|dc.contributor.advisor||Externe beoordelaar - External assesor,||
|dc.contributor.author||Drie, Iris van||
|dc.description.abstract||Background: Nutrient modelling of Thoroughbred mares managed under commercial management
conditions has identified a potential negative energy balance later in the breeding season that could
extend the interval from parturition to conception. Anecdotally, Standardbred mares are believed to
have a greater feed conversion efficiency than Thoroughbred mares and are managed with lower levels
of feed (pasture DM on offer) during breeding season. At present, there is no published data on the
association between foaling date and delayed conception in Standardbred mares.
Objective: To investigate the association between increased foaling date (days after August 1) and
delayed conception in a cohort of New Zealand Standardbred mares.
Methods: Official breeding records were collected from 558 Standardbred broodmares managed on
two farms during the seasons 2016-2017 and 2018-2019 breeding seasons. Horse and breeding record
data were obtained as an electronic extract from HRNZ. These records were collated and summarized
in Microsoft Excel. Data were examined using simple descriptive statistics and then examined
according to mare age, breeding status and foaling date. Pasture growth (kg DM/ha/day) were
obtained from official records. Kaplan Meier Survival curves were used to examine the interval from
parturition to conception, with and without mares that carried over.
Results: The mean foaling date was ~4 November for mares inseminated as dry mares and 14
November in wet mares. The mean conception date of the Standardbred mares was 27 November in
dry mares and 13 December in wet mares. Mares that foaled earlier in season had the longest interval
between foaling and conception, smallest percentage of mares bred on foal heat and smallest
percentage of mares that carried over. The group of mares that foaled latest in season had the shortest
interval, greatest percentage of mares bred on foal heat and greatest percentage of mares that carried
over. Stocking density was relatively low and pasture growth was mostly sufficient during the year.
Conclusion: Foaling late in the season was not associated with a delay in conception in Standardbred
mares. These findings indicate that they did not experience a negative energy balance. Further
research is required to investigate to what extent farm management influences mare reproductivity.||
|dc.subject||Master thesis: The association between an increase in foaling date
and delayed conception in a cohort of New Zealand Standardbred
|dc.title||Delayed conception in standardbred mares||
|dc.subject.keywords||Standardbred; mare; delayed; conception; New Zealand; interval; foaling||
|dc.subject.courseuu||Gezondheidszorg landbouwhuisdieren en vet. volksgezondheid||