I just analyzed this herd for another consultant.  On July 25 they switched from a Pioneer BMR to a Mycogen TMF corn silage. Fat came down a little but the preformed fatty acids significantly increased suggesting they are loosing body weight.  The mixed fatty acids went down without a change in de novo presumably to make room in the triglycerides for the high level of C18.  These data was from AgriMark which means we have milk fatty acids on every bulk tank.  Overall, I think there is a CLA effect in this herd as the de novo’s are low but the milk protein is in reasonable shape.