Lack of effects of an equine chorionic gonadotropin (eCG) administration between days 9 and 15 postpartum on reproductive performance in a Holstein dairy herd
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Media type:
E-Article
Title:
Lack of effects of an equine chorionic gonadotropin (eCG) administration between days 9 and 15 postpartum on reproductive performance in a Holstein dairy herd
Description:
<jats:title>Contents</jats:title><jats:p>Recently, it has been demonstrated that administration of equine chorionic gonadotropin (<jats:styled-content style="fixed-case">eCG</jats:styled-content>) in the postpartum period in dairy cows can enhance follicle growth, reduce the interval from calving to first ovulation and increase plasma estradiol concentrations, and, thus, could enhance reproductive performance in a dairy herd when administered on day 6 postpartum. The aim of this study was to investigate the effects of a single dose of <jats:styled-content style="fixed-case">eCG</jats:styled-content> between days 9 and 15 postpartum on parameters of reproductive performance in dairy cows. German Holstein cows (<jats:italic>n</jats:italic> = 1937; primiparous cows: <jats:italic>n</jats:italic> = 748; pluriparous cows: <jats:italic>n</jats:italic> = 1189) in a commercial dairy farm were randomly assigned to three experimental groups. Animals within the group <jats:styled-content style="fixed-case">eCG</jats:styled-content> received a single dose of 600 <jats:styled-content style="fixed-case">IU eCG</jats:styled-content> intramuscularly (i.m.) between days 9 and 15 postpartum followed by an i.m. administration of 500 μg cloprostenol after 14 days. Those of treatment group <jats:styled-content style="fixed-case">PG</jats:styled-content> received cloprostenol only between days 23 and 29 postpartum. Cows of the control group remained untreated. Starting on day 49 postpartum, cows were subjected to a Presynch‐Ovsynch protocol and inseminated artificially. The impact of application time (days postpartum) of <jats:styled-content style="fixed-case">eCG</jats:styled-content> on the intervals calving to first service and calving to conception was statistically not significant. Outcomes of reproductive performance (i.e. first service conception rate, proportion of pregnant cows until 100 and 150 days in milk [<jats:styled-content style="fixed-case">DIM</jats:styled-content>], number of inseminations until 150 <jats:styled-content style="fixed-case">DIM</jats:styled-content>, calving to first service interval and calving to conception interval) did not differ significantly between treatment group <jats:styled-content style="fixed-case">eCG</jats:styled-content> and group <jats:styled-content style="fixed-case">PG</jats:styled-content> compared to control group. Regarding postpartum <jats:styled-content style="fixed-case">eCG</jats:styled-content> administration, significant interactions between treatment and parity, season, milk yield, and early puerperal disorders, respectively, could not be shown. In conclusion, an <jats:styled-content style="fixed-case">eCG</jats:styled-content> treatment of dairy cows between days 9 and 15 postpartum to increase reproductive performance cannot be recommended under the given circumstances.</jats:p>