a b s t r a c tProstaglandin F2a (PGF) treatment is routinely used in the reproductive management of mares to induce luteolysis and allow a subsequent return to estrus. The objective of this retrospective study was to assess the effect of follicle size at the time of administration of cloprostenol on interval to subsequent ovulation. A secondary objective was to determine the incidence of hemorrhagic anovulatory follicle (HAF) formation after PGF administration. Reproductive records of 275 mares monitored over a total of 520 estrous cycles were evaluated. All mares received a single intramuscular dose of 250 mg of the synthetic PGF analog cloprostenol sodium between days 5 and 12 after ovulation. The average interval from PGF to ovulation was 8.4 AE 2.5 days. The interval from PGF administration to subsequent ovulation was inversely proportional to the diameter of the largest follicle at the time of treatment. Administration of cloprostenol to mares with a large (!35 mm in diameter) diestrous follicle resulted in one of three outcomesdovulation within 48 hours (13.4%) with variable uterine edema, ovulation after 48 hours usually accompanied by the presence of uterine edema (73.1%), or regression without ovulation followed by emergence and eventual ovulation of a new dominant follicle (13.4%). There was no effect of mare age or season on interval from PGF to ovulation. The overall incidence of HAF development after PGF administration in this study was low (2.5%).

Groundwater dynamics play an important role in runoff generation and hydrologic connectivity between hillslopes and streams. We monitored a network of 14 shallow groundwater (GW)

Hydrogeophysical surveys were carried out in a 3.2km2 Scottish catchment where previous isotope studies inferred significant groundwater storage that makes important contributions to streamflow.We used electrical resistivity tomography (ERT) to characterise the architecture of glacial drifts and make an approximation of catchment-scale storage. Four ERT lines (360-535m in length) revealed extensive 5-10m deep drift cover on steeper slopes, which extends up to 20-40m in valley bottom areas. Assuming low clay fractions, we interpret variable resistivity as correlating with variations in porosity and water content. Using Archie's Law as a first approximation, we compute likely bounds for storage along the ERT transects. Areas of highest groundwater storage occur in valley bottom peat soils (up to 4m deep) and underlying drift where up to 10,000mm of precipitation equivalent may be stored. This is consistent with groundwater levels which indicate saturation to within 0.2m of the surface. However, significant slow groundwater flow paths occur in the shallower drifts on steeper hillslopes, where point storage varies between ~1,000mm-5,000mm. These fluxes maintain saturated conditions in the valley bottom and are recharged from drift-free areas on the catchment interfluves. The surveys indicate that catchment scale storage is >2,000mm which is consistent with tracer-based estimates.

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