353. Appraisal: The obligation to give the evaluated worth of an animal
…it shall be according to the kohein’s appraisal. (Leviticus 27:12)
There is also an obligation to fulfill one’s obligation when he commits the value of an animal to the Temple. Unlike the case of human beings, who have standard amounts despite physical characteristics (as described in Mitzvah #350), an animal would be appraised by a kohein to determine its value.
The reason for this mitzvah, as described in Mitzvah #350, is that a person’s word is his bond. He should not renege on any obligation he makes, certainly not in commitments he makes to the Temple.
As stated in the past few mitzvos, laws of consecrating property to the Temple apply in all times and places but we must be careful not to sanctify things nowadays. However, if one pledges an animal’s worth in this day and age, the mitzvah of having a kohein appraise it does not apply.
This mitzvah is discussed in the Talmud in tractates Bechoros (14b) and Temurah (32b). It is codified in the Mishneh Torah in the fifth chapter of Hilchos Arachin and is #115 of the 248 positive mitzvos in the Rambam’s Sefer HaMitzvos.