Growth vat

The growth vat is a building added by the Biotech DLC. It allows the gestation and accelerated aging of babies and children.

Acquisition

Growth vats can be constructed once the Growth vats research project has been completed. Each requires 150 Steel, 4 Components and 8,000 ticks (2.22 mins) of work.

Summary

While hosting a human, growth vats require a constant 200W of power as well as nutrition. Both raw and processed foods, including nutrient paste, can be inserted.^[Hay?] None of the usual mood bonuses or maluses from different food types, such as from human meat, are applied. Hosting an embryo costs 6 nutrition per day and aging a child costs 3 nutrition per day. The vat's contents can be ejected immediately by the player by canceling vat growth; if it was an embryo, it will be destroyed. When no pawn is inside, the power consumption reduces to 80W

If the vat has no power or nutrition, the being inside will enter bio-starvation, increasing in severity by 50% per day starved, and decreasing 10% per day properly supplied or spent outside the vat. Bio-starvation increases nutrition consumption in a vat by +10% at all severities, and kills at 100%. If a bio-starved pawn leaves the vat, a number of status effects will be applied to them. See bio-starvation for a full list.

Baby creation

Growth vats can be used to grow an embryo in 9 days, twice as fast as natural pregnancy, and regardless of either parent's Fertility (as long as it's above 0%). This comes without risk to the mother, but the baby can still arrive sick.

Growth vats have a birth quality of 70%. There is roughly an 89.1% chance for the baby to be born healthy.

Children

Colonists under 18 can also have their aging sped up by 20x, i.e., it takes 3 days to age 1 year. This ignores the default 4x aging multiplier for babies and children, so a vat is 5x faster than that. While in the vat, a pawn's needs are frozen like in cryptosleep, and children will not gain growth points. Every 3 days that a baby or child is in the vat, they'll received 8000 experience towards a random skill. The skill selected is entirely random and does not prefer passions, though it will ignore skills that are disabled due to backstory or traits. The experience ignores the daily limit of XP to a skill and is not affected by global learning rate (for example, the Fast Learner trait), but is modified by the child's current passion level in the skill chosen.

As a child spends a maximum of 54 days inside a growth vat from birth to age 18, a child gains a maximum of 18 of these experience bonuses, for a total of 144,000 experience. If distributed evenly across skills, a child can expect to see an average of raw a 12,000 experience per skill. Ignoring passions that are changed at growth moments, this average XP would cause a no-passion skill to reach level 2, a regular passion skill level 4, and a burning passion skill level 5. Exact distribution will vary randomly, and passions can be altered at growth moments, affecting this gain rate. Overall, however, it is very unlikely for any given skill to reach more than level 8 even with a burning passion in it from the start.

Non-psychopath parents (including surrogates) will have a −4 My child is in a growth vat moodlet while their kid is inside. This can be altered by ideoligion.

Biological Age	Time in vat		No Vat
Biological Age	Base Vat	Vats: Essential^[1]	400% Aging^[2]
+1 Year^[3]	3 days	2.3 days	15 days
+3 Years^[3]	9 days	6.9 days	45 days
Embryo to 0	9 days	9 days	18 days
Embryo to 3	18 days	18 days	63 days
Embryo to 18	63 days	52.6 days	322 days
Age 0 to 3	9 days	9 days	45 days
Age 3 to 13	30 days	23.1 days	152.4 days
Age 13 to 18	15 days	11.5 days	106.6 days

↑ Growth Vats: Essential does not apply to pawns without the ideoligion, i.e. embryos and babies age normally.
↑ Default child aging value from 0 to 11. Note that children will start to age slower from this speed after reaching 11 biological years of age. See Children#Aging for more details.
↑ ^3.0 ^3.1 Assuming a child between age 3 and 11

Ideology

Ideoligions can have an optional Growth Vats precept with two options:

"Growth vats: Essential" boosts grow vat speed by +30% (children grow 26x faster) if the child has the ideoligion. Babies and embryos are not boosted. It negates the parent mood penalty, instead giving parents +2 mood for their own child in a vat.^[Verify] When expectations are moderate or higher, it gives parents a −2 Child not in growth vat mood for their child not being in a vat (stacking up to 3 times), pregnant pawns gain a −5 Natural pregnancy mood when pregnant, and all colonists gain a −3 No growth vats moodlet if the colony has no growth vats.^[Verify]

"Growth vats: Prohibited" gives negative mood for growth vats in your colony, and when any embryo or child is in a growth vat. The My child is in a growth vat increases to −8 (stacking 3 times, nullified by the psychopath trait), and gives a +1 Child not in growth vat mood for their child not being in a vat (stacking 3 times). All colonists gain a −3 Growth vat moodlet if the colony has a growth vat.

If neither precept is chosen, the ideoligion has no effect.

