Trenbolone Acetate: An anabolic steroid used mainly as an anabolic agent in veterinary practice.Anabolic Agents: These compounds stimulate anabolism and inhibit catabolism. They stimulate the development of muscle mass, strength, and power.Drug Implants: Small containers or pellets of a solid drug implanted in the body to achieve sustained release of the drug.Zeranol: A non-steroidal estrogen analog.Estrenes: Unsaturated derivatives of the ESTRANES with methyl groups at carbon-13, with no carbon at carbon-10, and with no more than one carbon at carbon-17. They must contain one or more double bonds.Meat: The edible portions of any animal used for food including domestic mammals (the major ones being cattle, swine, and sheep) along with poultry, fish, shellfish, and game.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Estradiol: The 17-beta-isomer of estradiol, an aromatized C18 steroid with hydroxyl group at 3-beta- and 17-beta-position. Estradiol-17-beta is the most potent form of mammalian estrogenic steroids.Melengestrol Acetate: A 6-methyl PROGESTERONE acetate with reported glucocorticoid activity and effect on ESTRUS.Trimethylsilyl Compounds: Organic silicon derivatives used to characterize hydroxysteroids, nucleosides, and related compounds. Trimethylsilyl esters of amino acids are used in peptide synthesis.Drug Combinations: Single preparations containing two or more active agents, for the purpose of their concurrent administration as a fixed dose mixture.Random Allocation: A process involving chance used in therapeutic trials or other research endeavor for allocating experimental subjects, human or animal, between treatment and control groups, or among treatment groups. It may also apply to experiments on inanimate objects.United States Department of Agriculture: A cabinet department in the Executive Branch of the United States Government concerned with improving and maintaining farm income and developing and expanding markets for agricultural products. Through inspection and grading services it safeguards and insures standards of quality in food supply and production.Weight Gain: Increase in BODY WEIGHT over existing weight.Acetates: Derivatives of ACETIC ACID. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain the carboxymethane structure.Dystocia: Slow or difficult OBSTETRIC LABOR or CHILDBIRTH.Body Composition: The relative amounts of various components in the body, such as percentage of body fat.Phenethylamines: A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed)Muscle Development: Developmental events leading to the formation of adult muscular system, which includes differentiation of the various types of muscle cell precursors, migration of myoblasts, activation of myogenesis and development of muscle anchorage.Animal Feed: Foodstuff used especially for domestic and laboratory animals, or livestock.Testosterone: A potent androgenic steroid and major product secreted by the LEYDIG CELLS of the TESTIS. Its production is stimulated by LUTEINIZING HORMONE from the PITUITARY GLAND. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to DIHYDROTESTOSTERONE or ESTRADIOL.Eating: The consumption of edible substances.Cyproterone Acetate: An agent with anti-androgen and progestational properties. It shows competitive binding with dihydrotestosterone at androgen receptor sites.Adipose Tissue: Specialized connective tissue composed of fat cells (ADIPOCYTES). It is the site of stored FATS, usually in the form of TRIGLYCERIDES. In mammals, there are two types of adipose tissue, the WHITE FAT and the BROWN FAT. Their relative distributions vary in different species with most adipose tissue being white.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Insulin-Like Growth Factor I: A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor.Fetal Stem Cells: Cells derived from a FETUS that retain the ability to divide, proliferate and provide progenitor cells that can differentiate into specialized cells.Body Weight: The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.