Texas Roger has it correct with one exception.
Date of death stepped up cost basis applies to breeding stock and calves, the sale of cows and bulls (breeding stock) are reported on form 4797, part 1 (Long term capital gain, business property using DofD cost basis).
The sale of calves would be reported on schedule F as earned income, on line 1a,b,and c (calves purchased for resale) using DofD cost basis as your cost on 1b. This is assuming they are continuing the farm business themselves and will sell the calves at a later date than DofD.
