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Same game i mentioned in my other questions. Artificial gravity, robotic harvesting/replanting, and plenty of energy are available on the ship. The farming block is 50x70x10 meters in total but i would prefer to only use 50x50x10m for the farming to allow local housing and storage in the remaining area.

The bottom 5 meters of the farm area are taken up by two 2.25m floors of dirt floored pastures 1 holding dairy goats the other chickens (the other half meter is the floor between them and the dirt). The top 5m are five 1m tall hydroponics beds for animal feed.

Between google and talking to a friend that raises chickens we figured the chicken pasture and 1 level of feed would be enough for about 800 chickens. Which comes out to about 300 eggs and 12.7kg of meat a day.

The problem is the goats. Depending on which anecdotal article you read they need anything between 30 and 200 sqft to run around in but 1ac can only hold 6-8 goats. Or in metric 25 goats to a hectare. With the pasture being 1/4 of a hectare and each of the 4 remaining hydro levels also being 1/4 we should easily be able to feed 30 goats, yes?

But that is ignoring the usually superior production of hydroponics. If there is anything about hydroponic yields of hay/alfalfa other than week old sprouts i can't find it. Or even better comparisons between hydroponic yield and regular farming yield.

Edit: whoops, in the rewrite i somehow lost that the goats are almost entirely there for dairy. Originally it was going to be cows, but goats make far more milk for the space.

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    $\begingroup$ In a ship, I'd guess most of the feed will look more like yeast, algae/kelp cake, and other feeds that SEEM like processed foods. Consider insects and snails as protein sources for both the crew and the animals (easily grown in enclosed conditions with relative high yields). $\endgroup$
    – DWKraus
    Sep 28 at 1:24
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    $\begingroup$ IMO, you would not bring goats, or possibly even chickens, as a meat source in a spaceship where you are worrying about space and resources. Why literally waste resources to tropic level loss growing animal feed when you can grow human feed and feed more people with the same resources? Those resources to feed 30 goats could instead continuously feed 30 people indefinitely, while 30 goats would only provide food the one time they are slaughtered. That would break my suspension of disbelief right there. Even more so if you try getting into the nitty gritty of it was made to work. $\endgroup$
    – DKNguyen
    Sep 28 at 2:02
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    $\begingroup$ 2 reasons, number 1 morale. Not sure about where you live but in most of the world most people are not willing to eat a purely plant based diet for an extended amount of time. Number 2, 30 goats isn't just meat one time when you slaughter them. It is about 100 liters of milk every day some of which can be turned into cheese/cream/ice cream. More food variety is a huge morale boost as well. As a side note, that much growing space would feed about 150 people on vegan diets. $\endgroup$
    – Rasip
    Sep 28 at 3:00
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    $\begingroup$ I came here to posit what Rasip said in his rebuttal. On top of food variety, which is a heaven send in almost any situation, it provides people with a small modicum of hobbying. For those people who love animals, they could take it upon themselves to name & care for the animals, which in itself is a huge morale boost. Humans are naturally very social creatures, and oftentimes animals provide a source of social interaction without the stress that comes with navigation the social minefield that is interpersonal communication. $\endgroup$ Sep 28 at 14:56
  • $\begingroup$ Some relevant reading: dairyglobal.net/health-and-nutrition/nutrition/… (Ok, it's for cows, not goats. But the humans could eat it too). $\endgroup$
    – Kingsley
    Sep 29 at 1:10

7 Answers 7

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GMO crops

You gots to have goats! Assert your hydroponic fodder crops have been modified to be more productive.

Genetic Engineering Technologies for Improving Crop Yield and Quality

In conclusion, genetic engineering technologies make the process of crop improvement more efficient and controllable. With the continuous improvement of related technologies, the process of accurately improving important agronomic traits such as crop yield and quality and, further, directionally creating new crop germplasm has been accelerated.

The linked article has a lot of stuff on currently used techniques. You can tweak one of these since this is nearfuture scifi so that any wet blankets in your audience cannot protest such a thing is impossible.

GMO improvement of hydroponic crops is a cool thing to think about. In many ways the reverse of GMO for fields crops. Drought tolerance - not an issue. Pest and pathogen resistance - that stuff is just a drain on resources. Nutrient uptake efficiency - no need to be efficient in the hydroponic stack. All emphasis is on grow, grow, grow.

Have your area the way you envision it and assert the plants have been modified to be awesome. Your goats and chickens are modified too, of course. I will note here that pygmy goats take up less space.

