Demand is skyrocketing in China for mice that mimic the diseases of humans

They're bred to be sick and live in a lab, so they and any of their progeny would not be likely to survive very long. They're not zombies, so them biting other animals wouldn't be a huge concern either.

What happens if man made super food like the Broccoli escapes it's man made field? Nothing. It can't compete with plants in the harsh natural competition for the survival of the fittest, because it hasn't been bred for that. It's only been bred to grow and grow, not to a wage war for survival against it's surroundings like all other plants in nature do.

The protections are not to protect us from the mice, it’s to protect the mice from us. The value of the mice is in their purity. Imagine basing a 1bn investment in a new drug based on trials that it turned out were tainted because a mouse caught something from a human handler beforehand. Hence 17k a mouse.

>What would happen if the mice escaped the facility, and bite other animals or humans

Genes don't typically transfer that way. Except for extraordinary circumstances where the disease is caused by some sort of virus, getting bit by someone with hemophilia or cystic fibrosis or down syndrome isn't going to give you the disease.

>or breed with 'normal' mice

It's not impossible for this to happen, but in general these mice have been bred for generations in a lab environment where they are provided with food and water without having to find it on their own. The world is already a harsh place for a normal mouse that is well adapted to it, so if you add in a "soft" mouse with some sort of debilitating genetic disorder, I wouldn't worry too much about it taking over the world.

>Mice are so easy to keep, they could be entitely mechanicly reared, and an experiment involving 1000 mice should be a simple matter of a few clicks on a computer.

I invite you to go visit a laboratory that works with rodent models for a few days and see if you still think this is true. I would love to be proven wrong, but in my experience animal experiments are as non-automatable as human clinical trials. As a simple example, in my PhD I spent months injecting mice with cancer cells, measuring the tumor outgrowth, then harvesting the tumors, grinding them up and sequencing them. You can see the schematics of some of those experiments in one of my manuscripts (https://elifesciences.org/articles/41090 -- free to access). Each one of those experiments relied on dozens of different techniques (from cloning to making viruses to culturing cells to animal husbandry), most of which are not easy to automate because they vary from experiment to experiment. For instance, just to grow the cells for injection into animals, you need to monitor plates of cells growing in a sealed 37º incubator, wash and re-feed them as necessary over a period of days to weeks. Then, on the day of injection, you need to wash and spin them down, resuspend in an injection solution, put them on ice, go down to the mouse house, shave the mice, anesthetize them and then inject them. You don't want too much time to elapse between when you prep the cells and when you inject them or they might die. At every step there are biosafety constraints that limit your movements and how you dispose of garbage which would be challenging to scale up to a totally automated system. Every different cell line/type you inject has different kind of growth requirements and idiosyncrasies in how they like to be handled. I suppose you could program machines to do this for one cell line, but it would be a monumentally difficult task to do it for every cell line and get good results. Then there's the matter of just handling the animals. I would love to see a machine that could do this (and maybe one day there will be) but for the moment you need training in how to carefully and safely grab mice, restrain them, inject them and so on.

The costs of maintaining mice is also much larger than it seems (perhaps compared to mice kept as pets). A major cost is the daily tasks associated with husbandry, like cleaning cages, sick checks, genotyping, etc. At least at my institute it was ~$1.50 per day per cage (up to 5 mice) in support costs, not including the ~$30-50 it costs to raise a wild-type mouse to the point where you could do the experiment (more for some genetically modified mice). An experiment with 500 mice (100 x 5 conditions) would cost you $15-20k, which would massively balloon the cost of research.

Finally, there are major ethical concerns with using more animals than necessary for any experiment. Animal work is carefully regulated by internal and external ethics committees and oversight of all ongoing experiments. The number of animals to be used for any given project must be justified with statistical analysis suggesting that you are using no more than necessary and will indeed be able to show the expected results. If you propose experiments using large numbers of animals you must have a good explanation for why you need such numbers.

Anyway, it's not really that simple or cheap to do animal experiments, especially at large scale.

Most animal experiments are performed only if an effect size large enough to be ascertained using a small number of mice (i.e. <10, typically) is predicted based on in vitro or other models. Grant funded researchers do not typically have the resources to maintain such large colonies as you propose.

Also, most mice used in experimentation are inbred strains. Most human studies rely on such huge sample sizes to to identify low effect sizes within a diverse population.

I believe the mice used in a lot of research studies need to be genetically identical, so they need to be certain generation crosses

The expenses associated with animal husbandry at most research institutes raise the price to ~$1/day per cage of 5 mice.

Adding to what josephpmay said, there's the issue of dealing genetic drift, so some groups have expensive-to-maintain systems to deal with that [0]. Which looks like restarting the line every 5 generations.

I have more experience with tissue culture than mice, but that's sounds surprisingly similar to passaging tissue cultures over and over [1]. Eventually you get to far out and have to start fresh, going back to stock cells.

[0] https://www.jax.org/jax-mice-and-services/find-and-order-jax...

[1] https://en.wikipedia.org/wiki/Immortalised_cell_line

Transgenes can affect the fertility of mice or mess with their sexual behavior, it's not uncommon for transgenic lines to have erratic breeding schedules and reduced litter sizes compared to wild-type. Then if you get a litter, maternal care is very important. If a transgene messes up the mother's ability/drive to feed the pups, then they aren't going to make it very long (though you can foster/wet nurse them). Finally, depending on the required genetic profile, you may have a situation where only 50% or less of the offspring have the transgene of interest.

Some of this is "worst case scenario" stuff that wont apply to most lines. The real reason for the high price is mostly 1) that its expensive to make the transgenic mice in the first place and 2) demand is high enough that they can get away with charging that much.