Dairy farmers are practically swimming in excess milk, and their problem is multiplying by the day.

In 2006, farmers turned to a new method of sorting the sperm of bulls so they would produce more profitable milk-producing female offspring. At the time, global milk demand was outpacing supply.

The cutting edge technology, which relies on size differences between the X and Y chromosomes, should have been a boon to farmers. However, the first wave of cows bred using the gender selection technology has entered milking herds across America just as milk prices plunged, forcing dairy farmers to sell their milk below production cost.

Though retail prices have only dropped 24 percent in a year, wholesale prices went from an average of $19.30 per 100 pounds in July 2008 to $11.30 in July 2009. The National Milk Producers Federation has resorted to paying farmers to send herds to slaughter to drive up prices, culling 230,000 cows since January.

But even that mass slaughter won’t reduce the impact to the industry as the heifers produced with the sorting technique continue to reach breeding age. 63,000 extra dairy cows will be put into milk production this year, and that number will increase to 161,000 next year and possibly double again in 2011.

“Just as the industry starts to recover from these difficult times, we’re going to see these heifers enter the marketplace,” Ray Souza, president of Western United Dairymen, told the New York Times.

Experts say that in the long run, the technology should bring the extra profits that dairy farmers had hoped for, but recovery may be slow.

While that may be bad news to dairy farmers, the success of the sorting method also means that parents wishing to select the sex of their human offspring may be one step closer to having that choice. A fertility institute in Washington is studying whether the technique can be used safely in people, though it will then have to win approval from the FDA.