This study evaluated the implementation of reproductive technologies and their effects on pregnancy rates (PRs) and calving distribution. Producers (n = 11) were enrolled in Level 1 or 2 and subsequently transitioned to Level 2 or 3. Level 1: females were exposed to natural service (NS) only versus estrous synchronization (7d-CIDR) before NS (SynNS). Level 2: SynNS versus fixed-time artificial insemination (SynAI; 7d-CO-Synch + CIDR) with conventional semen. Level 3: conventional versus sex-skewed semen (FTAI-con and FTAI-sexed, respectively). Artificial insemination occurred 60–66 h post CIDR removal (SynAI; FTAI-con; FTAI-sexed) and bulls were introduced on d 0 (NS and SynNS) or 10–14 d post artificial insemination (SynAI; FTAI-con; FTAI-sexed). Breeding season PRs did not differ between treatments (p > 0.50). In Level 2, SynNS had greater 21 d PRs compared to SynAI (p < 0.01). For Level 3, FTAI-con had greater 21 d PRs compared to FTAI-sexed (p < 0.01). In Level 1, the proportion of cows that calved by day 14 was greater for SynNS compared to NS (p < 0.01). In Level 2, SynAI had a greater proportion calved by day 7 (p = 0.01); however, SynNS had a greater proportion calved by day 21 and 42 (p < 0.01). In Level 3, FTAI-con had a greater proportion calved by day 14 and 21 (p < 0.01) compared to FTAI-sexed. In conclusion, reproductive technologies altered the calving distribution with more calves born earlier.
Zoca et al. (Fri,) studied this question.