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    Re: [RC] Pasture - Lisa Redmond


    Claudia--
    
    The recommendation is the standard one for those who have no choice but to
    use endophyte infested pasture.  But, as you experienced, it's still not a
    fail-safe.  The problem is that the effects of the toxins on estrogen and
    progesterone are secondary--that is, they don't act directly on the tissues
    which produce those two hormones.  So it takes longer for those hormones to
    respond to the removal of the endophyte from the diet.  With the drug
    treatment, the response is much quicker.  My research showed an increase in
    progesterone and a decrease in estrogen within about 7 days on average.  The
    prolactin responds within 24 hours--not surprising, since the toxins act at
    the prolactin receptors in the pituitary gland.  Block the receptors, and
    you get prolactin release.  The estrogen response takes a little longer,
    because during mid-pregnancy the estrogen precursors are being produced by
    fetal ovaries or testicles.  Also, it's not so much the actual levels of
    progesterone and estrogen in the system as it is the ratio of one to the
    other.  Therefore, if for some reason the ratio isn't back to normal you may
    still experience problems like retained placentas.
    
    My first study with mares was to test the effects of withdrawal from the
    pasture on the mares, because they discovered by accident on the previous
    study that when they started removing mares from the infested pasture to try
    to stop the mare and foal deaths, the mares started developing udder tissue
    and making milk.  That led to my first mare project, and ultimately to the
    domperidone (Equidone) research. We did still have some retained placentas
    even on the controlled withdrawal study.  Also, when I did a dose study on
    the domperidone, when we started going higher that the initial dosage we
    started seeing more retained placentas--which led me back to the above
    conclusion, that it's the progesterone/estrogen ratios that cause those
    particular problems.  Now that I've had a few years to reflect on the work I
    did then, I wonder if maybe that might be some sort of rebound effect of
    removing the toxins from the mare's system, and a consequence of an altered
    growth curve for the foals in utero.
    
    You mentioned that the pasture was only 50% infected, and Bette just sent me
    a private email wondering about levels, so I'll address that here--it
    doesn't take much....a pasture doesn't have to be 100% infected to cause a
    problem.  However, once the drug becomes available commercially mare owners
    can start using those pastures again as long as the  mares are receiving the
    Equidone.  I know I did the research so I'm probably a little biased in
    favor of it, but if the herd manager and the project vet were impressed with
    the results of the drug, it has to be pretty close to a miracle
    drug--neither man is ever easily impressed by anything.
    
    
    
    
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    Replies
    RE: [RC] Pasture, Snodgrass, Bonnie
    Re: [RC] Pasture, Lisa Redmond
    Re: [RC] Pasture, Bette Lamore
    Re: [RC] Pasture, Lisa Redmond
    Re: [RC] Pasture, Claudia Provin