I know nothing about lentil hay, but have noticed with our family milk cow, that she gives less milk when fed high quality alfalfa then she does when given course feeds such as timothy grass mix bales. Since she is fed along with the beef cows, I kind of use her as a test subject for how my rations are working out in general. Cows need roughages to slow the progression of the food through their digestive tract to get the full benefit out of it.
