Temura 19. My answer to the difficulty in the Rambam. I can not tell if this is what Rav Shach intended in order to answer the question or Rav Isaac Zev of Brisk. But at any rate, this is the answer that occurred to me as I was going to and back from the sea.

Introduction. A Sheep is pregnant. Is the baby sheep part of the mother? 

This issue comes up in the Gemara Temura 19. There we have a case someone dedicated a female sheep to be a guilt offering -which it can not be. While a sin offering is female, a guilt offering is male.(Leviticus 5). But let's say the sheep was not pregnant at the time it was dedicated and then became pregnant. Then she and her offspring are sent to pasture until the get some defect and then sold and with the money the owner buys a male sheep to be used for his guilt offering. But let's say the sheep was pregnant at the time. Then if she gives birth to a male sheep that can be used for a guilt offering in the view of R Elazar. The sages however disagree and say the law is the same as above. They are sent to pasture and sold. Ravina says the reason for R Elazar is the infant sheep is not considered part of the mother. So the dedication applies to the infant. But the Rambam holds the law is like the sages that the sheep and her male offspring are sent to pasture and also that the offspring is not part of the mother.

 I am freezing cold from the sea. But I was thinking about the subject in Temura 19 on the way back.  So I thought I should write down this thought while it is fresh in my mind..The issue is how can the unborn sheep of a female pesach/passover sacrifice have to be redeemed instead of being brought as a peace offering.

You can ask why should this be a problem? Answer: we hold that the unborn is not part of the mother. So when he declares the mother to be a pesach [passover sacrifice] [even though a female can not be a pesach], that holiness ought to settle on the unborn infant sheep.

Answer to the  above problem. Something can have קדושת הגוף [holiness of the body] and still not be fit for the altar. So the infant has קדושת הגוף [holiness of the body] but still can not be brought as a sacrifice and so must be redeemed.

How do you see this principle? From R. Akiva and R.Yochanan that an animal with a defect --if brought up on the altar by accident, does not come down. But if the defect came before the consecration, it comes down. This applies to a female burnt offering also --even though she has holiness of body, still she comes down.. Thus: something can have קדושת הגוף [holiness of the body] and still not be fit for the altar.

The difficult part of this is the infant sheep has no defect. So even though the mother can not be brought as a sacrifice, the infant should be. 

I want to mention that even though we hold the unborn is not part of the mother, that is not totally so. For if it would be the case that the declaration on the mother would have nothing to do with the baby sheep, then it would be "hulin"[not sacred at all.] [So instead we say it has enough connection to the mother in so far as if he says this animal is a passover sacrifice, that holiness settles on the unborn baby sheep as well.]]

The faulty consecration of the mother can not be thought to be irrelevant to the infant sheep since if so the infant would be secular. So in that sense the infant is like an animal that and a defect and then was consecrated. (I mean that there is a defect in the very act of consecration.) So even though it has holiness of body it is not brought as a sacrifice.

Background information: A Passover offering can only be a male. So let's say one consecrates a female for a Passover offering and she gives birth to a male. 

This is one of those issues  where the Rambam seems to contradict the Gemara directly. Yet there are ways of answering for him.

The issue is this. The Rambam decided the law that if the mother sheep was pregnant or not, the sheep that was born is sold.[The money is then used to bring a peace offering].  This is not like R. Elazar who said in the case she was pregnant (at the time of consecration), the born sheep can be brought as a Passover offering. Ravina [in Temura page 19 side a] says the reason for R Elazar is the sheep that has not been born yet is thought to be separate from the mother. So it certainly looks that the reason the sages said the born sheep can not be brought is that they hold the sheep in the womb of the mother is considered as part of the mother.

Yet the Rambam decided like the sages in Temura pg 19, but also that the unborn sheep is separate from the mother.

This looks to be a contradiction. Rav Isaac Zev [son of Rav Chaim of Brisk] says to answer the Rambam we can say the sages agree that the unborn sheep is not part of the mother, [in spite of the clear implication of the Gemara]. But that just like when the mother was not pregnant yet and then became as such then the unborn is dragged along with her category--to be sold and the money used to buy a peace offering. So they say the same thing even when she was already pregnant.

Rav Shach asks the question that this clearly not like the opinion that the unborn is not part of the mother. He attempts to find a different answer for the Rambam. --that  the fact that the mother sheep could only be sanctified as far as monetary values goes, that is what causes the unborn sheep also to be dragged along with that.