DES MOINES — Mike Naig led the five-man race to become Iowa Republicans’ nominee for state agriculture secretary, but results were incomplete by late Tuesday evening.And a winner may not be decided even after all the votes are counted.Naig, the current state ag secretary, led the Republican primary with just more than 35 percent of the vote, according to early results posted on the Iowa Secretary of State’s website just before 11 p.m.State senator Dan Zumbach was in second place at 22 percent, followed by former Iowa Farm Bureau leader Craig Lang at 18 percent and Ray Gaesser at 16 percent.