Observations on the Degree of Expression of Estrus in Cattle

The repeatability and heritability of heat symptoms and the relationship of heat to conception were investigated. The heritability of the expression of heat was 0.21. Heifers that conceived at first service had a rating for expression of heat of 0.22 unit higher, whereas, those that conceived at the second service had a rating of 0.17 unit higher, than those that failed to conceive. Both values were significant. The degree of expression of heat is useless in selecting for an increased conception rate. Editor.