Yog, peb tsiaj txhu cim crayon tuaj yeem siv los ua tail-chalking ntawm nyuj kom pom qhov kub tiag tiag (estrus). tail-chaling lub crayon ntawm nyuj txhua txhua hnub, tsis txhob hnov ​​qab tso ib tug du tiav rau ntawm daim tawv nqaij, thaum tus nyuj nyob rau hauv tshav kub (ostrus), cov xim cim rau tus Tsov tus tw ntawm nyuj ua wrinkles, ces peb paub qhov twg. nyuj yog nyob rau hauv tiag tiag tshav kub thiab nqa tawm qhov tseeb thiab sij hawm insemination.

Qhov no tsiaj txhu cim crayons yog tshwj xeeb tsim los rau yooj yim tail-chalking ntawm nyuj nyob rau hauv ib tug dav kub ntau yam, qhov no tsiaj marker crayon yog tag nrho cov huab cua tsis kam thiab tuaj yeem raug cim rau ntawm cov nyuj qhuav lossis ntub dej.