In explanation of this, it appears from Rashi that in contrast with the harvest of produce, someone who tithes his animal fulfills a biblical commandment, but if he neglects to do so he has merely missed his opportunity to fulfill the mitzvah, but he can still derive benefit from the animals. The Sages established these times of year in order to force the farmers to tithe the animals – something the Torah did not actually require. The Rambam disagrees, arguing that there is a biblical obligation to tithe animals and that the Sages simply established the appropriate times to do so.
When is the season for tithing animals?
The Mishnah on today’s daf (=page) teaches that there are three geranot (literally “threshing floors”) for tithing animals. Although the Sages differ with regard to the exact dates, one is just before Passover, one before Shavuot and one around the time of Rosh HaShanah. The Gemara explains these dates as relating to the times that cattle usually give birth. Some give birth at the beginning of the winter, some in the spring and some in the summer.
The term geranot (“threshing floors”) used in the Mishnah is borrowed from ordinary tithes, since crops of grains and fruits only become obligated in tithing from the time that they are harvested and brought to the granary to be processed. At that time the harvest of a given year is viewed as completed and the produce cannot be eaten until it has had terumah and tithes taken and set aside for the kohanim, levi’im and so forth. In a parallel manner, there are set periods during the year that the newborn animals are viewed as a group ready for processing, and tithes must be taken.
The Mishnah concludes that in truth, all of the animals born in a given year will be considered a single group for the purpose of tithing. The three periods established by the Sages serve to clarify that until the arrival of the tithing period it is permitted to sell or slaughter the animals even without tithing them. Once the tithing period has arrived, however, he must not slaughter them without tithing them first. Nevertheless, if he did slaughter them he is not culpable.