Increased Pregnancy Rates of Gender-Sorted Semen Confirmed

Back in time, the biggest objection to using gender-sorted semen was the comparison of higher pregnancy rates with conventional semen. It is well known from field results that sorting technology has evolved, proving its repeatable accuracy rates over gender. Now, recent field results also show that gender-sorted semen significantly improved its pregnancy rates, proven in a reproducible way in different systems around the world.

A new study has compared the major results of gender-sorted semen pregnancy rates on Irish dairy farms from 2013 to its most recent performance in 2022, including a wide range of A.I. services (Agriland, 2023). The statistical analysis indicated that pregnancy rate for gender-sorted semen in 2022 is at 60%, compared to the standard conventional A.I., which is at 63%. This indicates a relative pregnancy rate of gender-sorted semen that is 95% closer to the target rates of conventional semen.

This independent commercial field study, undertaken by ICBF, Teagasc and the partner A.I. companies (i.e., Dovea A.I., Eurogene/A.I. Services, Munster Bovine and Progressive Genetics), also showed that gender-sorted semen increased overall performance by >10% relative points, rising from 84% in 2013 to 95% in 2022 (Read Ultraplus launch Media Release).

The period of significant improvements shown in this study overlaps with the commercial availability of 4M™ and posteriorly Ultraplus™ (2022) semen, reflecting the effect of these technologies on field results for pregnancy rates. In addition to better conception, it is well established that gender-sorted semen has also shown high gender accuracy, producing more female calves to generate the expected cost-benefit ratio for farms using this technology.

The analysis was based on over 1.83M conventional inseminations and 86K gender-sorted semen inseminations completed over a 5-year period (2017 to 2022) and is the most comprehensive analysis of the performance of gender-sorted semen in a commercial field setting ever undertaken. All inseminations were completed by A.I. technicians from the partner A.I. companies and within a time frame that allowed them to be validated against a subsequent birth event. Statistical analysis was undertaken of the field data, with important factors such as year, herd, parity, days in milk and cow genetic merit all accounted for in the model. Results from the study are given in Table 1 below.

Table 1. Summary performance of gender-sorted versus conventional semen on Irish dairy farms.

Whilst the results indicate a relative performance over the 5-year period of 92%, they also highlight further improvements in the technology based on 2022 inseminations only (at 95% relative performance). Indeed, this positive time trend is evident within the overall dataset, which highlights the ongoing improvements that there have been in the technology over the past 5 years.

Another important outcome from the analysis is that when just the phenotypic pregnancy rate is observed, there is no difference in the gender-sorted semen product compared to conventional A.I., with both having the same pregnancy rate. However, this is related to the fact that gender-sorted semen is being used selectively on heifers and cows, with adherence to the strict protocols being promoted by Teagasc and the partner A.I. companies, e.g., only use on cows that are breeding naturally, in good condition, with sufficient days calved etc. As a result, the phenotypic pregnancy rates for the gender-sorted semen is biased upwards, with this bias then getting accounted for in the subsequent statistical analysis.

Commenting on the analysis, Dr. Margaret Kelleher, ICBF (who undertook the overall analysis) noted that the results were an important outcome for dairy farmers using (or planning to use) the gender-sorted semen product this Spring. “In the past, the relative performance of gender-sorted semen compared to conventional was seen as a big barrier to its potential usage by Irish farmers. The fact that the relative performance is now 92% and improving, should hopefully encourage more dairy farmers to consider using the product in their breeding programs this Spring.”

Dr. Stephen Butler, Teagasc, echoed these comments noting that it was a fantastic endorsement of the collaborative nature of the Irish cattle breeding industry, that this sort of comprehensive analysis could be undertaken. He looked forward to the continued roll-out of the technology, in line with additional lab capacity, further improvement in the technology and also further extension work in the field, promoting the use of the technology.

Commenting on the results, Dr. Bernard Eivers, who represents the A.I. industry on the DAFM dairy calf working group, noted that whilst the results were positive, it was critical that dairy farmers do not get complacent about the technology. Eivers says, “Yes, the results are good, but as an industry, we need to continue to ensure that the technology gets applied correctly on farms, otherwise there will be disappointments.” That said, he encouraged those dairy farmers that have not yet tried the technology to consider it this breeding season. “Our experience is that dairy farmers starting with the technology generally will try 10-15 straws, depending on their herd size and we would encourage more farmers to adopt this approach this breeding season,” he adds.

Dr. Andrew Cromie, GM for Sexing Technologies Europe thanked Margaret, Stephen and the partner A.I. companies for undertaking the seminal piece of work. “The analysis is a defining piece of work for the continued roll-out of the technology on Irish dairy farms,” Cromie notes. “The fact that dairy farmers can now have access to a technology that will help them address future challenges regarding dairy male calves, with limited impact on dairy herd fertility is a significant step forward.” He looks forward to continuing to work with ICBF, Teagasc and the partner A.I. companies in the further roll-out of the technology across more dairy farms, including also the opportunities to look at gender-sorted beef semen and also the use of gender-sorted semen through future fresh semen services.