Hot topic: Comparison of sex-sorted and conventional semen within a fixed-time artificial insemination protocol designed for dairy heifers

• Published in: Journal of dairy science Vol. 96; no. 2; pp. 854 - 856
• Main Authors: Mallory, D.A., Lock, S.L., Woods, D.C., Poock, S.E., Patterson, D.J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.02.2013
• Subjects: Animals; artificial insemination; body weight; Cattle; controlled internal drug release devices; controlled internal drug release insert; dairy heifer; dairy heifers; Dairying - methods; estrus; Estrus Detection - methods; Estrus Synchronization - methods; Female; fixed-time artificial insemination; gonadotropin-releasing hormone; heat; Holstein; Insemination, Artificial - methods; Insemination, Artificial - veterinary; Male; Pregnancy; semen; Semen - metabolism; Sex Preselection - methods; Sex Preselection - veterinary; sex-sorted semen; sires; Time Factors; sex-sorted semen; fixed-time artificial insemination; controlled internal drug release insert; dairy heifer
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2012-5850

The objective was to compare pregnancy per AI (P/AI) with conventional (CON) or sex-sorted (SS) semen from a single sire within a fixed-time AI (FTAI) program designed for dairy heifers. Holstein heifers (n=240) were assigned to treatment (CON or SS) according to body weight and reproductive tract score. All heifers underwent FTAI by using the “Show-Me-Synch” protocol [controlled internal drug release (CIDR) insert from d 0 to 14 followed by PGF2α (25mg i.m.) 16d after insert removal (d 30) with GnRH (100µg i.m.) and FTAI at 66h after PGF2α]. A single professional technician performed the FTAI. Heifers were fitted with heat detection patches at PGF2α to characterize estrous response. Estrous response did not differ between CON (63/120; 53%) and SS (70/120; 58%) treatments. The CON heifers, however, achieved greater FTAI P/AI (82/120; 68%) compared with SS (45/120; 38%) heifers. The P/AI did not differ for CON heifers that exhibited or failed to exhibit estrus before FTAI [44/63 (70%) vs. 38/57(67%), respectively]. For SS heifers, however, those that exhibited estrus had greater P/AI compared with those that failed to exhibit estrus [32/70 (46%) vs. 13/50 (26%)]. Pregnancy per AI resulting from FTAI was greater for heifers that were inseminated with CON semen compared with those that received SS semen. The expression of estrus before FTAI did not affect P/AI when CON semen was used, whereas the P/AI with SS semen was greater for heifers detected in estrus. Further studies are required to develop strategies for using sex-sorted semen when inseminating heifers at predetermined fixed times on the basis of expression of estrus before FTAI.