All animals must enter the pen to be tithed, except for a hybrid, a tereifah, [an animal] born by Caesarean section, one before its time, and an orphan. Which is an orphan? Any [animal] whose mother died or was slaughtered. Rabbi Yehoshua says: Even if its mother was slaughtered and the hide is intact, [the offspring] is not an orphan.

There are three designated dates for the maaser of animals: fifteen days before Pesach, fifteen days before Shavuos, [and] fifteen days before Succos; these are the words of R’ Akiva. Ben Azzai says: [The three periods are] on the twenty-ninth of Adar, on the first of Sivan, on the twenty-ninth of Av. R’ Eliezer and R’ Shimon say: [The three periods are] the first of Nissan, the first of Sivan, and the twenty-ninth of Elul. Why did they say the twenty-ninth [of Elul], instead of saying the first of Tishrei? Because it is a holiday and it is impossible to separate maaser on a holiday; they therefore advanced it to the twenty-ninth of Elul. R’ Meir says: The first of Elul is the beginning of the year for the maaser of animals. Ben Azzai says: Those born in Elul are tithed by themselves.

All [animals] born from the first of Tishrei until the twenty-ninth of Elul combine [for maaser]. Five [that were born] before Rosh Hashanah and five [that were born] after Rosh Hashanah do not combine; five before the designated day and five after the designated day do combine. If so, with regard to what is it stated [that] there are three designated dates for the maaser of animals? That until the designated day arrives, one may sell or slaughter; [but] once the designated day arrives, he may no longer slaughter; however, if he did slaughter, he is exempt.

How does one separate maaser from them? He gathers them into a pen, and makes a small opening for them, so that two cannot exit at once. He [then] counts with a rod: “One, two, three, four, five, six, seven, eight, nine” —- and the [animal] which exits tenth he marks with a red dye, and pronounces: “This one is maaser.” [If] he did not mark it with red dye, or if he did not count them with a rod, or he counted them when they were crouching or standing, they are [nevertheless] counted for maaser. [If] he owned one hundred and took ten, [or he owned] ten and took one, it is not maaser. R’ Yose the son of R’ Yehudah says: This is maaser. [If] one of the counted jumped back into their midst, they are exempt. [If one of the] animals designated as maaser [jumped] into their midst, they must all be left to pasture until they develop blemishes, and may be eaten in their blemished [state] by their owners.