2309.90.42 - Described in general note 15 of the tariff schedule and entered pursuant to its provisions

This HTS category encompasses preparations used in animal feeding that contain milk or milk derivatives, and which are not specifically covered by other subdivisions within 2309.90.4. The defining characteristic is the presence of milk or its derivatives as a significant component, contributing to the nutritional profile of the animal feed. These preparations are typically formulated to provide essential nutrients for livestock, poultry, aquaculture, or other animals, often catering to specific life stages or dietary needs.

This classification is distinguished from its siblings, 2309.90.44 and 2309.90.48, by its specific inclusion of milk or milk derivatives and the absence of the specific conditions met by those other categories. While 2309.90.44 pertains to feeds described in additional U.S. note 2 to chapter 23, and 2309.90.48 covers all other "other" categories not elsewhere specified, this node precisely targets milk-based animal feed preparations not falling into those defined exceptions.

Within this category, further subdivisions exist to refine the classification of milk-derivative animal feeds. The subcategory 2309.90.42.10 is dedicated to "Milk replacer," which are specifically formulated to substitute for whole milk in the diet of young animals. All other remaining milk-derivative animal feeds not fitting the description of milk replacer are classified under the residual subcategory 2309.90.42.90, "Other," ensuring comprehensive coverage of this product type.