the present invention is based upon the discovery that although the above - described active ingredients have been utilized for promoting the growth rate of poultry and farm animals , the effect of said compounds in favorably altering the acetate : propionate ratio during the microbiological processes taking place in the rumen have been hitherto unknown and not predictable from knowledge of the prior use and activity of said compounds . the novel method of the present invention comprises orally administering to ruminants such as cattle , sheep and goats antibiotic av290 or the above - identified salts , complexes , and derivatives thereof in amounts sufficient to promote the formation of propionates while suppressing the formation of acetates . advantageously , we have found that by orally administering to said ruminants antibiotic av290 or the above - identified salts , complexes , or derivatives thereof ( and / or mixtures thereof ) in amounts of from about 10 mg . to about one gram per head per day from about 0 . 05 mg . to about 50 . 0 mg ./ kg . of body weight per day , the acetate : propionate ratio is altered in favor of the propionates in the course of the microbiological digestive processes taking place in the rumen of said animals . thus , by promoting the formation of propionates and suppressing the formation of acetates , the incidence of ketosis among said ruminants is minimized . the active compounds of this invention , antibiotic av290 and the salts , complexes , and derivatives thereof , can be conveniently administered to cattle , sheep and goats as feed additives in amounts ranging from about 8 grams to about one kilogram per ton of feed to provide 10 mg . to one gram per head per day or 0 . 05 mg . to 50 . 0 mg ./ kg . of body weight per day of said compound . should it be desired , antibiotic av290 and its pharmaceutically acceptable salts , complexes , and derivatives may also be formulated for oral administration as feed premixes , concentrates , tablets , pills and boluses , which may be prepared by accepted and well known methods , using pharmaceutically acceptable carriers , diluents , binding and lubricating agents . the present invention is further illustrated by the non - limiting examples set forth below : evaluation of the in vitro efficacy of the antibiotic av290 for altering the acetic acid : propionic acid ration during fermentation in rumen fluid the steers used in the experiment have surgically installed fistulas that open into the rumen . the steers are offered water and a daily ration of alfalfa hay ad libitum as well as 10 lbs . of a standard 15 % protein grain ration of the following composition : ______________________________________component percent by weight______________________________________corn 32 . 7barley 10 . 0oats 7 . 5molasses 10 . 0soybean oil meal ( 48 % protein ) 13 . 8beet pulp 2 . 5corn gluten feed 12 . 5distillers grain 7 . 5trace mineral mix 0 . 05salt 1 . 0dicalcium phosphate 2 . 0______________________________________ a sample of rumen fluid ( 500 ml .) is aspirated into a flask and strained through four layers of cheesecloth to remove coarse feed particles . ten ml . of the clarified centrifuged at 2 , 000 × g for 15 minutes and the clear supernatant removed for analysis by gas chromatography to determine concentrations of acetic and propionic acid , and butyric acid in the samples . the data obtained are summarized in table i and show the molar percent of each volatile fatty acid ( vfa ) produced during fermentation in the presence of antibiotic av290 as well as the ratio , acetic to propionic acid ; while in table ii the same data are expressed as percent change from the control . table i______________________________________ level of ratiotreat - drug in sub - molar percent of vfa acetic / ment strate ; ppm acetic propionic butyric propionic______________________________________control 0 58 . 9 24 . 4 16 . 7 2 . 41 5 , 000 53 . 9 29 . 8 16 . 3 1 . 81av 290 1 , 000 55 . 2 33 . 2 11 . 5 1 . 66sulfate 200 56 . 4 29 . 4 14 . 2 1 . 92 100 56 . 0 30 . 6 13 . 4 1 . 83 40 56 . 6 25 . 3 18 . 1 2 . 24av 290 5 , 000 55 . 2 31 . 4 13 . 4 1 . 76lauryl 1 , 000 55 . 3 31 . 1 13 . 6 1 . 78sulfate 200 56 . 8 30 . 3 13 . 8 1 . 87 40 57 . 1 24 . 8 18 . 1 2 . 30______________________________________ table ii__________________________________________________________________________percent change from control percent change fromlevel of drug in percent change from control control : ratiotreatment substrate ; ppm acetic propionic butyric acetic / propionic__________________________________________________________________________ 5 , 000 - 8 . 5 + 22 . 1 - 2 . 4 - 24 . 9av 290 1 , 000 - 6 . 3 + 36 . 1 - 31 . 1 - 31 . 1sulfate 200 - 4 . 2 + 20 . 5 - 15 . 0 - 20 . 3 40 - 3 . 9 + 3 . 6 + 8 . 4 - 7 . 1av 290 5 , 000 - 6 . 3 + 28 . 7 - 19 . 8 - 27 . 0lauryl 1 , 000 - 6 . 1 + 27 . 5 - 18 . 6 - 26 . 1sulfate 200 - 3 . 6 + 24 . 2 - 22 . 2 - 22 . 4 40 - 3 . 1 + 1 . 6 + 8 . 4 - 4 . 6__________________________________________________________________________ the above data clearly show that antibiotic av290 preparations are effective in increasing the propionic acid production while simultaneously suppressing acetic acid production during fermentation in rumen fluid . evaluation of the in vivo efficacy of antibiotic av290 for altering the acetic acid : propionic acid ratio during fermentation in the rumen of sheep twenty - four whether lambs , weighing approximately 40 kg . each , are randomly allotted to four groups of 6 lambs each . one group serves as unmedicated control and receives water and the following diet ad libitum : ______________________________________component percent by weight______________________________________ground corn cob 35 . 