I hasten to add that the decline in the U.S. has been more severe over a longer time. As this Congressional Research Service report summarizes:
"Increased dairy cow output and advances in dairy farm technology and management have led to a sharp reduction in the number of dairy farms (Figure 3). Annual losses averaged 96,000 operations in the late 1960s and 37,000 in the 1970s. In recent years, the annual drop in dairy farm operations has slowed to about 2,000 to 5,000 farms per year. Operations totaled 65,000 on December 31, 2009."I've not really looked at the comparative size of the dairy farms in the two countries. In both there's been consolidation, but I don't have the data on how much and the productivity of cows. It's worth noting that in NZ the total number of cows has increased slightly; in the U.S. the number has decreased by a lot. The dairy industry in the U.S. sells in the domestic market while in NZ they export. I'm sure that makes a difference in discussing dairy support programs, but I don't know how.