It occurred to me that they would be missing animal products - all your meats, leathers, cheeses, wool, etc. is tracked elsewhere in the entity resources structure (so it doesn't have to be recalculated after worldgen).
I checked the embark, the leathers, meat, cheese, wool... its all still there. No issues.
If the civilization already had access to the creature by other means, then you'll be fine, but if you were adding a special creature (e.g. no biomes) to pack/pull/mount/pet/minion then its products will
NOT be automatically included - I just checked the code, and I can't find evidence of that being done afterwards, so you
do need to add those yourself, and doing it correctly is a bit complicated:
* If the civilization has USE_ANIMAL_PRODUCTS:
** if the creature/caste lacks CAN_LEARN or the civ's ethic for EAT_SAPIENT_OTHER is set to ACCEPTABLE, REQUIRED, or PERSONAL_MATTER:
*** add to fish_races/fish_castes if it has FISHITEM
*** add to egg_races/egg_castes if it has LAYS_EGGS
*** for each entry in caste_raw.unknown2.materials where the entry in caste_raw.unknown2.unk_2f30 is zero:
**** for every reaction product that the material has:
***** if the reaction product ID matches any reaction that produces SKIN_TANNED (e.g. TAN_A_HIDE), add the product material to resources.organic.leather
**** if the material has the MEAT flag, add it to resources.misc_mat.meat
**** if the material has the LEATHER flag, add it to resources.misc_mat.leather and resources.misc_mat.crafts
**** if the material has the BONE flag, add it to resources.misc_mat.crafts and resources.refuse.bone
**** if the material has the SHELL flag, add it to resources.misc_mat.crafts and resources.refuse.shell
**** if the material has the PEARL flag, add it to resources.misc_mat.crafts and resources.refuse.pearl
**** if the material has the HORN flag, add it to resources.misc_mat.crafts and resources.refuse.horn
**** if the material has the TOOTH flag, add it to resources.misc_mat.crafts and resources.refuse.ivory
*** add caste_raw.unknown2.mat_type/mat_index to resources.misc_mat.meat
** add each material from caste_raw.extracts.extract_mat/matidx to resources.misc_mat.extracts
** if caste.extracts.milkable_mat/matidx is valid, add it to resources.misc_mat.extracts if valid
** if the entity has PERMITTED_JOB:SHEARER and PERMITTED_JOB:SPINNER:
*** for each entry in caste_raw.shearable_tissue_layer, add all shearable YARN tissue materials to resources.organic.wool (part_idx/unk_8 into body_info.body_parts[], then layer_idx/unk_18 into body_part_raw.tissue_id, then that tissue_id into creature_raw.tissue[] to get the mat_type/index)
** if caste.extracts.blood_mat/matidx is valid, add it to resources.misc_mat.extracts if valid
** if caste.extracts.webber_mat/matidx is valid and made of SILK, add it to resources.misc_mat.crafts and resources.organic.silk
** for each entry in caste_raw.body_info.attacks
*** add each value for specialattack_mat_type/index to resources.misc_mat.extracts, though to avoid bug #1044 you should first make sure the corresponding specialattack_type is equal to INJECT_EXTRACT (0) and the matter state is not equal to GAS (2)
** for each entry in caste_raw.secretion, add mat_type/index to resources.misc_mat.extracts if the matter_state is not equal to GAS (2)
** if you added an entry to resources.misc_mat.extracts that has a CHEESE_MAT reaction product, add that product material to resources.misc_mat.cheese