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    $\begingroup$ I will note further that pygmy goats could be genetically modified to produce chocolate milk. $\endgroup$
    – Tom
    Sep 28 at 23:24
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To answer your question

If you assume you are providing 2 decks about 2.5m each, that gives you 5000m^2 of ground space. If we are also not too concerned about humane treatment, then you need about 2.8 m^2 per goat of living space. We can also vastly reduce grazing space with hydroponically grown grasses which can produce a theoretical maximum of about 19kg/m^2/yr. Each goat needs about 500kg of feed a year meaning you only need about a total of 29m^2 per goat. I will actually estimate this closer to 35m^2 per goat because you also need to account for things like walk ways, food processing spaces, veterinarian spaces, supply storages, etc. allowing you to maintain a herd of about 45 mothers, 90 calves, and 5 studs. If you assume you are slaughtering about 80 calves a year, that is about 5-6kg of meat a day... or if you are not raising calves for meat, but just enough to replace attrition, you could have closer to 120 milk goats, 15 calves, and 5 studs for a dairy production of up to 120 gallons of milk a day. Milk itself is mostly water, but if you wanted to process it into cheese so that you have a meat substitute, then you would get 43.5 kg of cheese. So lets assume you want meat, cheese, and milk for a nice varied diet, you can produce about 3kg of goat meat, 19kg of cheese, and 30 gallons of milk a day.

Since the average person eats 100-300g of meat, eggs, and cheese a day (depending on cultural preferences) This would be enough to feed a crew of about 180-530 which should be plenty given the size of your crew compartment.

But you should also include fish tanks

There is a livestock that is much better than chickens or goats: fish. For starters, fish is rich in Omega-3 fatty acids which is one of the few essential nutrients that your body can not produce from other sources and is really hard to get out of a vegetarian diet. You need it to maintain good health, and fish have it in much higher ratios than other meats; so, you can maintain a healthy lifestyle eating less meat if the meat you are eating is fish.

Secondly, they need much less feed because they are mostly sedentary, cold blooded animals. It only takes 1.6kg of fish feed per 1 kg of meat making fish farming ~3-20x as efferent as other common sources of meat. Furthermore, fish can be fed algae which grows MUCH faster than grass the grasses you need to feed goats and chickens. Agriculturally grown fish could use this same space to grow about 500kg of meat per day making them ~83 times as efficient as goats for meat and ~12x as efficient as goats for milk.

So I'm not saying you can't do chickens and goats in this space since you've allotted enough room given the right techniques, plus they may be seen as good for your quality of life, but you may want to consider adding fish as a major protein source to reduce your total livestock space requirements. If just 60% of your protein requirements were met by fish, you could reduce the amount of space needed for raising livestock by about 1/2.

https://animals.mom.com/how-much-land-to-keep-goats-12595099.html

https://ourworldindata.org/grapher/feed-required-to-produce-one-kilogram-of-meat-or-dairy-product

https://www.skretting.com/en-us/transparency-and-trust/faqs/how-much-feed-is-needed-to-grow-a-farmed-fish/

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    $\begingroup$ Nobody likes milk so much that they'll lift many tons of soil and habitat into orbit and then share a huge fraction of their own air, water, and food with the milk machine and even clean up the milk machine's poo. Adults drink water, tea, coffee, or old fashioneds, and babies are kept on the planet surface. $\endgroup$
    – Tom
    Sep 28 at 5:09
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    $\begingroup$ Plant-based milk and dairy products are getting better all the time - by the time we're in space they will be indistinguishable from the real thing, if not better. Goats are smelly, disruptive, way too clever, and willing to munch on almost anything, including critical infrastructure. Do not bring goats. Even the chickens are a waste, if you absolutely can't imagine a world where you have to go temporarily without eggs, maybe bring a few quails. $\endgroup$
    – Ottie
    Sep 28 at 8:11
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    $\begingroup$ @Graham Also, water can be harvested from asteroids/comets so you can entirely avoid lifting it. $\endgroup$
    – Neinstein
    Sep 28 at 12:14
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    $\begingroup$ @Krupip I attached sources for food yield based on feed. For fish meat per day I had to aggregate many sources, so not much worth re-finding them all but together I got the information that you can raise 15-25kg of tilapia per m^3 of water with fish reaching harvest maturity in 8-9 months & fish being 68% meat yielding ~40-67g of meat/m^3/day. I also found a source for algae growth showing it can grown at rates well over the food needs of the fish, but the tank conditions needed to sustain more than 15kg/m^3 of water are not conducive to algae which is why I went with the lower fish density. $\endgroup$
    – Nosajimiki
    Sep 28 at 16:24
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    $\begingroup$ @DrakeP They need 1.7kg per kg of animal weight... so they also make a really good space savers. Some off the cuff estimations say that the kinds of feed that crickets eat is not as space efficient as fish feeds, but that they need less living space; so, either choice will give very similar space reductions. $\endgroup$
    – Nosajimiki
    Sep 29 at 18:55
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You could just grow cultured animal cells lines in fermentation tanks etc or even just algae/plant cells that are processed and flavored to resemble meat products.

