(a) Poisonous or deleterious substances include, but are not limited to the following:(1) fluorine and any mineral or mineral mixture which is to be used directly for the feeding of domestic animals and in which the fluorine exceeds 0.20% for breeding and dairy cattle; 0.30% for slaughter cattle; 0.30% for sheep; 0.35% for lambs; 0.45% for swine; and 0.60% for poultry;(2) fluorine-bearing ingredients when used in such amounts that they raise the fluorine content of the total ration (exclusive of roughage) above the following amounts: 0.04% for breeding and dairy cattle; 0.009% for slaughter cattle; 0.006% for sheep; 0.01% for lambs; 0.015% for swine; and 0.03% for poultry;(3) soybean meal, flakes, or pellets or other vegetable meals, flakes, or pellets which have been extracted with trichloroethylene or other chlorinated solvents;(4) sulfur dioxide, sulfurous acid, and salts of sulfurous acid when used in or on feeds or feed ingredients which are considered or reported to be a significant source of vitamin B1 (thiamine);(5) artificial color that has not been cleared for safety for use in feeds. Evidence of safety must include a clearance for use of these color additives under the provisions of the Federal Food, Drug, and Cosmetic Act. No artificial color material shall be used to enhance the natural color of the feed or feed ingredient whereby inferiority would be concealed; and(6) grain, oilseeds, processed grain and oilseed meals containing aflatoxin B1, B2, G1, G2 above 20 parts per billion (ppb) individually or total except that with proper labeling as approved by the Office of the Texas State Chemist as follows: 300 ppb in oilseed, processed grain, and oilseed meal may not enter commerce and a record of disposition shall be submitted to the Office of the Texas State Chemist.(b) All screenings or by-products of grains and seeds containing weed seeds, when used in commercial feed or sold as such to the ultimate consumer, shall be ground fine enough or otherwise treated to destroy viability of such weed seeds so that the finished product contains no viable prohibited noxious weed seeds and not more than 50 viable restricted weed seeds per pound, and not more than 100 of other weed seeds per pound.(c) The Service may require evidence satisfactory to the Service of:(1) the safety of any commercial feed if such feed includes ingredients not approved either by the FDA or AAFCO (the Association of American Feed Control Officials); or(2) the efficacy of any commercial feed when such feeds do not meet minimum standards of nutrition for the targeted animal as set forth by recognized authorities on animal nutrition.