The livestock auction operations referred to in section 13(b)(13) are those engaged in by the farmer “as an adjunct” to the raising of livestock. This phrase limits the relative extent to which the farmer may conduct livestock auctions and claim exemption under section 13(b)(13). To qualify under the exemption provision, the auction operations should be an established part of the farmer’s raising of the livestock and subordinate to it. (Hearnsberger v. Gillespie, 435 F. 2d 926 (C.A. 8).) The auction operations should not be conducted on so large a scale as to predominate over the raising of livestock. The livestock auction should be adjunct to the farmer’s raising of livestock not only when he engages in it on his own account, but also when he joins with other farmers to hold an auction.