This International Standard specifies a method for the determination of the fat content of animal feeding stuffs. The method is applicable to animal feeding stuffs except oilseeds and oilseed residues. For the purposes of this method, the following two categories of animal feeding stuffs are distinguished. Samples of products in category В need a hydrolysis step prior to extraction. Category B: — straight feeds of animal origin including milk products; — straight feeds of vegetable origin from which fats cannot be extracted without prior hydrolysis; in particular: gluten, yeast, soya and potato proteins, and heat-treated feeds; — compound feeds containing the preceding products in such quantities that at least 20 % of the fat content stems from these products. Category A: — animal feeding stuffs not mentioned under category B. NOTE For oilseed residues, a method for the determination of the "oil content" by hexane extraction is specified in ISO 734-1 [2], whereas a method for the determination of the "oil content" by diethyl ether extraction is specified in ISO 736 [3]. For oilseeds, a method for the determination of the "oil content" by hexane extraction is specified in ISO 659 [1].