Summer grass

Question
Knowing that spring grass can be detrimental to horses if grazing is not monitored, my question is about Horses that are never stalled.  Mine are on pasture year round, but are supplemented with hay, as right now there are more weeds than grass.  I plan to get rid of the weeds, and plant grass in one pasture at a time  (I have two pastures), keeping the horses in one to give the newly planted pasture time to get in shape.  Then I plan to turn the horses onto the fresh pasture and then do the same process with the other pasture.  My question is this:  Is the limitation of spring grass for all horses, or just horses that are stalled?  Also, is it only spring grass, or, when the grass grows up during the summer, is there a problem as well?  I understand that the concentration of high carbohydrates is a problem with spring grass, but wondered if that lessens as spring turns to summer.

Answer
First, I apologize for the delay in answering -

Now, on to your questions - I too keep my horses on pasture 24/7/365 as much as possible.  In the spring, they are allowed to stay on the pasture as it grows, with no limitations.  

People tend to run into trouble when they wait to turn horses out on pasture in the spring until the pasture is full and lush - then don' limit the time at first.  The quick change in the type of feeding is what can cause problems.  Also, horses that are insulin resistant may have problems with the grass and the sugar/carbohydrate contents.  Lastly, I belive I have read the time of day can also play a part -early morning with dew for example - but I cannot confirm this myself.

I cannot give you very specific information on the affects of spring vs summer grass - however there are many on-line resources available if you do a little key word searching.  

If you do go from poor pasture to the new pasture, you may want to do it a bit gradually, remember the new pasture itself will take time to get established - you don't want it to be eaten al the way down before the grass has time to really establish roots, otherwise you may end up with bare patches and more weeds again.

I personally would let the new pasture get pretty well established, then turn out gradually - maybe a few hours the first few days, then during daytime (or night) for a few days, then if the pasture looks like it can take it, full turn out. This of course depends on the size of the pasture too.

Lisa