Jerry Rosman, a pig farmer in Iowa, was cultivating GMO corn,(Roundup Ready and BT) and fed this corn to his pigs. Result: his sows became infertile, and then after one year he went bankrupt. See the whole interview here:


Is it an incident isolated to Iowa ? Check this article from Greenpeace.
"Austrian scientists fed mice over a course of 20 weeks a mixture of 33 percent Monsanto GE corn (NK 603 x MON 810) and non-GE corn. These mice gave birth to less babies and lighter babies in their third and fourth litters. Mice fed on non-GE corn had babies as normal. These differences are statistically significant."
To have a more global idea on the issue and the relation between GMOs and sterilisation, please read the book Seeds of Destruction: The Hidden Agenda of Genetic Manipulation