Sorry, I call BS. How would hitting a cow on the runway cause it to overrun? Even if it hit the MLG and took out brakes on one side it the 73 should still stop fine. Does it seem odd to anyone that the pilot involved is making statements this early? Arse covering by Lion air for sure!
Wait for the report, blah blah but I reckon we'll find that the overrun was caused by something else and the cows were grazing off the end of the runway and were hit by the plane then.