Abstract: Methods of controlling Mycoplasma infections which comprise administering to an infected or susceptible warm-blooded animal an effective amount of a new macrocin or lactenocin ester derivative of the formula: ##STR1## wherein R is formyl or hydroxymethyl; R.sup.1 is hydrogen, acetyl or propionyl; R.sup.2 is hydrogen or ##STR2## and R.sup.3 is hydrogen, acetyl, propionyl, n-butyryl or isovaleryl; provided that one of R.sup.1 or R.sup.3 must be other than hydrogen; or a pharmaceutically acceptable acid addition salts thereof.

Abstract: Antibiotic A53868 factor A, which is N.sup.2 -glycyl-N-(2-methylene-2-phosphonoethyl)leucinamide, and the formula: ##STR1## and the salts thereof, which are useful as antibiotics or as intermediates to antibiotics; methods of preparing A53868 factor A by fermentation of Streptomyces luridus; and the microorganism S. luridus NRRL 15101.

Abstract: Antibiotic A53868 factor A, which is N.sup.2 -glycyl-N-(2-methylene-2-phosphonoethyl)leucinamide, and the formula: ##STR1## and the salts thereof, which are useful as antibiotics or as intermediates to antibiotics; methods of preparing A53868 factor A by fermentation of Streptomyces luridus; and the microorganism S. luridus NRRL 15101.

Abstract: The antibiotic, avilamycin, is useful in the treatment or prevention of swine dysentery.

Abstract: Methods of controlling Pasteurella infections are provided which comprise administering to an infected or susceptible warm-blooded aninal an effective amount of a composition comprising (1) a suitable pharmaceutical vehicle and (2) a compound selected from the group consisting of desmycosin, lactenocin, cirramycin A.sub.1, 23-deoxy-5-0-mycaminosyltylonolide, antibiotic M-4365 G.sub.2, 9-dihydrodesmycosin, 9-dihydrolactenocin, 20-dihydrodesmycosin, 20-dihydrolactenocin, rosaramicin, and the pharmaceutically acceptable acid addition salts of these compounds.

Abstract: Method of controlling Ureaplasma infections which comprises administering to an infected or susceptible warm-blooded animal an effective amount of 5-0-mycaminosyl tylonolide or a pharmaceutically acceptable acid addition salt thereof.

Abstract: Method of controlling Pasteurella infections which comprises administering to an infected or susceptible warm-blooded animal an effective amount of 5-O-mycaminosyl tylonolide or a pharmaceutically acceptable acid addition salt thereof.

Abstract: Controlled release formulations useful in the prolonged treatment and control of microbial infections in animals are comprised of a microbial agent intimately dispersed throughout a copolymer derived from lactic acid and glycolic acid. A method for providing protection to animals for extended periods of time following a single administration is provided.

Abstract: Antibiotic compositions comprising tylosin and apramycin are effective in the treatment and control of colibacillosis in weanling pigs, and demonstrate greater effectiveness than apramycin alone or tylosin alone.