When a person purchases lambs that were born this year or they were given to him as a present, he is not obligated to tithe them. The obligation applies only when the animals are born in his domain. Accordingly, if partners enter into a partnership with regard to animals: one brings 100 and the other brings 100 and they have them intermingle and own them jointly, these 200 are exempt from the requirement to tithe. The rationale is that each of the lambs is considered as having been sold. Similarly, if brothers inherit lambs in their first year of life from their father, they are exempt from the requirement to tithe.
The offspring born to the partners or the brothers after the partnership was established, by contrast, from their jointly owned animals are obligated to be tithed. Similarly, if a partnership was established with money or brothers purchased animals from the funds of the estate, the offspring born afterwards are obligated to be tithed, for they were born in their domain and they are considered as one person.
If the brothers and the partners divided their property after animals were born to them in their joint domain and then reestablished their partnership, the animals born previously are exempt from the requirement to tithe. The rationale is that when the assets of the partnership or the estate were divided, everything is considered as having been sold and animals that are sold are exempt. And when the partnership was reestablished, no new offspring was born to them afterwards. Even though they divided kids for kids and lambs for lambs, and even if they divided them by tens, they are all exempt from the tithes and considered as having been purchased.