An evaluation of timing of AI with frozen sex-sorted semen in lactating dairy cows in pasture-based seasonal-calving herds

Authors

Evelyn Drake, Victoria Aublet, ShaunaA. Holden, Chloe Millar, Stephen G. Moore, ClioMaicas, Andrew R. Cromie, Federico Randi, Patrick Lonergan, Stephen T. Butler

Publication information

World Buiatric Congress 2022. Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co. Cork. School of Agriculture and Food Science, University College Dublin. Ceva Sante Animale, Libourne (France). Irish Cattle Breeding Federation.

OBJECTIVES

The objective was to use ovulation synchronization with a PRID-Ovsynchprotocol for timed artificial insemination (TAI), to evaluate the effect of timing of insemination (16 h or 22 h after the second GnRH) with frozen sex-sorted semen on fertility performance in pasture-based seasonal calving herds.

MATERIALS AND METHODS

Ejaculates from 3 different bulls were split and processed to provide frozen sex-sorted semen at 4×106 sperm per straw (SexedUltra-4M; SS) and frozen conventional semen at 15×106
spermper straw (CONV).
A modified PRID-Ovsynch protocol was used for estrous synchronization (Fig1).
TAI occurred 16 h after the second GnRH injection for cows assigned to CONV and 16 h sexed semen(SS-16) treatment, cows in (SS-22) received TAI with sexed semen 22 h following the
second GnRH injection.
Pregnancy diagnosis was conducted by ultrasound scanning 35-40 d after FTAI (n=2175records available for analysis).

Figure 1.

RESULTS

P/AI was greater for CONV compared to both SS-16 and SS-22 (Fig.2).
The relative P/AI for SS-16 and SS-22 vs. CONV were 81% and 84%, respectively.
There were significant bull and treatment by bull interaction effects.
The study identified a marked herd to herd variation (the relative P/AI for the combined SS treatments vs. CONV rangedfrom 50.9% to 116.8%).
The best third of herds achieved a mean relative P/AI of 101.5% (range=93.9% to 116.8%), indicating that P/AI equivalent to CONV is achievable with SS.
Conversely, the lower third of herds achieved a mean relative P/AI of 67.4% (range=50.9% to 76.9%).
Interestingly, the third of herds with the poorest relative P/AI had greater P/AI with CONV than the third of herds with the best relative P/AI, indicating a satisfactory response to the synchronization protocol on the induction of a fertile ovulation event in these herds.

CONCLUSIONS

The use of PRID-Ovsynch protocol for FTAI allowed for satisfactory P/AI varying between 60% for CONV to ~50% for SS.

Marked variation existed between herds ,however, with one third of herds achieving P/AI results equal to CONVENTIONAL

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