methionine 66 %/ 54 %/ 8 %. 100 g of the pellets produced according to example 12 are coated using a total of 4 g ethyl cellulose ( inside 1 g , outside 3 g ) and 2 g sodium stearate as filler . the methionine content is 84 . 8 % and the undissolved portion of the methionine 73 %/ 63 %/ 19 %. 100 g of the pellets produced according to example 1 are coated in only one layer with a solution of 7 . 5 g ethyl cellulose in 200 ml ethanol without using a filler . the methionine content is 83 . 4 % and the particular undissolved portion of methionine 88 %/ 81 %/ 54 %. this reference test shows that , given a relatively thick and elastic coating of the active - substance core in one layer , the greatest part of the methionine remains undissolved even after a total of 24 hours . 100 g of the pellets produced according to example 1 are coated in only 1 layer with a solution of 5 g ethyl cellulose in 400 ml ethanol in which 2 . 5 g sodium aluminum silicate are suspended . the methionine content is 83 . 1 % and the particular undissolved portion of the methionine 36 %/ 19 %/ 0 %. this test shows in comparison to example 3 that the coating with the same amount of ethyl cellulose and sodium aluminum silicate but in only one layer protects the methionine only to an insufficient extent from dissolution already under the conditions in the rumen . on the other hand , this coating is suitable for non - ruminants since only 81 % of the active substance has been released after 8 hours . the slow - release effect obtained brings about a uniform supplying of the organism with the active substance in 2 doses / day . the following investigations using animal tests demonstrate the superior action of the product of the invention . the rise of the methionine content in the blood plasma of milk cows was examined . since all nutrients contained in milk and their precursors are supplied to the mammary gland with the blood stream , the methionine from a protected product must arrive there in the blood . the extent of the rise of methionine in the blood plasma upon administration of defined amounts of protected methionine is tested in preliminary examinations in which methionine preparations are introduced directly into the abomasum after 6 hours pre - incubation in the rumen ( simulation of the natural dwell time ). the product to be tested was sewn in portions of 25 g into nylon bags ( 30 μm pore size ) and pre - incubated for 6 hours in the rumen of the test cows ( 3 animals ) ( max . 6 - 8 bags per animal ). after having been removed , the bags were cleaned of fodder particles but not washed . the contents of all bags were pooled and weighed to determine the substance loss . the methionine content was determined in a specimen of the pre - incubated , pooled material , from which the methionine amount which disappeared during the 6 hours can be calculated at 17 % by weight and the amount of rumenstable methionine at 83 % by weight . a known product which was also tested ( reference example 17 ) was 100 % stable in the rumen . the pre - incubated material was then weighed into gelatin capsules which dissolve within a few minutes in the abomasum . the administration took place four times daily in the 3 animals through the rumen fistula directly into the abomasum . 25 g methionine per day was administered in this manner over a period of four days ( day 1 - 4 ). day 0 served for obtaining the control parameters . on days 0 , 3 and 4 blood samples were taken from the animals by means of puncturing the vena jugularis at 1 p . m . and 4 p . m . the content of free methionine in the rumen was determined in these samples . there was a rise of the plasma methionine level of approximately 100 % in the middle of days 3 and 4 in comparison to day 0 . in the test , the animals received ( 4 per product ) 30 . 6 g dl - methionine in the form of pellets produced according to example 12 which were coated using a total of 4 % by weight ethyl cellulose relative to the weight of the active - substance core ( inside 0 . 5 %, outside 3 . 5 %) and using 2 % by weight sodium aluminum silicate as filler ( example 16 ) and received 25 g in the form of active - substance granulates which contain 50 % by weight dl - methionine and obtain their protection from a coating with monocarboxylic acids with 14 - 22 atoms ( reference example 17 ). the animals received the above in a complete ration which consisted of 10 % hay , 30 % grass silage , 20 % corn silage ( together 15 kg dry mass / day ) and 40 % of a grain / coarse soya bean meal feed concentrate ( 6 kg dry mass / day ). such products are known from european patent ep 0 037 478 and german de patent 22 12 568 and are commercially obtainable . the amounts were calculated in such a manner that , based on the rumen stability of the products measured in the preliminary test , approximately 25 g dl - met should pass into the small intestine ( 83 % stability for example 16 and 100 % for reference 17 ). the preparations were administered for 12 days ( day 1 - 12 ). on days 0 , 10 , 12 and 14 , blood samples were taken ( vena jugularis , 11 . 50 a . m . and 2 . 50 p . m .). the table shows the results of the measurements . the methionine content rises in the blood plasma in both instances . the rise in example 16 with 188 % on day 10 is distinctly higher in comparison to reference 17 with 28 %. on day 12 , the last day of the oral administration , the corresponding values are + 151 % and + 5 %. two days after discontinuation , the methionine content in the blood plasma has fallen back again to the starting level and in the reference treatment it is even 10 % below the starting value . the differences in the methionine content in the manure correspond to these findings . whereas in the middle of days 10 and 12 0 . 074 % methionine was found in the manure of the four cows in example 16 , 0 . 246 % was found in reference 17 . __________________________________________________________________________the influence of protected methionine products on the plasma methioninelevel of cows after afeeding with feed concentrate ( kf ) ( average of 4 cows and 2 times ofday ) daily met ( g ) in the blood met level ( μmole / l ) rise of the blooddaily met small intestine control no met met - leveladministration ( calculated from two values each ( rel . increase in %) via the kf ( g ) preliminary test ) day 0 day 10 day 12 day 14 day 10 day day__________________________________________________________________________ 1430 . 6 25 . 4 8 . 3 ± 4 . 0 23 . 8 ± 8 . 8 20 . 8 ± 6 . 0 8 . 4 ± 5 . 8 188 151 125 . 0 25 . 0 13 . 4 ± 4 . 2 17 . 2 ± 4 . 8 14 . 1 ± 5 . 9 12 . 1 ± 4 . 5 28 5 - 10__________________________________________________________________________
a dosage form for administering physiologically active substances to animals , especially ruminant animals . the dosage unit includes a core which contains the active substance and a coating . the coating has selected areas which are thinner than the average thickness of the coating and / or areas which are predetermined rupture sites . these thin areas or predetermined rupture sites are constructed and arranged so as to detach and / or rupture under the conditions which are present after oral administration of the dosage form . as a result , the delayed release of the physiologically - active substance is accelerated . for example , the coating may be formulated to not be affected in the first stomach of a ruminant but to rapidly disintegrate in the animal &# 39 ; s second stomach .