Bechoros9: 1
מַעְשַׂר בְּהֵמָה נוֹהֵג בָּאָרֶץ וּבְחוּצָה לָאָרֶץ; בִּפְנֵי הַבַּיִת וְשֶׁלֹּא בִפְנֵי הַבַּיִת; בְּחֻלִּין, אֲבָל לֹא בְמֻקְדָּשִׁין. וְנוֹהֵג בְּבָקָר וּבְצֹאן, וְאֵינָן מִתְעַשְּׂרִים מִזֶּה עַל זֶה; בִּכְבָשִׂים וּבְעִזִּים, וּמִתְעַשְּׂרִין מִזֶּה עַל זֶה; בֶּחָדָשׁ וּבַיָּשָׁן, וְאֵינָן מִתְעַשְּׂרִין מִזֶּה עַל זֶה. שֶׁהָיָה בַדִּין: מָה אִם הֶחָדָשׁ וְהַיָּשָׁן, שֶׁאֵינָן כִּלְאַיִם זֶה בָזֶה, אֵין מִתְעַשְּׂרִין מִזֶּה עַל זֶה — הַכְּבָשִׂים וְהָעִזִּים, שֶׁהֵם כִּלְאַיִם זֶה בָזֶה, אֵינוֹ דִין שֶׁלֹּא יִתְעַשְּׂרוּ מִזֶּה עַל זֶה? תַּלְמוּד לוֹמַר: ,,וָצֹאן” — מַשְׁמָע כָּל צֹאן אֶחָד.
The maaser of animals applies within the Land [of Israel] and outside of the Land; when the Temple is in existence and when it is not in existence; [and it is taken] from ordinary animals but not from consecrated ones. It applies to both cattle and flocks, but one may not be taken as maaser for the other; [and] to sheep and goats, which may be taken as maaser for each other; to both new animals and old ones, and one may not be taken as maaser for the other. For it might have been argued [that] if new animals and old animals, which are not kilayim with each other, may yet not serve as maaser for each other —- [then] is it not logical that sheep and goats, which are kilayim with each other, may [surely] not be taken as maaser for each other? Thus, Scripture states (Lev. 27:32): and flocks, implying that all types of flocks are considered [as] one.