Jaiminīya Upaniṣad Brāhmaṇa 3.34.5

3.34.5

yādṛśasyo ha vai reto bhavati tādṛśaṃ sambhavati yadi vai puruṣasya puruṣa eva yadi gor gaur eva yady aśvasyāśva eva yadi mṛgasya mṛga eva
yasyaiva reto bhavati tad eva sambhavati /

Whatever [creature's] semen it is, of such a kind does [the offspring] come into being: if indeed of a human, a human; if of a cow, a cow; if of a horse, a horse; if of a wild beast, a wild beast. Whosever semen it is, that very one comes into being.