010-1 Wyo. Code R. § 1-2
All cattle qualifying for Wyoming Lean Beef shall meet the following standards:
(a) They shall graze the summer before slaughter in Wyoming. Cattle in pastures where they have free access to land within Wyoming shall be deemed to be living within Wyoming even though part of the pasture is outside Wyoming. Cattle owned by a bona fide Wyoming resident but historically grazed outside the State on a Wyoming brand permit shall be eligible for the program.
(b) They shall be primarily grass fed cattle. For purposes of these regulations, legumes, forbs and other plant materials consumed under range or pasture conditions shall be considered as "grass".
(c) They shall not be held in close confinement except for short periods in connection with operations necessary in the management of the cattle, including but not limited to calving, branding, vaccinating, weaning, transportation and slaughter. Confinement shall be considered as that consistent with good management including the feeding of concentrates.
(d) They shall have a hot carcass weight of at least four hundred (400) pounds.
(e) They shall have an untrimmed fat depth over the ribeye muscle at the twelfth (12th) rib of less than or equal to three tenths (0.3) of one inch.
(f) Carcasses shall be electrically stimulated within one (1) hour after stunning.
(g) They shall not exceed thirty-two (32) months of age at the time of slaughter.
(h) They shall not have been given any steroids (synthetic or natural) or any other growth promoting hormone. This regulation shall not be construed to prohibit the use of parasiticides.
(i) They shall not have been given any subtherapeutic levels of antibiotics. This standard shall not be construed as prohibiting the use of therapeutic levels of any antibiotic for therapeutic purposes. The practice of feeding antibiotics to calves for up to 10 days at weaning or during periods of stress for the control of shipping fever and other diseases shall be deemed a therapeutic practice. There shall be strict compliance with approved withdrawal periods for all antibiotics.
j) Ground beef shall meet all standards as established in above paragraphs (a),(b),(c),(h) and (i) and in addition shall have a fat content less than or equal to twenty (20%) percent, carcasses from animals that exceed 32 months of age can be used for ground beef but shall hot under any circumstances be marketed as wholesale or retail cuts.
010-1 Wyo. Code R. § 1-2