Glossary: Non-return rate

Term:

Non-return rate

Abbreviation:
NRR

Definition:
Percentage of females that are inseminated for the first time during a given period of time (such as a month) and have not been recorded as having returned for another service within a specified number of days (e.g. 24, 56, 90). A binary measure denoting whether or not a cow returns to estrus following a certain period of mating. Frequently studied intervals are 28 days (NR28), 56 days (NR56) or 90 days (NR90). The reference period recommended by Interbull is 56 days. This trait can be evaluated for both heifers and cows.

Reference:
ICAR Guideline

Guidelines for Recording Artificial insemination and Embryo Transfer and Reporting Fertiity

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