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.

Automated summary

The study examined the effect of residual feed intake adjusted for backfat thickness on pregnancy rate in Angus heifers. The results showed that selecting for feed efficiency may have negative consequences on fertility.