Analysis

If the Learning need is nonexistent, then growth vats will not negatively impact a pawn's development:

Babies (0-3) can be placed in the growth vat to speed up reaching toddler age. There are no apparent ill effects on the baby, and they even train an age-3 valid skill (Shooting, Melee, Social).
- However, parents who dislike growth vats gain the −4 moodlet, and it negates the mood buffs from having a happy baby in the colony.
If a child (3-13) is at growth tier 8, then no more growth points can be obtained, though children can learn from Work Watching or Lessons. Either way, the benefits are minor: these children will be a few days from growing up naturally.
Aging a teen (13-17) to 18 has no ill effect, and removes the body size and work penalties from being underaged. This costs up to 15 days of an almost-adult's time.

In these cases, vats exchange time for the cost of nutrition and power. Each vat doesn't consume much power, while nutrition can usually be solved by simply growing more food. For reference, growing a child is just under 2 colonists' worth of food. An embryo is roughly equal to 4 colonists for the duration, consuming 60 simple meals over the 9 days.

On the other hand, completely vatgrowing baseliners will have them end up being fairly weak pawns. A vatgrown child will end up with 0 passions, very weak skills, and 3 random traits - a wanderer or just about any prisoner recruit is likely to just be better, without consuming nearly as much nutrition. Regardless, vats will ignore the game's natural population curve, and will always be able to fight, haul, and clean competently. Of these, hauling and cleaning can be accomplished with lifters and cleansweepers, both which are cheap and very early on the mechanitor progression path.

With gene editing

Notice that vatgrowing baseliners will end up with poor results. With the gene system, it is entirely viable to create a vatgrown army, either with in-game gene modding, or a player-created xenotype. The genetics system is a natural fit to growth vats.

For example, a simple xenogerm consisting of Great Shooting / Psychite Dependency / Psychically deaf will create a pawn with a passion and 8 free levels of Shooting, easy mood regulation through yayo, and a hunger rate of only 70%. An amazing Shooting Specialist. Lategame colonies can form dozens of vatgrown soldiers with this xenogerm, completely blasting through the game's intended population level, only being limited by growing space. This becomes even more powerful when considering xenotypes you can create at the start of the game, which can be min-maxed as much as you'd like.

Nutrition

While raw food can be put into the dispenser, virtually any means of cooking a meal gives more nutrition per food item. The absolute best way to prepare food is the nutrient paste meal, which triples nutrition. However, colonists won't automatically dispense nutrient paste for a growth vat; they will only haul meals on the floor to it. See Nutrient paste#Manually producing meals for how you can stockpile nutrient paste.

Without nutrient paste researched, or if you don't want to micromanage everything, baby food is the next best way to prepare vegetables. Simple meals are the next best way to prepare other food items.

There are no penalties to anyone for using insect meat, already-butchered human meat, or other usually undesirable food items in a vat.

Organ harvesting

Main article: Human resources

Children can be organ harvested as soon as they are 3 years old.

It takes a total of 90 simple meals or 1620 baby food to grow a set of organs (54 nutrition to grow an embryo, 27 nutrition to grow a newborn to 3). Depending on preparation method, this costs 900 (meals) or 810 (baby food) items of virtually any raw food. 810 corn is worth 891, plus preparation time. Human meat is cheaper.
You can harvest 1 kidney ( 900), 1 lung ( 1,000), and either a heart or a liver ( 1,200), for a total of 3100.
- If you can create prosthetic hearts, you can spend a prosthetic heart (230) to get both a heart and a liver, for a net total of 4070.

Therefore, each vat-child nets a profit of 2209 in organs by using corn, before Trade Price Improvement and difficulty. But, other than the usual organ harvesting penalties, vatgrowing organs has 2 downsides:

Children have lower HP. If an operation fails, then even a "minor" failure is likely to outright kill.
Children will be related to somebody in the colony. If the parents are not a psychopath, then their mood will be greatly hit.

Basically, an organ harvesting operation using a Cannibalism: Acceptable and Organ Use: Acceptable ideoligion, with a psychopath/prisoner mother and psychopath/slave father (male prisoners cannot fertilize embryos and slaves are cheap and disposable) is highly profitable, and comes with no mood downsides. You can give the child EMP grenades and make them "guilty", removing the moodlet for colonist death. All that's needed is a good doctor, some medicine, and preferably a hospital bed. Without a pro-organ ideoligion, mood impacts start to matter more, but... it can still be profitable.

Of course, creating a proper organ farm should be compared to the money you'd get from a "normal" Human resources setup. At a certain point, selling human leather and raider organs should be enough money to buy anything you'd need.

Version history

Biotech DLC Release - Added.
1.4.3682 - Fix: Embryo skin color not preserved in growth vat between save/load.

[1] Growth Vats: Essential does not apply to pawns without the ideoligion, i.e. embryos and babies age normally.

[2] Default child aging value from 0 to 11. Note that children will start to age slower from this speed after reaching 11 biological years of age. See Children#Aging for more details.

[Non-baby-3] 3.0 ^3.1 Assuming a child between age 3 and 11

[1]

[2]

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