| Autor: |
Masello M; Department of Animal Science, Cornell University, Ithaca, NY 14853., Perez MM; Department of Animal Science, Cornell University, Ithaca, NY 14853., Granados GE; Department of Animal Science, Cornell University, Ithaca, NY 14853., Stangaferro ML; Department of Animal Science, Cornell University, Ithaca, NY 14853., Ceglowski B; Dairy Health and Management Services, Lowville, NY 13367., Thomas MJ; Dairy Health and Management Services, Lowville, NY 13367., Giordano JO; Department of Animal Science, Cornell University, Ithaca, NY 14853. Electronic address: jog25@cornell.edu. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of dairy science [J Dairy Sci] 2019 Feb; Vol. 102 (2), pp. 1671-1681. Date of Electronic Publication: 2018 Dec 24. |
| DOI: |
10.3168/jds.2018-15200 |
| Abstrakt: |
Our objective was to compare the insemination dynamics and time to pregnancy for up to 100 d after the beginning of the artificial insemination period (AIP) for heifers managed with first artificial insemination (AI) service programs that relied primarily on insemination at detected estrus (AIE) after PGF 2α treatments, timed artificial insemination (TAI), or a combination of both. Holstein heifers were randomly assigned to receive first AI service with sex-selected semen after 368 ± 10 d of age with (1) AIE after synchronization of estrus with up to 3 PGF 2α treatments every 14 d starting on the first day of the AIP (PGF+AIE; n = 317). Heifers not AIE up to 9 d after the third PGF 2α received a 5-d Cosynch protocol with progesterone supplementation [GnRH + controlled internal drug release insert (CIDR)-5 d-CIDR removal and PGF 2α -3 d-GnRH and TAI] before TAI. Heifers detected in estrus from CIDR removal and PGF 2α until the day before TAI received AIE with no GnRH treatment; (2) 2 PGF 2α treatments 14 d apart with the second treatment at the beginning of the AIP (PGF+TAI; n = 334). Heifers received AIE for up to 9 d after the second PGF 2α treatment. Heifers not AIE received TAI after the 5-d Cosynch protocol and (3) TAI after the 5-d Cosynch protocol (ALL-TAI; n = 315). Heifers failing to conceive to a previous AI received a subsequent AI with conventional semen at detected estrus or TAI after the 5-d Cosynch protocol. Binomial outcomes were analyzed by logistic regression, whereas time to AI and pregnancy were analyzed with Cox's regression. The hazard of first AI up to 45 d of the AIP was greater for ALL-TAI than for PGF+AIE [hazard ratio (HR) = 1.72; 95% confidence interval (CI) =1.45 to 2.03] and PGF+TAI (HR = 1.51; 95% CI = 1.28 to 1.77), but similar for PGF+AIE and PGF+TAI (HR = 1.14; 95% CI = 0.97 to 1.33). A greater proportion of heifers received AIE in PGF+AIE (98.7%) than in PGF+TAI (78.5%). Overall, first service pregnancy per AI did not differ (PGF+AIE = 42.0%; PGF+TAI = 47.3%, ALL-TAI = 43.8%). Time to pregnancy was reduced for ALL-TAI compared with PGF+AIE (HR = 1.20, 95% CI = 1.02 to 1.42), but was similar to that of PGF+TAI (HR = 1.13, 95% CI = 0.96 to 1.33). Time to pregnancy did not differ for PGF+AIE and PGF+TAI (HR = 1.07, 95% CI = 0.91 to 1.25). Median days to pregnancy were 27, 23, and 21 for heifers in PGF+AIE, PGF+TAI, and ALL-TAI, respectively. We concluded that an ALL-TAI program for first service reduced time to pregnancy, albeit a relatively small reduction, when compared with a program that relied primarily on AIE after induction of estrus with PGF 2α treatments. The program that combined synchronization of estrus and TAI (PGF+TAI) resulted in similar time to pregnancy than the predominant TAI and predominant AIE programs.
(Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.) |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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