We went to a dystocia clinic put on by dr mortimer who teaches vets in colo.
Collectively, his students will be involved in --i think--20,000 births a spring---ojt deals with several big ranches.
He calls 'back feet first' presentation 'normal'--occuring in about 5%. 'Tail first' is true breech.
One tip i got, like when head first and leg back---is to use a toilet plunger to push calf back in, so you had more room to straighten leg out.
Another--from somewhere--is have a package of Crisco---you can get it in 1/4 # sticks, like margarine----for a cow that;s dried out----with some body heat and smearing around, it makes a pretty good "slickem"
Our rule is if no visible progress--and she is trying, stage 2---we'll give heifers 30 min, cows an hour.
Sometimes a guy feels like a dope--few yrs ago, i had a cow i'd thought several times was gonna calve, over a couple days---but never even saw a water bag----finally decided something was up---somehow the calfs mouth was way open, had tore up cow plum up to where it starts over pelvis, jaw was shattered, calf dead---and i'd never ever really seen her get serious and push. Now, any doubt, and i stick an arm in them---and if i reach in and feet are right there, it's coming out--i've lost far more calves by "give her another 30 min" than i have by intervening and moving on.