What does this research mean for the field?

The implementation of reproductive technologies, including estrous synchronization and artificial insemination, shifts calving distribution to result in more calves being born earlier in the season without altering overall breeding season pregnancy rates. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To evaluate the effects of reproductive technologies on pregnancy rates and calving distribution in beef herds.

May 17, 2026Open Access

A Comparison of Implementation of Synchronization, Artificial Insemination and Sex-Skewed Semen on Reproductive Performance and Calving Distribution in Beef Herds

Puntos clave

To evaluate the effects of reproductive technologies on pregnancy rates and calving distribution in beef herds.
Randomized trial involving 11 producers
Comparison of natural service, estrous synchronization, and artificial insemination
Assessment of pregnancy rates and calving timeline across different treatment levels.
No difference in overall pregnancy rates across treatments (p > 0.50)
Greater 21-day pregnancy rates for estrous synchronization compared to artificial insemination (p < 0.01)
Conventional semen resulted in better early calving rates compared to sex-skewed semen (p < 0.01).

Resumen

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.

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