First-service pregnancy rate among beef heifers with different residual feed intake

The effect of residual feed intake (a measure of feed efficiency) adjusted for backfat thickness (RFI fat ) on pregnancy rate (PR) was examined in Angus heifers over 2 yr. High- or Low-RFI heifers were timed artificially inseminated (TAI) with semen from High- or Low-RFI sires, respectively. There was a negative association (P < 0.05) between RFIfat value and PR in Year II for Low-RFI heifers. In Year I, the interaction between RFIfat and AI sires was significant in High-RFI heifers (P < 0.05) and tended to differ in Low-RFI heifers (P < 0.1). Therefore, selecting for feed efficiency may have negative consequences on fertility.