Furqon, Ahmad, Irida Novianti, Wike Andre Septian, Rafika Febriani Putri, Chairdin Dwi Nugraha, and Suyadi Suyadi. 2021. “The Effect of Different Breeds and Ages on Semen Production at Singosari National Insemination Center”. TERNAK TROPIKA Journal of Tropical Animal Production 22 (2):147-52. https://ternaktropika.ub.ac.id/index.php/tropika/article/view/512.