Right.
I guess an easy explanation is that it used to be, when you sold the cull cow, that the cow would pay to feed the heifer to become a cow. But when you face a cash crunch temporarily in the cattle industry, you sell what you have to in order to pay the bills.
So what guys have done is they've sold the younger cattle. A heifer calf may have been worth $500, but the cow is now worth $150 or whatever. That's why the cow herds have gotten older.