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dc.contributor.authorMaicas, C.
dc.contributor.authorHutchinson, Ian A.
dc.contributor.authorKenneally, Jonathon
dc.contributor.authorGrant, Jim
dc.contributor.authorCromie, A. R.
dc.contributor.authorLonergan, P.
dc.contributor.authorButler, Stephen T.
dc.identifier.citationMaicas, C., Hutchinson, I., Kenneally, J., Grant, J., Cromie, A., Lonergan, P. and Butler, S. Fertility of fresh and frozen sex-sorted semen in dairy cows and heifers in seasonal-calving pasture-based herds. Journal of Dairy Science. 2019, 102 (11), 10530-10542, doi:
dc.description.abstractOur objective in this study was to evaluate the reproductive performance of dairy heifers and cows inseminated with fresh or frozen sex-sorted semen (SS) in seasonal-calving pasture-based dairy herds. Ejaculates of 10 Holstein-Friesian bulls were split and processed to provide (1) fresh conventional semen at 3 × 106 sperm per straw (CONV); (2) fresh SS at 1 × 106 sperm per straw (SS-1M); (3) fresh SS semen at 2 × 106 sperm per straw (SS-2M); and (4) frozen SS at 2 × 106 sperm per straw (SS-FRZ). Generalized linear mixed models were used to evaluate the effect of semen treatment and other explanatory variables on pregnancy per artificial insemination (P/AI) in heifers (n = 3,214) and lactating cows (n = 5,457). In heifers, P/AI was greater for inseminations with CONV (60.9%) than with SS-FRZ (52.8%) but did not differ from SS-1M (54.2%) or SS-2M (53.5%). Cows inseminated with CONV had greater P/AI (48.0%) than cows inseminated with SS, irrespective of treatment (SS-1M, SS-2M, and S-FROZEN; 37.6, 38.9, and 40.6%, respectively). None of the SS treatments differed from each other with regard to P/AI in either heifers or cows. The relative performance of SS compared with CONV was also examined [i.e., relative P/AI = (SS P/AI)/(CONV P/AI) × 100]. Frozen SS achieved relative P/AI >84%. Bull affected P/AI in both heifers and cows, but no bull by semen treatment interaction was observed. In heifers, P/AI increased with increasing Predicted Transmitting Ability for milk protein percentage. In cows, P/AI increased with increasing Economic Breeding Index (EBI) and with days in milk (DIM) at AI but decreased with increasing EBI milk subindex, parity and with DIM2. Cows in parity ≥5 had the lowest P/AI and differed from cows in parities 1, 2, or 3. Dispatch-to-AI interval of fresh semen did not affect P/AI in lactating cows, but a dispatch-to-AI interval by bull interaction was detected whereby P/AI was constant for most bulls but increased with greater dispatch-to-AI intervals for 2 bulls. In conclusion, frozen SS achieved greater P/AI relative to conventional semen than was previously reported in lactating cows. Fresh SS did not achieve greater P/AI than frozen SS, regardless of whether the sperm dose per straw was 1 × 106 or 2 × 106. A bull effect for all semen treatments, as well as a dispatch-to-AI interval by bull interaction for fresh semen, highlights the importance of using a large team of bulls for breeding management.en_US
dc.relation.ispartofseriesJournal of Dairy Science;
dc.rightsAttribution-NonCommercial-ShareAlike 3.0 United States*
dc.subjectsexed semenen_US
dc.subjectpasture-based systemen_US
dc.titleFertility of fresh and frozen sex-sorted semen in dairy cows and heifers in seasonal-calving pasture-based herdsen_US
dc.contributor.sponsorTeagasc Walsh Fellowship programmeen_US
dc.contributor.sponsorTeagasc postdoctoral fellowshipen_US
dc.contributor.sponsorDovea Geneticsen_US
dc.contributor.sponsorMunster AIen_US
dc.contributor.sponsorProgressive Geneticsen_US
dc.contributor.sponsorNational Cattle Breeding Centreen_US
dc.contributor.sponsorABP Food Groupen_US
dc.contributor.sponsorDawn Meatsen_US
dc.contributor.sponsorSlaney Linden Foodsen_US
dc.contributor.sponsorIrish Farmers Journalen_US
dc.contributor.sponsorIrish Cattle Breeding Federationen_US

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