Hereditary Variation in Conception Rate of Holstein-Friesian Cattle

Abstract

Summary Variation in conception rates (based on birth of a live calf from first insemination to a high-fertility service sire) of 1,406 Holstein females was studied at one or two service periods (1,824 records) in 41 artificially inseminated herds. Fertility did not vary significantly between herds. Conception rates ranged from 43 to 94% in 27 paternal half-sib groups of heifers (P The heritability of conception rate was estimated from intrasire correlations of paternal half-sib groups to be approximately 8.5%. A comparison of the records of daughters at both service periods from 22 sires showed a trend toward an interaction between sire and parity of daughters (P ≠ 0.07). The value of selection in improving conception rate is discussed.