Forage only is great, if you have the right climate, soil, grass, stocking rate, and cattle - but in many instances, if you don't have that perfect combination, eschewing all supplementation can put you and your animals in a bad situation.
A very true statement. Being from KY it would be hard to develope bulls on fescue based pastures without some form of supplementation. Other forages can be grown to develope bulls on a forage based diet, but with summers here that are so unpredictable as far as moisture is concerned, I elect not to try. Bulls here are weaned (March) and are put on the best pasture with a 13% protein grower ration (For those in KY-TN familiar with CPC Commodities, Grower 13% LS) that is high in fiber, low in energy (No corn) but gives supplemental protein for the fescue during the summer months. Bulls have access to this until the first week og September when they are then scanned. The rest of the fall/winter they are fed free choice hay and about 4-5 pounds of the same mixture. Bulls are then offered the following spring at about 17-19 months of age and they are in good condition, not fat but in good condition where they do not need to be "Let down" before turning out. Been doing this for several years now with the fall calving herd and seems to be working fine. Funny though, when talking to some cattlemen, most will say they like that sort of developement plan, however, will then and go purchase the fattest, poor moving bull in a sale.....Have always been told that fat sells. Pretty much true I guess, but I will not feed them that hard.