concurring: The petitioner has sustained his burden of proof on the issues raised and the case should not be decided upon reasoning which was not the basis for the Commissioner’s determination and was not timely injected into the case. However, the result might be different if the point had been made that the petitioner’s business was essentially that of selling high-grade Guernseys for profit and his dairy business was subordinate. The fact that young animals were retained for substantial periods of time as a part of the herd might not be determinative of that issue. The largest returns were from sales. The dairy paid a much smaller part of the expenses, but it no doubt demonstrated the quality of the animals and made them more attractive to possible purchasers. It is obvious that the petitioner always intended to sell most of the animals retained, and it is conceivable that his purpose in retaining many of them was to sell them at prices based upon the distinction that they had been members of his outstanding herd.