Short answer. Only the remains that survived the calamity. Article 591 of the Civil Code provides that if the entire herd perishes due to contagious disease or another uncommon event — without any fault on the usufructuary's part — the usufructuary's only obligation is to deliver whatever remains were saved from the disaster.
What the law says
the usufructuary shall fulfill his obligation by delivering to the owner the remains which may have been saved from the misfortune.
Civil Code, Article 591 — Usufruct of Livestock. Read the full provision →
Total loss from disease: limited obligation
Article 591 of the Civil Code provides a graduated set of rules for livestock usufructs. For ordinary deaths from natural causes or predator attacks, the usufructuary must replace the lost animals with young from the herd. But when all the animals perish due to a contagious disease or other uncommon event — and the usufructuary is not at fault — the standard replacement obligation cannot apply. In that case, the law limits the usufructuary's duty to delivering the remains which may have been saved from the misfortune. Whatever was salvageable goes to the owner; that is all.
The fault requirement
This limited-obligation rule applies only when the total loss occurred without the fault of the usufructuary. If the usufructuary's negligence contributed to the spread of disease — by failing to isolate sick animals, neglecting veterinary care, or ignoring warning signs — the protection of Article 591 does not apply. The usufructuary bears the risk of losses that result from their own negligence. The reduced obligation is a concession to events genuinely beyond the usufructuary's control, not a shield for poor husbandry.
When only part of the herd is lost
Article 591 also addresses partial losses from the same kind of accident. If part of the herd perishes without the usufructuary's fault, the usufruct simply continues on the surviving animals. The usufructuary does not need to replace the dead ones in this scenario — the usufruct contract adjusts to the remaining animals and continues. The combination of these rules means that disease catastrophes are borne proportionally: total loss yields minimal obligation; partial loss yields a continuing usufruct on what survives.
Sterile animals and other special cases
Article 591 adds that when the usufruct covers sterile animals, it is governed as though the animals were fungible things — meaning the usufructuary must return an equal number and quality of animals of the same kind, rather than being expected to produce offspring that will never exist. If you are administering a livestock usufruct with unusual circumstances — sterile stock, endangered species, or highly specialised breeding animals — the specific rules governing your situation may require careful analysis. A lawyer familiar with property law can help you determine your exact obligations.