keep the donors on the hungry side, when i first started flushing alot of cows about 2 years ago, i let my donors eat and eat, got them on the big side. The Vet told me to back them off, put them on stalks or summer pasteur and make them work for their meals, and my egg results when up in a hurry. For the Recipts I always use something with a lot of copper in it. Kansas State Uniersity has a lot of trials on their website that shows 75% of all cattle don't have proper copper levels, and copper has been traced to reproduction. Results this year where great for me, 83% conception rate on recipts. It helps in my opinion.