High production costs and falling commodity prices over the past four years are forcing more and more dairy farmers out of business in Iowa and other dairy states, according to agribusiness experts and farm groups.The global flood of milk has depressed prices to about half what they were in 2014, and they still haven't hit all-time lows. But U.S. production has continued to increase despite the large number of dairy cows being culled from herds, said University of Wisconsin-Madison dairy policy analyst Mark Stephenson."The catastrophe is that we're still producing more milk month after month after month," Stephenson said, adding that the U.S. would need to see a significant increase in exports for dramatic improvement in prices.The proposed United States-Mexico-Canada trade agreement, which is expected to gain some dairy access in Canada, is not expected to change that. Regional leaders view the possible gains from the agreement "as too small and too far in the future to help (U.S.) dairy farmers," said the Chicago Federal Reserve Bank recently.