Chlortetracycline: A TETRACYCLINE with a 7-chloro substitution.Oxytetracycline: A TETRACYCLINE analog isolated from the actinomycete STREPTOMYCES rimosus and used in a wide variety of clinical conditions.Demeclocycline: A TETRACYCLINE analog having a 7-chloro and a 6-methyl. Because it is excreted more slowly than TETRACYCLINE, it maintains effective blood levels for longer periods of time.Food Additives: Substances which are of little or no nutritive value, but are used in the processing or storage of foods or animal feed, especially in the developed countries; includes ANTIOXIDANTS; FOOD PRESERVATIVES; FOOD COLORING AGENTS; FLAVORING AGENTS; ANTI-INFECTIVE AGENTS (both plain and LOCAL); VEHICLES; EXCIPIENTS and other similarly used substances. Many of the same substances are PHARMACEUTIC AIDS when added to pharmaceuticals rather than to foods.Sulfamethazine: A sulfanilamide anti-infective agent. It has a spectrum of antimicrobial action similar to other sulfonamides.Sperm Capacitation: The structural and functional changes by which SPERMATOZOA become capable of oocyte FERTILIZATION. It normally requires exposing the sperm to the female genital tract for a period of time to bring about increased SPERM MOTILITY and the ACROSOME REACTION before fertilization in the FALLOPIAN TUBES can take place.Tetracyclines: Closely congeneric derivatives of the polycyclic naphthacenecarboxamide. (Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1117)Streptomyces aureofaciens: An actinomycete from which the antibiotic CHLORTETRACYCLINE is obtained.Tetracycline: A naphthacene antibiotic that inhibits AMINO ACYL TRNA binding during protein synthesis.Acrosome: The cap-like structure covering the anterior portion of SPERM HEAD. Acrosome, derived from LYSOSOMES, is a membrane-bound organelle that contains the required hydrolytic and proteolytic enzymes necessary for sperm penetration of the egg in FERTILIZATION.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Animal Feed: Foodstuff used especially for domestic and laboratory animals, or livestock.Tylosin: Macrolide antibiotic obtained from cultures of Streptomyces fradiae. The drug is effective against many microorganisms in animals but not in humans.Spermatozoa: Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.Carbadox: An antibacterial agent that has been used in veterinary practice for treating swine dysentery and enteritis and for promoting growth. However, its use has been prohibited in the UK following reports of carcinogenicity and mutagenicity. (From Martindale, The Extra Pharmacopoeia, 30th ed, p125)Tetracycline Resistance: Nonsusceptibility of bacteria to the action of TETRACYCLINE which inhibits aminoacyl-tRNA binding to the 30S ribosomal subunit during protein synthesis.Acrosome Reaction: Changes that occur to liberate the enzymes of the ACROSOME of a sperm (SPERMATOZOA). Acrosome reaction allows the sperm to penetrate the ZONA PELLUCIDA and enter the OVUM during FERTILIZATION.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Drug Residues: Drugs and their metabolites which are found in the edible tissues and milk of animals after their medication with specific drugs. This term can also apply to drugs found in adipose tissue of humans after drug treatment.