Is slaughtering a usurped animal to fulfill a religious obligation valid?

Primary text

Slaughtering a usurped sheep to fulfill a mandatory religious duty is not valid, irrespective of whether the owner consents or not, or whether compensation is provided. The evidence for this ruling is that the act was not a valid act of worship at its commencement, and therefore cannot become one during its execution, similar to an act initially intended for consumption that is later intended as an offering, or manumission intended for atonement.