Synthetic meat

[The Grand Nudger]

1) We wouldn't have to slaughter them at all, let alone look for ways to keep them comfortable and "happy" while doing so, if we could successfully replace their meat with in vitro meat.

2) It sounds to me like you're a fatalist when it suits you. The fact is, this analogy was employed precisely to show you that we have a choice in how we treat the animals. Arguably they have already been dealt a shitty hand. Now, what are we going to do about it, given the opportunity to help them? Pretend we can't so that our businesses remain lucrative?

3) It's very informative. It's the same situation the animals we slaughter are in reality that we would be in my scenario. Except we are talking about a future where we won't be subject to limitations and necessity, in this respect. One where we'll have a viable alternative to getting our meat unethically, as we do at present.

1.) Replacing their meat does not replace the other products, or byproducts such as fertility.
2.)A factual appraisal of the situation at hand is hardly fatalism.  I hope we come up with something better.  In vitro isn't that thing, awesome as it is..for what it is, a meat substitute.
3.)It's not the situation of the animals where it goes off the rails.  We are not alien conquerors come from space who merely choose to kill and eat animals.  We are codependent with our livestock and yes...even their deaths, it's not a simple issue of replacing their meat.  We haven;t felt that way in awhile, sure. We insulated ourselves from that realization with mountains and mountains of crude. In retrospect, this was a mistake.

In answer, I think, to all of the rest of the questions in your post;

Fertility is the stuff we grow food out of, sustainable fertility is the stuff that creates a closed (or semi closed) production system.  To source it, we choose between phosphorous mines and oil wells, or pastures and slaughterhouses.  That's where our food comes from - even the vegetables.  One or the other..mostly a mix. 

Reduced (or criminalized) livestock production means less available fertility, a burden that will have to be accepted and carried the only other source, oil.  I take it as a given, as a person interested in animal rights, economic issues, health,  and sustainability, you will not be satisfied with a meat substitute that simply moves the killing from the slaughterhouse and hides it out of view elsewhere.  

The systemic failures of our current food policies and production models are simply inherited by in vitro meat. What's needed, if we hope to feed ourselves for any length of time on this rock and do the least harm to our fellow animals (humans included).... is affordable food, healthier fields, environmental remediation, and better integration of production models which will..by necessity include livestock operations.  Not tube grown luxury items that make for a guilt free t-bone.