[Spaceships] Living Cargo

[Varyon]

First, you'll have to decide if the weight and price are for just the livestock, or if they include some portable living arrangements (like the mentioned livestock trailer). The latter is easy - you can just transport the livestock as-is in steerage cargo. For the former, you'll either need to transport the livestock in Cage* systems or purchase some amenities that will allow you to transform your steerage cargo into proper holding areas - which will basically mean retrofitting your ship to turn that steerage cargo into Cage systems.

If going with the former - and note the lack of rules for this in SS2 strongly imply the latter is more likely what was intended - needs for space, air, and food/water roughly scale by SM. An SM-2 animal needs half as much space and food/water as an SM+0 one, while an SM+2 animal needs twice as much of each as that SM+0 one. Being in a Habitat system covers the space, air and water requirements, but you'll need to either buy and carry food or have Total Life Support for your animals to keep them fed. Note the scaling also applies to hibernation chambers - a single cabin can be made into 8 SM-2 hibernation chambers, 4 SM+0 ones, or 2 SM+2 ones.

If going with the latter, as noted you just carry the livestock as steerage cargo, but you'll still need to feed them if you lack Total Life Support. I don't think SS2 gives guidelines on feed for livestock - if not, multiply tons by 0.8; this is the number of SM+0 equivalents you need to supply food for (for reference, this is calculated by assuming the livestock trailer functionally turns steerage cargo into cages; as every cabin can be turned into cages enough for 4 SM+0 animals or 5 tons of cargo, dividing tons by 5 to determine number of cabins and multiplying this by 4 should give us our number, and 4/5 is 0.8).

Carrying livestock in this manner for a long period of time isn't very good on the animals - the 1% die-off per week without intervention (Veterinary or similar) represents this, although arguably it may be rather lenient. Hibernation chambers should avoid this problem. "Housing" the animals in Open Spaces would work better for a lot of livestock, although that's likely to be less mass-efficient - as an entire SM+8 Habitat would house up to 24 SM+0 animals, I'd eyeball that each Open Space would be sufficient for around 12, but you'll likely need to supplement their food. This method would likely reduce the die-off markedly - perhaps 1% per month rather than per week.

*Technically, a good deal of livestock won't really need actual cages, but the difference in mass isn't really worth bothering with.