1. Ravina: we do not follow רובא דתלי במעשה

On the previous Daf, Rebbe Yishmael ruled that if a purchased goat is over a year old, its next offspring is a ספק בכור, because we do not know whether it previously gave birth. The Gemara objected that he should follow the majority of goats, which give birth in their first year, making the next offspring a definite non-bechor. Ravina answers that Rebbe Yishmael can agree with the Rabbonon, who normally follow the majority: כי אזלי רבנן בתר רובא – when do the Rabbonon follow the majority? ברובא דלא תלי במעשה – Only where the majority does not depend on an action being performed (e.g., the majority of children, who will naturally mature). אבל רובא דתלי במעשה לא – But where the majority depends on an action being performed, they do not follow the majority. Since a goat only gives birth if a male mated with it, an action which may not have occurred, Rebbe Yishmael holds we do not assume it previously gave birth.

1. Machlokes about טינוף exempting from bechor status

A Baraisa expands on the machlokes recorded in our Mishnah. Rebbe Yishmael says that if a purchased goat gives birth within its first year, it is certainly a bechor. Rebbe Yehoshua relates that the Sages said that the sign of (miscarried) offspring in small livestock is טינוף – a soiling discharge, and a miscarriage also exempts future offspring. Rebbe Yehoshua himself says that a goat which soiled at six months old can still give birth within its first year. [Rebbe Akiva’s view is presented below.] The Gemara asks if Rebbe Yishmael holds that טינוף actually does not exempt future offspring. It answers that if טינוף definitely occurred, Rebbe Yishmael may agree that it exempts future offspring; however, Rebbe Yishmael holds אין חוששין לטינוף – we are not concerned that soiling may have occurred, and Rebbe Yehoshua holds that even where no טינוף was seen, we are חושש for it. Alternatively, although Rebbe Yishmael would also be concerned for טינוף, he holds מטנפת אינה חוזרת ויולדת בתוך שנתה – [a goat] which soils cannot again give birth within its first year. Since it gave birth within its first year, טינוף could not have occurred. Rebbe Yehoshua holds that it can give birth within its first year even after טינוף.

1. Machlokes if חלב פוטר

At the end of the Baraisa, Rebbe Akiva says that he disagrees with Rebbe Yehoshua’s criteria. Rather, כל שידוע שביכרה – wherever it is known that [the animal] already gave birth to its firstborn, the Kohen receives nothing of the next offspring. Wherever it is certain that it did not previously give birth, the next offspring belongs to the Kohen. ספק יאכל במומו לבעלים – Where there is an uncertainty, [the next offspring] is eaten in its blemished state by the owner. Rebbe Chanina of Sura explained: חלב פוטר איכא בינייהו – the point of contention between [Rebbe Akiva and Rebbe Yehoshua] is whether milk production exempts future offspring from bechor status. Rebbe Akiva holds חלב פוטר, saying: הלך אחר רוב בהמות – follow the majority of animals, ורוב בהמות אין חולבות אלא אם כן יולדות – and most animals do not produce milk unless they have previously given birth; thus, the next offspring is a definite non-bechor. Rebbe Yehoshusa argues: הא איכא מיעוטא דחולבות אף על פי שאין יולדות – but there is a minority of animals which produce milk even though they have not yet given birth. However, the Gemara ultimately proves that Rebbe Yehoshua is not concerned for the minority and therefore reverses these two opinions.