0dehydrated alfalfa meal 20 . 0ground corn 19 . 4cane molasses 12 . 0soybean oil meal ( 48 % protein ) 12 . 0dicalcium phosphate 1 . 0iodized salt 0 . 5trace mineral mix 0 . 1vitamin a and d . sub . 3 premix 0 . 02corn oil 0 . 01______________________________________ the other three groups receive water and the same diet ad libitum , except that 20 , 50 or 100 ppm . of av290 lauryl sulfate is incorporated into the diet of the respective groups . after 19 days on the diet , the sheep are sacrificed and samples of rumen fluid are obtained and analyzed as in example 1 . the data obtained are summarized in table iii and show the molar percent of each volatile fatty acid ( vfa ) produced in the presence of av290 as well as the ratio of acetic to propionic acid ; while in table iv the same data are expressed as percent change from the control . table iii______________________________________ level ratio oftreat - of drug vfa molar percent acetic / ment in feed ; ppm acetic propionic butyric propionic______________________________________control 0 69 . 1 15 . 7 15 . 2 4 . 40av 290 20 64 . 8 22 . 7 12 . 5 2 . 85lauryl 50 62 . 7 26 . 9 10 . 4 2 . 33sulfate 100 58 . 1 32 . 0 9 . 9 1 . 82______________________________________ table iv______________________________________ level ratiotreat - of drug percent change from control acetic / ment in feed ; ppm acetic propionic butyric propionic______________________________________av 290 20 - 6 . 2 + 44 . 2 - 17 . 8 - 35 . 2lauryl 50 - 9 . 3 + 71 . 3 - 31 . 6 - 47 . 0sulfate 100 - 15 . 9 + 103 . 8 - 34 . 9 - 58 . 6______________________________________ the above data , especially those found in table iv , clearly show that av290 lauryl sulfate is very effective in increasing the propionic acid production while suppressing the acetic acid production in vivo , when orally administered to sheep . evaluation of the efficacy of av290 for altering the acetic acid : propionic acid ratio during fermentation in the rumen of cattle eighteen feedlot cattle , weighing approximately b 350 kg . each , are randomly allotted to three groups of 6 animals each . water and the ration described in example 2 are offered to the animals ad libitum . one group serves as unmedicated control , while groups two and three each receive in their daily diet 33 ppm . or 99 ppm . of av290 lauryl sulfate , respectively . the feeding trial is conducted for a period of 56 days , with rumen fluid samples being obtained from the animals on days 14 , 28 and 56 after the beginning of the trial . the rumen fluid samples are handled and analyzed for volatile fatty acids ( vfa ) by the method of example 1 . the thus obtained data are summarized in table v , while in table vi the same data are expressed as percent change from the controls . table v__________________________________________________________________________ ratio oflevel of drug date / days vfa molar percent acetic / treatment in feed ; ppm from start acetic propionic butyric propionic__________________________________________________________________________ 14 69 . 2 17 . 4 13 . 4 3 . 98control 0 28 69 . 6 18 . 6 11 . 8 3 . 74 56 65 . 8 19 . 4 14 . 8 3 . 39 14 65 . 7 22 . 0 12 . 3 2 . 98 33 28 64 . 8 22 . 5 12 . 7 2 . 88av 290 56 61 . 5 23 . 2 15 . 2 2 . 65lauryl 14 61 . 9 28 . 2 9 . 9 2 . 20sulfate 99 28 60 . 1 28 . 9 11 . 1 2 . 08 56 58 . 8 28 . 3 12 . 9 2 . 08__________________________________________________________________________ table vi__________________________________________________________________________ ratio : level of drug date / days percent change from controls acetic / treatment in feed ; ppm from start acetic propionic butyric propionic__________________________________________________________________________ 14 - 5 . 1 + 26 . 4 - 8 . 2 - 24 . 9av 290 33 28 - 6 . 9 + 21 . 0 + 7 . 6 - 23 . 0lauryl 56 - 4 . 3 + 19 . 6 + 2 . 7 - 21 . 8sulfate 14 - 10 . 5 + 62 . 1 + 26 . 1 - 44 . 7 99 28 - 13 . 5 + 55 . 4 + 5 . 9 - 44 . 4 56 - 10 . 6 + 45 . 9 + 12 . 8 - 38 . 6__________________________________________________________________________ it can be clearly seen from table v and especially from table vi that the oral administration of av290 lauryl sulfate to cattle via their diet very effectively alters the vfa production during fermentation in the rumen of said animals in favor of propionic acid .
this invention relates to a method for improving the production of propionic acid and thus increasing the propionate : acetate ratio in the course of the microbiological conversion of cellulose and starch containing feedstuffs to short chain volatile fatty acids in the ruminant animal . this invention further relates to the use of antibiotic av290 , antibiotic av290 sulfate , an antibiotic av290 - syntan complex , an antibiotic av290 - alkyl sulfate complex , and / or an antibiotic av290 alkylated derivative for increasing the production of propionic acid and suppressing the production of acetic acid during the microbiological digestive processes taking place in the animal rumen and treating ketosis .