Perhaps not as 'tasty' as fresh meat but then you'll have the prospect of that fresh, juicy, sizzling hot steak with all the trimmings and your name on it waiting for you at your next port of call. Something to look froward to after weeks of processed gloop that almost (but not quite) tastes as good as the 'real thing' - despite saying it does on the pre-sealed package its served in.

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    $\begingroup$ This! Also, reading the first question about ships @Rasip said of 3d printers to make everything. So, what the problem with labmeat? $\endgroup$ Sep 28 at 14:33
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Wrong animals

Why bring goats for dairy when you have a spaceship full of mammals? Through targeted hormonal treatment, your cosmonauts (male or female, although the females will find it easier) can produce a small amount of milk, which they can sell/contribute to the communal kitchen, or have processed for their own consumption. They can even experiment with the effect of spices and other ingredients on the flavour! It's obviously a rare delicacy, but quite trendy, and considered more humane than milking animal livestock.

For eggs, families are encouraged to keep quail. Being responsible for a living being is considered good practice for children and helps them socialise and participate in communal work. Quail are quieter and smaller than chickens, while also producing edible eggs (smaller in numbers and size) and high-quality fertiliser. Ideally they would be fed with appropriate food scraps, but that would depend on what food you're growing and whether there are any components that would be undesirable for humans but adequate for birds.

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  • $\begingroup$ I've heard it said that one can milk "anything with nipples." $\endgroup$
    – Tom
    Sep 28 at 23:32
  • $\begingroup$ I'm not sure what sort of quail my SO keeps, but it's really noisy, as equally loud as a rooster (especially at 3am!). $\endgroup$
    – Kingsley
    Sep 29 at 1:18
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    $\begingroup$ @Kingsley disappointing, but useful, first-hand experience on quail. Space quail may have been bred/genetically modified to only make delicate, melodious sounds no earlier than 7am. $\endgroup$
    – Ottie
    Sep 29 at 10:53
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Vegetable Lamb (Goat) of Tartary

enter image description here

Since we are in the future there is no need to grow plants to feed animals to feed the astronauts. Just grow the meat directly from the ground.

Genetically modify the plants on board so they produce something similar to animal flesh. Also modify the beans and nuts so they have more of the same fats as animal milk. Then your plant milk will taste like animal milk.

Or ditch the animal diet altogether and declare that the problem you propose for your spaceship has already run its course on the surface. In the future, due to overpopulation, people don't eat much meat any more. So there is no need to give them meat on the spaceship.

They would be like, "Hey Sanjay, what's this pink squidgy thing that came out of the food dispenser? Wait, an animal -- euugh!"

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  • $\begingroup$ Downvote because Vegetable Goat has a tart Tartary taste. $\endgroup$
    – Willk
    Sep 28 at 15:11
  • $\begingroup$ @Willk Tart like fresh yoghurt. Yum yum. $\endgroup$
    – Daron
    Sep 28 at 15:14
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    $\begingroup$ Over population already means many people in the world are forced to live vegetarian lifestyles... this does not mean that there are not portions of the population that eat all the meat they want. The rich will always be able to afford luxury at the expense of starving the poor, and chances are, if you can afford space flight, you are one of those rich people. Otherwise, I do like this answer since just because you can afford meat on an over populated Earth does not mean you can afford it in space. $\endgroup$
    – Nosajimiki
    Sep 28 at 15:19
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    $\begingroup$ @Nosajimiki We are free to declare the future Earth is any way we wish. There is a whole franchise based on the premise that Earth becomes a nice place for everyone. $\endgroup$
    – Daron
    Sep 28 at 15:42
  • $\begingroup$ Some edible species do allow harvesting from vegetation. Like the Burgundy snail, or escargot. $\endgroup$
    – Goodies
    Sep 29 at 21:54
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...the goats are almost entirely there for dairy. Originally it was going to be cows, but goats make far more milk for the space...

In that case, skip the cows/goats entirely! In the present day there is already a company producing dairy proteins via GMO-engineered fungi (similar to how beer is naturally brewed using yeast). Give that technology a few decades of continuous research & development, and by the time humanity reaches your near-future setting we'll have more dairy-brewers than dairy-farmers!

Of particular importance to your space-faring application is the fact that that such a dairy-brewing facility would operate more like small-brewery than a small-farm - which not only makes automation easier, but could also fit into a much smaller physical volume, and likely with a smaller overall energy cost.

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The only possible solution for the lack of space is the spinning cylinder that generates artificial gravity. To keep the goats active they will be pushed to walk continuously along the spin direction.

For the food there is something that is even more productive than hydroponic and they are the algae. A mix of them including spirulina would do the job. And, if there is any doubt, goats can eat them. Well, that was a special case, but I assumed that the science is so advanced that farmers have also a selection of bacteria (fermenting or not) prepared to make the food more digestible, they should be part of the farm.

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