[Activity of serum gonadotropins in pregnant zebras and mares].

The research investigates the activity of serum gonadotropins in pregnant zebras and horses. The study found that while the hormone is active over different periods in the two species, it has a more significant effect in horses.

Research Methodology

• Blood was collected from 28 pregnant zebra mares in the Kruger National Park. The serum was separated and stored for later analysis.
• An additional thirteen selected samples were specifically tested for gonadotrophic activity. The pregnancy status was determined from a fetal growth curve.
• For comparison, blood samples from nine pregnant horse mares were collected. One mare contributed seven samples, another contributed four, and the remaining seven mares each contributed one sample. The stage of pregnancy in these cases was calculated from the date of last service.
• To estimate the levels of gonadotrophic activity in the serum samples, researchers examined the effect of the serum on the weight of mouse ovaries.
• Five groups of five virgin female white mice were injected with varying amounts of serum, and then their ovaries were weighed after a set period. This data was used to draw up a response curve.

Research Findings

• The research found that while the serum gonadotropin activity at various stages of pregnancy for horse and zebra mares were generally similar, there were also distinct differences.
• In horses, the activity was greater and occurred over a shorter period. The hormone disappeared by day 160 to 180 of pregnancy.
• In contrast, zebra mares showed a lower level of activity during the peak period (65th to 80th days), but the hormone could still be detected up to 229 days after conception. It was absent by 365 days.

Implications of the Study

• The activity of serum gonadotropins in pregnant mares can differ significantly between species, and understanding these differences could provide important insights into gestational processes in different equine species.
• The longer period of detectable activity in zebras suggests a slower and possibly more prolonged process of gestational development. This could have implications for conservation and breeding programs.