Put Weight on Weanlings & Yearlings!!!

  The first thing to do when trying to optimize a feeding program is to get your hay tested.  I like to use www.equi-analytical.com because the testing is squewed towards horses and your local labs could be more geared to the cattle industry.  Make sure to include testing for lysine.  Testing will run about $30.  The testing will show any deficiencies you need  to supplement for as well as save money by not adding unnecessary ones.  To your hay lab results add the values for the oats and concentrates you also feed (figure out the #s).  Nutrients that are most important in weanlings and yearlings are calories, protein (lysine) Ca and P.  A growing horses needs the energy (calories) first.  Adequate levels of protein are important because the first limiting amino acid (lysine) is directly related to the quality and quantity of the protein source.  Ca and P exist in a sybiotic relationship and are necessary for bone formation amungst other things.  They are often refered to as a ratio, Ca.  You want atleast twice as much Ca as P (2:1) but you can go as high as 6:1 with no illeffects.
 
  Now back to the original question and the diet you provide, on the surface I'm going to say you lack in lysine and Ca right off the top.  Assuming you feed grass hay and oats, they lack in lysine and Ca.  You probably aren't feeding a significant amount of the 12% feed to really bump up the numbers.  Slow growth is also an indication of inadequate energy.  Do not add fats at this age as they do not provide the building blocks for a growing horse.  (think if it as feeding french fries to a 5 year old)  Do they have big baby bellies?  That's an indication of too high a fiber hay (mature) that their immature systems have trouble breaking down and digesting.  I would also be providing a freechoice vit/mineral supplement that complements your hay.  For grass hay, look for something around 20%Ca, 10%P and 100,000 IU vit A.
 
  The good news is when they grow slowly, you're not going to see OCD and other growth related diseases.  I'd rather see a smallish and slim yearling over one who's allready at his mature height and overweight with upright pasterns.