There's such a thing as  'easy keepers'  and  some that  aren't! 
 You apparently have selected appropriately.   
After a snow,   driving  past thousands of  cows headed towards town,  you can plainly see who's are, and who's aren't. 
The easy keepers are the last to melt snow off their back.   Nice and insulated from  the  backfat and  haircoat.