Explanation #1: Rashi explains that the Halachah is not like this Beraisa, because above the Tana forbade the excrement of dogs and Chazeirim, even when they do they do not contain skins; This does not however, apply to human excrement, which is Asur under all circumstances.

Explanation #1(cont.): This implies that Rava is not speaking about the excrement of chickens ...

Explanation #1(cont.): Also in the other Beraisa, the text does not mention chickens' excrement at all, and the Tana does not argue with the earlier Beraisa.

Conclusion: According to all this, we will have to declare chickens' excrement forbidden.

Qualification: Rabeinu Yehudah explains however, that this speaks specifically in their chicken-run, where there is a strong smell. But where they strut around the house, there is no reason to forbid it.

Explanation #2: The Yerushalmi states that one only need be stringent with regard to Edume'an chickens. Tosfos however, does knot know the reason for this (See Mesores ha'Shas).

Explanation #2 (cont.): Furthermore, the Yerushalmi states that one keep a four Amah distance from the excrement of animals. Rebbi Shmuel b'Rebbi. Yitzchak confines this to a donkey.

Halachah: Some commentaries explain that our bathrooms which are deep, as long as there is a Mechitzah in front of it, it has the Din of a foul smell that is not accompanied by something real.

Precedent: Like the Gemara will say later (on Daf 26.) in connection with Persian bathrooms.

Inference: The Ri explains that since the Gemara asks this question without reservations, it implies that 'Libo Ro'eh es ha'Ervah is Asur'.

Conflicting Opinion: Only Rashi's Talmid, Rabeinu Yeshayah rules like the Tana Kama, who holds that 'Libo Ro'eh es ha'Ervah is permitted'.

Proof for First Opinion: The Gemara shortly however, seems to hold that it is Asur, since the Amora'im argue over where 'the heel sees the Ervah', implying that they agree that 'Libo Ro'eh es ha'Ervah is Asur'.

Reason: The reason for this is that we decree his heel touching, in case his hands come to touch.

Clarification: Rashi explains 'of earthenware that absorbs.

Clarification (cont.): This implies that a vessel that does not absorb, such as one made of glass, is perhaps permitted, provided one adds a Revi'is of water ...

Conclusion: But a potty made of earthenware, it may well be that adding water will not help.