Here's a link to an article in BEEF. This will probably tell you all you ever wanted to know about pine needle abortion from a rancher's perspective
http://beefmagazine.com/mag/beef_needle_nightmare/
The year we had our wreck, my neighbor to the south's herd of 400 had an abortion/premature delivery rate of 30%, along with a good friend who lives in South Dakota with a herd of 700. The South Dakota rancher saved most of his premies since he lives at a much lower elevation, and underdeveloped lungs could still do the job.
Be glad you aren't familiar with pine needle problems!