Effects of presynchronization and length of proestrus on fertility of grazing dairy cows subjected to a 5-day timed artificial insemination protocol

E. S. Ribeiro, A. P.A. Monteiro, F. S. Lima, H. Ayres, R. S. Bisinotto, M. Favoreto, L. F. Greco, R. S. Marsola, W. W. Thatcher, J. E.P. Santos

Research output: Contribution to journalArticle

Abstract

The objectives were to compare the effects of 2 methods of presynchronization and 2 lengths of proestrus on fertility of grazing dairy cows subjected to a 5-d timed artificial insemination (AI) protocol at initiation of breeding season. Lactating dairy cows (n=1,754) from 3 seasonal grazing farms were blocked within farm by breed, parity, and days in milk (DIM). Study d 0 was considered the day of AI of cows in COS72 (72h of proestrus). Within each block, cows were randomly assigned to 1 of 2 presynchronization treatments: a PGF-based program, Presynch, consisting of 2 injections of PGF administered on d -32 and -18, or a PGF-GnRH-based program, Double-Ovsynch (DO), consisting of GnRH on d -25, PGF on d -18, and GnRH on d -15. Within each of the 2 presynchronization treatments, cows were randomly assigned to 1 of 2 lengths of proestrus within the 5-d timed AI protocol, consisting of GnRH on d -8, PGF on d -3 and -2, and GnRH+AI at either 58h (COS58) or 72h (COS72) after the d -3 PGF injection. Ovaries were scanned by ultrasonography twice, on d -42 and -32, to determine estrous cyclicity before enrollment in the study. Blood was sampled and analyzed for concentrations of estradiol on the day of AI. Pregnancies per AI (P/AI) were determined 30 and 65 d after AI. Presynchronization did not affect the concentration of estradiol at AI (DO=6.4 vs. Presynch=5.8pg/mL), detection of estrus at AI (20.8 vs. 25.9%), or P/AI on d 30 (56.8 vs. 59.1%) and 65 (52.5 vs. 52.4%) after the first AI. Cows receiving COS72 had increased concentration of estradiol (6.6 vs. 5.5pg/mL) and detection of estrus at AI (28.5 vs. 10.8%) compared with cows receiving COS58. Length of proestrus did not affect P/AI on d 30 (COS72=58.7 vs. COS58=56.1%) but, in Presynch cows, COS58 was detrimental to fertility on d 65 after AI (54.9 vs. 46.5%). Pregnancy loss between gestational d 30 and 65 was greater for Presynch than for DO (7.6 vs. 11.3%), but it was not affected by length of proestrus. Estrous cyclic cows had greater P/AI than anovular cows on d 30 (61.7 vs. 35.1%) and 65 (56.1 vs. 30.7%), but no interaction between estrous cyclic status and treatments was detected. Crossbred Holstein/Jersey cows had superior fertility than their purebred counterparts during the breeding season. The Presynch and DO protocols resulted in similar fertility with no overall difference between the presynchronization methods; however, limiting the length of proestrus to 58h reduced P/AI in the 5-d timed AI protocol when cows had their estrous cycle presynchronized with Presynch but not with DO.

Original languageEnglish (US)
Pages (from-to)2513-2522
Number of pages10
JournalJournal of Dairy Science
Volume95
Issue number5
DOIs
StatePublished - May 1 2012

Keywords

  • 5-day timed artificial insemination
  • Grazing dairy cow
  • Presynchronization
  • Proestrus

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

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    Ribeiro, E. S., Monteiro, A. P. A., Lima, F. S., Ayres, H., Bisinotto, R. S., Favoreto, M., Greco, L. F., Marsola, R. S., Thatcher, W. W., & Santos, J. E. P. (2012). Effects of presynchronization and length of proestrus on fertility of grazing dairy cows subjected to a 5-day timed artificial insemination protocol. Journal of Dairy Science, 95(5), 2513-2522. https://doi.org/10.3168/jds.2011-4921