This is the second calf born under 40lbs. Actually one is a Set Me Free X Unstoppable calf that weighed 35 lb. The other is a I-80 X Jake's Proud Jazz calf weighing 39 lb. All of the other calves this spring have been around 70-100 lb. Mothers are fat, been out on grass the last month of pregnancy. Vaccinated annually. mineral blocks year round. Never had this before. The Unstoppable cow above had a first calf (Jesse James) that weighed 60 lb. The Jake's Proud Jazz was a first timer. Any ideas of what is going on. the calves are alive, vibrant, running, eating, just look like little fawns.