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Reproductive efficiency in grazing lactating dairy cows under a programmed reproductive management system
Author(s) -
Cavestany D,
Betancour H,
Blanc JE,
Lemaire C,
Slavica J,
Moreira F,
Piaggio J,
Risco C
Publication year - 2007
Publication title -
australian veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.382
H-Index - 59
eISSN - 1751-0813
pISSN - 0005-0423
DOI - 10.1111/j.1751-0813.2006.00100.x
Subject(s) - artificial insemination , zoology , estrous cycle , insemination , seasonal breeder , pregnancy rate , grazing , pasture , pregnancy , biology , medicine , agronomy , ecology , genetics
Objective To evaluate the effectiveness of a reproductive management program consisting of combinations of Ovsynch/TAI and prostaglandin (PG) F 2α treatments in Holstein dairy cows under a pasture‐based dairying system. Design Field trial. Procedure A total of 1177 cows in 8 commercial dairy farms were randomly allocated to control and treatment groups. Treatment group cows received one of two interventions depending upon the number of days postpartum (DPP) before the planned start of breeding. Cows more than 50 DPP by the planned start of breeding received the Ovsynch/TAI treatment, consisting of gonadotrophin releasing hormone (GnRH) – PGF 2α – GnRH plus timed artificial insemination. Cows between 40 and 50 DPP received a PGF 2α treatment followed by oestrus detection and, if the cow was not seen in oestrus, the cow received a second PGF 2α 14 days later. Control cows were submitted to twice a day heat detection followed by artificial insemination. The experimental period was the start of the breeding season plus 21 days for cows over 50 DPP at the start of breeding, and was 40–61 DPP for cows that calved later and passed their voluntary waiting period after the start of the breeding season. Results Submission rate was higher for the treated group than for the control group (84.9% vs. 55.1%; P < 0.0001), as was the conception rate (51.0% vs. 46.1%; P < 0.03). Due to farm variations, pregnancy rate was similar in both groups (38.5% vs. 28.2%; P > 0.1). Within the treated group, conception rate and pregnancy rate of the cows inseminated after a PGF 2α were higher than for timed artificial inseminated cows (51.4% vs. 32.6%; P < 0.001), and (37.8% vs. 32.6%; P < 0.001). Conclusion A programmed reproductive management protocol may improve reproductive efficiency in dairy farms with seasonal breeding, by increasing submission and conception rates at the beginning of the breeding season and/or at the end of the voluntary waiting period. Fertility of cows bred after a PGF 2α synchronised heat was greater than after an Ovsynch/TAI protocol.