Effect of interval between induction of ovulation and artificial insemination (AI) and supplemental progesterone for resynchronization on fertility of dairy cows subjected to a 5-d timed AI program》.pdf

J. Dairy Sci. 93 :5798–5808 doi:10.3168/jds.2010-3516 © American Dairy Science Association® , 2010. Effect of interval between induction of ovulation and artificial insemination (AI) and supplemental progesterone for resynchronization on fertility of dairy cows subjected to a 5-d timed AI program R. S. Bisinotto,* E. S. Ribeiro,* L. T. Martins,* R. S. Marsola,* L. F. Greco,* M. G. Favoreto,* C. A. Risco,† W. W. Thatcher,* and J. E. P. Santos *1 *Department of Animal Sciences, University of Florida, Gainesville 32611 †College of Veterinary Medicine, University of Florida, Gainesville 32610 ABSTRACT cows supplemented with progesterone had greater P/AI compared with unsupplemented cows (51.3 vs. 43.1%). Objectives were to investigate 2 intervals from induc- Premature ovulation tended to be greater for RCON tion of ovulation to artificial insemination (AI) and the than RCIDR cows (7.5 vs. 3.6%), although synchroni- effect of supplemental progesterone for resynchroniza- zation of the estrous cycle after timed AI was similar tion on fertility of lactating dairy cows subjected to a between treatments. Timing of induction of ovulation 5-d timed AI program. In experiment 1, 1,227 Holstein with GnRH relative to insemination did not affect P/ cows had their estrous cycles presynchronized with 2 AI of dairy cows enrolled in a 5-d timed AI program. injections of PGF2α at 46 and 60 d in milk (DIM). Furthermore, during resynchronization starting on d 34 The timed AI protocols were initiated with GnRH at after the first AI, supplementation with progesterone 72 DIM, followed by 2 injections of PGF2α at 77 and improved P/AI in cows subjected to the 5-d timed AI 78 DIM a