Every now and then a milk fever problem occurs in beef cattle that have been fed broiler litter.  This condition is caused by a calcium deficiency in the cow.  It is treatable with excellent success rates if the cow is found in a timely manner.  The general treatment is IV and/or subcutaneous administration of calcium gluconate, best done by a veterinarian.  In cows fed broiler litter over the winter feeding period, they are consuming enormous quantities of calcium from the litter, which causes their hormonal system to sequester the calcium into the bones.  Once the cow calves and has a large calcium demand for milk production her hormonal system cannot reverse fast enough so she becomes calcium deficient and exhibits milk fever.  It generally occurs in older cows (7+), that are quite productive (i.e., wean a heavy calf) and about 2 days to 2 weeks after calving.  The cow will be lying in cow fashion but her head will usually be turned back into her flank and she appears very listless and can't get up.  Some operations have fed litter for years with no milk fever problems, while some experience a few cases every year.  The only sure way to prevent it is to not feed litter.  Some management options to reduce the incidence are to fall calve, thus reduce or eliminate the amount of litter fed prior to calving and separate the older cows and feed them predominantly hay until they calve and then put them on litter.  Incorporation of various salts into the mix has shown limited benefit.  If you need further information please do not hesitate to contact me.